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Author name code: berghmans
ADS astronomy entries on 2022-09-14
author:"Berghmans, David"
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Title: Two-Spacecraft Detection of Short-period Decayless Kink
Oscillations of Solar Coronal Loops
Authors: Zhong, Sihui; Nakariakov, Valery M.; Kolotkov, Dmitrii Y.;
Verbeeck, Cis; Berghmans, David
2022arXiv220901917Z Altcode:
Decayless kink oscillations of an ensemble of loops are captured
simultaneously by the High Resolution Imager (HRI) of the Extreme
Ultraviolet Imager (EUI) and the Atmospheric Imaging Assembly (AIA)
from 22:58 UT on 5 November to 00:27 UT on 6 November 2021. Oscillations
are analysed by processing image sequences taken by the two instruments
with a motion magnification technique. The analysed loops are around 51
Mm in length, and oscillate with short periods of 1-3 min (1.6 min in
average) and displacement amplitudes of 27-83 km. The signals recorded
by AIA are delayed by 66 s as compared to HRI, which coincides with
the light travel time difference from the Sun to each instrument. After
correction of this time difference, the cross-correlation coefficient
between the signals from the two data varies from 0.82 to 0.97,
indicating that they are well consistent. This work confirms that HRI
sees the same oscillations as AIA, which is the necessary first step
before proceeding to the detection of shorter time scales by EUI. In
addition, our results indicate the robustness of the de-jittering
procedure in the study of kink oscillations with HRI.
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Title: What drives decayless kink oscillations in active region
coronal loops on the Sun?
Authors: Mandal, Sudip; Chitta, Lakshmi P.; Antolin, Patrick; Peter,
Hardi; Solanki, Sami K.; Auchère, Frédéric; Berghmans, David;
Zhukov, Andrei N.; Teriaca, Luca; Cuadrado, Regina A.; Schühle,
Udo; Parenti, Susanna; Buchlin, Éric; Harra, Louise; Verbeeck, Cis;
Kraaikamp, Emil; Long, David M.; Rodriguez, Luciano; Pelouze, Gabriel;
Schwanitz, Conrad; Barczynski, Krzysztof; Smith, Phil J.
2022arXiv220904251M Altcode:
We study here the phenomena of decayless kink oscillations in a system
of active region (AR) coronal loops. Using high resolution observations
from two different instruments, namely the Extreme Ultraviolet Imager
(EUI) on board Solar Orbiter and the Atmospheric Imaging Assembly
(AIA) on board the Solar Dynamics Observatory, we follow these AR
loops for an hour each on three consecutive days. Our results show
significantly more resolved decayless waves in the higher-resolution
EUI data compared with the AIA data. Furthermore, the same system of
loops exhibits many of these decayless oscillations on Day-2, while on
Day-3, we detect very few oscillations and on Day-1, we find none at
all. Analysis of photospheric magnetic field data reveals that at most
times, these loops were rooted in sunspots, where supergranular flows
are generally absent. This suggests that supergranular flows, which
are often invoked as drivers of decayless waves, are not necessarily
driving such oscillations in our observations. Similarly, our findings
also cast doubt on other possible drivers of these waves, such as a
transient driver or mode conversion of longitudinal waves near the loop
footpoints. In conclusion, through our analysis we find that none of
the commonly suspected sources proposed to drive decayless oscillations
in active region loops seems to be operating in this event and hence,
the search for that elusive wave driver needs to continue.
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Title: Coronal mass ejection followed by a prominence eruption and
a plasma blob as observed by Solar Orbiter
Authors: Bemporad, A.; Andretta, V.; Susino, R.; Mancuso, S.; Spadaro,
D.; Mierla, M.; Berghmans, D.; D'Huys, E.; Zhukov, A. N.; Talpeanu,
D. -C.; Colaninno, R.; Hess, P.; Koza, J.; Jejčič, S.; Heinzel,
P.; Antonucci, E.; Da Deppo, V.; Fineschi, S.; Frassati, F.; Jerse,
G.; Landini, F.; Naletto, G.; Nicolini, G.; Pancrazzi, M.; Romoli,
M.; Sasso, C.; Slemer, A.; Stangalini, M.; Teriaca, L.
2022A&A...665A...7B Altcode: 2022arXiv220210294B
Context. On 2021 February 12, two subsequent eruptions occurred above
the western limb of the Sun, as seen along the Sun-Earth line. The
first event was a typical slow coronal mass ejection (CME), followed
∼7 h later by a smaller and collimated prominence eruption,
originating south of the CME, followed by a plasma blob. These
events were observed not only by the SOHO and STEREO-A missions,
but also by the suite of remote-sensing instruments on board Solar
Orbiter. <BR /> Aims: We show how data acquired by the Full Sun
Imager (FSI), the Metis coronagraph, and the Heliospheric Imager
(HI) from the Solar Orbiter perspective can be combined to study
the eruptions and different source regions. Moreover, we show how
Metis data can be analyzed to provide new information about solar
eruptions. <BR /> Methods: Different 3D reconstruction methods were
applied to the data acquired by different spacecraft, including
remote-sensing instruments on board Solar Orbiter. Images acquired
by the two Metis channels in the visible light (VL) and H I Ly-α
line (UV) were combined to derive physical information about the
expanding plasma. The polarization ratio technique was also applied
for the first time to Metis images acquired in the VL channel. <BR
/> Results: The two eruptions were followed in 3D from their source
region to their expansion in the intermediate corona. By combining
VL and UV Metis data, the formation of a post-CME current sheet (CS)
was followed for the first time in the intermediate corona. The
plasma temperature gradient across a post-CME blob propagating
along the CS was also measured for the first time. Application
of the polarization ratio technique to Metis data shows that by
combining four different polarization measurements, the errors are
reduced by ∼5 − 7%. This constrains the 3D plasma distribution
better. <P />Movies associated to Figs. 4-7 are available at <A
href="https://www.aanda.org/10.1051/0004-6361/202243162/olm">https://www.aanda.org</A>
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Title: Defining the Middle Corona
Authors: West, Matthew J.; Seaton, Daniel B.; Wexler, David B.;
Raymond, John C.; Del Zanna, Giulio; Rivera, Yeimy J.; Kobelski,
Adam R.; DeForest, Craig; Golub, Leon; Caspi, Amir; Gilly, Chris R.;
Kooi, Jason E.; Alterman, Benjamin L.; Alzate, Nathalia; Banerjee,
Dipankar; Berghmans, David; Chen, Bin; Chitta, Lakshmi Pradeep; Downs,
Cooper; Giordano, Silvio; Higginson, Aleida; Howard, Russel A.; Mason,
Emily; Mason, James P.; Meyer, Karen A.; Nykyri, Katariina; Rachmeler,
Laurel; Reardon, Kevin P.; Reeves, Katharine K.; Savage, Sabrina;
Thompson, Barbara J.; Van Kooten, Samuel J.; Viall, Nicholeen M.;
Vourlidas, Angelos
2022arXiv220804485W Altcode:
The middle corona, the region roughly spanning heliocentric altitudes
from $1.5$ to $6\,R_\odot$, encompasses almost all of the influential
physical transitions and processes that govern the behavior of
coronal outflow into the heliosphere. Eruptions that could disrupt
the near-Earth environment propagate through it. Importantly, it
modulates inflow from above that can drive dynamic changes at lower
heights in the inner corona. Consequently, this region is essential
for comprehensively connecting the corona to the heliosphere and for
developing corresponding global models. Nonetheless, because it is
challenging to observe, the middle corona has been poorly studied by
major solar remote sensing missions and instruments, extending back to
the Solar and Heliospheric Observatory (SoHO) era. Thanks to recent
advances in instrumentation, observational processing techniques,
and a realization of the importance of the region, interest in the
middle corona has increased. Although the region cannot be intrinsically
separated from other regions of the solar atmosphere, there has emerged
a need to define the region in terms of its location and extension
in the solar atmosphere, its composition, the physical transitions
it covers, and the underlying physics believed to be encapsulated by
the region. This paper aims to define the middle corona and give an
overview of the processes that occur there.
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Title: A highly dynamic small-scale jet in a polar coronal hole
Authors: Mandal, Sudip; Chitta, Lakshmi Pradeep; Peter, Hardi;
Solanki, Sami K.; Cuadrado, Regina Aznar; Teriaca, Luca; Schühle,
Udo; Berghmans, David; Auchère, Frédéric
2022A&A...664A..28M Altcode: 2022arXiv220602236M
We present an observational study of the plasma dynamics at the base
of a solar coronal jet, using high resolution extreme ultraviolet
imaging data taken by the Extreme Ultraviolet Imager on board Solar
Orbiter, and by the Atmospheric Imaging Assembly on board Solar
Dynamics Observatory. We observed multiple plasma ejection events
over a period of ∼1 h from a dome-like base that is ca. 4 Mm wide
and is embedded in a polar coronal hole. Within the dome below the
jet spire, multiple plasma blobs with sizes around 1−2 Mm propagate
upwards to the dome apex with speeds of the order of the sound speed
(ca. 120 km s<SUP>−1</SUP>). Upon reaching the apex, some of these
blobs initiate flows with similar speeds towards the other footpoint
of the dome. At the same time, high speed super-sonic outflows
(∼230 km s<SUP>−1</SUP>) are detected along the jet spire. These
outflows as well as the intensity near the dome apex appear to be
repetitive. Furthermore, during its evolution, the jet undergoes
many complex morphological changes, including transitions between
the standard and blowout type eruption. These new observational
results highlight the underlying complexity of the reconnection
process that powers these jets and they also provide insights into
the plasma response when subjected to rapid energy injection. <P
/>Movies associated to Figs. 1, 2, and 4 are available at <A
href="https://www.aanda.org/10.1051/0004-6361/202243765/olm">https://www.aanda.org</A>
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Title: The Solaris Solar Polar MIDEX-Class Mission Concept: Revealing
the Mysteries of the Sun's Poles
Authors: Hassler, Donald M.; Harra, Louise K.; Gibson, Sarah; Thompson,
Barbara; Gusain, Sanjay; Berghmans, David; Linker, Jon; Basu, Sarbani;
Featherstone, Nicholas; Hoeksema, J. Todd; Viall, Nicholeen; Newmark,
Jeffrey; Munoz-Jaramillo, Andres; Upton, Lisa A.
2022cosp...44.1528H Altcode:
Solaris is an exciting, innovative & bold mission of discovery to
reveal the mysteries of the Sun's poles. Solaris was selected for Phase
A development as part of NASA's MIDEX program. Solaris builds upon
the legacy of Ulysses, which flew over the solar poles, but Solaris
provides an entirely new feature remote sensing, or IMAGING. Solaris
will be the first mission to image the poles of the Sun from ~75
degrees latitude and provide new insight into the workings of the
solar dynamo and the solar cycle, which are at the foundation of our
understanding of space weather and space climate. Solaris will also
provide enabling observations for improved space weather research,
modeling and prediction with time series of polar magnetograms and
views of the ecliptic from above, providing a unique view of the
corona, coronal dynamics, and CME eruption. To reach the Sun's poles,
Solaris will first travel to Jupiter, and use Jupiter's gravity to
slingshot out of the ecliptic plane, and fly over the Sun's poles
at ~75 degrees latitude. Just as our understanding of Jupiter &
Saturn were revolutionized by polar observations from Juno and Cassini,
our understanding of the Sun will be revolutionized by Solaris.
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Title: A spectral solar irradiance monitor (SoSpIM) on the JAXA
Solar-C (EUVST) space mission
Authors: Harra, Louise K.; Watanabe, Kyoko; Haberreiter, Margit;
Hori, Tomoaki; Hara, Hirohisa; Kretzschmar, Matthieu; Woods, Thomas;
Shimizu, Toshifumi; Krucker, Samuel; Berghmans, David; Jin, Hidekatsu;
Dominique, Marie; Eparvier, Francis G.; Gissot, Samuel; Leng Yeo, Kok;
Pfiffner, Dany; Milligan, Ryan; Thiemann, Edward; Miyoshi, Yoshizumi;
Imada, Shinsuke; Kawate, Tomoko; Chamberlin, Phillip; Rozanov, Eugene;
Silvio Koller, -.; Barczynski, Krzysztof; Nozomu; Nishitani; Ieda,
Akimasa; Langer, Patrick; Meier, Leandro; Tye, Daniel; Alberti, Andrea
2022cosp...44..834H Altcode:
The JAXA Solar-C (EUVST) mission (Shimizu et al., 2020) is designed
to comprehensively understand how mass and energy are transferred
throughout the solar atmosphere. The EUV High-Throughput Spectroscopic
Telescope (EUVST) onboard does this by observing all the temperature
regimes of the atmosphere from the chromosphere to the corona
simultaneously. To enhance the EUVST scientific capabilities,
there will be a Solar Spectral Irradiance Monitor (SoSpIM). SoSpIM
will work hand-in-hand scientifically with EUVST, by providing the
full Sun irradiance at sub-second time cadence combined with the
spatially resolved spectroscopy from EUVST. The SoSPIM instrument
will specifically address two aspects. These are: · Understand how
the solar atmosphere becomes unstable, releasing the energy that
drives solar flares - achieved through probing fast time cadence
solar flare variations. · Measuring solar irradiance that impacts
the Earth's thermosphere and the mesosphere, linking to spatially
resolved measurements of the solar atmosphere with EUVST. SoSpIM will
provide high time resolution measurements in 2 channels (a) in the
corona through channel 1 (EUV) and (b) in the lower atmosphere through
channel 2 (Lyman alpha). Each channel impacts different layers of the
Earth's atmosphere.
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Title: Small-scale coronal brightenings as seen by Solar Orbiter
Authors: Peter, Hardi; Berghmans, David; Chitta, Lakshmi Pradeep
2022cosp...44.1323P Altcode:
The corona of the Sun shows variability over a wide range of scales,
in space, time and energy. The power-law-like distributions small-scale
coronal brightenings events have been used to propose self-similarity
of the involved processes. Already during the cruise phase, Solar
Orbiter was close enough to the Sun so that images provided by the
Extreme Ultraviolet Imager (EUI) are among the highest resolution
coronal data acquired so far. The small brightenings found in the
quiet Sun, now often termed campfires, could be considered as the small
end of the distribution of coronal transients. Mostly, these coronal
brightenings occur very low in the atmosphere, essentially just above
the chromosphere. Still they show a variety of morphology, ranging
from dot-like to loop-like with propagating disturbances, small jets,
or miniature flux-rope eruptions. This variety of the phenomenology on
the smallest resolvable scales points towards a conclusion that there is
not one single process that can drive small-scale brightenings. This is
supported by studies relating the EUV brightenings to the underlying
magnetic field: a part of the cases shows a relation to changes of
the surface magnetic flux, while in other cases it is very hard to
find any connection to the magnetic field. In the quiet Sun these
small brightenings are mostly found at the edges of bright elements
of the chromospheric network, which they have in common with another
class of brightenings seen at lower temperatures in the transition
region, namely explosive events. These transients have been proposed
as being due to reconnection, have a similar size and lifetime as
the small brightenings, but mostly seem to lack a component at high
temperatures. It might well be that these explosive events are related
to one particular type of the campfires, e.g. the jet-types, but that
remains to be studied. Modelling work on small brightenings is not
yet very abundant. One 3D MHD model of the quiet Sun shows coronal
brightenings that share properties with the observations. Here the
brightening is caused (mostly) by component reconnection, but also
one case of a twisted flux rope is found in the simulation data,
other (future) models most likely will reveal that also different
processes could produce similar brightenings. Because of timing and
the mission profile, so far remote sensing observations have been
taken mostly in regions of quiet Sun. With the perihelion in March
2022 Solar Orbiter will not only be closer than 0.3 AU from the Sun,
providing coronal observations at even higher resolution than before,
but also active region observations are planned. These might extend
the zoo of the small-scale coronal transients to small features in
active regions that might show properties similar or different from
the quiet Sun coronal brightenings. Either way, this will provide a
challenge for our understanding of the small-scale corona.
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Title: The Magnetic Origin of Solar Campfires: Observations by Solar
Orbiter and SDO
Authors: Panesar, Navdeep Kaur; Zhukov, Andrei; Berghmans, David;
Auchere, Frederic; Müller, Daniel; Tiwari, Sanjiv Kumar; Cheung, Mark
2022cosp...44.2564P Altcode:
Solar campfires are small-scale, short-lived coronal brightenings,
recently observed in 174 Å images by Extreme Ultraviolet Imager (EUI)
on board Solar Orbiter (SolO). Here we investigate the magnetic origin
of 52 campfires, in quiet-Sun, using line-of-sight magnetograms from
Solar Dynamics Observatory (SDO)/Helioseismic and Magnetic Imager
(HMI) together with extreme ultraviolet images from SolO /EUI and
SDO/Atmospheric Imaging Assembly (AIA). We find that the campfires
are rooted at the edges of photospheric magnetic network lanes; (ii)
most of the campfires reside above neutral lines and 77% of them appear
at sites of magnetic flux cancelation between the majority-polarity
magnetic flux patch and a merging minority-polarity flux patch, with
a flux cancelation rate of ∼1018 Mx hr‑1; some of the smallest
campfires come from the sites where magnetic flux elements were barely
discernible in HMI; (iii) some of the campfires occur repeatedly
from the same neutral line; (iv) in the large majority of instances
(79%), campfires are preceded by a cool-plasma structure, analogous to
minifilaments in coronal jets; and (v) although many campfires have
"complex" structure, most campfires resemble small-scale jets, dots,
or loops. Thus, "campfire" is a general term that includes different
types of small-scale solar dynamic features. They contain sufficient
magnetic energy (∼1026-1027 erg) to heat the solar atmosphere
locally to 0.5-2.5 MK. Their lifetimes range from about 1 minute to
over 1 hour, with most of the campfires having a lifetime of <10
minutes. The average lengths and widths of the campfires are 5400 ±
2500 km and 1600 ± 640 km, respectively. Our observations suggest that
(a) the presence of magnetic flux ropes may be ubiquitous in the solar
atmosphere and not limited to coronal jets and larger-scale eruptions
that make CMEs, and (b) magnetic flux cancelation, most likely driven
by magnetic reconnection in the lower atmosphere, is the fundamental
process for the formation and triggering of most campfires.
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Title: Transient small-scale brightenings in the quiet solar corona:
a model for campfires observed with Solar Orbiter
Authors: Chen, Yajie; Peter, Hardi; Berghmans, David; Tian, Hui;
Auchère, Frédéric; Przybylski, Damien
2022cosp...44.2557C Altcode:
Recent observations by the Extreme Ultraviolet Imager (EUI) on
board Solar Orbiter have revealed prevalent small-scale transient
brightenings in the quiet solar corona termed "campfires". To
understand the generation mechanism of these coronal brightenings,
we constructed a self-consistent and time-dependent quiet-Sun
model extending from the upper convection zone to the lower corona
using a realistic three-dimensional radiation magnetohydrodynamic
simulation. From the model we have synthesized the coronal emission
in the EUI 174 passband. We identified several transient coronal
brightenings similar to those in EUI observations. The size and
lifetime of these coronal brightenings are mostly 0.5-4 Mm and ~2 min,
respectively. These brightenings are generally located at a height of
2-4 Mm above the photosphere, and the local plasma is often heated
above 1 MK. By examining the magnetic field structures before and
after the occurrence of brightenings, we concluded that these coronal
brightenings are generated by component magnetic reconnection between
interacting bundles of magnetic field lines or neighboring field lines
within highly twisted flux ropes. Occurring in the coronal part of
the atmosphere, these events generally reveal no obvious signature
of flux emergence or cancellation in photospheric magnetograms. These
transient coronal brightenings may play an important role in heating
of the local coronal plasma.
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Title: Fine-scale, Dot-like, Brightenings in an Emerging Flux Region:
SolO/EUI Observations, and Bifrost MHD Simulations
Authors: Tiwari, Sanjiv Kumar; Berghmans, David; De Pontieu, Bart;
Hansteen, Viggo; Panesar, Navdeep Kaur
2022cosp...44.2529T Altcode:
Numerous tiny bright dots are observed in SolO's EUI/\hri\ data
of an emerging flux region (a coronal bright point) in 174 \AA,
emitted by the coronal plasma at $\sim$1 MK. These dots are roundish,
with a diameter of 675$\pm$300 km, a lifetime of 50$\pm$35 seconds,
and an intensity enhancement of 30% $\pm$10% from their immediate
surroundings. About half of the dots remain isolated during their
evolution and move randomly and slowly ($<$10 \kms). The other half
show extensions, appearing as a small loop or surge/jet, with intensity
propagations below 30\,\kms. Some dots form at the end of a fine-scale
explosion. Many of the bigger and brighter EUI/HRI dots are discernible
in SDO/AIA 171 \AA\ channel, have significant EM in the temperature
range of 1--2 MK, and are often located at polarity inversion lines
observed in HMI LOS magnetograms. Bifrost MHD simulations of an emerging
flux region do show dots in synthetic Fe IX/X images, although dots
in simulations are not as pervasive as in observations. The dots
in simulations show distinct Doppler signatures -- blueshifts and
redshifts coexist, or a redshift of the order of 10 \kms\ is followed
by a blueshift of similar or higher magnitude. The synthetic images of
O V/VI and Si IV lines, which form in the transition region, also show
the dots that are observed in Fe IX/X images, often expanded in size,
or extended as a loop, and always with stronger Doppler velocities (up
to 100 \kms) than that in Fe IX/X lines. Our results, together with the
field geometry of dots in the simulations, suggest that most dots in
emerging flux regions form in the lower solar atmosphere (at $\approx$1
Mm) by magnetic reconnection between emerging and pre-existing/emerged
magnetic field. The dots are smaller in Fe IX/X images (than in O V/VI
& Si IV lines) most likely because only the hottest counterpart of
the magnetic reconnection events is visible in the hotter emission. Some
dots might be manifestations of magneto-acoustic shocks (from the
lower atmosphere) through the line formation region of Fe IX/X. A
small number of dots could also be a response of supersonic downflows
impacting transition-region/chromospheric density.
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Title: Following prominences eruption from Sun to Parker Solar Probe
with multi-spacecraft observations
Authors: Niembro, Tatiana; Reeves, Kathy; Berghmans, David; Seaton,
Daniel; Andretta, Vincenzo; Hess, Phillip
2022cosp...44.1464N Altcode:
In the early hours of 2021 April 25, Solar Probe Cup on-board Parker
Solar Probe (PSP) registered the passage of a solar wind structure
characterized by a clear and constant alpha to proton density ratio
above 6% during three hours that remained present but faint and
intermittently within a twelve-hour window. PSP was behind the Sun
relative to the Earth, but the spacecraft location was visible to
both Solar Orbiter (SO) and STEREO-A (STA). SO and PSP were in nearly
perfect quadrature. In this work, we report the helium-enriched plasma
structure from the Sun to PSP combining multi-spacecraft remote sensing
and in situ measurements. We identify a prominence as the likely source,
visible in both STA/EUVI and SO/EUI. The associated CME was observed in
STA/COR2, and SO/Metis and SoloHI and reached PSP when it was located
at 46 solar radii, 8 hours after the spacecraft registered a crossing
of the heliospheric current sheet. Except for the extraordinary alpha
ratio enhancement, the CME showed ordinary plasma signatures and a
complex magnetic field with an overall enhancement. The PSP/WISPR
images show a structure entering the field of view a few hours before
the in situ crossing followed by repetitive transient structures that
are the result of flying through the CME body. We believe this to be
the first example of a CME being imaged by PSP/WISPR directly before
and during being detected in situ.
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Title: How Can Solar-C/SOSPIM Contribute to the Understanding of
Quasi-Periodic Pulsations in Solar Flares?
Authors: Dominique, Marie; Harra, Louise K.; Watanabe, Kyoko; Hara,
Hirohisa; Zhukov, Andrei; Shimizu, Toshifumi; Berghmans, David;
Dolla, Laurent; Gissot, Samuel; Pfiffner, Dany; Imada, Shinsuke;
Silvio Koller, -.; Meier, Leandro; Tye, Daniel; Alberti, Andrea
2022cosp...44.2524D Altcode:
Quasi-periodic pulsations (QPPs) refer to nearly-periodic oscillations
that are often observed in irradiance time series during solar flares
and have also been reported in several stellar flares. In the last
years, several statistical studies based on Soft X-ray measurements
have reached the conclusion that QPPs are present in most solar
flares of class M and above. Still, as of today, we are still unsure
of what causes QPPs. Several models could explain the presence of
QPPs with periods matching the ones observed. More detailed analysis
of the observational signatures of QPPs might help determine which
of those models are actually playing a role in the generation of
QPPs. However, as QPPs is a small timescale process (the period of
QPPs is often reported to be less than a minute), such an analysis
requires instruments with a good signal-to-noise and high sampling
rate. In this context, the spectral solar irradiance monitor SOSPIM,
that will be part of the JAXA SOLAR C mission and that will complement
the EUVST spectrograph measurements, could be a valuable asset. SOSPIM
will observe the solar chromosphere and corona in the Lyman-alpha
and EUV spectral ranges at high cadence. In this presentation, we
review the current knowledge of QPPs and describe what could be the
contribution of SOSPIM to push their understanding one step forward.
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Title: Coronal Microjets in Quiet-sun Regions Observed with the
Extreme Ultraviolet Imager Onboard Solar Orbiter
Authors: Hou, Zhenyong; He, Jiansen; Berghmans, David; Teriaca, Luca;
Wang, Linghua; Schuehle, Udo; Tian, Hui; Chen, Yajie; Chen, Hechao;
Gao, Yuhang; Bai, Xianyong
2022cosp...44.2536H Altcode:
We report the smallest coronal jets ever observed in the quiet Sun
with recent high resolution observations from the High Resolution
Telescopes (HRI-EUV and HRI-Lyα) of the Extreme Ultraviolet
Imager (EUI) onboard Solar Orbiter. In the HRI-EUV (174 Å) images,
these microjets usually appear as nearly collimated structures with
brightenings at their footpoints. Their average lifetime, projected
speed, width, and maximum length are 4.6 min, 62 km $s^{-1}$, 1.0 Mm,
and 7.7 Mm, respectively. Inverted-Y shaped structures and moving blobs
can be identified in some events. A subset of these events also reveal
signatures in the HRI-Lyα (H I Lyα at 1216 Å) images and the extreme
ultraviolet images taken by the Atmospheric Imaging Assembly onboard the
Solar Dynamics Observatory. Our differential emission measure analysis
suggests a multi-thermal nature and an average density of ~1.4x10^9
$cm^{-3}$ for these microjets. Their thermal and kinetic energies were
estimated to be ~3.9x10$^{24}$ erg and ~2.9x10$^{23}$ erg, respectively,
which are of the same order of the released energy predicted by the
nanoflare theory. Most events appear to be located at the edges of
network lanes and magnetic flux concentrations, suggesting that these
coronal microjets are likely generated by magnetic reconnection between
small-scale magnetic loops and the adjacent network field.
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Title: High frequency oscillations in Solar Orbiter/EUI observations
Authors: Petrova, Elena; Berghmans, David; van Doorsselaere, Tom;
Magyar, Norbert
2022cosp...44.1348P Altcode:
The power required to heat the corona is well established and
constitutes 100-200 $W\cdot m^{-2}$ for the Quiet sun regions and
approximately $10^4 \: W \cdot m^{-2}$ for the active regions. However,
the waves that are resolved using existing instruments do not appear
to show enough power to satisfy the condition, though the estimated
values are subjected to uncertainty. On the other hand, the frequency
range of the observed waves via imaging instruments is limited due
to instrumental constraints, making it impossible to observe waves
with a higher frequency that can potentially contain a substantial
amount of the energy flux. The unprecedented high cadence of the EUI
HRI imager onboard the Solar Orbiter allows accessing high cadence
and high temporal resolution images of the solar corona. The current
talk addresses the transverse oscillations detected in data from
the HRIEUV on Feb 23 with a cadence of 2 seconds. It was located
at the distance of 0.52 AU, resulting in a spatial resolution of 1
pixel corresponding to 200 km on the Sun. 1 event was analyzed, and
transverse oscillations were detected in the two loops with lengths of
11.7 Mm 4.5 Mm. The observed wave phenomenon is interpreted as decayless
kink oscillations. The periods of the analyzed oscillations are 30
and 14 s, corresponding to longer and shorter loops, respectively,
which lie outside of the range of periods for the previously detected
kink oscillations. The waves demonstrate high energy flux values,
with 6.5 and 2 $kW \cdot m^{-2}$, which exceeds the radiative losses
from these coronal loops. Performed numerical modeling supports
the energy estimations derived from the observations. The matter of
omnipresence of these oscillations is to be investigated with future
HRIEUV observations. However, if the omnipresence is confirmed, detected
short-period oscillations could become a potential candidate to play
a role in coronal heating.
---------------------------------------------------------
Title: Automatic detection of small-scale EUV brightenings observed
by the Solar Orbiter/EUI
Authors: Alipour, N.; Safari, H.; Verbeeck, C.; Berghmans, D.;
Auchère, F.; Chitta, L. P.; Antolin, P.; Barczynski, K.; Buchlin,
É.; Aznar Cuadrado, R.; Dolla, L.; Georgoulis, M. K.; Gissot, S.;
Harra, L.; Katsiyannis, A. C.; Long, D. M.; Mandal, S.; Parenti,
S.; Podladchikova, O.; Petrova, E.; Soubrié, É.; Schühle, U.;
Schwanitz, C.; Teriaca, L.; West, M. J.; Zhukov, A. N.
2022A&A...663A.128A Altcode: 2022arXiv220404027A
Context. Accurate detections of frequent small-scale extreme ultraviolet
(EUV) brightenings are essential to the investigation of the physical
processes heating the corona. <BR /> Aims: We detected small-scale
brightenings, termed campfires, using their morphological and
intensity structures as observed in coronal EUV imaging observations
for statistical analysis. <BR /> Methods: We applied a method based
on Zernike moments and a support vector machine (SVM) classifier
to automatically identify and track campfires observed by Solar
Orbiter/Extreme Ultraviolet Imager (EUI) and Solar Dynamics Observatory
(SDO)/Atmospheric Imaging Assembly (AIA). <BR /> Results: This method
detected 8678 campfires (with length scales between 400 km and 4000 km)
from a sequence of 50 High Resolution EUV telescope (HRI<SUB>EUV</SUB>)
174 Å images. From 21 near co-temporal AIA images covering the same
field of view as EUI, we found 1131 campfires, 58% of which were
also detected in HRI<SUB>EUV</SUB> images. In contrast, about 16%
of campfires recognized in HRI<SUB>EUV</SUB> were detected by AIA. We
obtain a campfire birthrate of 2 × 10<SUP>−16</SUP> m<SUP>−2</SUP>
s<SUP>−1</SUP>. About 40% of campfires show a duration longer than 5
s, having been observed in at least two HRI<SUB>EUV</SUB> images. We
find that 27% of campfires were found in coronal bright points and
the remaining 73% have occurred out of coronal bright points. We
detected 23 EUI campfires with a duration greater than 245 s. We found
that about 80% of campfires are formed at supergranular boundaries,
and the features with the highest total intensities are generated at
network junctions and intense H I Lyman-α emission regions observed
by EUI/HRI<SUB>Lya</SUB>. The probability distribution functions for
the total intensity, peak intensity, and projected area of campfires
follow a power law behavior with absolute indices between 2 and 3. This
self-similar behavior is a possible signature of self-organization,
or even self-organized criticality, in the campfire formation
process. <P />Supplementary material (S1-S3) is available at <A
href="https://www.aanda.org/10.1051/0004-6361/202243257/olm">https://www.aanda.org</A>
---------------------------------------------------------
Title: Prominence eruption observed in He II 304 Å up to >6
R<SUB>⊙</SUB> by EUI/FSI aboard Solar Orbiter
Authors: Mierla, M.; Zhukov, A. N.; Berghmans, D.; Parenti, S.;
Auchère, F.; Heinzel, P.; Seaton, D. B.; Palmerio, E.; Jejčič, S.;
Janssens, J.; Kraaikamp, E.; Nicula, B.; Long, D. M.; Hayes, L. A.;
Jebaraj, I. C.; Talpeanu, D. -C.; D'Huys, E.; Dolla, L.; Gissot, S.;
Magdalenić, J.; Rodriguez, L.; Shestov, S.; Stegen, K.; Verbeeck,
C.; Sasso, C.; Romoli, M.; Andretta, V.
2022A&A...662L...5M Altcode: 2022arXiv220515214M
<BR /> Aims: We report observations of a unique, large prominence
eruption that was observed in the He II 304 Å passband of the Extreme
Ultraviolet Imager/Full Sun Imager telescope aboard Solar Orbiter on
15-16 February 2022. <BR /> Methods: Observations from several vantage
points - Solar Orbiter, the Solar-Terrestrial Relations Observatory,
the Solar and Heliospheric Observatory, and Earth-orbiting satellites -
were used to measure the kinematics of the erupting prominence and the
associated coronal mass ejection. Three-dimensional reconstruction was
used to calculate the deprojected positions and speeds of different
parts of the prominence. Observations in several passbands allowed us
to analyse the radiative properties of the erupting prominence. <BR />
Results: The leading parts of the erupting prominence and the leading
edge of the corresponding coronal mass ejection propagate at speeds
of around 1700 km s<SUP>−1</SUP> and 2200 km s<SUP>−1</SUP>,
respectively, while the trailing parts of the prominence are
significantly slower (around 500 km s<SUP>−1</SUP>). Parts of the
prominence are tracked up to heights of over 6 R<SUB>⊙</SUB>. The
He II emission is probably produced via collisional excitation rather
than scattering. Surprisingly, the brightness of a trailing feature
increases with height. <BR /> Conclusions: The reported prominence
is the first observed in He II 304 Å emission at such a great
height (above 6 R<SUB>⊙</SUB>). <P />Movies are available at <A
href="https://www.aanda.org/10.1051/0004-6361/202244020/olm">https://www.aanda.org</A>
---------------------------------------------------------
Title: Observation of Magnetic Switchback in the Solar Corona
Authors: Telloni, Daniele; Zank, Gary P.; Stangalini, Marco;
Downs, Cooper; Liang, Haoming; Nakanotani, Masaru; Andretta,
Vincenzo; Antonucci, Ester; Sorriso-Valvo, Luca; Adhikari, Laxman;
Zhao, Lingling; Marino, Raffaele; Susino, Roberto; Grimani, Catia;
Fabi, Michele; D'Amicis, Raffaella; Perrone, Denise; Bruno, Roberto;
Carbone, Francesco; Mancuso, Salvatore; Romoli, Marco; Da Deppo, Vania;
Fineschi, Silvano; Heinzel, Petr; Moses, John D.; Naletto, Giampiero;
Nicolini, Gianalfredo; Spadaro, Daniele; Teriaca, Luca; Frassati,
Federica; Jerse, Giovanna; Landini, Federico; Pancrazzi, Maurizio;
Russano, Giuliana; Sasso, Clementina; Berghmans, David; Auchère,
Frédéric; Aznar Cuadrado, Regina; Chitta, Lakshmi P.; Harra, Louise;
Kraaikamp, Emil; Long, David M.; Mandal, Sudip; Parenti, Susanna;
Pelouze, Gabriel; Peter, Hardi; Rodriguez, Luciano; Schühle, Udo;
Schwanitz, Conrad; Smith, Phil J.; Verbeeck, Cis; Zhukov, Andrei N.
2022arXiv220603090T Altcode:
Switchbacks are sudden, large radial deflections of the solar wind
magnetic field, widely revealed in interplanetary space by the Parker
Solar Probe. The switchbacks' formation mechanism and sources are still
unresolved, although candidate mechanisms include Alfvénic turbulence,
shear-driven Kelvin-Helmholtz instabilities, interchange reconnection,
and geometrical effects related to the Parker spiral. This Letter
presents observations from the Metis coronagraph onboard Solar Orbiter
of a single large propagating S-shaped vortex, interpreted as first
evidence of a switchback in the solar corona. It originated above
an active region with the related loop system bounded by open-field
regions to the East and West. Observations, modeling, and theory provide
strong arguments in favor of the interchange reconnection origin of
switchbacks. Metis measurements suggest that the initiation of the
switchback may also be an indicator of the origin of slow solar wind.
---------------------------------------------------------
Title: High frequency decayless waves with significant energy in
Solar Orbiter/EUI observations
Authors: Petrova, Elena; Magyar, Norbert; Van Doorsselaere, Tom;
Berghmans, David
2022arXiv220505319P Altcode:
High-frequency wave phenomena present a great deal of interest as one
of the possible candidates to contribute to the energy input required
to heat the corona as a part of the AC heating theory. However, the
resolution of imaging instruments up until the Solar Orbiter have made
it impossible to resolve the necessary time and spatial scales. The
present paper reports on high-frequency transverse motions in a small
loop located in a quiet Sun region of the corona. The oscillations were
observed with the HRIEUV telescope (17.4 nm) of the EUI instrument
onboard the Solar Orbiter. We detect two transverse oscillations
in short loops with lengths of 4.5 Mm and 11 Mm. The shorter loop
displays an oscillation with a 14 s period and the longer a 30 s
period. Despite the high resolution, no definitive identification as
propagating or standing waves is possible. The velocity amplitudes
are found to be equal to 72 km/s and 125 km/s, respectively, for the
shorter and longer loop. Based on that, we also estimated the values
of the energy flux contained in the loops - the energy flux of the 14
s oscillation is 1.9 kW m^-2 and of the 30 s oscillation it is 6.5 kW
m^-2 . While these oscillations have been observed in the Quiet Sun,
their energy fluxes are of the same order as the energy input required
to heat the active solar corona. Numerical simulations were performed
in order to reproduce the observed oscillations. The correspondence of
the numerical results to the observations provide support to the energy
content estimates for the observations. Such high energy densities
have not yet been observed in decayless coronal waves, and this is
promising for coronal heating models based on wave damping.
---------------------------------------------------------
Title: SolO/EUI Observations of Ubiquitous Fine-scale Bright Dots
in an Emerging Flux Region: Comparison with a Bifrost MHD Simulation
Authors: Tiwari, Sanjiv K.; Hansteen, Viggo H.; De Pontieu, Bart;
Panesar, Navdeep K.; Berghmans, David
2022ApJ...929..103T Altcode: 2022arXiv220306161T
We report on the presence of numerous tiny bright dots in and around
an emerging flux region (an X-ray/coronal bright point) observed with
SolO's EUI/HRI<SUB>EUV</SUB> in 174 Å. These dots are roundish and have
a diameter of 675 ± 300 km, a lifetime of 50 ± 35 s, and an intensity
enhancement of 30% ± 10% above their immediate surroundings. About
half of the dots remain isolated during their evolution and move
randomly and slowly (<10 km s<SUP>-1</SUP>). The other half show
extensions, appearing as a small loop or surge/jet, with intensity
propagations below 30 km s<SUP>-1</SUP>. Many of the bigger and brighter
HRI<SUB>EUV</SUB> dots are discernible in the SDO/AIA 171 Å channel,
have significant emissivity in the temperature range of 1-2 MK, and
are often located at polarity inversion lines observed in SDO/HMI LOS
magnetograms. Although not as pervasive as in observations, a Bifrost
MHD simulation of an emerging flux region does show dots in synthetic
Fe IX/X images. These dots in the simulation show distinct Doppler
signatures-blueshifts and redshifts coexist, or a redshift of the
order of 10 km s<SUP>-1</SUP> is followed by a blueshift of similar
or higher magnitude. The synthetic images of O V/VI and Si IV lines,
which represent transition region radiation, also show the dots that
are observed in Fe IX/X images, often expanded in size, or extended
as a loop, and always with stronger Doppler velocities (up to 100
km s<SUP>-1</SUP>) than that in Fe IX/X lines. Our observation and
simulation results, together with the field geometry of dots in the
simulation, suggest that most dots in emerging flux regions form in the
lower solar atmosphere (at ≍ 1 Mm) by magnetic reconnection between
emerging and preexisting/emerged magnetic field. Some dots might be
manifestations of magnetoacoustic shocks through the line formation
region of Fe IX/X emission.
---------------------------------------------------------
Title: The magnetic drivers of campfires seen by the Polarimetric
and Helioseismic Imager (PHI) on Solar Orbiter
Authors: Kahil, F.; Hirzberger, J.; Solanki, S. K.; Chitta, L. P.;
Peter, H.; Auchère, F.; Sinjan, J.; Orozco Suárez, D.; Albert,
K.; Albelo Jorge, N.; Appourchaux, T.; Alvarez-Herrero, A.; Blanco
Rodríguez, J.; Gandorfer, A.; Germerott, D.; Guerrero, L.; Gutiérrez
Márquez, P.; Kolleck, M.; del Toro Iniesta, J. C.; Volkmer, R.;
Woch, J.; Fiethe, B.; Gómez Cama, J. M.; Pérez-Grande, I.; Sanchis
Kilders, E.; Balaguer Jiménez, M.; Bellot Rubio, L. R.; Calchetti,
D.; Carmona, M.; Deutsch, W.; Fernández-Rico, G.; Fernández-Medina,
A.; García Parejo, P.; Gasent-Blesa, J. L.; Gizon, L.; Grauf, B.;
Heerlein, K.; Lagg, A.; Lange, T.; López Jiménez, A.; Maue, T.;
Meller, R.; Michalik, H.; Moreno Vacas, A.; Müller, R.; Nakai,
E.; Schmidt, W.; Schou, J.; Schühle, U.; Staub, J.; Strecker, H.;
Torralbo, I.; Valori, G.; Aznar Cuadrado, R.; Teriaca, L.; Berghmans,
D.; Verbeeck, C.; Kraaikamp, E.; Gissot, S.
2022A&A...660A.143K Altcode: 2022arXiv220213859K
Context. The Extreme Ultraviolet Imager (EUI) on board the Solar Orbiter
(SO) spacecraft observed small extreme ultraviolet (EUV) bursts,
termed campfires, that have been proposed to be brightenings near the
apexes of low-lying loops in the quiet-Sun atmosphere. The underlying
magnetic processes driving these campfires are not understood. <BR
/> Aims: During the cruise phase of SO and at a distance of 0.523
AU from the Sun, the Polarimetric and Helioseismic Imager on Solar
Orbiter (SO/PHI) observed a quiet-Sun region jointly with SO/EUI,
offering the possibility to investigate the surface magnetic field
dynamics underlying campfires at a spatial resolution of about 380
km. <BR /> Methods: We used co-spatial and co-temporal data of the
quiet-Sun network at disc centre acquired with the High Resolution
Imager of SO/EUI at 17.4 nm (HRI<SUB>EUV</SUB>, cadence 2 s) and the
High Resolution Telescope of SO/PHI at 617.3 nm (HRT, cadence 2.5
min). Campfires that are within the SO/PHI−SO/EUI common field
of view were isolated and categorised according to the underlying
magnetic activity. <BR /> Results: In 71% of the 38 isolated events,
campfires are confined between bipolar magnetic features, which seem to
exhibit signatures of magnetic flux cancellation. The flux cancellation
occurs either between the two main footpoints, or between one of the
footpoints of the loop housing the campfire and a nearby opposite
polarity patch. In one particularly clear-cut case, we detected the
emergence of a small-scale magnetic loop in the internetwork followed
soon afterwards by a campfire brightening adjacent to the location
of the linear polarisation signal in the photosphere, that is to
say near where the apex of the emerging loop lays. The rest of the
events were observed over small scattered magnetic features, which
could not be identified as magnetic footpoints of the campfire hosting
loops. <BR /> Conclusions: The majority of campfires could be driven
by magnetic reconnection triggered at the footpoints, similar to the
physical processes occurring in the burst-like EUV events discussed
in the literature. About a quarter of all analysed campfires, however,
are not associated to such magnetic activity in the photosphere, which
implies that other heating mechanisms are energising these small-scale
EUV brightenings.
---------------------------------------------------------
Title: Comparing the Heliospheric Cataloging, Analysis, and Techniques
Service (HELCATS) Manual and Automatic Catalogues of Coronal Mass
Ejections Using Solar Terrestrial Relations Observatory/Heliospheric
Imager (STEREO/HI) Data
Authors: Rodriguez, L.; Barnes, D.; Hosteaux, S.; Davies, J. A.;
Willems, S.; Pant, V.; Harrison, R. A.; Berghmans, D.; Bothmer, V.;
Eastwood, J. P.; Gallagher, P. T.; Kilpua, E. K. J.; Magdalenic, J.;
Mierla, M.; Möstl, C.; Rouillard, A. P.; Odstrčil, D.; Poedts, S.
2022SoPh..297...23R Altcode:
We present the results of a comparative study between automatic
and manually compiled coronal mass ejection (CME) catalogues based
on observations from the Heliospheric Imagers (HIs) onboard NASA's
Solar Terrestrial Relations Observatory (STEREO) spacecraft. Using
the Computer Aided CME Tracking software(CACTus), CMEs are identified
in HI data using an automatic feature-detection algorithm, while
the Heliospheric Imagers Catalogue(HICAT) includes CMEs that are
detected by visual inspection of HI images. Both catalogues were
compiled as part of the EU FP7 Heliospheric Cataloguing, Analysis and
Techniques Service (HELCATS) project (www.helcats-fp7.eu). We compare
observational parameters of the CMEs from CACTus to those listed in
HICAT, such as CME frequency, position angle (PA), and PA-width. We
also compare CACTus-derived speeds to speeds derived from applying
geometric modelling to the majority of the HICAT CMEs, the results
of which are listed in the HELCATS Heliospheric Imagers Geometric
Catalogue(HIGeoCAT). We find that both CACTus and HICAT catalogues
contain a similar number of events when we exclude events narrower than
20<SUP>∘</SUP>, which are not included in the HICAT catalogue but are
found to be identified by CACTus. PA-distributions are strongly peaked
around 90<SUP>∘</SUP> and 270<SUP>∘</SUP>, with a slightly larger
CME frequency northwards of the equatorial plane (particularly for the
STEREO-A versions of both catalogues). The CME PA-widths in both HICAT
and CACTus catalogues peak at approximately 60<SUP>∘</SUP>. Manually
derived speeds from HIGeoCAT and automatically derived speeds by
CACTus correlate well for values lower than 1000 km s<SUP>−1</SUP>,
in particular when CMEs are propagating close to the plane of the sky.
---------------------------------------------------------
Title: Stereoscopy of extreme UV quiet Sun brightenings observed by
Solar Orbiter/EUI
Authors: Zhukov, A. N.; Mierla, M.; Auchère, F.; Gissot, S.;
Rodriguez, L.; Soubrié, E.; Thompson, W. T.; Inhester, B.; Nicula, B.;
Antolin, P.; Parenti, S.; Buchlin, É.; Barczynski, K.; Verbeeck, C.;
Kraaikamp, E.; Smith, P. J.; Stegen, K.; Dolla, L.; Harra, L.; Long,
D. M.; Schühle, U.; Podladchikova, O.; Aznar Cuadrado, R.; Teriaca,
L.; Haberreiter, M.; Katsiyannis, A. C.; Rochus, P.; Halain, J. -P.;
Jacques, L.; Berghmans, D.
2021A&A...656A..35Z Altcode: 2021arXiv210902169Z
Context. The three-dimensional fine structure of the solar atmosphere
is still not fully understood as most of the available observations
are taken from a single vantage point. <BR /> Aims: The goal of the
paper is to study the three-dimensional distribution of the small-scale
brightening events ("campfires") discovered in the extreme-UV quiet Sun
by the Extreme Ultraviolet Imager (EUI) aboard Solar Orbiter. <BR />
Methods: We used a first commissioning data set acquired by the EUI's
High Resolution EUV telescope on 30 May 2020 in the 174 Å passband and
we combined it with simultaneous data taken by the Atmospheric Imaging
Assembly (AIA) aboard the Solar Dynamics Observatory in a similar 171
Å passband. The two-pixel spatial resolution of the two telescopes
is 400 km and 880 km, respectively, which is sufficient to identify
the campfires in both data sets. The two spacecraft had an angular
separation of around 31.5° (essentially in heliographic longitude),
which allowed for the three-dimensional reconstruction of the campfire
position. These observations represent the first time that stereoscopy
was achieved for brightenings at such a small scale. Manual and
automatic triangulation methods were used to characterize the campfire
data. <BR /> Results: The height of the campfires is located between
1000 km and 5000 km above the photosphere and we find a good agreement
between the manual and automatic methods. The internal structure of
campfires is mostly unresolved by AIA; however, for a particularly
large campfire, we were able to triangulate a few pixels, which are
all in a narrow range between 2500 and 4500 km. <BR /> Conclusions: We
conclude that the low height of EUI campfires suggests that they belong
to the previously unresolved fine structure of the transition region and
low corona of the quiet Sun. They are probably apexes of small-scale
dynamic loops heated internally to coronal temperatures. This work
demonstrates that high-resolution stereoscopy of structures in the
solar atmosphere has become feasible.
---------------------------------------------------------
Title: How Can Solar-C/SOSPIM Contribute to the Understanding of
Quasi-Periodic Pulsations in Solar Flares?
Authors: Dominique, Marie; Dolla, Laurent; Zhukov, Andrei; Alberti,
Andrea; Berghmans, David; Gissot, Samuel; Hara, Hirohisa; Harra,
Louise; Imada, Shinsuke; Koller, Silvio; Meier, Leandro; Pfiffner,
Daniel; Shimizu, Toshifumi; Tye, Daniel; Watanabe, Kyoko
2021AGUFMSH25E2124D Altcode:
Quasi-periodic pulsations (QPPs) refer to nearly-periodic oscillations
that are often observed in irradiance time series during solar flares
and have also been reported in several stellar flares. In the last
years, several statistical studies based on Soft X-ray measurements
have reached the conclusion that QPPs are present in most solar flares
of class M and above. Still, the mechanism at the origin of QPPs is
under debate. Are they caused by waves or periodic fluctuations of the
magnetic reconnection driving the flare? Analyzing the characteristics
of QPPs and their evolution during the flare could help identifying
their origin. However, QPPs sometimes exhibit very different
periodicities, and do not always happen during the same phase of the
flare. All this could point to the coexistence of QPPs with different
origin mechanism, and indicates the need for more observations. In this
context, the spectral solar irradiance monitor SOSPIM, that will be
part of the JAXA SOLAR C mission and that will complement the EUVST
spectrograph measurements, could be a valuable asset. SOSPIM will
observe the solar chromosphere and corona in the Lyman-alpha and EUV
spectral ranges at high cadence. In this presentation, we review the
current knowledge of QPPs and describe what could be the contribution
of SOSPIM to push their understanding one step forward.
---------------------------------------------------------
Title: Full Vector Velocity Reconstruction Using Solar Orbiter
Doppler Map Observations.
Authors: Podladchikova, Olena; Harra, Louise; Barczynski, Krzysztof;
Mandrini, Cristina; Auchere, F.; Berghmans, David; Buchlin, Eric;
Dolla, Laurent; Mierla, Marilena; Parenti, Susanna; Rodriguez, Luciano
2021AGUFMNG35B0432P Altcode:
The Solar Orbiter mission opens up opportunities forthe
combined analysis of measurements obtained by solar imagers and
spectrometers. For the first time, different space spectrometerswill
be located at wide angles to each other, allowing three-dimensional
(3D) spectroscopy of the solar atmosphere.The aim of this work is to
prepare the methodology to facilitate the reconstruction of 3D vector
velocities from two stereoscopicLOS Doppler velocity measurements using
the Spectral Imaging of the Coronal Environment (SPICE) on board the
Solar Orbiter andthe near-Earth spectrometers, while widely separated in
space. We develop the methodology using the libraries designed earlier
for the STEREO mission but applied to spectroscopicdata from the Hinode
mission and the Solar Dynamics Observatory. We use well-known methods
of static and dynamic solar rotationstereoscopy and the methods of
EUV stereoscopic triangulation for optically-thin coronal EUV plasma
emissions. We develop new algorithms using analytical geometry in
space to determine the 3D velocity in coronal loops. We demonstrate
our approach with the reconstruction of 3D velocity vectors in plasma
flows along "open" and "closed"magnetic loops. This technique will be
applied first to an actual situation of two spacecraft at different
separations with spectrometers onboard (SPICE versus the Interface
Region Imaging Spectrograph (IRIS) and Hinode imaging spectrometer)
during the Solar Orbiternominal phase. We summarise how these
observations can be coordinated.
---------------------------------------------------------
Title: Campfires observed by EUI: What have we learned so far?
Authors: Berghmans, David; Auchere, F.; Zhukov, Andrei; Mierla,
Marilena; Chen, Yajie; Peter, Hardi; Panesar, Navdeep; Chitta, Lakshmi
Pradeep; Antolin, Patrick; Aznar Cuadrado, Regina; Tian, Hui; Hou,
Zhenyong; Podladchikova, Olena
2021AGUFMSH21A..02B Altcode:
Since its very first light images of the corona, the EUI/HRIEUV
telescope onboard Solar Orbiter has observed small localised
brightenings in the Quiet Sun. These small localised brightenings,
have become known as campfires, and are observed with length scales
between 400 km and 4000 km and durations between 10 sec and 200
sec. The smallest and weakest of these HRIEUV brightenings have
not been previously observed. Simultaneous observations from the
EUI High-resolution Lyman- telescope (HRILYA) do not show localised
brightening events, but the locations of the HRIEUV events clearly
correspond to the chromospheric network. Comparisons with simultaneous
AIA images shows that most events can also be identified in the
17.1 nm, 19.3 nm, 21.1 nm, and 30.4 nm pass-bands of AIA, although
they appear weaker and blurred. Some of the larger campfires have
the appearance of small interacting loops with the brightening
expanding from the contact point of the loops. Our differential
emission measure (DEM) analysis indicated coronal temperatures. We
determined the height for a few of these campfires to be between 1
and 5 Mm above the photosphere. We interpret these events as a new
extension to the flare-microflare-nanoflare family. Given their low
height, the EUI campfires could stand as a new element of the fine
structure of the transition region-low corona, that is, as apexes
of small-scale loops that undergo internal heating all the way up to
coronal temperatures. 3D MHD simulations with the MURaM code revealed
brightenings that are in many ways similar to the campfires by EUI. The
brightenings in the simulations suggest that campfires are triggered by
component reconnection inside flux bundles rather than flux emergence
or cancellation. Nevertheless, some of the observed campfires can
be clearly linked to flux cancellation events and, intriguingly,
are preceded by an erupting cool plasma structure. Analysis of the
dynamics of campfires revealed that some have the appearance of coronal
microjets, the smallest coronal jets observed in the quiet Sun. The
HRIEUV images also reveal transient jets on a somewhat bigger scale
with repeated outflows on the order of 100 km s1. In this paper we
will provide an overview of the campfire related phenomena that EUI
has observed and discuss the possible relevance for coronal heating.
---------------------------------------------------------
Title: Stereoscopy of extreme UV quiet Sun brightenings observed by
Solar Orbiter/EUI
Authors: Zhukov, Andrei; Mierla, Marilena; Auchere, F.; Gissot,
Samuel; Rodriguez, Luciano; Soubrie, Elie; Thompson, William; Inhester,
Bernd; Nicula, Bogdan; Antolin, Patrick; Parenti, Susanna; Buchlin,
Eric; Barczynski, Krzysztof; Verbeeck, Cis; Kraaikamp, Emil; Smith,
Philip; Stegen, Koen; Dolla, Laurent; Harra, Louise; Long, David;
Schuhle, Udo; Podladchikova, Olena; Aznar Cuadrado, Regina; Teriaca,
Luca; Haberreiter, Margit; Katsiyannis, Athanassios; Rochus, Pierre;
Halain, Jean-Philippe; Jacques, Lionel; Berghmans, David
2021AGUFMSH21A..03Z Altcode:
We study the three-dimensional distribution of small-scale brightening
events (campfires) discovered in the extreme-ultraviolet (EUV) quiet Sun
by the EUI telescope onboard the Solar Orbiter mission. We use one of
the first commissioning data sets acquired by the HRI_EUV telescope of
EUI on 2020 May 30 in the 174 A passband, combined with the simultaneous
SDO/AIA dataset taken in the very similar 171 A passband. The spatial
resolution of the two telescopes is sufficient to identify the campfires
in both datasets. The angular separation between the two spacecraft of
around 31.5 degrees allowed for the three-dimensional reconstruction
of the position of campfires. This is the first time that stereoscopy
was achieved for structures at such a small scale. Manual and automatic
triangulation methods were used. The height of campfires is between 1000
km and 5000 km above the photosphere, and there is a good agreement
between the results of manual and automatic methods. The internal
structure of campfires is mostly not resolved by AIA, but for a large
campfire we could triangulate a few pixels, which are all in a narrow
height range between 2500 and 4500 km. The low height of campfires
suggests that they belong to the previously unresolved fine structure
of the transition region and low corona of the quiet Sun. They are
probably apexes of small-scale dynamic loops internally heated to
coronal temperatures. This work demonstrates that high-resolution
stereoscopy of structures in the solar atmosphere has become possible.
---------------------------------------------------------
Title: Extreme-UV quiet Sun brightenings observed by the Solar
Orbiter/EUI
Authors: Berghmans, D.; Auchère, F.; Long, D. M.; Soubrié, E.;
Mierla, M.; Zhukov, A. N.; Schühle, U.; Antolin, P.; Harra, L.;
Parenti, S.; Podladchikova, O.; Aznar Cuadrado, R.; Buchlin, É.;
Dolla, L.; Verbeeck, C.; Gissot, S.; Teriaca, L.; Haberreiter, M.;
Katsiyannis, A. C.; Rodriguez, L.; Kraaikamp, E.; Smith, P. J.;
Stegen, K.; Rochus, P.; Halain, J. P.; Jacques, L.; Thompson, W. T.;
Inhester, B.
2021A&A...656L...4B Altcode: 2021arXiv210403382B
Context. The heating of the solar corona by small heating events
requires an increasing number of such events at progressively smaller
scales, with the bulk of the heating occurring at scales that are
currently unresolved. <BR /> Aims: The goal of this work is to study the
smallest brightening events observed in the extreme-UV quiet Sun. <BR />
Methods: We used commissioning data taken by the Extreme Ultraviolet
Imager (EUI) on board the recently launched Solar Orbiter mission. On
30 May 2020, the EUI was situated at 0.556 AU from the Sun. Its
High Resolution EUV telescope (HRI<SUB>EUV</SUB>, 17.4 nm passband)
reached an exceptionally high two-pixel spatial resolution of 400
km. The size and duration of small-scale structures was determined
by the HRI<SUB>EUV</SUB> data, while their height was estimated
from triangulation with simultaneous images from the Atmospheric
Imaging Assembly (AIA) on board the Solar Dynamics Observatory
mission. This is the first stereoscopy of small-scale brightenings
at high resolution. <BR /> Results: We observed small localised
brightenings, also known as `campfires', in a quiet Sun region with
length scales between 400 km and 4000 km and durations between 10 s and
200 s. The smallest and weakest of these HRI<SUB>EUV</SUB> brightenings
have not been previously observed. Simultaneous observations from the
EUI High-resolution Lyman-α telescope (HRI<SUB>Lya</SUB>) do not show
localised brightening events, but the locations of the HRI<SUB>EUV</SUB>
events clearly correspond to the chromospheric network. Comparisons with
simultaneous AIA images shows that most events can also be identified
in the 17.1 nm, 19.3 nm, 21.1 nm, and 30.4 nm pass-bands of AIA,
although they appear weaker and blurred. Our differential emission
measure analysis indicated coronal temperatures peaking at log T ≈
6.1 − 6.15. We determined the height for a few of these campfires to
be between 1000 and 5000 km above the photosphere. <BR /> Conclusions:
We find that `campfires' are mostly coronal in nature and rooted in the
magnetic flux concentrations of the chromospheric network. We interpret
these events as a new extension to the flare-microflare-nanoflare
family. Given their low height, the EUI `campfires' could stand as a
new element of the fine structure of the transition region-low corona,
that is, as apexes of small-scale loops that undergo internal heating
all the way up to coronal temperatures.
---------------------------------------------------------
Title: Capturing transient plasma flows and jets in the solar corona
Authors: Chitta, L. P.; Solanki, S. K.; Peter, H.; Aznar Cuadrado,
R.; Teriaca, L.; Schühle, U.; Auchère, F.; Berghmans, D.; Kraaikamp,
E.; Gissot, S.; Verbeeck, C.
2021A&A...656L..13C Altcode: 2021arXiv210915106C
Intensity bursts in ultraviolet (UV) to X-ray wavelengths and plasma
jets are typical signatures of magnetic reconnection and the associated
impulsive heating of the solar atmospheric plasma. To gain new insights
into the process, high-cadence observations are required to capture
the rapid response of plasma to magnetic reconnection as well as the
highly dynamic evolution of jets. Here, we report the first 2 s cadence
extreme-UV observations recorded by the 174 Å High Resolution Imager of
the Extreme Ultraviolet Imager on board the Solar Orbiter mission. These
observations, covering a quiet-Sun coronal region, reveal the onset
signatures of magnetic reconnection as localized heating events. These
localized sources then exhibit repeated plasma eruptions or jet
activity. Our observations show that this spatial morphological change
from localized sources to jet activity could occur rapidly on timescales
of about 20 s. The jets themselves are intermittent and are produced
from the source region on timescales of about 20 s. In the initial
phases of these events, plasma jets are observed to exhibit speeds,
as inferred from propagating intensity disturbances, in the range of
100 km s<SUP>−1</SUP> to 150 km s<SUP>−1</SUP>. These jets then
propagate to lengths of about 5 Mm. We discuss examples of bidirectional
and unidirectional jet activity observed to have been initiated from
the initially localized bursts in the corona. The transient nature
of coronal bursts and the associated plasma flows or jets along with
their dynamics could provide a benchmark for magnetic reconnection
models of coronal bursts and jets. <P />Movies are available at <A
href="https://www.aanda.org/10.1051/0004-6361/202141683/olm">https://www.aanda.org</A>
---------------------------------------------------------
Title: Propagating brightenings in small loop-like structures in
the quiet-Sun corona: Observations from Solar Orbiter/EUI
Authors: Mandal, Sudip; Peter, Hardi; Chitta, Lakshmi Pradeep;
Solanki, Sami K.; Aznar Cuadrado, Regina; Teriaca, Luca; Schühle,
Udo; Berghmans, David; Auchère, Frédéric
2021A&A...656L..16M Altcode: 2021arXiv211108106M
Brightenings observed in solar extreme-ultraviolet images are generally
interpreted as signatures of micro- or nanoflares occurring in the
transition region or at coronal temperatures. Recent observations
with the Extreme Ultraviolet Imager (EUI) on board Solar Orbiter have
revealed the smallest of such brightenings (called campfires) in the
quiet-Sun corona. Analyzing EUI 174 Å data obtained at a resolution
of about 400 km on the Sun with a cadence of 5 s on 30 May 2020,
we report here a number of cases in which these campfires exhibit
propagating signatures along their apparently small (3-5 Mm) loop-like
structures. The measured propagation speeds are generally between 25
km s<SUP>−1</SUP> and 60 km s<SUP>−1</SUP>. If the loop plasma is
assumed to be at a million Kelvin, these apparent motions would be
slower than the local sound speed. Furthermore, these brightenings
exhibit nontrivial propagation characteristics such as bifurcation,
merging, reflection, and repeated plasma ejections. We suggest that
these features are manifestations of the internal dynamics of these
small-scale magnetic structures and could provide important insights
into the dynamic response (∼40 s) of the loop plasma to the heating
events and also into the locations of the heating events themselves. <P
/>Movies associated to Figs 2-5, A.1, and B.1 are available at <A
href="https://www.aanda.org/10.1051/0004-6361/202142041/olm">https://www.aanda.org</A>
---------------------------------------------------------
Title: The first coronal mass ejection observed in both visible-light
and UV H I Ly-α channels of the Metis coronagraph on board Solar
Orbiter
Authors: Andretta, V.; Bemporad, A.; De Leo, Y.; Jerse, G.; Landini,
F.; Mierla, M.; Naletto, G.; Romoli, M.; Sasso, C.; Slemer, A.;
Spadaro, D.; Susino, R.; Talpeanu, D. -C.; Telloni, D.; Teriaca, L.;
Uslenghi, M.; Antonucci, E.; Auchère, F.; Berghmans, D.; Berlicki,
A.; Capobianco, G.; Capuano, G. E.; Casini, C.; Casti, M.; Chioetto,
P.; Da Deppo, V.; Fabi, M.; Fineschi, S.; Frassati, F.; Frassetto,
F.; Giordano, S.; Grimani, C.; Heinzel, P.; Liberatore, A.; Magli, E.;
Massone, G.; Messerotti, M.; Moses, D.; Nicolini, G.; Pancrazzi, M.;
Pelizzo, M. -G.; Romano, P.; Schühle, U.; Stangalini, M.; Straus,
Th.; Volpicelli, C. A.; Zangrilli, L.; Zuppella, P.; Abbo, L.; Aznar
Cuadrado, R.; Bruno, R.; Ciaravella, A.; D'Amicis, R.; Lamy, P.;
Lanzafame, A.; Malvezzi, A. M.; Nicolosi, P.; Nisticò, G.; Peter,
H.; Plainaki, C.; Poletto, L.; Reale, F.; Solanki, S. K.; Strachan,
L.; Tondello, G.; Tsinganos, K.; Velli, M.; Ventura, R.; Vial, J. -C.;
Woch, J.; Zimbardo, G.
2021A&A...656L..14A Altcode:
Context. The Metis coronagraph on board Solar Orbiter offers a new
view of coronal mass ejections (CMEs), observing them for the first
time with simultaneous images acquired with a broad-band filter in
the visible-light interval and with a narrow-band filter around the
H I Ly-α line at 121.567 nm, the so-called Metis UV channel. <BR />
Aims: We show the first Metis observations of a CME, obtained on 16
and 17 January 2021. The event was also observed by the EUI/FSI imager
on board Solar Orbiter, as well as by other space-based coronagraphs,
such as STEREO-A/COR2 and SOHO/LASCO/C2, whose images are combined here
with Metis data. <BR /> Methods: Different images are analysed here
to reconstruct the 3D orientation of the expanding CME flux rope using
the graduated cylindrical shell model. This also allows us to identify
the possible location of the source region. Measurements of the CME
kinematics allow us to quantify the expected Doppler dimming in the
Ly-α channel. <BR /> Results: Observations show that most CME features
seen in the visible-light images are also seen in the Ly-α images,
although some features in the latter channel appear more structured
than their visible-light counterparts. We estimated the expansion
velocity of this event to be below 140 km s<SUP>−1</SUP>. Hence,
these observations can be understood by assuming that Doppler dimming
effects do not strongly reduce the Ly-α emission from the CME. These
velocities are comparable with or smaller than the radial velocities
inferred from the same data in a similar coronal structure on the
east side of the Sun. <BR /> Conclusions: The first observations by
Metis of a CME demonstrate the capability of the instrument to provide
valuable and novel information on the structure and dynamics of these
coronal events. Considering also its diagnostics capabilities regarding
the conditions of the ambient corona, Metis promises to significantly
advance our knowledge of such phenomena. <P />Movies are available at <A
href="https://www.aanda.org/10.1051/0004-6361/202142407/olm">https://www.aanda.org</A>
---------------------------------------------------------
Title: SWAP and the Middle Corona
Authors: West, Matthew; Seaton, Daniel; D'Huys, Elke; Berghmans,
David; Mierla, Marilena; Rachmeler, Laurel
2021AGUFMSH15D2053W Altcode:
The SWAP instrument on PROBA2 has been observing the Middle Corona
for over a solar cycle, it has helped shape our understanding of this
previously understudied region, and enabled research into the region by
providing the first uncompressed, high-cadence, large field-of-view EUV
observations of the region. In this presentation we provide an overview
of SWAPs imaging capabilities, techniques used to observe and enhance
observations of the region, and a review of the unique observations made
by SWAP. We present an overview of the phenomena that passes through and
interacts with the region, and how these structures are affected by the
ambient plasma properties, and in turn how the structures change the
region. Both dynamic and long-lived structures are discussed. We look
at the solar cycle dependence of structures observed in this region,
and we present some of the open questions pertaining to the region and
what needs to be done to further our understanding of the Middle Corona.
---------------------------------------------------------
Title: Evidence for local particle acceleration in the first recurrent
galactic cosmic ray depression observed by Solar Orbiter. The ion
event on 19 June 2020
Authors: Aran, A.; Pacheco, D.; Laurenza, M.; Wijsen, N.; Lario, D.;
Benella, S.; Richardson, I. G.; Samara, E.; Freiherr von Forstner,
J. L.; Sanahuja, B.; Rodriguez, L.; Balmaceda, L.; Espinosa Lara,
F.; Gómez-Herrero, R.; Steinvall, K.; Vecchio, A.; Krupar, V.;
Poedts, S.; Allen, R. C.; Andrews, G. B.; Angelini, V.; Berger, L.;
Berghmans, D.; Boden, S.; Böttcher, S. I.; Carcaboso, F.; Cernuda, I.;
De Marco, R.; Eldrum, S.; Evans, V.; Fedorov, A.; Hayes, J.; Ho, G. C.;
Horbury, T. S.; Janitzek, N. P.; Khotyaintsev, Yu. V.; Kollhoff, A.;
Kühl, P.; Kulkarni, S. R.; Lees, W. J.; Louarn, P.; Magdalenic, J.;
Maksimovic, M.; Malandraki, O.; Martínez, A.; Mason, G. M.; Martín,
C.; O'Brien, H.; Owen, C.; Parra, P.; Prieto Mateo, M.; Ravanbakhsh,
A.; Rodriguez-Pacheco, J.; Rodriguez Polo, O.; Sánchez Prieto, S.;
Schlemm, C. E.; Seifert, H.; Terasa, J. C.; Tyagi, K.; Verbeeck, C.;
Wimmer-Schweingruber, R. F.; Xu, Z. G.; Yedla, M. K.; Zhukov, A. N.
2021A&A...656L..10A Altcode:
Context. In mid-June 2020, the Solar Orbiter (SolO) mission reached its
first perihelion at 0.51 au and started its cruise phase, with most of
the in situ instruments operating continuously. <BR /> Aims: We present
the in situ particle measurements of the first proton event observed
after the first perihelion obtained by the Energetic Particle Detector
(EPD) suite on board SolO. The potential solar and interplanetary
(IP) sources of these particles are investigated. <BR /> Methods: Ion
observations from ∼20 keV to ∼1 MeV are combined with available
solar wind data from the Radio and Plasma Waves (RPW) instrument and
magnetic field data from the magnetometer on board SolO to evaluate
the energetic particle transport conditions and infer the possible
acceleration mechanisms through which particles gain energy. We compare
> 17-20 MeV ion count rate measurements for two solar rotations,
along with the solar wind plasma data available from the Solar Wind
Analyser (SWA) and RPW instruments, in order to infer the origin of
the observed galactic cosmic ray (GCR) depressions. <BR /> Results:
The lack of an observed electron event and of velocity dispersion at
various low-energy ion channels and the observed IP structure indicate
a local IP source for the low-energy particles. From the analysis
of the anisotropy of particle intensities, we conclude that the
low-energy ions were most likely accelerated via a local second-order
Fermi process. The observed GCR decrease on 19 June, together with the
51.8-1034.0 keV nuc<SUP>−1</SUP> ion enhancement, was due to a solar
wind stream interaction region (SIR). The observation of a similar
GCR decrease in the next solar rotation favours this interpretation
and constitutes the first observation of a recurrent GCR decrease
by SolO. The analysis of the recurrence times of this SIR suggests
that it is the same SIR responsible for the <SUP>4</SUP>He events
previously measured in April and May. Finally, we point out that
an IP structure more complex than a common SIR cannot be discarded,
mainly due to the lack of solar wind temperature measurements and the
lack of a higher cadence of solar wind velocity observations. <P
/>Movies associated to Figs. B.1 and B.2 are available at <A
href="https://www.aanda.org/10.1051/0004-6361/202140966/olm">https://www.aanda.org</A>
---------------------------------------------------------
Title: Transient small-scale brightenings in the quiet solar corona:
A model for campfires observed with Solar Orbiter
Authors: Chen, Yajie; Przybylski, Damien; Peter, Hardi; Tian, Hui;
Auchère, F.; Berghmans, D.
2021A&A...656L...7C Altcode: 2021arXiv210410940C
Context. Recent observations by the Extreme Ultraviolet Imager (EUI) on
board Solar Orbiter have characterized prevalent small-scale transient
brightenings in the corona above the quiet Sun termed campfires. <BR />
Aims: In this study we search for comparable brightenings in a numerical
model and then investigate their relation to the magnetic field and the
processes that drive these events. <BR /> Methods: We used the MURaM
code to solve the 3D radiation magnetohydrodynamic equations in a box
that stretches from the upper convection zone to the corona. The model
self-consistently produces a supergranular network of the magnetic
field and a hot corona above this quiet Sun. For the comparison with
the model, we synthesized the coronal emission as seen by EUI in its
174 Å channel, isolated the seven strongest transient brightenings,
and investigated the changes of the magnetic field in and around these
in detail. <BR /> Results: The transients we isolated have a lifetime of
about 2 min and are elongated loop-like features with lengths around 1
Mm to 4 Mm. They tend to occur at heights of about 2 Mm to 5 Mm above
the photosphere, a bit offset from magnetic concentrations that mark
the bright chromospheric network, and they reach temperatures of above
1 MK. As a result, they very much resemble the larger campfires found
in observations. In our model most events are energized by component
reconnection between bundles of field lines that interact at coronal
heights. In one case, we find that untwisting a highly twisted flux
rope initiates the heating. <BR /> Conclusions: Based on our study, we
propose that the majority of campfire events found by EUI are driven
by component reconnection and our model suggests that this process
significantly contributes to the heating of the corona above the quiet
Sun. <P />Movies associated to Figs. 2, 4, 5, and A1 are available at <A
href="https://www.aanda.org/10.1051/0004-6361/202140638/olm">https://www.aanda.org</A>
---------------------------------------------------------
Title: Stereoscopic measurements of coronal Doppler velocities
Authors: Podladchikova, O.; Harra, L.; Barczynski, K.; Mandrini,
C. H.; Auchère, F.; Berghmans, D.; Buchlin, É.; Dolla, L.; Mierla,
M.; Parenti, S.; Rodriguez, L.
2021A&A...655A..57P Altcode: 2021arXiv210802280P
Context. The Solar Orbiter mission, with an orbit outside the Sun-Earth
line and leaving the ecliptic plane, opens up opportunities for
the combined analysis of measurements obtained by solar imagers and
spectrometers. For the first time different space spectrometers will be
located at wide angles to each other, allowing three-dimensional (3D)
spectroscopy of the solar atmosphere. <BR /> Aims: The aim of this
work is to prepare a methodology to facilitate the reconstruction
of 3D vector velocities from two stereoscopic line of sight (LOS)
Doppler velocity measurements using the Spectral Imaging of the
Coronal Environment (SPICE) on board the Solar Orbiter and the
near-Earth spectrometers, while widely separated in space. <BR />
Methods: We developed the methodology using the libraries designed
earlier for the STEREO mission, but applied to spectroscopic data
from the Hinode mission and the Solar Dynamics Observatory. We used
well-known methods of static and dynamic solar rotation stereoscopy and
the methods of extreme ultraviolet (EUV) stereoscopic triangulation
for optically thin coronal EUV plasma emissions. We developed new
algorithms using analytical geometry in space to determine the 3D
velocity in coronal loops. <BR /> Results: We demonstrate our approach
with the reconstruction of 3D velocity vectors in plasma flows along
`open' and `closed' magnetic loops. This technique will be applied
to an actual situation of two spacecraft at different separations
with spectrometers on board during the Solar Orbiter nominal phase:
SPICE versus the Interface Region Imaging Spectrograph (IRIS) and
Hinode imaging spectrometer. We summarise how these observations can
be coordinated. <P />Movies associated to Fig. 1 are available at <A
href="https://www.aanda.org/10.1051/0004-6361/202140457/olm">https://www.aanda.org</A>
---------------------------------------------------------
Title: The Magnetic Origin of Solar Campfires
Authors: Panesar, Navdeep K.; Tiwari, Sanjiv K.; Berghmans, David;
Cheung, Mark C. M.; Müller, Daniel; Auchere, Frederic; Zhukov, Andrei
2021ApJ...921L..20P Altcode: 2021arXiv211006846P
Solar campfires are fine-scale heating events, recently observed by
Extreme Ultraviolet Imager (EUI) on board Solar Orbiter. Here we use EUI
174 Å images, together with EUV images from Solar Dynamics Observatory
(SDO)/Atmospheric Imaging Assembly (AIA), and line-of-sight magnetograms
from SDO/Helioseismic and Magnetic Imager (HMI) to investigate the
magnetic origin of 52 randomly selected campfires in the quiet solar
corona. We find that (i) the campfires are rooted at the edges of
photospheric magnetic network lanes; (ii) most of the campfires reside
above the neutral line between majority-polarity magnetic flux patch and
a merging minority-polarity flux patch, with a flux cancelation rate of
~10<SUP>18</SUP> Mx hr<SUP>-1</SUP>; (iii) some of the campfires occur
repeatedly from the same neutral line; (iv) in the large majority of
instances, campfires are preceded by a cool-plasma structure, analogous
to minifilaments in coronal jets; and (v) although many campfires have
"complex" structure, most campfires resemble small-scale jets, dots,
or loops. Thus, "campfire" is a general term that includes different
types of small-scale solar dynamic features. They contain sufficient
magnetic energy (~10<SUP>26</SUP>-10<SUP>27</SUP> erg) to heat the solar
atmosphere locally to 0.5-2.5 MK. Their lifetimes range from about 1
minute to over 1 hr, with most of the campfires having a lifetime of
<10 minutes. The average lengths and widths of the campfires are 5400
± 2500 km and 1600 ± 640 km, respectively. Our observations suggest
that (a) the presence of magnetic flux ropes may be ubiquitous in the
solar atmosphere and not limited to coronal jets and larger-scale
eruptions that make CMEs, and (b) magnetic flux cancelation is the
fundamental process for the formation and triggering of most campfires.
---------------------------------------------------------
Title: Coronal Microjets in Quiet-Sun Regions Observed with the
Extreme Ultraviolet Imager on Board the Solar Orbiter
Authors: Hou, Zhenyong; Tian, Hui; Berghmans, David; Chen, Hechao;
Teriaca, Luca; Schühle, Udo; Gao, Yuhang; Chen, Yajie; He, Jiansen;
Wang, Linghua; Bai, Xianyong
2021ApJ...918L..20H Altcode: 2021arXiv210808718H
We report the smallest coronal jets ever observed in the quiet Sun with
recent high-resolution observations from the High Resolution Telescopes
(HRI<SUB>EUV</SUB> and HRI<SUB>Lyα</SUB>) of the Extreme Ultraviolet
Imager on board the Solar Orbiter (SO). In the HRI<SUB>EUV</SUB>
(174 Å) images, these microjets usually appear as nearly collimated
structures with brightenings at their footpoints. Their average
lifetime, projected speed, width, and maximum length are 4.6 minutes,
62 km s<SUP>-1</SUP>, 1.0 Mm, and 7.7 Mm, respectively. Inverted-Y
shaped structures and moving blobs can be identified in some events. A
subset of these events also reveal signatures in the HRI<SUB>Lyα</SUB>
(H I Lyα at 1216 Å) images and the extreme ultraviolet images
taken by the Atmospheric Imaging Assembly (AIA) on board the Solar
Dynamics Observatory (SDO). Our differential emission-measure (EM)
analysis suggests a multithermal nature and an average density of ~1.4
× 10<SUP>9</SUP> cm<SUP>-3</SUP> for these microjets. Their thermal
and kinetic energies were estimated to be ~3.9 × 10<SUP>24</SUP> erg
and ~2.9 × 10<SUP>23</SUP> erg, respectively, which are of the same
order of the released energy predicted by the nanoflare theory. Most
events appear to be located at the edges of network lanes and magnetic
flux concentrations, suggesting that these coronal microjets are likely
generated by magnetic reconnection between small-scale magnetic loops
and the adjacent network field.
---------------------------------------------------------
Title: Magnetic imaging of the outer solar atmosphere (MImOSA)
Authors: Peter, H.; Ballester, E. Alsina; Andretta, V.; Auchère, F.;
Belluzzi, L.; Bemporad, A.; Berghmans, D.; Buchlin, E.; Calcines, A.;
Chitta, L. P.; Dalmasse, K.; Alemán, T. del Pino; Feller, A.; Froment,
C.; Harrison, R.; Janvier, M.; Matthews, S.; Parenti, S.; Przybylski,
D.; Solanki, S. K.; Štěpán, J.; Teriaca, L.; Bueno, J. Trujillo
2021ExA...tmp...95P Altcode:
The magnetic activity of the Sun directly impacts the Earth and human
life. Likewise, other stars will have an impact on the habitability of
planets orbiting these host stars. Although the magnetic field at the
surface of the Sun is reasonably well characterised by observations,
the information on the magnetic field in the higher atmospheric layers
is mainly indirect. This lack of information hampers our progress in
understanding solar magnetic activity. Overcoming this limitation would
allow us to address four paramount long-standing questions: (1) How
does the magnetic field couple the different layers of the atmosphere,
and how does it transport energy? (2) How does the magnetic field
structure, drive and interact with the plasma in the chromosphere and
upper atmosphere? (3) How does the magnetic field destabilise the outer
solar atmosphere and thus affect the interplanetary environment? (4)
How do magnetic processes accelerate particles to high energies? New
ground-breaking observations are needed to address these science
questions. We suggest a suite of three instruments that far exceed
current capabilities in terms of spatial resolution, light-gathering
power, and polarimetric performance: (a) A large-aperture UV-to-IR
telescope of the 1-3 m class aimed mainly to measure the magnetic
field in the chromosphere by combining high spatial resolution
and high sensitivity. (b) An extreme-UV-to-IR coronagraph that is
designed to measure the large-scale magnetic field in the corona with
an aperture of about 40 cm. (c) An extreme-UV imaging polarimeter
based on a 30 cm telescope that combines high throughput in the
extreme UV with polarimetry to connect the magnetic measurements
of the other two instruments. Placed in a near-Earth orbit, the data
downlink would be maximised, while a location at L4 or L5 would provide
stereoscopic observations of the Sun in combination with Earth-based
observatories. This mission to measure the magnetic field will finally
unlock the driver of the dynamics in the outer solar atmosphere and
thereby will greatly advance our understanding of the Sun and the
heliosphere.
---------------------------------------------------------
Title: Vector Velocities Measurements with the Solar Orbiter SPICE
Spectrometer
Authors: Podladchikova, O.; Harra, L.; Barczynski, K.; Mandrini,
C.; Auchère, F.; Berghmans, D.; Buchlin, E.; Dolla, L.; Mierla, M.;
Parenti, S.; Rodriguez, L.
2021AAS...23831312P Altcode:
The Solar Orbiter mission, with an orbit outside the Sun-Earth
line and leaving the ecliptic plane, opens up opportunities for
the combined analysis of measurements obtained by solar imagers and
spectrometers. For the first time, different spectrometers will be
located at wide angles to each other, allowing three-dimensional (3D)
spectroscopy of the solar atmosphere. Here we develop a methodology to
prepare for this kind of analysis, by using data from the Hinode mission
and the Solar Dynamics Observatory, respectively. We employ solar
rotation to simulate measurements of spectrometers with different views
of the solar corona. The resulting data allow us to apply stereoscopic
tie-pointing and triangulation techniques designed for the STEREO
spacecraft pair, and to perform 3D analysis of the Doppler shifts of
a quasi-stationary active region. Our approach allows the accurate
reconstruction of 3D velocity vectors in plasma flows along "open" and
"closed" magnetic loops. This technique will be applied to the actual
situation of two spacecraft at different separations with spectrometers
on board (the Solar Orbiter Spectral Imaging of the Coronal Environment
versus the Interface Region Imaging Spectrograph (IRIS) and Hinode
imaging spectrometer) and we summarise how these observations can be
coordinated to assess vector velocity measurements. This 3D spectroscopy
method will facilitate the understanding of the complex flows that
take place throughout the solar atmosphere.
---------------------------------------------------------
Title: Signatures of coronal hole substructure in the solar wind:
combined Solar Orbiter remote sensing and in situ measurements
Authors: Horbury, T. S.; Laker, R.; Rodriguez, L.; Steinvall, K.;
Maksimovic, M.; Livi, S.; Berghmans, D.; Auchere, F.; Zhukov, A. N.;
Khotyaintsev, Yu. V.; Woodham, L.; Matteini, L.; Stawarz, J.; Woolley,
T.; Bale, S. D.; Rouillard, A.; O'Brien, H.; Evans, V.; Angelini,
V.; Owen, C.; Solanki, S. K.; Nicula, B.; Muller, D.; Zouganelis, I.
2021arXiv210414960H Altcode:
Context. The Sun's complex corona is the source of the solar wind
and interplanetary magnetic field. While the large scale morphology
is well understood, the impact of variations in coronal properties
on the scale of a few degrees on properties of the interplanetary
medium is not known. Solar Orbiter, carrying both remote sensing
and in situ instruments into the inner solar system, is intended
to make these connections better than ever before. Aims. We combine
remote sensing and in situ measurements from Solar Orbiter's first
perihelion at 0.5 AU to study the fine scale structure of the solar
wind from the equatorward edge of a polar coronal hole with the aim
of identifying characteristics of the corona which can explain the in
situ variations. Methods. We use in situ measurements of the magnetic
field, density and solar wind speed to identify structures on scales
of hours at the spacecraft. Using Potential Field Source Surface
mapping we estimate the source locations of the measured solar wind
as a function of time and use EUI images to characterise these solar
sources. Results. We identify small scale stream interactions in the
solar wind with compressed magnetic field and density along with speed
variations which are associated with corrugations in the edge of the
coronal hole on scales of several degrees, demonstrating that fine
scale coronal structure can directly influence solar wind properties
and drive variations within individual streams. Conclusions. This early
analysis already demonstrates the power of Solar Orbiter's combined
remote sensing and in situ payload and shows that with future, closer
perihelia it will be possible dramatically to improve our knowledge
of the coronal sources of fine scale solar wind structure, which is
important both for understanding the phenomena driving the solar wind
and predicting its impacts at the Earth and elsewhere.
---------------------------------------------------------
Title: The Extreme ultraviolet imager onboard Solar Orbiter
Authors: Berghmans, David; Harra, Louise K.; Zhukov, Andrei; Auchere,
Frederic; Long, David; Schuehle, Udo; Rochus, Pierre
2021cosp...43E.949B Altcode:
The Extreme Ultraviolet Imager (EUI) is part of the remote sensing
instrument package of the ESA/NASA Solar Orbiter mission that will
explore the inner heliosphere and observe the Sun from vantage points
close to the Sun and out of the ecliptic. With EUI we aim to improve our
understanding of the structure and dynamics of the solar atmosphere,
globally as well as at high resolution, and from high solar latitude
perspectives. The EUI consists of three telescopes, the Full Sun Imager
(FSI) and two High Resolution Imagers (HRIs), which are optimised
to image in Lyman-$\alpha$ and EUV (174 \AA, 304 \AA) to provide a
coverage from chromosphere up to corona. The EUI instrument design
will be reviewed, and its scientific objectives and plans will be
discussed. Early results of the EUI commissioning will be presented.
---------------------------------------------------------
Title: Magnetic Imaging of the Outer Solar Atmosphere (MImOSA):
Unlocking the driver of the dynamics in the upper solar atmosphere
Authors: Peter, H.; Alsina Ballester, E.; Andretta, V.; Auchere, F.;
Belluzzi, L.; Bemporad, A.; Berghmans, D.; Buchlin, E.; Calcines, A.;
Chitta, L. P.; Dalmasse, K.; del Pino Aleman, T.; Feller, A.; Froment,
C.; Harrison, R.; Janvier, M.; Matthews, S.; Parenti, S.; Przybylski,
D.; Solanki, S. K.; Stepan, J.; Teriaca, L.; Trujillo Bueno, J.
2021arXiv210101566P Altcode:
The magnetic activity of the Sun directly impacts the Earth and human
life. Likewise, other stars will have an impact on the habitability
of planets orbiting these host stars. The lack of information on the
magnetic field in the higher atmospheric layers hampers our progress in
understanding solar magnetic activity. Overcoming this limitation would
allow us to address four paramount long-standing questions: (1) How
does the magnetic field couple the different layers of the atmosphere,
and how does it transport energy? (2) How does the magnetic field
structure, drive and interact with the plasma in the chromosphere and
upper atmosphere? (3) How does the magnetic field destabilise the outer
solar atmosphere and thus affect the interplanetary environment? (4)
How do magnetic processes accelerate particles to high energies? New
ground-breaking observations are needed to address these science
questions. We suggest a suite of three instruments that far exceed
current capabilities in terms of spatial resolution, light-gathering
power, and polarimetric performance: (a) A large-aperture UV-to-IR
telescope of the 1-3 m class aimed mainly to measure the magnetic
field in the chromosphere by combining high spatial resolution and high
sensitivity. (b) An extreme-UV-to-IR coronagraph that is designed to
measure the large-scale magnetic field in the corona with an aperture
of about 40 cm. (c) An extreme-UV imaging polarimeter based on a 30
cm telescope that combines high throughput in the extreme UV with
polarimetry to connect the magnetic measurements of the other two
instruments. This mission to measure the magnetic field will unlock
the driver of the dynamics in the outer solar atmosphere and thereby
greatly advance our understanding of the Sun and the heliosphere.
---------------------------------------------------------
Title: 3D Visualisation of Solar Data with JHelioviewer
Authors: Mueller, D.; Nicula, B.; Verstringe, F.; Bourgoignie, B.;
Csillaghy, A.; Laube, S.; Berghmans, D.; Ireland, J.; Fleck, B.
2020AGUFMSH0360001M Altcode:
The Solar Orbiter and Parker Solar Probe missions focus on exploring
the linkage between the Sun and the heliosphere. These new missions
are collecting unique data that will allow us to study the coupling
between macroscopic physical processes to those on kinetic scales, the
generation of solar energetic particles and their propagation into the
heliosphere and the origin and acceleration of solar wind plasma. <P
/>The scientific community now has access to large volumes of complex
remote-sensing and in-situ observations from different vantage points,
complemented by petabytes of simulation data. Answering overarching
science questions like "How do solar transients drive heliospheric
variability and space weather?" will only be possible if the science
community has the necessary tools at hand to visualize these data
and assimilate them into sophisticated models. <P />A key piece
needed to bridge the gap between observables, derived quantities like
magnetic field extrapolations and model output is a tool to routinely
and intuitively visualise large heterogeneous, multidimensional,
time-dependent data sets. The open-source JHelioviewer software,
which is part of the ESA/NASA Helioviewer Project, is addressing this
need. This contribution highlights recent extensions of JHelioviewer's
functionality, in particular those of interest for Solar Orbiter.
---------------------------------------------------------
Title: The LUCI instrument
Authors: West, M. J.; Kintziger, C.; Haberreiter, M.; Berghmans, D.;
Gissot, S.; Golub, L.; Shestov, S.; Davies, J. A.; Luntama, J. P.
2020AGUFMSH0300007W Altcode:
LUCI (Lagrange eUv Coronal Imager) is a solar imager in the Extreme
UltraViolet (EUV) that is being developed as part of the Lagrange
mission, a mission designed to be positioned at the L5 Lagrangian
point to monitor space weather from its source on the Sun, through the
heliosphere, to the Earth. LUCI will provide solar coronal images at
a 2-3 minute cadence in a pass-band centred on 19.5 nm. Observations
made through this pass-band allow for the detection and monitoring of
semi-static coronal structures such as coronal holes, prominences,
and active regions; as well as transient phenomena such as solar
flares, limb Coronal Mass Ejections (CMEs), EUV waves, and coronal
dimmings. <P />In this presentation I will discuss LUCI's latest
design characteristics and the rationale behind several of the design
decisions. I will present the observational advantages for space-weather
monitoring from the L5 point, especially with an instrument such as
LUCI, which will have a novel off-axis 'wide' field-of-view, designed
to observe the solar disk extending out in to the middle corona, close
to the the Sun-Earth line. I will present proxy data highlighting
structures that can be seen in this region and the current roadmap
for the instrument development.
---------------------------------------------------------
Title: Long-term Evolution of the Solar Corona Using PROBA2 Data
Authors: West, M. J.; Mierla, M.; Janssens, J.; D'Huys, E.; Wauters,
L.; Seaton, D. B.; Berghmans, D.; Podladchikova, O.
2020AGUFMSH0300011W Altcode:
We use the SWAP imager onboard PROBA2 mission to study the evolution of
large-scale EUV structures in the solar corona observed throughout Solar
Cycle 24 (from 2010 to 2019). We look at the evolution of the coronal
features on-disk and at different heights above the solar surface
and compare them at different phases of the solar cycle, as well as
with sunspot number evolution and with the PROBA2/LYRA signal. We
find that the three time series (SWAP on-disk average brightness,
sunspot number and LYRA irradiance) are very well correlated, with
correlation coefficients around 0.9. Large-scale off-limb structures
were visible from around March 2010 to around March 2016, meaning that
they were absent at the minimum phase of solar activity.
---------------------------------------------------------
Title: Observation of Smallest Ever Detected Brightening Events with
the Solar Orbiter EUI HRI-EUV Imager
Authors: Parenti, S.; Berghmans, D.; Buchlin, E.; Teriaca, L.; Auchere,
F.; Harra, L.; Long, D.; Rochus, P. L.; Schühle, U.; Aznar Cuadrado,
R.; Gissot, S.; Kraaikamp, E.; Smith, P.; Stegen, K.; Verbeeck, C.
2020AGUFMSH038..01P Altcode:
The Extreme Ultraviolet Imager (EUI) suite on board Solar Orbiter
acquired its first images in May 2020. The passband of the 17.4 nm
High Resolution Imager (HRI-EUV) is dominated by emission lines of
Fe IX and Fe X, that is the 1 million degree solar corona. The solar
atmosphere at this temperature is dynamic at all scales, down to the
highest spatial resolution available from instruments priori to Solar
Orbiter. During the Commissioning phase, HRI-EUV acquired several high
temporal resolution (a few seconds) sequences at quiet Sun regions at
disk center. The instrument revealed a multitude of brightenings at
the smallest-ever detectable spatial scales which, at that time, was
about 400 km (two pixels). These events appear to be present everywhere
all the time. We present the first results of the analysis of these
sequences with the aim of understanding the role of these small scale
events in the heating of the solar corona.
---------------------------------------------------------
Title: First results from the EUI and SPICE observations of Alpha
Leo near Solar Orbiter first perihelion
Authors: Buchlin, E.; Teriaca, L.; Giunta, A. S.; Grundy, T.; Andretta,
V.; Auchere, F.; Peter, H.; Berghmans, D.; Carlsson, M.; Fludra, A.;
Harra, L.; Hassler, D.; Long, D.; Rochus, P. L.; Schühle, U.; Aznar
Cuadrado, R.; Caldwell, M.; Caminade, S.; DeForest, C.; Fredvik, T.;
Gissot, S.; Heerlein, K.; Janvier, M.; Kraaikamp, E.; Kucera, T. A.;
Müller, D.; Parenti, S.; Schmutz, W. K.; Sidher, S.; Smith, P.;
Stegen, K.; Thompson, W. T.; Verbeeck, C.; Williams, D.; Young, P. R.
2020AGUFMSH0360024B Altcode:
On June 16th 2020 Solar Orbiter made a dedicated observing campaign
where the spacecraft pointed to the solar limb to allow some of the
high resolution instruments to observe the ingress (at the east limb)
and later the egress (west limb) of the occultation of the star Alpha
Leonis by the solar disk. The star was chosen because its luminosity and
early spectral type ensure high and stable flux at wavelengths between
100 and 122 nanometers, a range observed by the High Resolution EUI
Lyman alpha telescope (HRI-LYA) and by the long wavelength channel
of the SPICE spectrograph. Star observations, when feasible, allow
to gather a great deal of information on the instrument performances,
such as the radiometric performance and the instrument optical point
spread function (PSF). <P />We report here the first results from the
above campaign for the two instruments.
---------------------------------------------------------
Title: Solar Orbiter: connecting remote sensing and in situ
measurements
Authors: Horbury, T. S.; Auchere, F.; Antonucci, E.; Berghmans, D.;
Bruno, R.; Carlsson, M.; del Toro Iniesta, J. C.; Fludra, A.; Harra,
L.; Hassler, D.; Heinzel, P.; Howard, R. A.; Krucker, S.; Livi, S. A.;
Long, D.; Louarn, P.; Maksimovic, M.; Mueller, D.; Owen, C. J.; Peter,
H.; Rochus, P. L.; Rodriguez-Pacheco, J.; Romoli, M.; Schühle, U.;
Solanki, S. K.; Teriaca, L.; Wimmer-Schweingruber, R. F.; Zouganelis,
Y.; Laker, R.
2020AGUFMSH038..10H Altcode:
A key science goal of the Solar Orbiter mission is to make connections
between phenomena on the Sun and their manifestations in interplanetary
space. To that end, the spacecraft carries a carefully tailored
payload of six remote sensing instruments and four making in situ
measurements. During June 2020, while the spacecraft was around 0.5
AU from the Sun, the remote sensing instruments operated for several
days. While this was primarily an engineering activity, the resulting
observations provided outstanding measurements and represent the ideal
first opportunity to investigate the potential for making connections
between the remote sensing and in situ payloads on Solar Orbiter. <P
/>We present a preliminary analysis of the available remote sensing and
in situ observations, showing how connections can be made, and discuss
the potential for further, more precise mapping to be performed as
the mission progresses.
---------------------------------------------------------
Title: First Images and Initial In-Flight Performance of the Extreme
Ultraviolet Imager On-Board Solar Orbiter.
Authors: Auchere, F.; Gissot, S.; Teriaca, L.; Berghmans, D.; Harra,
L.; Long, D.; Rochus, P. L.; Smith, P.; Schühle, U.; Stegen, K.;
Aznar Cuadrado, R.; Heerlein, K.; Kraaikamp, E.; Verbeeck, C.
2020AGUFMSH0360025A Altcode:
The Extreme Ultraviolet Imager (EUI) on board Solar Orbiter is
composed of two High Resolution Imagers working at 121.6 (HRI-LYA,
H I, chromosphere) and 17.4 nm (HRI-EUV, Fe IX/X, corona) and one
dual-band Full Sun Imager (FSI) working at 30.4 nm (He II, transition
region) and 17.4 nm (Fe IX/X, corona). During the commissioning period
following the launch of Solar Orbiter and two and a half months of
outgassing, EUI acquired its first solar images on May 12th, 2020 at
about 0.67 AU. Most of the capabilities of the instrument have been
tested during the following weeks, which revealed excellent overall
performance. HRI-EUV already provided images with an angular resolution
equivalent to ~0.6" (2 pixels) at 1 A.U. HRI-LYA will routinely provide
images of the Sun at Lyman alpha, which have been otherwise relatively
rare, with sub-second cadence capability. FSI will provide context for
connection science but it will also explore regions of the corona never
imaged before at EUV wavelengths, owing to its 3.8° field of view. EUI
uses a complex on-board image processing system including advanced
image compression and event detection algorithms. In particular,
commissioning tests confirm the good performance of the compression,
which is critical given the limited total telemetry volume imposed by
the mission profile. In this paper, we present the main characteristics
of the first images taken in each channel and we provide an initial
assessment of the in-flight performance.
---------------------------------------------------------
Title: First results from combined EUI and SPICE observations of
Lyman lines of Hydrogen and He II
Authors: Teriaca, L.; Aznar Cuadrado, R.; Giunta, A. S.; Grundy, T.;
Parenti, S.; Auchere, F.; Vial, J. C.; Fludra, A.; Berghmans, D.;
Carlsson, M.; Harra, L.; Hassler, D.; Long, D.; Peter, H.; Rochus,
P. L.; Schühle, U.; Buchlin, E.; Caldwell, M.; Caminade, S.; DeForest,
C.; Fredvik, T.; Gissot, S.; Heerlein, K.; Janvier, M.; Kraaikamp,
E.; Kucera, T. A.; Mueller, D.; Schmutz, W. K.; Sidher, S.; Smith, P.;
Stegen, K.; Thompson, W. T.; Verbeeck, C.; Williams, D.; Young, P. R.
2020AGUFMSH0360003T Altcode:
The Solar Orbiter spacecraft carries a powerful set of remote
sensing instruments that allow studying the solar atmosphere with
unprecedented diagnostic capabilities. Many such diagnostics require
the simultaneous usage of more than one instrument. One example of that
is the capability, for the first time, to obtain (near) simultaneous
spatially resolved observations of the emission from the first three
lines of the Lyman series of hydrogen and of He II Lyman alpha. In fact,
the SPectral Imaging of the Coronal Environment (SPICE) spectrometer
can observe the Lyman beta and gamma lines in its long wavelength
(SPICE-LW) channel, the High Resolution Lyman Alpha (HRI-LYA) telescope
of the Extreme Ultraviolet Imager (EUI) acquires narrow band images in
the Lyman alpha line while the Full Disk Imager (FSI) of EUI can take
images dominated by the Lyman alpha line of ionized Helium at 30.4 nm
(FSI-304). Being hydrogen and helium the main components of our star,
these very bright transitions play an important role in the energy
budget of the outer atmosphere via radiative losses and the measurement
of their profiles and radiance ratios is a fundamental constraint to
any comprehensive modelization effort of the upper solar chromosphere
and transition region. Additionally, monitoring their average ratios
can serve as a check out for the relative radiometric performance of
the two instruments throughout the mission. Although the engineering
data acquired so far are far from ideal in terms of time simultaneity
(often only within about 1 h) and line coverage (often only Lyman beta
was acquired by SPICE and not always near simultaneous images from all
three telescopes are available) the analysis we present here still
offers a great opportunity to have a first look at the potential of
this diagnostic from the two instruments. In fact, we have identified
a series of datasets obtained at disk center and at various positions
at the solar limb that allow studying the Lyman alpha to beta radiance
ratio and their relation to He II 30.4 as a function of the position
on the Sun (disk center versus limb and quiet Sun versus coronal holes).
---------------------------------------------------------
Title: Very high-resolution observations of the solar atmosphere
in H I Lyman alpha and Fe IX-X at 17.4 nm as seen by EUI aboard
Solar Orbiter
Authors: Aznar Cuadrado, R.; Berghmans, D.; Teriaca, L.; Gissot,
S.; Schühle, U.; Auchere, F.; Harra, L.; Long, D.; Rochus, P. L.;
Heerlein, K.; Kraaikamp, E.; Smith, P.; Stegen, K.; Verbeeck, C.
2020AGUFMSH0360026A Altcode:
The Extreme Ultraviolet Imager (EUI) aboard Solar Orbiter consists of
three telescopes, the Full Sun Imager (FSI) and two High Resolution
Imagers (HRIs). The two HRI telescopes provide images of the base
of the corona, near to the chromosphere, and of the 1 million K
corona. In fact, the HRI-EUV telescope operates around 17.4 nm to
obtain images dominated by emission from lines generated from Fe-IX
and X ions, formed at about 1 MK, while the HRI-LYA telescope provides
narrow band images dominated by the H I Lyman alpha line at 121.6 nm,
formed in the upper chromosphere/lower transition region of the solar
atmosphere around 20,000 K. Thus, the two imagers provide a powerful
diagnostics of the solar structural organization, in terms of loop
hierarchies and connectivity. Here we present an analysis of the first
two near-simultaneous (within 15s) high-resolution images of the solar
quiet atmosphere obtained near disk center by the two high-resolution
telescopes on May 30th 2020, during the commissioning phase of the
mission , when Solar Orbiter was at about 0.56 AU from the Sun.
---------------------------------------------------------
Title: Coordination within the remote sensing payload on the Solar
Orbiter mission
Authors: Auchère, F.; Andretta, V.; Antonucci, E.; Bach, N.;
Battaglia, M.; Bemporad, A.; Berghmans, D.; Buchlin, E.; Caminade,
S.; Carlsson, M.; Carlyle, J.; Cerullo, J. J.; Chamberlin, P. C.;
Colaninno, R. C.; Davila, J. M.; De Groof, A.; Etesi, L.; Fahmy,
S.; Fineschi, S.; Fludra, A.; Gilbert, H. R.; Giunta, A.; Grundy,
T.; Haberreiter, M.; Harra, L. K.; Hassler, D. M.; Hirzberger, J.;
Howard, R. A.; Hurford, G.; Kleint, L.; Kolleck, M.; Krucker, S.;
Lagg, A.; Landini, F.; Long, D. M.; Lefort, J.; Lodiot, S.; Mampaey,
B.; Maloney, S.; Marliani, F.; Martinez-Pillet, V.; McMullin, D. R.;
Müller, D.; Nicolini, G.; Orozco Suarez, D.; Pacros, A.; Pancrazzi,
M.; Parenti, S.; Peter, H.; Philippon, A.; Plunkett, S.; Rich, N.;
Rochus, P.; Rouillard, A.; Romoli, M.; Sanchez, L.; Schühle, U.;
Sidher, S.; Solanki, S. K.; Spadaro, D.; St Cyr, O. C.; Straus, T.;
Tanco, I.; Teriaca, L.; Thompson, W. T.; del Toro Iniesta, J. C.;
Verbeeck, C.; Vourlidas, A.; Watson, C.; Wiegelmann, T.; Williams,
D.; Woch, J.; Zhukov, A. N.; Zouganelis, I.
2020A&A...642A...6A Altcode:
Context. To meet the scientific objectives of the mission, the Solar
Orbiter spacecraft carries a suite of in-situ (IS) and remote sensing
(RS) instruments designed for joint operations with inter-instrument
communication capabilities. Indeed, previous missions have shown that
the Sun (imaged by the RS instruments) and the heliosphere (mainly
sampled by the IS instruments) should be considered as an integrated
system rather than separate entities. Many of the advances expected
from Solar Orbiter rely on this synergistic approach between IS and
RS measurements. <BR /> Aims: Many aspects of hardware development,
integration, testing, and operations are common to two or more
RS instruments. In this paper, we describe the coordination effort
initiated from the early mission phases by the Remote Sensing Working
Group. We review the scientific goals and challenges, and give an
overview of the technical solutions devised to successfully operate
these instruments together. <BR /> Methods: A major constraint for the
RS instruments is the limited telemetry (TM) bandwidth of the Solar
Orbiter deep-space mission compared to missions in Earth orbit. Hence,
many of the strategies developed to maximise the scientific return from
these instruments revolve around the optimisation of TM usage, relying
for example on onboard autonomy for data processing, compression,
and selection for downlink. The planning process itself has been
optimised to alleviate the dynamic nature of the targets, and an
inter-instrument communication scheme has been implemented which can
be used to autonomously alter the observing modes. We also outline the
plans for in-flight cross-calibration, which will be essential to the
joint data reduction and analysis. <BR /> Results: The RS instrument
package on Solar Orbiter will carry out comprehensive measurements
from the solar interior to the inner heliosphere. Thanks to the close
coordination between the instrument teams and the European Space
Agency, several challenges specific to the RS suite were identified
and addressed in a timely manner.
---------------------------------------------------------
Title: The Solar Orbiter Science Activity Plan. Translating solar
and heliospheric physics questions into action
Authors: Zouganelis, I.; De Groof, A.; Walsh, A. P.; Williams, D. R.;
Müller, D.; St Cyr, O. C.; Auchère, F.; Berghmans, D.; Fludra,
A.; Horbury, T. S.; Howard, R. A.; Krucker, S.; Maksimovic, M.;
Owen, C. J.; Rodríguez-Pacheco, J.; Romoli, M.; Solanki, S. K.;
Watson, C.; Sanchez, L.; Lefort, J.; Osuna, P.; Gilbert, H. R.;
Nieves-Chinchilla, T.; Abbo, L.; Alexandrova, O.; Anastasiadis, A.;
Andretta, V.; Antonucci, E.; Appourchaux, T.; Aran, A.; Arge, C. N.;
Aulanier, G.; Baker, D.; Bale, S. D.; Battaglia, M.; Bellot Rubio,
L.; Bemporad, A.; Berthomier, M.; Bocchialini, K.; Bonnin, X.; Brun,
A. S.; Bruno, R.; Buchlin, E.; Büchner, J.; Bucik, R.; Carcaboso,
F.; Carr, R.; Carrasco-Blázquez, I.; Cecconi, B.; Cernuda Cangas, I.;
Chen, C. H. K.; Chitta, L. P.; Chust, T.; Dalmasse, K.; D'Amicis, R.;
Da Deppo, V.; De Marco, R.; Dolei, S.; Dolla, L.; Dudok de Wit, T.;
van Driel-Gesztelyi, L.; Eastwood, J. P.; Espinosa Lara, F.; Etesi,
L.; Fedorov, A.; Félix-Redondo, F.; Fineschi, S.; Fleck, B.; Fontaine,
D.; Fox, N. J.; Gandorfer, A.; Génot, V.; Georgoulis, M. K.; Gissot,
S.; Giunta, A.; Gizon, L.; Gómez-Herrero, R.; Gontikakis, C.; Graham,
G.; Green, L.; Grundy, T.; Haberreiter, M.; Harra, L. K.; Hassler,
D. M.; Hirzberger, J.; Ho, G. C.; Hurford, G.; Innes, D.; Issautier,
K.; James, A. W.; Janitzek, N.; Janvier, M.; Jeffrey, N.; Jenkins,
J.; Khotyaintsev, Y.; Klein, K. -L.; Kontar, E. P.; Kontogiannis,
I.; Krafft, C.; Krasnoselskikh, V.; Kretzschmar, M.; Labrosse, N.;
Lagg, A.; Landini, F.; Lavraud, B.; Leon, I.; Lepri, S. T.; Lewis,
G. R.; Liewer, P.; Linker, J.; Livi, S.; Long, D. M.; Louarn, P.;
Malandraki, O.; Maloney, S.; Martinez-Pillet, V.; Martinovic, M.;
Masson, A.; Matthews, S.; Matteini, L.; Meyer-Vernet, N.; Moraitis,
K.; Morton, R. J.; Musset, S.; Nicolaou, G.; Nindos, A.; O'Brien,
H.; Orozco Suarez, D.; Owens, M.; Pancrazzi, M.; Papaioannou, A.;
Parenti, S.; Pariat, E.; Patsourakos, S.; Perrone, D.; Peter, H.;
Pinto, R. F.; Plainaki, C.; Plettemeier, D.; Plunkett, S. P.; Raines,
J. M.; Raouafi, N.; Reid, H.; Retino, A.; Rezeau, L.; Rochus, P.;
Rodriguez, L.; Rodriguez-Garcia, L.; Roth, M.; Rouillard, A. P.;
Sahraoui, F.; Sasso, C.; Schou, J.; Schühle, U.; Sorriso-Valvo, L.;
Soucek, J.; Spadaro, D.; Stangalini, M.; Stansby, D.; Steller, M.;
Strugarek, A.; Štverák, Š.; Susino, R.; Telloni, D.; Terasa, C.;
Teriaca, L.; Toledo-Redondo, S.; del Toro Iniesta, J. C.; Tsiropoula,
G.; Tsounis, A.; Tziotziou, K.; Valentini, F.; Vaivads, A.; Vecchio,
A.; Velli, M.; Verbeeck, C.; Verdini, A.; Verscharen, D.; Vilmer, N.;
Vourlidas, A.; Wicks, R.; Wimmer-Schweingruber, R. F.; Wiegelmann,
T.; Young, P. R.; Zhukov, A. N.
2020A&A...642A...3Z Altcode: 2020arXiv200910772Z
Solar Orbiter is the first space mission observing the solar plasma
both in situ and remotely, from a close distance, in and out of the
ecliptic. The ultimate goal is to understand how the Sun produces
and controls the heliosphere, filling the Solar System and driving
the planetary environments. With six remote-sensing and four in-situ
instrument suites, the coordination and planning of the operations are
essential to address the following four top-level science questions:
(1) What drives the solar wind and where does the coronal magnetic field
originate?; (2) How do solar transients drive heliospheric variability?;
(3) How do solar eruptions produce energetic particle radiation that
fills the heliosphere?; (4) How does the solar dynamo work and drive
connections between the Sun and the heliosphere? Maximising the
mission's science return requires considering the characteristics
of each orbit, including the relative position of the spacecraft
to Earth (affecting downlink rates), trajectory events (such
as gravitational assist manoeuvres), and the phase of the solar
activity cycle. Furthermore, since each orbit's science telemetry
will be downloaded over the course of the following orbit, science
operations must be planned at mission level, rather than at the level
of individual orbits. It is important to explore the way in which those
science questions are translated into an actual plan of observations
that fits into the mission, thus ensuring that no opportunities are
missed. First, the overarching goals are broken down into specific,
answerable questions along with the required observations and the
so-called Science Activity Plan (SAP) is developed to achieve this. The
SAP groups objectives that require similar observations into Solar
Orbiter Observing Plans, resulting in a strategic, top-level view of
the optimal opportunities for science observations during the mission
lifetime. This allows for all four mission goals to be addressed. In
this paper, we introduce Solar Orbiter's SAP through a series of
examples and the strategy being followed.
---------------------------------------------------------
Title: Models and data analysis tools for the Solar Orbiter mission
Authors: Rouillard, A. P.; Pinto, R. F.; Vourlidas, A.; De Groof, A.;
Thompson, W. T.; Bemporad, A.; Dolei, S.; Indurain, M.; Buchlin, E.;
Sasso, C.; Spadaro, D.; Dalmasse, K.; Hirzberger, J.; Zouganelis, I.;
Strugarek, A.; Brun, A. S.; Alexandre, M.; Berghmans, D.; Raouafi,
N. E.; Wiegelmann, T.; Pagano, P.; Arge, C. N.; Nieves-Chinchilla,
T.; Lavarra, M.; Poirier, N.; Amari, T.; Aran, A.; Andretta, V.;
Antonucci, E.; Anastasiadis, A.; Auchère, F.; Bellot Rubio, L.;
Nicula, B.; Bonnin, X.; Bouchemit, M.; Budnik, E.; Caminade, S.;
Cecconi, B.; Carlyle, J.; Cernuda, I.; Davila, J. M.; Etesi, L.;
Espinosa Lara, F.; Fedorov, A.; Fineschi, S.; Fludra, A.; Génot,
V.; Georgoulis, M. K.; Gilbert, H. R.; Giunta, A.; Gomez-Herrero, R.;
Guest, S.; Haberreiter, M.; Hassler, D.; Henney, C. J.; Howard, R. A.;
Horbury, T. S.; Janvier, M.; Jones, S. I.; Kozarev, K.; Kraaikamp,
E.; Kouloumvakos, A.; Krucker, S.; Lagg, A.; Linker, J.; Lavraud,
B.; Louarn, P.; Maksimovic, M.; Maloney, S.; Mann, G.; Masson, A.;
Müller, D.; Önel, H.; Osuna, P.; Orozco Suarez, D.; Owen, C. J.;
Papaioannou, A.; Pérez-Suárez, D.; Rodriguez-Pacheco, J.; Parenti,
S.; Pariat, E.; Peter, H.; Plunkett, S.; Pomoell, J.; Raines, J. M.;
Riethmüller, T. L.; Rich, N.; Rodriguez, L.; Romoli, M.; Sanchez,
L.; Solanki, S. K.; St Cyr, O. C.; Straus, T.; Susino, R.; Teriaca,
L.; del Toro Iniesta, J. C.; Ventura, R.; Verbeeck, C.; Vilmer, N.;
Warmuth, A.; Walsh, A. P.; Watson, C.; Williams, D.; Wu, Y.; Zhukov,
A. N.
2020A&A...642A...2R Altcode:
Context. The Solar Orbiter spacecraft will be equipped with a wide
range of remote-sensing (RS) and in situ (IS) instruments to record
novel and unprecedented measurements of the solar atmosphere and
the inner heliosphere. To take full advantage of these new datasets,
tools and techniques must be developed to ease multi-instrument and
multi-spacecraft studies. In particular the currently inaccessible
low solar corona below two solar radii can only be observed
remotely. Furthermore techniques must be used to retrieve coronal
plasma properties in time and in three dimensional (3D) space. Solar
Orbiter will run complex observation campaigns that provide interesting
opportunities to maximise the likelihood of linking IS data to their
source region near the Sun. Several RS instruments can be directed
to specific targets situated on the solar disk just days before
data acquisition. To compare IS and RS, data we must improve our
understanding of how heliospheric probes magnetically connect to the
solar disk. <BR /> Aims: The aim of the present paper is to briefly
review how the current modelling of the Sun and its atmosphere
can support Solar Orbiter science. We describe the results of a
community-led effort by European Space Agency's Modelling and Data
Analysis Working Group (MADAWG) to develop different models, tools,
and techniques deemed necessary to test different theories for the
physical processes that may occur in the solar plasma. The focus here
is on the large scales and little is described with regards to kinetic
processes. To exploit future IS and RS data fully, many techniques have
been adapted to model the evolving 3D solar magneto-plasma from the
solar interior to the solar wind. A particular focus in the paper is
placed on techniques that can estimate how Solar Orbiter will connect
magnetically through the complex coronal magnetic fields to various
photospheric and coronal features in support of spacecraft operations
and future scientific studies. <BR /> Methods: Recent missions such as
STEREO, provided great opportunities for RS, IS, and multi-spacecraft
studies. We summarise the achievements and highlight the challenges
faced during these investigations, many of which motivated the Solar
Orbiter mission. We present the new tools and techniques developed
by the MADAWG to support the science operations and the analysis of
the data from the many instruments on Solar Orbiter. <BR /> Results:
This article reviews current modelling and tool developments that ease
the comparison of model results with RS and IS data made available
by current and upcoming missions. It also describes the modelling
strategy to support the science operations and subsequent exploitation
of Solar Orbiter data in order to maximise the scientific output
of the mission. <BR /> Conclusions: The on-going community effort
presented in this paper has provided new models and tools necessary
to support mission operations as well as the science exploitation of
the Solar Orbiter data. The tools and techniques will no doubt evolve
significantly as we refine our procedure and methodology during the
first year of operations of this highly promising mission.
---------------------------------------------------------
Title: Understanding the origins of the heliosphere: integrating
observations and measurements from Parker Solar Probe, Solar Orbiter,
and other space- and ground-based observatories
Authors: Velli, M.; Harra, L. K.; Vourlidas, A.; Schwadron,
N.; Panasenco, O.; Liewer, P. C.; Müller, D.; Zouganelis, I.;
St Cyr, O. C.; Gilbert, H.; Nieves-Chinchilla, T.; Auchère, F.;
Berghmans, D.; Fludra, A.; Horbury, T. S.; Howard, R. A.; Krucker,
S.; Maksimovic, M.; Owen, C. J.; Rodríguez-Pacheco, J.; Romoli,
M.; Solanki, S. K.; Wimmer-Schweingruber, R. F.; Bale, S.; Kasper,
J.; McComas, D. J.; Raouafi, N.; Martinez-Pillet, V.; Walsh, A. P.;
De Groof, A.; Williams, D.
2020A&A...642A...4V Altcode:
Context. The launch of Parker Solar Probe (PSP) in 2018, followed
by Solar Orbiter (SO) in February 2020, has opened a new window in
the exploration of solar magnetic activity and the origin of the
heliosphere. These missions, together with other space observatories
dedicated to solar observations, such as the Solar Dynamics Observatory,
Hinode, IRIS, STEREO, and SOHO, with complementary in situ observations
from WIND and ACE, and ground based multi-wavelength observations
including the DKIST observatory that has just seen first light,
promise to revolutionize our understanding of the solar atmosphere
and of solar activity, from the generation and emergence of the Sun's
magnetic field to the creation of the solar wind and the acceleration of
solar energetic particles. <BR /> Aims: Here we describe the scientific
objectives of the PSP and SO missions, and highlight the potential for
discovery arising from synergistic observations. Here we put particular
emphasis on how the combined remote sensing and in situ observations of
SO, that bracket the outer coronal and inner heliospheric observations
by PSP, may provide a reconstruction of the solar wind and magnetic
field expansion from the Sun out to beyond the orbit of Mercury in the
first phases of the mission. In the later, out-of-ecliptic portions of
the SO mission, the solar surface magnetic field measurements from SO
and the multi-point white-light observations from both PSP and SO will
shed light on the dynamic, intermittent solar wind escaping from helmet
streamers, pseudo-streamers, and the confined coronal plasma, and on
solar energetic particle transport. <BR /> Methods: Joint measurements
during PSP-SO alignments, and magnetic connections along the same
flux tube complemented by alignments with Earth, dual PSP-Earth,
and SO-Earth, as well as with STEREO-A, SOHO, and BepiColumbo will
allow a better understanding of the in situ evolution of solar-wind
plasma flows and the full three-dimensional distribution of the
solar wind from a purely observational point of view. Spectroscopic
observations of the corona, and optical and radio observations,
combined with direct in situ observations of the accelerating solar
wind will provide a new foundation for understanding the fundamental
physical processes leading to the energy transformations from solar
photospheric flows and magnetic fields into the hot coronal plasma
and magnetic fields and finally into the bulk kinetic energy of the
solar wind and solar energetic particles. <BR /> Results: We discuss
the initial PSP observations, which already provide a compelling
rationale for new measurement campaigns by SO, along with ground-
and space-based assets within the synergistic context described above.
---------------------------------------------------------
Title: The Solar Orbiter mission. Science overview
Authors: Müller, D.; St. Cyr, O. C.; Zouganelis, I.; Gilbert, H. R.;
Marsden, R.; Nieves-Chinchilla, T.; Antonucci, E.; Auchère, F.;
Berghmans, D.; Horbury, T. S.; Howard, R. A.; Krucker, S.; Maksimovic,
M.; Owen, C. J.; Rochus, P.; Rodriguez-Pacheco, J.; Romoli, M.;
Solanki, S. K.; Bruno, R.; Carlsson, M.; Fludra, A.; Harra, L.;
Hassler, D. M.; Livi, S.; Louarn, P.; Peter, H.; Schühle, U.;
Teriaca, L.; del Toro Iniesta, J. C.; Wimmer-Schweingruber, R. F.;
Marsch, E.; Velli, M.; De Groof, A.; Walsh, A.; Williams, D.
2020A&A...642A...1M Altcode: 2020arXiv200900861M
<BR /> Aims: Solar Orbiter, the first mission of ESA's Cosmic Vision
2015-2025 programme and a mission of international collaboration between
ESA and NASA, will explore the Sun and heliosphere from close up and
out of the ecliptic plane. It was launched on 10 February 2020 04:03
UTC from Cape Canaveral and aims to address key questions of solar and
heliospheric physics pertaining to how the Sun creates and controls
the Heliosphere, and why solar activity changes with time. To answer
these, the mission carries six remote-sensing instruments to observe
the Sun and the solar corona, and four in-situ instruments to measure
the solar wind, energetic particles, and electromagnetic fields. In
this paper, we describe the science objectives of the mission, and how
these will be addressed by the joint observations of the instruments
onboard. <BR /> Methods: The paper first summarises the mission-level
science objectives, followed by an overview of the spacecraft and
payload. We report the observables and performance figures of each
instrument, as well as the trajectory design. This is followed by a
summary of the science operations concept. The paper concludes with a
more detailed description of the science objectives. <BR /> Results:
Solar Orbiter will combine in-situ measurements in the heliosphere
with high-resolution remote-sensing observations of the Sun to address
fundamental questions of solar and heliospheric physics. The performance
of the Solar Orbiter payload meets the requirements derived from the
mission's science objectives. Its science return will be augmented
further by coordinated observations with other space missions and
ground-based observatories. <P />ARRAY(0x207ce98)
---------------------------------------------------------
Title: The Solar Orbiter EUI instrument: The Extreme Ultraviolet
Imager
Authors: Rochus, P.; Auchère, F.; Berghmans, D.; Harra, L.; Schmutz,
W.; Schühle, U.; Addison, P.; Appourchaux, T.; Aznar Cuadrado,
R.; Baker, D.; Barbay, J.; Bates, D.; BenMoussa, A.; Bergmann, M.;
Beurthe, C.; Borgo, B.; Bonte, K.; Bouzit, M.; Bradley, L.; Büchel,
V.; Buchlin, E.; Büchner, J.; Cabé, F.; Cadiergues, L.; Chaigneau,
M.; Chares, B.; Choque Cortez, C.; Coker, P.; Condamin, M.; Coumar,
S.; Curdt, W.; Cutler, J.; Davies, D.; Davison, G.; Defise, J. -M.;
Del Zanna, G.; Delmotte, F.; Delouille, V.; Dolla, L.; Dumesnil, C.;
Dürig, F.; Enge, R.; François, S.; Fourmond, J. -J.; Gillis, J. -M.;
Giordanengo, B.; Gissot, S.; Green, L. M.; Guerreiro, N.; Guilbaud,
A.; Gyo, M.; Haberreiter, M.; Hafiz, A.; Hailey, M.; Halain, J. -P.;
Hansotte, J.; Hecquet, C.; Heerlein, K.; Hellin, M. -L.; Hemsley, S.;
Hermans, A.; Hervier, V.; Hochedez, J. -F.; Houbrechts, Y.; Ihsan,
K.; Jacques, L.; Jérôme, A.; Jones, J.; Kahle, M.; Kennedy, T.;
Klaproth, M.; Kolleck, M.; Koller, S.; Kotsialos, E.; Kraaikamp, E.;
Langer, P.; Lawrenson, A.; Le Clech', J. -C.; Lenaerts, C.; Liebecq,
S.; Linder, D.; Long, D. M.; Mampaey, B.; Markiewicz-Innes, D.;
Marquet, B.; Marsch, E.; Matthews, S.; Mazy, E.; Mazzoli, A.; Meining,
S.; Meltchakov, E.; Mercier, R.; Meyer, S.; Monecke, M.; Monfort,
F.; Morinaud, G.; Moron, F.; Mountney, L.; Müller, R.; Nicula, B.;
Parenti, S.; Peter, H.; Pfiffner, D.; Philippon, A.; Phillips, I.;
Plesseria, J. -Y.; Pylyser, E.; Rabecki, F.; Ravet-Krill, M. -F.;
Rebellato, J.; Renotte, E.; Rodriguez, L.; Roose, S.; Rosin, J.;
Rossi, L.; Roth, P.; Rouesnel, F.; Roulliay, M.; Rousseau, A.; Ruane,
K.; Scanlan, J.; Schlatter, P.; Seaton, D. B.; Silliman, K.; Smit,
S.; Smith, P. J.; Solanki, S. K.; Spescha, M.; Spencer, A.; Stegen,
K.; Stockman, Y.; Szwec, N.; Tamiatto, C.; Tandy, J.; Teriaca, L.;
Theobald, C.; Tychon, I.; van Driel-Gesztelyi, L.; Verbeeck, C.;
Vial, J. -C.; Werner, S.; West, M. J.; Westwood, D.; Wiegelmann, T.;
Willis, G.; Winter, B.; Zerr, A.; Zhang, X.; Zhukov, A. N.
2020A&A...642A...8R Altcode:
Context. The Extreme Ultraviolet Imager (EUI) is part of the remote
sensing instrument package of the ESA/NASA Solar Orbiter mission
that will explore the inner heliosphere and observe the Sun from
vantage points close to the Sun and out of the ecliptic. Solar Orbiter
will advance the "connection science" between solar activity and the
heliosphere. <BR /> Aims: With EUI we aim to improve our understanding
of the structure and dynamics of the solar atmosphere, globally as well
as at high resolution, and from high solar latitude perspectives. <BR />
Methods: The EUI consists of three telescopes, the Full Sun Imager and
two High Resolution Imagers, which are optimised to image in Lyman-α
and EUV (17.4 nm, 30.4 nm) to provide a coverage from chromosphere
up to corona. The EUI is designed to cope with the strong constraints
imposed by the Solar Orbiter mission characteristics. Limited telemetry
availability is compensated by state-of-the-art image compression,
onboard image processing, and event selection. The imposed power
limitations and potentially harsh radiation environment necessitate
the use of novel CMOS sensors. As the unobstructed field of view of
the telescopes needs to protrude through the spacecraft's heat shield,
the apertures have been kept as small as possible, without compromising
optical performance. This led to a systematic effort to optimise the
throughput of every optical element and the reduction of noise levels
in the sensor. <BR /> Results: In this paper we review the design
of the two elements of the EUI instrument: the Optical Bench System
and the Common Electronic Box. Particular attention is also given to
the onboard software, the intended operations, the ground software,
and the foreseen data products. <BR /> Conclusions: The EUI will
bring unique science opportunities thanks to its specific design,
its viewpoint, and to the planned synergies with the other Solar
Orbiter instruments. In particular, we highlight science opportunities
brought by the out-of-ecliptic vantage point of the solar poles,
the high-resolution imaging of the high chromosphere and corona,
and the connection to the outer corona as observed by coronagraphs.
---------------------------------------------------------
Title: LUCI onboard Lagrange, the next generation of EUV space
weather monitoring
Authors: West, Matthew J.; Kintziger, Christian; Haberreiter, Margit;
Gyo, Manfred; Berghmans, David; Gissot, Samuel; Büchel, Valeria;
Golub, Leon; Shestov, Sergei; Davies, Jackie A.
2020JSWSC..10...49W Altcode: 2020arXiv200904788W
Lagrange eUv Coronal Imager (LUCI) is a solar imager in the Extreme
UltraViolet (EUV) that is being developed as part of the Lagrange
mission, a mission designed to be positioned at the L5 Lagrangian
point to monitor space weather from its source on the Sun, through
the heliosphere, to the Earth. LUCI will use an off-axis two mirror
design equipped with an EUV enhanced active pixel sensor. This type
of detector has advantages that promise to be very beneficial for
monitoring the source of space weather in the EUV. LUCI will also
have a novel off-axis wide field-of-view, designed to observe the
solar disk, the lower corona, and the extended solar atmosphere close
to the Sun-Earth line. LUCI will provide solar coronal images at a
2-3 min cadence in a pass-band centred on 19.5. Observations made
through this pass-band allow for the detection and monitoring of
semi-static coronal structures such as coronal holes, prominences,
and active regions; as well as transient phenomena such as solar
flares, limb coronal mass ejections (CMEs), EUV waves, and coronal
dimmings. The LUCI data will complement EUV solar observations provided
by instruments located along the Sun-Earth line such as PROBA2-SWAP,
SUVI-GOES and SDO-AIA, as well as provide unique observations to improve
space weather forecasts. Together with a suite of other remote-sensing
and in-situ instruments onboard Lagrange, LUCI will provide science
quality operational observations for space weather monitoring.
---------------------------------------------------------
Title: Long-Term Evolution of the Solar Corona Using PROBA2 Data
Authors: Mierla, Marilena; Janssens, Jan; D'Huys, Elke; Wauters,
Laurence; West, Matthew J.; Seaton, Daniel B.; Berghmans, David;
Podladchikova, Elena
2020SoPh..295...66M Altcode: 2020arXiv200409785M
We use The Sun Watcher with Active Pixel System detector and Image
Processing (SWAP) imager onboard the Project for Onboard Autonomy 2
(PROBA2) mission to study the evolution of large-scale EUV structures
in the solar corona observed throughout Solar Cycle 24 (from 2010 to
2019). We discuss the evolution of the on-disk coronal features and
at different heights above the solar surface based on EUV intensity
changes. We also look at the evolution of the corona in equatorial and
polar regions and compare them at different phases of the solar cycle,
as well as with sunspot-number evolution and with the PROBA2/Large Yield
RAdiometer (LYRA) signal. The main results are as follows: The three
time series (SWAP on-disk average brightness, sunspot number, and LYRA
irradiance) are very well correlated, with correlation coefficients
around 0.9. The average rotation rate of bright features at latitudes
of +15<SUP>∘</SUP>, 0<SUP>∘</SUP>, and −15<SUP>∘</SUP> was
around 15 degree day<SUP>−1</SUP> throughout the period studied. A
secondary peak in EUV averaged intensity at the poles was observed on
the descending phase of SC24. These peaks (at North and South Poles,
respectively) seem to be associated with the start of the development of
the (polar) coronal holes. Large-scale off-limb structures were visible
from around March 2010 to around March 2016, meaning that they were
absent at the minimum phase of solar activity. A fan at the North Pole
persisted for more than 11 Carrington rotations (February 2014 to March
2015), and it could be seen up to altitudes of 1.6 R<SUB>⊙</SUB>.
---------------------------------------------------------
Title: The Solaris Solar Polar Mission
Authors: Hassler, Donald M.; Newmark, Jeff; Gibson, Sarah; Harra,
Louise; Appourchaux, Thierry; Auchere, Frederic; Berghmans, David;
Colaninno, Robin; Fineschi, Silvano; Gizon, Laurent; Gosain, Sanjay;
Hoeksema, Todd; Kintziger, Christian; Linker, John; Rochus, Pierre;
Schou, Jesper; Viall, Nicholeen; West, Matt; Woods, Tom; Wuelser,
Jean-Pierre
2020EGUGA..2217703H Altcode:
The solar poles are one of the last unexplored regions of the solar
system. Although Ulysses flew over the poles in the 1990s, it did
not have remote sensing instruments onboard to probe the Sun's polar
magnetic field or surface/sub-surface flows.We will discuss Solaris,
a proposed Solar Polar MIDEX mission to revolutionize our understanding
of the Sun by addressing fundamental questions that can only be answered
from a polar vantage point. Solaris uses a Jupiter gravity assist to
escape the ecliptic plane and fly over both poles of the Sun to >75
deg. inclination, obtaining the first high-latitude, multi-month-long,
continuous remote-sensing solar observations. Solaris will address key
outstanding, breakthrough problems in solar physics and fill holes in
our scientific understanding that will not be addressed by current
missions.With focused science and a simple, elegant mission design,
Solaris will also provide enabling observations for space weather
research (e.g. polar view of CMEs), and stimulate future research
through new unanticipated discoveries.
---------------------------------------------------------
Title: The Solar Orbiter EUI instrument: The Extreme Ultraviolet
Imager
Authors: Rochus, P. L.; Auchere, F.; Berghmans, D.; Harra, L.; Schmutz,
W. K.; Schühle, U.
2019AGUFMSH21D3291R Altcode:
The Extreme Ultraviolet Imager (EUI) is part of the remote sensing
instrument package of the ESA/NASA Solar Orbiter mission that will
explore the inner heliosphere and observe the Sun from vantage points
close to the Sun and out-of-the-ecliptic. <P />EUI aims at improving our
understanding of the structure and dynamics of the solar atmosphere. EUI
will take images of the solar atmosphere, globally as well as at high
resolution, and from high solar latitude perspectives. <P />EUI consists
of 3 telescopes that are optimized to image in Lyman-a and EUV 17.4nm
and 30.4 nm to provide a coverage from chromosphere up to corona. EUI
is designed to cope with the strong constraints that Solar Orbiter has
as a deep space mission. Limited telemetry availability is compensated
by state-of-the-art image compression, on board image processing and
event selection. The imposed power limitations and potentially harsh
radiation environment lead to the usage of novel CMOS sensors. As
the unobstructed field of view of the telescopes needs to protrude
through the spacecraft heat shield, the apertures were kept as small as
possible. This lead to a systematic effort to optimize the throughput
of every optical element and the reduction of noise levels in the
sensor. <P />In this paper we review the design of the two elements of
the EUI instrument: the Optical Bench System and the Common Electronic
Box. Particular attention is also given to the on board software,
the intended operations, the ground software and the foreseen data
products. <P />EUI will bring unique science opportunities thanks to its
specific design, its viewpoint and thanks to the planned synergies with
the other Solar Orbiter instruments. We highlight in particular science
opportunities brought by the out-of-ecliptic vantage point of the solar
poles, the high resolution imaging of the high chromosphere and corona,
and the connection to the outer corona as observed by coronagraphs.
---------------------------------------------------------
Title: From PROBA2/SWAP to Solar Orbiter/EUI: exploring the outer
edge of the EUV corona.
Authors: Berghmans, D.; D'Huys, E.; Zhukov, A.; Auchere, F.
2019AGUFMSH13A..01B Altcode:
SWAP is a small coronal EUV imager onboard the ESA microsatellite
PROBA2. Thanks to its large field of view (54 arcmin), spacecraft
offpoints and applied image processing, SWAP has been able to show the
structures of the EUV corona more than 1 Rsun above the limb. This
"middle corona" is in between the classical off limb EUV corona
as seen by e.g. SDO/AIA and the much further white light corona as
seen by e.g. the LASCO coronagraphs and is thus a poorly observed
region. The Middle Corona harbours interesting physics, as it is
here where the solar wind accelerates and the topology of streamers
and pseudo-streamers fade in the solar wind. SWAP imagery has shown
how 'coronal fan' structures in the middle corona survive many solar
rotations and how the extended corona above the solar poles reverses
polarity. The Full Sun Imager (FSI, part of Extreme Ultraviolet Imager
EUI onboard Solar Orbiter) will take this further with a field of view
of 228 arcmin. Furthermore, as embarked on the Solar Orbiter mission
(launch 2020) FSI will be the first to image all this from out of the
ecliptic. In this paper we will review the Middle Corona results of
SWAP and provide an outlook on what to expect from EUI/FSI.
---------------------------------------------------------
Title: PECASUS, European Space Weather Service Network for Aviation
Authors: Harri, A. M.; Kauristie, K.; Andries, J.; Gibbs, M.; Beck,
P.; Berdermann, J.; Perrone, L.; van den Oord, B.; Berghmans, D.;
Bergeot, N.; De Donder, E.; Latocha, M.; Dierckxsens, M.; Haralambous,
H.; Stanislawska, I. M.; Wilken, V.; Romano, V.; Kriegel, M.;
Österberg, K.
2019AGUFMSA33D3168H Altcode:
The PECASUS Consortium (European Consortium for Aviation Space weather
User Services) will provide a space weather service focusing on the
dissemination of warning messages ('advisories') towards aviation
actors and corresponds to extreme space weather events with impact
on aviation GNSS systems, HF communication and radiation levels at
flight altitudes. In November 2018 ICAO (International Civil Aviation
Organization) designated three global space weather service centers
to be operated by the European PECASUS consortium, by United States
and by the consortium of Australia, Canada, France and Japan. <P
/>PECASUS was set-up as a consortium bringing together a number of
European partners with proven space weather service capabilities. The
PECASUS consortium is coordinated by FMI (Finland) who is also the
ultimate responsible for communications towards the aviation sector. The
Advisory Messages are produced by STCE (Belgium) on the basis of expert
interpretation and data streams produced by DLR (Germany), INGV (Italy),
Seibersdorf Laboratories (Austria), STCE (Belgium), SRC (Poland) and
FU (Cyprus). In addition, the MetOffice (UK) will act as a resilience
node in case of a major failure in the network, while the KNMI (The
Netherlands) will take care of user liaison and monitor the PECASUS
performance. <P />The PECASUS Consortium was audited in February 2018
by space weather and operational management experts, nominated by the
World Meteorological Organisation (WMO). The audit addressed a broad
spectrum of criteria under Institutional, Operational, Technical and
Communication/ Dissemination categories. PECASUS was declared fully
compliant in all ICAO/WMO criteria with no areas for improvement
identified. <P />In this presentation we will describe the coordinated
action of three ICAO Space Weather Centers, PECASUS network and its
operations, and the vision of the PECASUS team to move forward. User
interactions such as education and training, user feedback at ESWW,
product and performance verification are part of PECASUS operations.
---------------------------------------------------------
Title: Assessment and recommendations for a consolidated European
approach to space weather - as part of a global space weather effort
Authors: Opgenoorth, Hermann J.; Wimmer-Schweingruber, Robert F.;
Belehaki, Anna; Berghmans, David; Hapgood, Mike; Hesse, Michael;
Kauristie, Kirsti; Lester, Mark; Lilensten, Jean; Messerotti, Mauro;
Temmer, Manuela
2019JSWSC...9A..37O Altcode:
Over the last 10-20 years there has been an ever-increasing
international awareness of risks to modern society from adverse and
potentially harmful - and in extreme cases even disastrous - space
weather events. Many individual countries and even international
organisations like the United Nations (UN) have begun to increase
their activities in preparing for and mitigating effects of adverse
space weather. As in the rest of the world there is also in Europe an
urgent need for coordination of Space Weather efforts in individual
countries as well as in and among European organisations such as
the European Space Agency (ESA) and the European Union (EU). This
coordination should not only improve our ability to meet space weather
risks, but also enable Europe to contribute to on-going global space
weather efforts. While space weather is a global threat, which needs a
global response, it also requires tailored regional and trans-regional
responses that require coordination at all levels. Commissioned by
the European Space Science Committee (ESSC) of the European Science
Foundation, the authors - together with ex-officio advice from ESA
and the EU - have over two years assessed European activities in the
realm of space weather and formulated a set of recommendations to ESA,
the EU and their respective member states, about how to prepare Europe
for the increasing impact of adverse space weather effects on man-made
infrastructure and our society as a whole. We have also analysed
parallel international activities worldwide, and we give advice how
Europe could incorporate its future activities into a global scheme.
---------------------------------------------------------
Title: The EUI instrument onboard Solar Orbiter: the EUV corona
imaged differently
Authors: Berghmans, David; Rochus, Pierre; Auchère, Frédéric;
Harra, Louise; Schmutz, Werner; Schühle, Udo
2018csc..confE..73B Altcode:
The ESA Solar Orbiter mission is designed to determine how the Sun
creates and controls the heliosphere. The spacecraft will bring
a combination of in situ and remote sensing instruments out of the
ecliptic (>30°) and close to the sun (0.3 solar-radii). The launch
of Solar Orbiter is expected (not earlier than) Feb 2019. The Extreme
Ultraviolet Imager is part of the remote-sensing package of Solar
Orbiter, to be operating during 3 ten-day periods of each orbit around
the Sun, which last roughly half a year. These 3 periods will correspond
to perihelion and maximal solar latitude north and south. The Extreme
Ultraviolet Imager is itself a suite of three UV and EUV telescopes
that observe the solar atmosphere both globally as well as at very
high resolution. The two high-resolution imagers (HRIs) will image the
solar atmosphere in the chromospheric Lyman alpha line and the coronal
17nm pass band with a resolution of 0.5 arcsec. From perihelion, this
will correspond to a pixel footprint on the solar disc of (110km)^2
. The Full Sun Imager (FSI), working at the 17.4 nm and 30.4 nm EUV
passbands, will provide a global view of the solar atmosphere and is
therefore an essential building block for the "connection science"
of the Solar Orbiter mission. The FSI field of view is large enough
(228arcmin) that, even at perihelion and at maximal off-points by Solar
Orbiter, the full solar disk remains in the field of view. This large
FOV and the FSI's high sensitivity will allow to image the "transition
corona" where the topology of streamers and pseudo-streamers fades in
the solar wind. Furthermore, FSI will be the first to image all this
from out of the ecliptic. In this talk we will give an overview of the
EUI instrument. We will focus on the novel aspects of EUI that will
allow it to image beyond what previous EUV imagers could show us: EUV
imaging from the highest solar latitude, with the widest field-of-view
and at highest spatial resolution.
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Title: Long-term evolution of the solar corona using SWAP data
Authors: Mierla, Marilena; D'Huys, Elke; Seaton, Daniel B.; Berghmans,
David; West, Matt; Podladchikova, Elena; Wauters, Laurence; Janssens,
Jan
2018csc..confE..78M Altcode:
In this work, we use the PROBA2/SWAP images to study the evolution of
the large-scale structures of the solar corona observed in the EUV
during the solar cycle 24 (from 2010 to 2018). We will discuss the
evolution of the corona at different heights above the solar surface
and the evolution of the corona over the poles. We compare it with
the sunspot number evolution.
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Title: Space Weather JHelioviewer in a Heterogeneous World
Authors: West, Matthew; Berghmans, David; Mueller, Daniel; Jiggens,
Piers; Verstringe, Freek; Nicula, Bogdan; Bourgoignie, Bram
2018cosp...42E3643W Altcode:
The Space Weather JHelioviewer project aims to augment the freely
available services of the Helioviewer project with space weather
relevant capabilities. As such, it merges the output of several
networked software services by combining the display of 1D data
(timelines), 2D data (solar images and spectrograms), 3D data
(multispacecraft imaging, magnetic field lines mod- elling), solar
event detections (e.g., HEK), and space weather alerts. This talk will
highlight the experiences gathered while incorporating this system
with several diverse datasets and services.
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Title: The EUI flight instrument of Solar Orbiter: from optical
alignment to end-to-end calibration
Authors: Halain, J. -P.; Renotte, E.; Auchère, F.; Berghmans, D.;
Delmotte, F.; Harra, L.; Schmutz, W.; Schühle, U.; Aznar Cuadrado,
R.; Dumesnil, C.; Gyo, M.; Kennedy, T.; Verbeeck, C.; Barbay, J.;
Giordanengo, B.; Gissot, S.; Gottwald, A.; Heerlein, K.; Hellin,
M. -L.; Hermans, A.; Hervier, V.; Jacques, L.; Laubis, C.; Mazzoli,
A.; Meining, S.; Mercier, R.; Philippon, A.; Roose, S.; Rossi, L.;
Scholze, F.; Smith, P.; Teriaca, L.; Zhang, X.; Rochus, P.
2018SPIE10699E..0HH Altcode:
The Extreme Ultraviolet Imager (EUI) instrument for the Solar Orbiter
mission will image the solar corona in the extreme ultraviolet (17.1
nm and 30.4 nm) and in the vacuum ultraviolet (121.6 nm) spectral
ranges. The development of the EUI instrument has been successfully
completed with the optical alignment of its three channels' telescope,
the thermal and mechanical environmental verification, the electrical
and software validations, and an end-toend on-ground calibration of
the two-units' flight instrument at the operating wavelengths. The
instrument has been delivered and installed on the Solar Orbiter
spacecraft, which is now undergoing all preparatory activities before
launch.
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Title: The detection of ultra-relativistic electrons in low Earth
orbit
Authors: Katsiyannis, Athanassios C.; Dominique, Marie; Pierrard,
Viviane; Rosson, Graciela Lopez; Keyser, Johan De; Berghmans, David;
Kruglanski, Michel; Dammasch, Ingolf E.; Donder, Erwin De
2018JSWSC...8A...1K Altcode: 2017arXiv171004653K
<BR /> Aims: To better understand the radiation environment in low
Earth orbit (LEO), the analysis of in-situ observations of a variety
of particles, at different atmospheric heights, and in a wide range of
energies, is needed. <BR /> Methods: We present an analysis of energetic
particles, indirectly detected by the large yield radiometer (LYRA)
instrument on board ESA's project for on-board autonomy 2 (PROBA2)
satellite as background signal. Combining energetic particle telescope
(EPT) observations with LYRA data for an overlapping period of time,
we identified these particles as electrons with an energy range
of 2 to 8 MeV. <BR /> Results: The observed events are strongly
correlated to geo-magnetic activity and appear even during modest
disturbances. They are also well confined geographically within the
L = 4-6 McIlwain zone, which makes it possible to identify their
source. <BR /> Conclusions: Although highly energetic particles are
commonly perturbing data acquisition of space instruments, we show in
this work that ultra-relativistic electrons with energies in the range
of 2-8 MeV are detected only at high latitudes, while not present in
the South Atlantic Anomaly region.
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Title: 3D Visualization of Solar Data: Preparing for Solar Orbiter
and Parker Solar Probe
Authors: Mueller, D.; Nicula, B.; Felix, S.; Verstringe, F.;
Bourgoignie, B.; Csillaghy, A.; Berghmans, D.; Jiggens, P.; Ireland,
J.; Fleck, B.
2017AGUFMSH23D2686M Altcode:
Solar Orbiter and Parker Solar Probe will focus on exploring the
linkage between the Sun and the heliosphere. These new missions will
collect unique data that will allow us to study, e.g., the coupling
between macroscopic physical processes to those on kinetic scales,
the generation of solar energetic particles and their propagation
into the heliosphere and the origin and acceleration of solar wind
plasma. Combined with the several petabytes of data from NASA's Solar
Dynamics Observatory, the scientific community will soon have access
to multidimensional remote-sensing and complex in-situ observations
from different vantage points, complemented by petabytes of simulation
data. Answering overarching science questions like "How do solar
transients drive heliospheric variability and space weather?" will
only be possible if the community has the necessary tools at hand. In
this contribution, we will present recent progress in visualizing the
Sun and its magnetic field in 3D using the open-source JHelioviewer
framework, which is part of the ESA/NASA Helioviewer Project.
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Title: Performances of swap on-board PROBA-2
Authors: Halain, J. -P.; Berghmans, D.; Defise, J. -F.; Rochus, P.;
Nicula, B.; de Groof, A.; Seaton, D.
2017SPIE10565E..0SH Altcode:
The PROBA2 mission has been launched on 2nd November2009 with a Rockot
launcher to a Sunsynchronous orbit at an altitude of 725 km. Its
nominal operation duration is two years with possible extension of
2 years. PROBA2 is a small satellite developed under an ESA General
Support Technology Program (GSTP) contract to perform an in-flight
demonstration of new space technologies and support a scientific
mission for a set of selected instruments. The mission is tracked by
the ESA Redu Mission Operation Center.
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Title: EUV high resolution imager on-board solar orbiter: optical
design and detector performances
Authors: Halain, J. P.; Mazzoli, A.; Rochus, P.; Renotte, E.; Stockman,
Y.; Berghmans, D.; BenMoussa, A.; Auchère, F.
2017SPIE10564E..3VH Altcode:
The EUV high resolution imager (HRI) channel of the Extreme Ultraviolet
Imager (EUI) on-board Solar Orbiter will observe the solar atmospheric
layers at 17.4 nm wavelength with a 200 km resolution. The HRI channel
is based on a compact two mirrors off-axis design. The spectral
selection is obtained by a multilayer coating deposited on the mirrors
and by redundant Aluminum filters rejecting the visible and infrared
light. The detector is a 2k x 2k array back-thinned silicon CMOS-APS
with 10 μm pixel pitch, sensitive in the EUV wavelength range. Due to
the instrument compactness and the constraints on the optical design,
the channel performance is very sensitive to the manufacturing,
alignments and settling errors. A trade-off between two optical
layouts was therefore performed to select the final optical design
and to improve the mirror mounts. The effect of diffraction by the
filter mesh support and by the mirror diffusion has been included
in the overall error budget. Manufacturing of mirror and mounts has
started and will result in thermo-mechanical validation on the EUI
instrument structural and thermal model (STM). Because of the limited
channel entrance aperture and consequently the low input flux, the
channel performance also relies on the detector EUV sensitivity,
readout noise and dynamic range. Based on the characterization of
a CMOS-APS back-side detector prototype, showing promising results,
the EUI detector has been specified and is under development. These
detectors will undergo a qualification program before being tested
and integrated on the EUI instrument.
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Title: JHelioviewer. Time-dependent 3D visualisation of solar and
heliospheric data
Authors: Müller, D.; Nicula, B.; Felix, S.; Verstringe, F.;
Bourgoignie, B.; Csillaghy, A.; Berghmans, D.; Jiggens, P.;
García-Ortiz, J. P.; Ireland, J.; Zahniy, S.; Fleck, B.
2017A&A...606A..10M Altcode: 2017arXiv170507628M
Context. Solar observatories are providing the world-wide community
with a wealth of data, covering wide time ranges (e.g. Solar and
Heliospheric Observatory, SOHO), multiple viewpoints (Solar TErrestrial
RElations Observatory, STEREO), and returning large amounts of data
(Solar Dynamics Observatory, SDO). In particular, the large volume of
SDO data presents challenges; the data are available only from a few
repositories, and full-disk, full-cadence data for reasonable durations
of scientific interest are difficult to download, due to their size
and the download rates available to most users. From a scientist's
perspective this poses three problems: accessing, browsing, and finding
interesting data as efficiently as possible. <BR /> Aims: To address
these challenges, we have developed JHelioviewer, a visualisation
tool for solar data based on the JPEG 2000 compression standard
and part of the open source ESA/NASA Helioviewer Project. Since the
first release of JHelioviewer in 2009, the scientific functionality
of the software has been extended significantly, and the objective
of this paper is to highlight these improvements. <BR /> Methods:
The JPEG 2000 standard offers useful new features that facilitate the
dissemination and analysis of high-resolution image data and offers
a solution to the challenge of efficiently browsing petabyte-scale
image archives. The JHelioviewer software is open source, platform
independent, and extendable via a plug-in architecture. <BR />
Results: With JHelioviewer, users can visualise the Sun for any time
period between September 1991 and today; they can perform basic image
processing in real time, track features on the Sun, and interactively
overlay magnetic field extrapolations. The software integrates solar
event data and a timeline display. Once an interesting event has
been identified, science quality data can be accessed for in-depth
analysis. As a first step towards supporting science planning of the
upcoming Solar Orbiter mission, JHelioviewer offers a virtual camera
model that enables users to set the vantage point to the location of
a spacecraft or celestial body at any given time.
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Title: Multi-instrument observations of the solar eclipse on 20
March 2015 and its effects on the ionosphere over Belgium and Europe
Authors: Stankov, Stanimir M.; Bergeot, Nicolas; Berghmans,
David; Bolsée, David; Bruyninx, Carine; Chevalier, Jean-Marie;
Clette, Frédéric; De Backer, Hugo; De Keyser, Johan; D'Huys, Elke;
Dominique, Marie; Lemaire, Joseph F.; Magdalenić, Jasmina; Marqué,
Christophe; Pereira, Nuno; Pierrard, Viviane; Sapundjiev, Danislav;
Seaton, Daniel B.; Stegen, Koen; Van der Linden, Ronald; Verhulst,
Tobias G. W.; West, Matthew J.
2017JSWSC...7A..19S Altcode:
A total solar eclipse occurred on 20 March 2015, with a totality
path passing mostly above the North Atlantic Ocean, which resulted
in a partial solar eclipse over Belgium and large parts of Europe. In
anticipation of this event, a dedicated observational campaign was set
up at the Belgian Solar-Terrestrial Centre of Excellence (STCE). The
objective was to perform high-quality observations of the eclipse and
the associated effects on the geospace environment by utilising the
advanced space- and ground-based instrumentation available to the STCE
in order to further our understanding of these effects, particularly on
the ionosphere. The study highlights the crucial importance of taking
into account the eclipse geometry when analysing the ionospheric
behaviour during eclipses and interpreting the eclipse effects. A
detailed review of the eclipse geometry proves that considering the
actual obscuration level and solar zenith angle at ionospheric heights
is much more important for the analysis than at the commonly referenced
Earth's surface or at the plasmaspheric heights. The eclipse occurred
during the recovery phase of a strong geomagnetic storm which certainly
had an impact on (some of) the ionospheric characteristics and perhaps
caused the omission of some "low-profile" effects. However, the analysis
of the ionosonde measurements, carried out at unprecedented high rates
during the eclipse, suggests the occurrence of travelling ionospheric
disturbances (TIDs). Also, the high temporal and spatial resolution
measurements proved very important in revealing and estimating
some finer details of the delay in the ionospheric reaction and the
ionospheric disturbances.
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Title: Provision of space weather bulletins in support to ESA missions
Authors: Kruglanski, Michel; Devos, Andy; Calders, Stijn; De Donder,
Erwin; Berghmans, David; Andries, Jesse; Crosby, Norma; Dierckxsens,
Mark; Glover, Alexi
2017EGUGA..1918071K Altcode:
The SSCC (SSA Space Weather Coordination Centre) is the focal point for
user support of the ESA Space Situational Awareness (SSA) Program Space
Weather Service Network (http://swe.ssa.esa.int/) and offers first line
support to end-users. Its activities are gradually expanding as more
products and tools are incorporated in the associated Network. Here
we report on the tailoring of the network resources at the SSCC in
order to produce space weather forecast notifications in support to
selected ESA missions. With the help of forecasters from the Expert
Service Centres (ECSs) for Solar Weather and for Space Radiation,
the SSCC already has provided dedicated notifications for various
missions including the launch window and the L2 insertion manoeuvre of
the GAIA mission, for the last aerobraking campaign of Venus Express,
during the trajectory around Comet 67P/Churyumov-Gerasimenko of the
Rosetta mission and the landing of Philae lander, for the flight of
the experimental IXV space plane, and for the launch LISA Pathfinder
mission and during the operations phase at L1. Examples of space weather
notification will be given. Those exercises are performed in a test
and evaluation context helping to evaluate the network capabilities
and to identify recommendations for improvement.
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Title: Solar signatures and eruption mechanism of the August 14,
2010 coronal mass ejection (CME)
Authors: D'Huys, Elke; Seaton, Daniel B.; De Groof, Anik; Berghmans,
David; Poedts, Stefaan
2017JSWSC...7A...7D Altcode: 2017arXiv170108814D
On August 14, 2010 a wide-angled coronal mass ejection (CME) was
observed. This solar eruption originated from a destabilized filament
that connected two active regions and the unwinding of this filament
gave the eruption an untwisting motion that drew the attention
of many observers. In addition to the erupting filament and the
associated CME, several other low-coronal signatures that typically
indicate the occurrence of a solar eruption were associated with this
event. However, contrary to what was expected, the fast CME (v >
900 km s<SUP>-1</SUP>) was accompanied by only a weak C4.4 flare. We
investigate the various eruption signatures that were observed for this
event and focus on the kinematic evolution of the filament in order to
determine its eruption mechanism. Had this solar eruption occurred just
a few days earlier, it could have been a significant event for space
weather. The risk of underestimating the strength of this eruption based
solely on the C4.4 flare illustrates the need to include all eruption
signatures in event analyses in order to obtain a complete picture of
a solar eruption and assess its possible space weather impact.
---------------------------------------------------------
Title: The discovery of an electron current at Earth's McIlwain L=6
Authors: Katsiyannis, A. C.; Dominique, M.; Pierrard, V.; Borremans,
K.; De Keyser, J.; Berghmans, D.; Kruglanski, M.; Dammasch, I.;
De Donder, E.
2016usc..confE..44K Altcode:
The Large Yield RAdiometer (LYRA) is an ultraviolet solar radiometer
on-board ESA's PROBA2 micro-satellite. Since its launch in 2009 to
an altitude of 735km, one of the most peculiar and intriguing results
of LYRA is the detection of short, strong, bursts that do not directly
correlate with solar coronal events, nor with pointing of the instrument
to Earth's upper atmosphere, but correlate well with high a_p index on
Earth's surface and the crossing by the satellite of the L=6 shell. Very
similar detections were more recently made by the Energetic Particles
Telescope (EPT) on board the PROBA-V micro-satellite, establishing the
identification of the detections as relativistic electrons of the 2.4-8
MeV energy range. Several attributes of those detections, including
their dependency to various space weather indexes (ap, D_st, etc),
their geographical distribution, a dawn/dusk asymmetry and others
will be presented. Open questions related to the discovery of this
phenomenon will also be discussed.
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Title: The qualification campaign of the EUI instrument of Solar
Orbiter
Authors: Halain, J. -P.; Rochus, P.; Renotte, E.; Hermans, A.; Jacques,
L.; Mazzoli, A.; Auchère, F.; Berghmans, D.; Harra, L.; Schühle,
U.; Schmutz, W.; Aznar Cuadrado, R.; Dumesnil, C.; Gyo, M.; Kennedy,
T.; Verbeeck, C.; Smith, P.
2016SPIE.9905E..2XH Altcode:
The Extreme Ultraviolet Imager (EUI) instrument is one of the ten
scientific instruments on board the Solar Orbiter mission to be launched
in October 2018. It will provide full-sun and high-resolution images of
the solar corona in the extreme ultraviolet (17.1 nm and 30.4 nm) and in
the vacuum ultraviolet (121.6 nm). The validation of the EUI instrument
design has been completed with the Assembly, Integration and Test
(AIT) of the instrument two-units Qualification Model (QM). Optical,
electrical, electro-magnetic compatibility, thermal and mechanical
environmental verifications were conducted and are summarized here. The
integration and test procedures for the Flight Model (FM) instrument
and sub-systems were also verified. Following the Qualification Review,
the flight instrument activities were started with the assembly of
the flight units. The mechanical and thermal acceptance tests and an
end-to-end final calibration in the (E)UV will then be conducted before
delivery for integration on the Solar Orbiter Spacecraft by end of 2016.
---------------------------------------------------------
Title: The Effect of Limited Sample Sizes on the Accuracy of the
Estimated Scaling Parameter for Power-Law-Distributed Solar Data
Authors: D'Huys, Elke; Berghmans, David; Seaton, Daniel B.; Poedts,
Stefaan
2016SoPh..291.1561D Altcode: 2016arXiv160506972D; 2016SoPh..tmp...82D
Many natural processes exhibit a power-law behavior. The power-law
exponent is linked to the underlying physical process, and therefore
its precise value is of interest. With respect to the energy content
of nanoflares, for example, a power-law exponent steeper than 2 is
believed to be a necessary condition for solving the enigmatic coronal
heating problem. Studying power-law distributions over several orders
of magnitudes requires sufficient data and appropriate methodology. In
this article we demonstrate the shortcomings of some popular methods in
solar physics that are applied to data of typical sample sizes. We use
synthetic data to study the effect of the sample size on the performance
of different estimation methods. We show that vast amounts of data are
needed to obtain a reliable result with graphical methods (where the
power-law exponent is estimated by a linear fit on a log-transformed
histogram of the data). We revisit published results on power laws for
the angular width of solar coronal mass ejections and the radiative
losses of nanoflares. We demonstrate the benefits of the maximum
likelihood estimator and advocate its use.
---------------------------------------------------------
Title: Observing the Unobservable: Identification and Characterisation
of Stealth Coronal Mass Ejections
Authors: D'Huys, Elke; Seaton, Daniel B.; Poedts, Stefaan; Berghmans,
David
2016SPD....4740401D Altcode:
I will present my doctoral thesis research on stealth CMEs: solar
coronal mass ejections that are clearly observed in coronagraph
data but do not show significant low-coronal or on-disk signatures
of eruption. This lack of coronal signatures makes it challenging to
determine their source region and predict their trajectory throughout
interplanetary space. We identified 40 such events and investigated
their properties both observationally and statistically. We found that
our sample size was insufficient to determine the scaling law for the
CME angular width reliably. We therefore analyzed in general what the
effect is of a limited sample size on the estimation of a power law
parameter. Armed with this knowledge, we returned to our sample of
stealth CMEs, re-analyzed the power law for their angular widths and
compared the results to the power law found for normal CMEs.
---------------------------------------------------------
Title: Validation of Earth atmosphere models using solar EUV
observations from the CORONAS and PROBA2 satellites in occultation
mode
Authors: Slemzin, Vladimir; Ulyanov, Artyom; Gaikovich, Konstantin;
Kuzin, Sergey; Pertsov, Andrey; Berghmans, David; Dominique, Marie
2016JSWSC...6A...7S Altcode:
Aims: Knowledge of properties of the Earth's upper atmosphere is
important for predicting the lifetime of low-orbit spacecraft as well as
for planning operation of space instruments whose data may be distorted
by atmospheric effects. The accuracy of the models commonly used for
simulating the structure of the atmosphere is limited by the scarcity
of the observations they are based on, so improvement of these models
requires validation under different atmospheric conditions. Measurements
of the absorption of the solar extreme ultraviolet (EUV) radiation in
the upper atmosphere below 500 km by instruments operating on low-Earth
orbits (LEO) satellites provide efficient means for such validation
as well as for continuous monitoring of the upper atmosphere and for
studying its response to the solar and geomagnetic activity. Method:
This paper presents results of measurements of the solar EUV radiation
in the 17 nm wavelength band made with the SPIRIT and TESIS telescopes
on board the CORONAS satellites and the SWAP telescope on board the
PROBA2 satellite in the occulted parts of the satellite orbits. The
transmittance profiles of the atmosphere at altitudes between 150 and
500 km were derived from different phases of solar activity during solar
cycles 23 and 24 in the quiet state of the magnetosphere and during
the development of a geomagnetic storm. We developed a mathematical
procedure based on the Tikhonov regularization method for solution of
ill-posed problems in order to retrieve extinction coefficients from
the transmittance profiles. The transmittance profiles derived from
the data and the retrieved extinction coefficients are compared with
simulations carried out with the NRLMSISE-00 atmosphere model maintained
by Naval Research Laboratory (USA) and the DTM-2013 model developed at
CNES in the framework of the FP7 project ATMOP. Results: Under quiet
and slightly disturbed magnetospheric conditions during high and low
solar activity the extinction coefficients calculated by both models
agreed with the measurements within the data errors. The NRLMSISE-00
model was not able to predict the enhancement of extinction above
300 km observed after 14 h from the beginning of a geomagnetic storm
whereas the DTM-2013 model described this variation with good accuracy.
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Title: PROBA2: a Micro-Satellite Observing the Sun
Authors: Katsiyannis, A.; Dominique, M.; Seaton, D. B.; Berghmans,
D.; West, M. J.; Dolla, L.; Ryan, D.; Bonte, K.; Kretzschmar, M.;
Dammasch, I. E.; Wauters, L.; Rachmeler, L. A.
2015AGUFMSH21B2415K Altcode:
PROBA2 (http://proba2.oma.be) is an ESA micro-satellite that was
launched in November 2009. It carries two solar-observing instruments:
SWAP, an EUV imager observing the one-million-degree corona, and
LYRA, a UV-EUV radiometer acquiring time-series in four broadband
channels. The characteristics of both instruments make them highly
complementary to bigger missions such as SDO for the observation of
solar eruptions and flares. SWAP benefits from a large field-of-view and
flexible off-pointing capabilities that allow the instrument to fill
part of the observational gap between imagers and coronographs and to
shed a new light on eruptive events (see e.g. West and Seaton, 2015;
Kumar and Cho, 2014; Byrne et al., 2014) LYRA acquires at a very fast
cadence (20 Hz nominally) and with a high signal-to-noise ratio, and
can therefore be used for the detailed analysis of the short-timescale
variations of solar irradiance, such as the so-called quasi-periodic
pulsations appearing in flares that could be intrinsically related to
the nature of the flaring process (see e.g. Dolla et al., 2012). The
two instruments provide data suitable for the detection of space
weather related events such as flares, CMEs, dimmings, EUV waves,
etc. Automated tools (e.g. SOFAST, see Bonte et al. 2012) are already
operational and are used daily in the frame of space weather services
such as the ESA's Space Weather Coordination Centre (SSCC). These
tools should be soon enriched with new capabilities.
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Title: Detection of EUV/Soft X-ray bremsstrahlung emission at
terrestrial altitudes above 750 km
Authors: Katsiyannis, A.; Dominique, M.; De Keyser, J.; Berghmans,
D.; Michel, K.; Dammasch, I. E.; Borremans, K.; De Donder, E.; Ben
Moussa, A.
2015AGUFMSM41F2560K Altcode:
LYRA is a fast radiometer on-board the PROBA-2 mission designed to
observe the solar activity from UV to Soft X-rays and consists of three
redundant units of four different optical bandpasses each. Since the
start of operation in 2010, LYRA regularly observes disturbances with a
characteristic signature that have no direct solar origin. Instead the
frequency of occurrence correlates with the ApA_p index of geomagnetic
activity on Earth's surface and the location of these detections
coincides with the McIlwain L ≈ 3 zon. By comparing the wavelength
sensitivity of the main PROBA-2 instruments, the wavelength range of
the detected photons can be narrowed down to the range of 0.07-1 KeV
(1-17 nm) and the altitudes of their source to those above PROBA-2's
orbit (~750 km). A discussion on the magnetospheric origins of this
emission is included.
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Title: The extreme UV imager telescope on-board the Solar Orbiter
mission: overview of phase C and D
Authors: Halain, J. -P.; Rochus, P.; Renotte, E.; Hermans, A.; Jacques,
L.; Auchère, F.; Berghmans, D.; Harra, L.; Schühle, U.; Schmutz,
W.; Zhukov, A.; Aznar Cuadrado, R.; Delmotte, F.; Dumesnil, C.; Gyo,
M.; Kennedy, T.; Smith, P.; Tandy, J.; Mercier, R.; Verbeeck, C.
2015SPIE.9604E..0GH Altcode:
The Solar Orbiter mission is composed of ten scientific instruments
dedicated to the observation of the Sun's atmosphere and its
heliosphere, taking advantage of an out-of ecliptic orbit and at
perihelion reaching a proximity close to 0.28 A.U. On board Solar
Orbiter, the Extreme Ultraviolet Imager (EUI) will provide full-Sun
image sequences of the solar corona in the extreme ultraviolet (17.1
nm and 30.4 nm), and high-resolution image sequences of the solar disk
in the extreme ultraviolet (17.1 nm) and in the vacuum ultraviolet
(121.6 nm). The EUI concept uses heritage from previous similar extreme
ultraviolet instrument. Additional constraints from the specific orbit
(thermal and radiation environment, limited telemetry download) however
required dedicated technologies to achieve the scientific objectives
of the mission. The development phase C of the instrument and its
sub-systems has been successfully completed, including thermomechanical
and electrical design validations with the Structural Thermal Model
(STM) and the Engineering Model (EM). The instrument STM and EM units
have been integrated on the respective spacecraft models and will
undergo the system level tests. In parallel, the Phase D has been
started with the sub-system qualifications and the flight parts
manufacturing. The next steps of the EUI development will be the
instrument Qualification Model (QM) integration and qualification
tests. The Flight Model (FM) instrument activities will then follow
with the acceptance tests and calibration campaigns.
---------------------------------------------------------
Title: PROBA2/SWAP EUV images of the large-scale EUV corona up to 3
solar radii: Can we close the gap in coronal magnetic field structure
between 1.3 and 2.5 solar radii?
Authors: De Groof, Anik; Seaton, Daniel B.; Rachmeler, Laurel;
Berghmans, David
2015TESS....140901D Altcode:
The EUV telescope PROBA2/SWAP has been observing the solar corona in
a bandpass near 17.4 nm since February 2010. SWAP's wide field-of-view
provides a unique and continuous view of the extended EUV corona up to
2-3 solar radii. By carefully processing and combining multiple SWAP
images, low-noise composites were produced that reveal large-scale,
EUV-emitting, coronal structures. These extended structures appear
mainly above or at the edges of active regions and typically curve
towards the poles. As they persist for multiple Carrington rotations
and cannot easily be related to white-light features, they give an
interesting view on how the coronal magnetic field is structured
between 1.3 and 2-3 solar radii, in the gap between SDO/AIA’s FOV
and typical lower boundaries of coronagraph FOVs. With the help of
magnetic field models, we analyse the geometry of the extended EUV
structures in more detail and compare with sporadic EUV coronagraph
measurements up to as close as 1.5Rs. The opportunities that Solar
Orbiter’s future observations will bring are explored.
---------------------------------------------------------
Title: 3D Visualization of Solar Data: Preparing for Solar Orbiter
and Solar Probe Plus
Authors: Mueller, D.; Felix, S.; Meier, S.; Csillaghy, A.; Nicula,
B.; Verstringe, F.; Bourgoignie, B.; Berghmans, D.; Jiggens, P.
2014AGUFMSH21B4098M Altcode:
The next generation of ESA/NASA heliophysics missions, Solar Orbiter
and Solar Probe Plus, will focus on exploring the linkage between the
Sun and the heliosphere. These new missions will collect unique data
that will allow us to study, e.g., the coupling between macroscopic
physical processes to those on kinetic scales, the generation of solar
energetic particles and their propagation into the heliosphere and
the origin and acceleration of solar wind plasma. Since 2010, NASA's
Solar Dynamics Observatory returns 1.4 TB/day of high-resolution
solar images, magnetograms and EUV irradiance data. Within a few
years, the scientific community will thus have access to petabytes of
multidimensional remotesensing and complex in-situ observations
from different vantage points, complemented by petabytes of simulation
data. Answering overarching science questions like "How do solar
transients drive heliospheric variability and space weather?" will only
be possible if the community has the necessary tools at hand. As of
today, there is an obvious lack of capability to both visualize these
data and assimilate them into sophisticated models to advance our
knowledge. A key piece needed to bridge the gap between observables,
derived quantities like magnetic field extrapolations and model output
is a tool to routinely and intuitively visualize large heterogeneous,
multidimensional, timedependent data sets. As of today, the space
science community is lacking the means to do this (i) on a routine
basis, (ii) for complex multidimensional data sets from various
instruments and vantage points and (iii) in an extensible and modular
way that is open for future improvements and interdisciplinary usage. In
this contribution, we will present recent progress in visualizing the
Sun and its magnetic field in 3D using the open-source JHelioviewer
framework, which is part of the ESA/NASA Helioviewer Project. Among
other features, JHelioviewer offers efficient region-of-interest-based
data streaming, metadata and event catalog integration, as well as an
interface to access science-quality data. In addition to its usage by
the solar physics community, JHelioviewer has already been successfully
adapted for application in planetary sciences and medical imaging.
---------------------------------------------------------
Title: Observational Characteristics of Coronal Mass Ejections
without Low-coronal Signatures
Authors: D'Huys, E.; Seaton, D. B.; Poedts, S.; Berghmans, D.
2014ApJ...795...49D Altcode: 2014arXiv1409.1422D
Solar eruptions are usually associated with a variety of phenomena
occurring in the low corona before, during, and after the onset of
eruption. Though easily visible in coronagraph observations, so-called
stealth coronal mass ejections (CMEs) do not obviously exhibit any
of these low-coronal signatures. The presence or absence of distinct
low-coronal signatures can be linked to different theoretical models
to establish the mechanisms by which the eruption is initiated
and driven. In this study, 40 CMEs without low-coronal signatures
occurring in 2012 are identified. Their observational and kinematic
properties are analyzed and compared to those of regular CMEs. Solar
eruptions without clear on-disk or low-coronal signatures can lead to
unexpected space weather impacts, since many early warning signs for
significant space weather activity are not present in these events. A
better understanding of their initiation mechanism(s) will considerably
improve the ability to predict such space weather events.
---------------------------------------------------------
Title: The extreme UV imager of solar orbiter: from detailed design
to flight model
Authors: Halain, J. -P.; Rochus, P.; Renotte, E.; Auchère, F.;
Berghmans, D.; Harra, L.; Schühle, U.; Schmutz, W.; Zhukov, A.;
Aznar Cuadrado, R.; Delmotte, F.; Dumesnil, C.; Gyo, M.; Kennedy,
T.; Mercier, R.; Verbeeck, F.; Thome, M.; Heerlein, K.; Hermans, A.;
Jacques, L.; Mazzoli, A.; Meining, S.; Rossi, L.; Tandy, J.; Smith,
P.; Winter, B.
2014SPIE.9144E..08H Altcode:
The Extreme Ultraviolet Imager (EUI) on-board the Solar Orbiter mission
will provide full-sun and high-resolution image sequences of the solar
atmosphere at selected spectral emission lines in the extreme and vacuum
ultraviolet. After the breadboarding and prototyping activities that
focused on key technologies, the EUI project has completed the design
phase and has started the final manufacturing of the instrument and its
validation. The EUI instrument has successfully passed its Critical
Design Review (CDR). The process validated the detailed design of
the Optical Bench unit and of its sub-units (entrance baffles, doors,
mirrors, camera, and filter wheel mechanisms), and of the Electronic
Box unit. In the same timeframe, the Structural and Thermal Model
(STM) test campaign of the two units have been achieved, and allowed
to correlate the associated mathematical models. The lessons learned
from STM and the detailed design served as input to release the
manufacturing of the Qualification Model (QM) and of the Flight Model
(FM). The QM will serve to qualify the instrument units and sub-units,
in advance of the FM acceptance tests and final on-ground calibration.
---------------------------------------------------------
Title: Validation of the Earth atmosphere models using the EUV solar
occultation data from the CORONAS and PROBA 2 instruments
Authors: Slemzin, Vladimir; Kuzin, Sergey; Berghmans, David; Pertsov,
Andrey; Dominique, Marie; Ulyanov, Artyom; Gaikovich, Konstantin
2014cosp...40E3125S Altcode:
Absorption in the atmosphere below 500 km results in attenuation of
the solar EUV flux, variation of its spectra and distortion of solar
images acquired by solar EUV instruments operating on LEO satellites
even on solar synchronous orbits. Occultation measurements are
important for planning of solar observations from these satellites,
and can be used for monitoring the upper atmosphere as well as for
studying its response to the solar activity. We present the results of
the occultation measurements of the solar EUV radiation obtained by
the CORONAS-F/SPIRIT telescope at high solar activity (2002), by the
CORONAS-Photon/TESIS telescope at low activity (2009), and by the SWAP
telescope and LYRA radiometer onboard the PROBA 2 satellite at moderate
activity (2010). The measured attenuation profiles and the retrieved
linear extinction coefficients at the heights 200-500 km are compared
with simulations by the NRLMSIS-00 and DTM2013 atmospheric models. It
was shown that the results of simulations by the DTM2013 model are well
agreed with the data of measurements at all stages of solar activity
and in presence of the geomagnetic storm, whereas the results of the
NRLMSISE-00 model significantly diverge from the measurements, in
particular, at high and low activity. The research leading to these
results has received funding from the European Union’s Seventh
Programme for Research, Technological Development and Demonstration
under Grant Agreement “eHeroes” (project No.284461, www.eheroes.eu).
---------------------------------------------------------
Title: The SWAP EUV imager onboard PROBA2: 3 years of observations
Authors: West, Matthew; Berghmans, David; Seaton, Daniel
2014cosp...40E3622W Altcode:
The Sun Watcher with Active Pixels and Image Processing (SWAP)
imager is an EUV solar telescope on board ESA's Project for Onboard
Autonomy 2 (PROBA2) mission launched on 2 November 2009. SWAP has
a spectral bandpass centered on 17.4 nm and provides images of the
low solar corona over a 54x54 arcmin field-of-view with 3.2 arcsec
pixels and an imaging cadence of about two minutes. SWAP is designed
to monitor all space-weather-relevant events and features in the low
solar corona. The SWAP telescope is designed with various innovative
technologies, including an off-axis optical design and a CMOS-APS
detector. I will present what has been learnt from 3 years of SWAP
operations, the advantages of the CMOS detector and SWAPs setup,
and a few unique PROBA2/SWAP observations.
---------------------------------------------------------
Title: The EUI Data Center at the Royal Observatory of Belgium:
challenges and solutions
Authors: Verbeeck, Cis; Stegen, Koen; Berghmans, David; West, Matthew;
Kraaikamp, Emil; Gissot, Samuel; Giordanengo, Boris; Nicula, Bogdan
2014cosp...40E3498V Altcode:
ESA’s Solar Orbiter mission is conceived to perform a close-up study
of the Sun and the inner heliosphere. With a perihelion close at 0.29
AU and a maximum aphelion at about 0.85 AU, Solar Orbiter ventures
closer to the Sun than any spacecraft before. Furthermore, about 3
years after launch, the spacecraft will begin an out-of-ecliptic phase,
with inclinations gradually increasing up to 30 degrees. Solar Orbiter
will be launched in 2017 and its nominal mission will last until 2024
(with the possibility of an extended mission until 2026). It will
provide unique data and imagery of the Sun. The Extreme Ultraviolet
Imager (EUI) suite onboard Solar Orbiter is composed of two High
Resolution Imagers (HRI, one at Lyman-alpha and one at 174 Angstrom),
and one dual band Full-Sun imager (FSI) working alternatively at
the 174 and 304 Angstrom EUV passbands. The EUI Data Center (EDC),
under PI supervision and located at the Royal Observatory of Belgium
(Brussels), will be the single point of contact for instrument planning
activities and for data deliveries to the Solar Orbiter archive at ESAC
(Madrid), and is currently in its design phase. The EUI Data Center
will be responsible for delivery to ESAC and the maintenance of the
pipeline software that will process EUI data from telemetry packets
to higher level data products. It will also ensure the delivery of
these data products to the Solar Orbiter Data Archive, and maintain
the instrument user manual that documents the processing of EUI
non-science TM packets at ESOC (Darmstadt). The EDC will monitor any
anomaly affecting the EUI instrument and produce on a regular basis
the Instrument Operations Reports including an instrument health and
science performance review. Here, we present an overview of the EDC and
how it envisages to tackle some specific challenges. Since EUI will
only observe during three “science windows” of 10 days each per
orbit of about 165 days and in view of a severely limited telemetry,
it is important to implement observing strategies that maximize the
science return on the targets: active regions, coronal hole boundaries,
quiet Sun, and flares. In order to allow scientists to select a proper
target region on the Sun, precursor observations will be downlinked with
low latency before the start of the science windows. The spacecraft can
then be pointed towards the selected region such that high resolution
instruments such as HRI contain this region within their field of
view. Given the limited telemetry and delayed ground contacts, it is
especially hard to decide when to observe and store high-cadence data
in order to catch a large flare. To address this challenge, the EUI
consortium has developed a dedicated automatic onboard trigger that
detects large flares.
---------------------------------------------------------
Title: SWAP Observations of the Long-term, Large-scale Evolution of
the Extreme-ultraviolet Solar Corona
Authors: Seaton, Daniel B.; De Groof, Anik; Shearer, Paul; Berghmans,
David; Nicula, Bogdan
2013ApJ...777...72S Altcode: 2013arXiv1309.1345S
The Sun Watcher with Active Pixels and Image Processing (SWAP) EUV solar
telescope on board the Project for On-Board Autonomy 2 spacecraft has
been regularly observing the solar corona in a bandpass near 17.4 nm
since 2010 February. With a field of view of 54 × 54 arcmin, SWAP
provides the widest-field images of the EUV corona available from
the perspective of the Earth. By carefully processing and combining
multiple SWAP images, it is possible to produce low-noise composites
that reveal the structure of the EUV corona to relatively large
heights. A particularly important step in this processing was to remove
instrumental stray light from the images by determining and deconvolving
SWAP's point-spread function from the observations. In this paper,
we use the resulting images to conduct the first-ever study of the
evolution of the large-scale structure of the corona observed in the
EUV over a three year period that includes the complete rise phase of
solar cycle 24. Of particular note is the persistence over many solar
rotations of bright, diffuse features composed of open magnetic fields
that overlie polar crown filaments and extend to large heights above
the solar surface. These features appear to be related to coronal fans,
which have previously been observed in white-light coronagraph images
and, at low heights, in the EUV. We also discuss the evolution of the
corona at different heights above the solar surface and the evolution
of the corona over the course of the solar cycle by hemisphere.
---------------------------------------------------------
Title: On-Orbit Degradation of Solar Instruments
Authors: BenMoussa, A.; Gissot, S.; Schühle, U.; Del Zanna, G.;
Auchère, F.; Mekaoui, S.; Jones, A. R.; Walton, D.; Eyles, C. J.;
Thuillier, G.; Seaton, D.; Dammasch, I. E.; Cessateur, G.; Meftah,
M.; Andretta, V.; Berghmans, D.; Bewsher, D.; Bolsée, D.; Bradley,
L.; Brown, D. S.; Chamberlin, P. C.; Dewitte, S.; Didkovsky, L. V.;
Dominique, M.; Eparvier, F. G.; Foujols, T.; Gillotay, D.; Giordanengo,
B.; Halain, J. P.; Hock, R. A.; Irbah, A.; Jeppesen, C.; Judge,
D. L.; Kretzschmar, M.; McMullin, D. R.; Nicula, B.; Schmutz, W.;
Ucker, G.; Wieman, S.; Woodraska, D.; Woods, T. N.
2013SoPh..288..389B Altcode: 2013arXiv1304.5488B
We present the lessons learned about the degradation observed in
several space solar missions, based on contributions at the Workshop
about On-Orbit Degradation of Solar and Space Weather Instruments
that took place at the Solar Terrestrial Centre of Excellence (Royal
Observatory of Belgium) in Brussels on 3 May 2012. The aim of this
workshop was to open discussions related to the degradation observed
in Sun-observing instruments exposed to the effects of the space
environment. This article summarizes the various lessons learned
and offers recommendations to reduce or correct expected degradation
with the goal of increasing the useful lifespan of future and ongoing
space missions.
---------------------------------------------------------
Title: The SWAP EUV Imaging Telescope Part I: Instrument Overview
and Pre-Flight Testing
Authors: Seaton, D. B.; Berghmans, D.; Nicula, B.; Halain, J. -P.; De
Groof, A.; Thibert, T.; Bloomfield, D. S.; Raftery, C. L.; Gallagher,
P. T.; Auchère, F.; Defise, J. -M.; D'Huys, E.; Lecat, J. -H.; Mazy,
E.; Rochus, P.; Rossi, L.; Schühle, U.; Slemzin, V.; Yalim, M. S.;
Zender, J.
2013SoPh..286...43S Altcode: 2012SoPh..tmp..217S; 2012arXiv1208.4631S
The Sun Watcher with Active Pixels and Image Processing (SWAP) is
an EUV solar telescope onboard ESA's Project for Onboard Autonomy 2
(PROBA2) mission launched on 2 November 2009. SWAP has a spectral
bandpass centered on 17.4 nm and provides images of the low solar
corona over a 54×54 arcmin field-of-view with 3.2 arcsec pixels and
an imaging cadence of about two minutes. SWAP is designed to monitor
all space-weather-relevant events and features in the low solar
corona. Given the limited resources of the PROBA2 microsatellite,
the SWAP telescope is designed with various innovative technologies,
including an off-axis optical design and a CMOS-APS detector. This
article provides reference documentation for users of the SWAP image
data.
---------------------------------------------------------
Title: Preface
Authors: Berghmans, D.; De Groof, A.; Dominique, M.; Hochedez, J. -F.;
Leibacher, J. W.
2013SoPh..286....1B Altcode:
No abstract at ADS
---------------------------------------------------------
Title: SoFAST: Automated Flare Detection with the PROBA2/SWAP
EUV Imager
Authors: Bonte, K.; Berghmans, D.; De Groof, A.; Steed, K.; Poedts, S.
2013SoPh..286..185B Altcode: 2012SoPh..tmp..288B
The Sun Watcher with Active Pixels and Image Processing (SWAP)
EUV imager onboard PROBA2 provides a non-stop stream of coronal
extreme-ultraviolet (EUV) images at a cadence of typically 130
seconds. These images show the solar drivers of space-weather, such
as flares and erupting filaments. We have developed a software tool
that automatically processes the images and localises and identifies
flares. On one hand, the output of this software tool is intended
as a service to the Space Weather Segment of ESA's Space Situational
Awareness (SSA) program. On the other hand, we consider the PROBA2/SWAP
images as a model for the data from the Extreme Ultraviolet Imager (EUI)
instrument prepared for the future Solar Orbiter mission, where onboard
intelligence is required for prioritising data within the challenging
telemetry quota. In this article we present the concept of the software,
the first statistics on its effectiveness and the online display in
real time of its results. Our results indicate that it is not only
possible to detect EUV flares automatically in an acquired dataset,
but that quantifying a range of EUV dynamics is also possible. The
method is based on thresholding of macropixelled image sequences. The
robustness and simplicity of the algorithm is a clear advantage for
future onboard use.
---------------------------------------------------------
Title: The SWAP EUV Imaging Telescope. Part II: In-flight Performance
and Calibration
Authors: Halain, J. -P.; Berghmans, D.; Seaton, D. B.; Nicula, B.;
De Groof, A.; Mierla, M.; Mazzoli, A.; Defise, J. -M.; Rochus, P.
2013SoPh..286...67H Altcode: 2012SoPh..tmp..317H; 2012arXiv1210.3551H
The Sun Watcher with Active Pixel System detector and Image
Processing (SWAP) telescope was launched on 2 November 2009
onboard the ESA PROBA2 technological mission and has acquired
images of the solar corona every one to two minutes for more than
two years. The most important technological developments included in
SWAP are a radiation-resistant CMOS-APS detector and a novel onboard
data-prioritization scheme. Although such detectors have been used
previously in space, they have never been used for long-term scientific
observations on orbit. Thus SWAP requires a careful calibration to
guarantee the science return of the instrument. Since launch we have
regularly monitored the evolution of SWAP's detector response in-flight
to characterize both its performance and degradation over the course
of the mission. These measurements are also used to reduce detector
noise in calibrated images (by subtracting dark-current). Because
accurate measurements of detector dark-current require large telescope
off-points, we also monitored straylight levels in the instrument to
ensure that these calibration measurements are not contaminated by
residual signal from the Sun. Here we present the results of these
tests and examine the variation of instrumental response and noise as
a function of both time and temperature throughout the mission.
---------------------------------------------------------
Title: The Projects for Onboard Autonomy (PROBA2) Science Centre:
Sun Watcher Using APS Detectors and Image Processing (SWAP) and
Large-Yield Radiometer (LYRA) Science Operations and Data Products
Authors: Zender, J.; Berghmans, D.; Bloomfield, D. S.; Cabanas Parada,
C.; Dammasch, I.; De Groof, A.; D'Huys, E.; Dominique, M.; Gallagher,
P.; Giordanengo, B.; Higgins, P. A.; Hochedez, J. -F.; Yalim, M. S.;
Nicula, B.; Pylyser, E.; Sanchez-Duarte, L.; Schwehm, G.; Seaton,
D. B.; Stanger, A.; Stegen, K.; Willems, S.
2013SoPh..286...93Z Altcode: 2012SoPh..tmp..142Z
The PROBA2 Science Centre (P2SC) is a small-scale science operations
centre supporting the Sun observation instruments onboard PROBA2:
the EUV imager Sun Watcher using APS detectors and image Processing
(SWAP) and Large-Yield Radiometer (LYRA). PROBA2 is one of ESA's
small, low-cost Projects for Onboard Autonomy (PROBA) and part of
ESA's In-Orbit Technology Demonstration Programme. The P2SC is hosted
at the Royal Observatory of Belgium, co-located with both Principal
Investigator teams. The P2SC tasks cover science planning, instrument
commanding, instrument monitoring, data processing, support of outreach
activities, and distribution of science data products. PROBA missions
aim for a high degree of autonomy at mission and system level, including
the science operations centre. The autonomy and flexibility of the P2SC
is reached by a set of web-based interfaces allowing the operators as
well as the instrument teams to monitor quasi-continuously the status of
the operations, allowing a quick reaction to solar events. In addition,
several new concepts are implemented at instrument, spacecraft, and
ground-segment levels allowing a high degree of flexibility in the
operations of the instruments. This article explains the key concepts
of the P2SC, emphasising the automation and the flexibility achieved
in the commanding as well as the data-processing chain.
---------------------------------------------------------
Title: Temperature Response of the 171 Å Passband of the SWAP Imager
on PROBA2, with a Comparison to TRACE, SOHO, STEREO, and SDO
Authors: Raftery, Claire L.; Bloomfield, D. Shaun; Gallagher, Peter
T.; Seaton, Daniel B.; Berghmans, David; De Groof, Anik
2013SoPh..286..111R Altcode:
We calculated the temperature response of the 171 Å passbands of
the Sun Watcher using APS detectors and image Processing (SWAP)
instrument onboard the PRoject for OnBoard Autonomy 2 (PROBA2)
satellite. These results were compared to the temperature responses
of the Extreme Ultraviolet Imaging Telescope (EIT) onboard the Solar
and Heliospheric Observatory (SOHO), the Transition Region and Coronal
Explorer (TRACE), the twin Extreme Ultraviolet Imagers (EUVI) onboard
the Solar TErrestrial RElations Observatory (STEREO) A and B spacecraft,
and the Atmospheric Imaging Assembly (AIA) onboard the Solar Dynamics
Observatory (SDO). Multiplying the wavelength-response functions
for each instrument by a series of isothermal synthetic spectra and
integrating over the range 165 - 195 Å produced temperature-response
functions for the six instruments. Each temperature response was
then multiplied by sample differential emission-measure functions
for four different solar conditions. For any given plasma condition
(e.g. quiet Sun, active region), it was found that the overall variation
with temperature agreed remarkably well across the six instruments,
although the wavelength responses for each instrument have some
distinctly different features. Deviations were observed, however,
when we compared the response of any one instrument to different solar
conditions, particularly for the case of solar flares.
---------------------------------------------------------
Title: Signatures of Slow Solar Wind Streams from Active Regions in
the Inner Corona
Authors: Slemzin, V.; Harra, L.; Urnov, A.; Kuzin, S.; Goryaev, F.;
Berghmans, D.
2013SoPh..286..157S Altcode: 2012arXiv1203.6756S; 2012SoPh..tmp..144S
The identification of solar-wind sources is an important question
in solar physics. The existing solar-wind models (e.g., the
Wang-Sheeley-Arge model) provide the approximate locations of the
solar wind sources based on magnetic field extrapolations. It has been
suggested recently that plasma outflows observed at the edges of active
regions may be a source of the slow solar wind. To explore this we
analyze an isolated active region (AR) adjacent to small coronal hole
(CH) in July/August 2009. On 1 August, Hinode/EUV Imaging Spectrometer
observations showed two compact outflow regions in the corona. Coronal
rays were observed above the active-region coronal hole (ARCH) region
on the eastern limb on 31 July by STEREO-A/EUVI and at the western
limb on 7 August by CORONAS-Photon/TESIS telescopes. In both cases
the coronal rays were co-aligned with open magnetic-field lines given
by the potential field source surface model, which expanded into the
streamer. The solar-wind parameters measured by STEREO-B, ACE, Wind,
and STEREO-A confirmed the identification of the ARCH as a source
region of the slow solar wind. The results of the study support the
suggestion that coronal rays can represent signatures of outflows
from ARs propagating in the inner corona along open field lines into
the heliosphere.
---------------------------------------------------------
Title: Study of a Prominence Eruption using PROBA2/SWAP and
STEREO/EUVI Data
Authors: Mierla, M.; Seaton, D. B.; Berghmans, D.; Chifu, I.; De Groof,
A.; Inhester, B.; Rodriguez, L.; Stenborg, G.; Zhukov, A. N.
2013SoPh..286..241M Altcode: 2012SoPh..tmp...66M; 2012arXiv1203.6732M
Observations of the early rise and propagation phases of solar eruptive
prominences can provide clues about the forces acting on them through
the behavior of their acceleration with height. We have analyzed such an
event, observed on 13 April 2010 by SWAP on PROBA2 and EUVI on STEREO. A
feature at the top of the erupting prominence was identified and tracked
in images from the three spacecraft. The triangulation technique was
used to derive the true direction of propagation of this feature. The
reconstructed points were fitted with two mathematical models: i) a
power-law polynomial function and ii) a cubic smoothing spline, in order
to derive the accelerations. The first model is characterized by five
degrees of freedom while the second one is characterized by ten degrees
of freedom. The results show that the acceleration increases smoothly,
and it is continuously increasing with height. We conclude that the
prominence is not accelerated immediately by local reconnection,
but rather is swept away as part of a large-scale relaxation of the
coronal magnetic field.
---------------------------------------------------------
Title: Solar TErrestrial Relations Observatory-A (STEREO-A) and
PRoject for On-Board Autonomy 2 (PROBA2) Quadrature Observations of
Reflections of Three EUV Waves from a Coronal Hole
Authors: Kienreich, I. W.; Muhr, N.; Veronig, A. M.; Berghmans, D.;
De Groof, A.; Temmer, M.; Vršnak, B.; Seaton, D. B.
2013SoPh..286..201K Altcode: 2012SoPh..tmp..138K
We investigate the interaction of three consecutive large-scale coronal
waves with a polar coronal hole, simultaneously observed on-disk by the
Solar TErrestrial Relations Observatory (STEREO)-A spacecraft and on
the limb by the PRoject for On-Board Autonomy 2 (PROBA2) spacecraft on
27 January 2011. All three extreme ultraviolet (EUV) waves originate
from the same active region, NOAA 11149, positioned at N30E15 in the
STEREO-A field of view and on the limb in PROBA2. For the three primary
EUV waves, we derive starting velocities in the range of ≈ 310 km
s<SUP>−1</SUP> for the weakest up to ≈ 500 km s<SUP>−1</SUP>
for the strongest event. Each large-scale wave is reflected at the
border of the extended coronal hole at the southern polar region. The
average velocities of the reflected waves are found to be smaller than
the mean velocities of their associated direct waves. However, the
kinematical study also reveals that in each case the ending velocity
of the primary wave matches the initial velocity of the reflected
wave. In all three events, the primary and reflected waves obey the
Huygens-Fresnel principle, as the incident angle with ≈ 10° to
the normal is of the same magnitude as the angle of reflection. The
correlation between the speed and the strength of the primary EUV waves,
the homologous appearance of both the primary and the reflected waves,
and in particular the EUV wave reflections themselves suggest that the
observed EUV transients are indeed nonlinear large-amplitude MHD waves.
---------------------------------------------------------
Title: Space Weather and Particle Effects on the Orbital Environment
of PROBA2
Authors: West, Matthew; Seaton, Dan; Dominique, Marie; Berghmans,
David; Nicula, Bogdan; Pylyser, Erik; Stegen, Koen; De Keyser, Johan
2013EGUGA..1510865W Altcode:
Data from the EUV imager SWAP and UV/EUV radiometer LYRA on board the
PROBA2 spacecraft are regularly affected by space weather conditions
along the spacecraft's orbital path. While these effects are generally
removed from calibrated data intended for scientific analysis, they
provide an interesting opportunity to characterize the evolution
near-Earth space environment as the result of changing space weather
conditions. Here we present an analysis of these space weather effects
on PROBA2 observations and some conclusions about both the long-term
evolution of the inner magnetosphere and short-term events driven by
the active sun.
---------------------------------------------------------
Title: Quasi-Periodic Pulsations during the onset of solar flares:
multi-instrumental comparison
Authors: West, M. J.; Dolla, L.; Marque, C.; Seaton, D. B.; Van
Doorsselaere, T.; Dominique, M.; Berghmans, D.; Cabanas, C.; De Groof,
A.; Schmutz, W.; Verdini, A.; Zender, J.; Zhukov, A. N.
2013enss.confE..82W Altcode:
Quasi-periodic pulsations have been observed in the rising phase of
solar flares for many years. Observations have been made over a wide
spectral range, extending from X-rays to radio wavelengths. The
current generation of spacebourne instruments, especially SDO,
EVE and ESP, have exceptionally high sampling rates and allow us
to make more detailed observations of this phenomena. In this work,
we compare short-period oscillations (around 10 s) observed in flare
events by multiple instruments: the radiometer channels of SDO/EVE-ESP
(soft X-ray, coronal and chromospheric passbands), the EUV channels of
the radiometer PROBA2/LYRA, the RHESSI passbands and short-wavelength
radio observations.
---------------------------------------------------------
Title: The EUI instrument on board the Solar Orbiter mission: from
breadboard and prototypes to instrument model validation
Authors: Halain, J. -P.; Rochus, P.; Renotte, E.; Appourchaux, T.;
Berghmans, D.; Harra, L.; Schühle, U.; Schmutz, W.; Auchère, F.;
Zhukov, A.; Dumesnil, C.; Delmotte, F.; Kennedy, T.; Mercier, R.;
Pfiffner, D.; Rossi, L.; Tandy, J.; BenMoussa, A.; Smith, P.
2012SPIE.8443E..07H Altcode:
The Solar Orbiter mission will explore the connection between the Sun
and its heliosphere, taking advantage of an orbit approaching the Sun at
0.28 AU. As part of this mission, the Extreme Ultraviolet Imager (EUI)
will provide full-sun and high-resolution image sequences of the solar
atmosphere at selected spectral emission lines in the extreme and vacuum
ultraviolet. To achieve the required scientific performances under the
challenging constraints of the Solar Orbiter mission it was required
to further develop existing technologies. As part of this development,
and of its maturation of technology readiness, a set of breadboard and
prototypes of critical subsystems have thus been realized to improve
the overall instrument design. The EUI instrument architecture, its
major components and sub-systems are described with their driving
constraints and the expected performances based on the breadboard and
prototype results. The instrument verification and qualification plan
will also be discussed. We present the thermal and mechanical model
validation, the instrument test campaign with the structural-thermal
model (STM), followed by the other instrument models in advance of
the flight instrument manufacturing and AIT campaign.
---------------------------------------------------------
Title: Plasmoid Ejection at a Solar Total Eclipse
Authors: Koutchmy, S.; Bazin, C.; Berghmans, D.; De Groof, A.;
Druckmüller, M.; Tavabi, E.; Engell, A.; Filippov, B.; Golub, L.;
Lamy, Ph.; Linker, J.; Mikic, Z.; Mouette, J.; Nitschelm, Ch.; Seaton,
D.; Slemzin, V.
2012EAS....55..223K Altcode:
The existence of coronal plasmoids has been postulated for many years
in order to supply material to streamers and possibly to the solar
wind (SW). The W-L SoHO C2 Lasco coronagraph observations were made
under the 2.2 solar radii (R0) occulting disk to look at the ultimate
sources of the SW; EUV imagers are preferably devoted to the analysis
of the corona on and very near the solar disk. Here, in addition to
eclipse white-light (W-L) snapshots, we used the new SWAP space-borne
imager designed for the systematic survey of coronal activity in the
EUV lines near 17.4 nm, over a field of view (FOV) up to 2 R0. Using
summed and co-aligned images, the corona can then be evaluated for the
1st time up to the limit of this FOV. At the time of the July 11, 2010,
solar total eclipse a 20h continuous run of observations was collected,
including images taken during eclipse totality from several ground
observing locations where W-L data were collected. A plasmoid-like
off-limb event was followed using the SWAP summed
---------------------------------------------------------
Title: A Collaborative Research Environment for Heliophysics
Authors: Bentley, R. D.; Berghmans, D.; Csillaghy, A.
2012EGUGA..1412873B Altcode:
Heliophysics is the study of the effect of the Sun on the Solar
System; it is a relatively new science that combines the solar,
heliospheric, geophysics and planetary communities. The subject is
an example of the increasing desire to address science problems that
span disciplinary boundaries and provides a good example of the issues
involved. The communities that constitute heliophysics have grown up
independently and there are differences in the way that their data
are stored and used. Although a number of capabilities relevant to
heliophysics have been established under auspices of various projects
and organisations, the fact that they have not followed any underlying
strategy is now inhibiting our ability to do this type of science. The
Heliophysics Integrated Observatory (HELIO), a research infrastructure
funded under Capacities programme of the EC's 7th Framework Programme
(FP7), was designed around a service-oriented architecture with needed
capabilities that support metadata curation and search, data location
and retrieval, and data processing and storage being established as
independent services. In addition, a number of virtual observatories
have been established that address aspects of the overall problem
of heliophysics within the NASA's Heliophysics Science Division. We
examine the capabilities of these resources and look at where their
strengths and weaknesses lie. We identify some of the steps that are
needed to improve interoperability between the initiatives and consider
how they could be brought together to form a Collaborative Research
Environment for Heliophysics (CREH). The Coordination Action for the
integration of Solar System Infrastructure and Science (CASSIS) has the
objective of exploring ways to improve interoperability for all aspects
of Solar System Science. CASSIS is funded under Capacities specific
programme of the European Commission's Seventh Framework Programme
(FP7) and grew out of the HELIO, Europlanet RI and SOTERIA projects;
it also includes other key partners such as NASA, ESA, and NOAA. We
welcome participation by other interested organisations
---------------------------------------------------------
Title: STEREO-A and PROBA2 Quadrature Observations of Reflections
of three EUV Waves from a Coronal Hole
Authors: Kienreich, Ines Waltraud; Muhr, Nicole; Veronig, Astrid;
Berghmans, David; de Groof, Anik; Temmer, Manuela; Vršnak, Bojan;
Seaton, Dan
2012arXiv1204.6472K Altcode: 2012arXiv1204.6472W
We investigate the interaction of three consecutive large-scale coronal
waves with a polar coronal hole, simultaneously observed on-disk by the
Solar TErrestrial Relations Observatory (STEREO)-A spacecraft and on
the limb by the PRoject for On-Board Autonomy 2 (PROBA2) spacecraft on
January 27, 2011. All three extreme-ultraviolet(EUV) waves originate
from the same active region NOAA 11149 positioned at N30E15 in the
STEREO-A field-of-view and on the limb in PROBA2. We derive for the
three primary EUV waves start velocities in the range of ~310 km/s for
the weakest up to ~500 km/s for the strongest event. Each large-scale
wave is reflected at the border of the extended coronal hole at the
southern polar region. The average velocities of the reflected waves
are found to be smaller than the mean velocities of their associated
direct waves. However, the kinematical study also reveals that in each
case the end velocity of the primary wave matches the initial velocity
of the reflected wave. In all three events the primary and reflected
waves obey the Huygens-Fresnel principle, as the incident angle with
~10° to the normal is of the same size as the angle of reflection. The
correlation between the speed and the strength of the primary EUV waves,
the homologous appearance of both the primary and the reflected waves,
and in particular the EUV wave reflections themselves implicate that the
observed EUV transients are indeed nonlinear large-amplitude MHD waves.
---------------------------------------------------------
Title: Time Delays in Quasi-periodic Pulsations Observed during the
X2.2 Solar Flare on 2011 February 15
Authors: Dolla, L.; Marqué, C.; Seaton, D. B.; Van Doorsselaere,
T.; Dominique, M.; Berghmans, D.; Cabanas, C.; De Groof, A.; Schmutz,
W.; Verdini, A.; West, M. J.; Zender, J.; Zhukov, A. N.
2012ApJ...749L..16D Altcode: 2012arXiv1203.6223D
We report observations of quasi-periodic pulsations (QPPs) during the
X2.2 flare of 2011 February 15, observed simultaneously in several
wavebands. We focus on fluctuations on timescale 1-30 s and find
different time lags between different wavebands. During the impulsive
phase, the Reuven Ramaty High Energy Solar Spectroscopic Imager
channels in the range 25-100 keV lead all the other channels. They
are followed by the Nobeyama RadioPolarimeters at 9 and 17 GHz and the
extreme-ultraviolet (EUV) channels of the Euv SpectroPhotometer (ESP)
on board the Solar Dynamic Observatory. The zirconium and aluminum
filter channels of the Large Yield Radiometer on board the Project for
On-Board Autonomy satellite and the soft X-ray (SXR) channel of ESP
follow. The largest lags occur in observations from the Geostationary
Operational Environmental Satellite, where the channel at 1-8 Å leads
the 0.5-4 Å channel by several seconds. The time lags between the
first and last channels is up to ≈9 s. We identified at least two
distinct time intervals during the flare impulsive phase, during which
the QPPs were associated with two different sources in the Nobeyama
RadioHeliograph at 17 GHz. The radio as well as the hard X-ray channels
showed different lags during these two intervals. To our knowledge,
this is the first time that time lags are reported between EUV and
SXR fluctuations on these timescales. We discuss possible emission
mechanisms and interpretations, including flare electron trapping.
---------------------------------------------------------
Title: Preliminary Results on Irradiance Measurements from Lyra
and Swap
Authors: Kumara, S. T.; Kariyappa, R.; Dominique, M.; Berghmans, D.;
Damé, L.; Hochedez, J. F.; Doddamani, V. H.; Chitta, Lakshmi Pradeep
2012AdAst2012E...5K Altcode: 2012AdAst2012E..10K
No abstract at ADS
---------------------------------------------------------
Title: Hierarchical approach to forecasting recurrent solar wind
streams
Authors: Shugay, Yu. S.; Veselovsky, I. S.; Seaton, D. B.; Berghmans,
D.
2011SoSyR..45..546S Altcode:
The hierarchical approach to predicting quasi-stationary, high-speed
solar wind (SW) streams is described. This approach integrates various
types of data into a single forecasting system by means of an ensemble
of experts. The input data included the daily values of the coronal
hole areas, which were calculated from the ultraviolet images of
the Sun, and the speed of the SW streams during the previous solar
rotations. The coronal hole areas were calculated from the images taken
by the SWAP instrument aboard the PROBA2 satellite in the spectral
interval centered at a wavelength of 17.4 nm and by the AIA instrument
aboard the SDO spacecraft in the interval of wavelengths centered
at 19.3 and 17.1 nm. The forecast was based on the data for 2010,
corresponding to the rising phase of the 24th solar cycle. On the
first hierarchical level, a few simple model estimates were obtained
for the speed of the SW streams from the input data of each type. On
the second level of hierarchy, the final 3 day ahead forecast of the
SW velocity was formulated on the basis of the obtained estimates. The
proposed hierarchical approach improves the accuracy of forecasting
the SW velocity. In addition, in such a method of prediction, the
data gaps in the records of one instrument do not crucially affect
the final result of forecasting of the system as a whole.
---------------------------------------------------------
Title: LYRA and SWAP, the two Solar Instruments on-board PROBA2
Authors: Dominique, M.; Berghmans, D.; Schmutz, W. K.; Dammasch, I.;
De Groof, A.; Halain, J.; Hochedez, J.; Kretzschmar, M.; Seaton, D. B.
2011AGUFMSH13B1949D Altcode:
PROBA2 (http://proba2.sidc.be) is an ESA micro-satellite that was
launched in November 2009. Two instruments on-board, SWAP and LYRA, are
devoted to solar observations. SWAP (PI: D. Berghmans) is an EUV imager
observing the corona with a bandpass centered on 174 Å at a cadence of
1-2 min. Its high contrast images, large FOV and flexible off-pointing
capabilities make SWAP particularly well suited for the study of coronal
eruptions. LYRA (PI: M. Dominique) is a UV-EUV radiometer observing
in four spectral channels, chosen for their relevance in solar physics
and aeronomy. Its very fast acquisition cadence (up to 100 Hz) allows
scientists to perform detailed analysis of solar flares. We discuss
the characteristics of both instruments, review their performance and
evolution, and highlight their complementarity to other missions. We
also present the data products that can be downloaded from the mission
website and give an overview of the various investigations for which
SWAP and LYRA data are currently used (CMEs, flares, solar variability,
and many others).
---------------------------------------------------------
Title: LYRA Observations of Two Oscillation Modes in a Single Flare
Authors: Van Doorsselaere, T.; De Groof, A.; Zender, J.; Berghmans,
D.; Goossens, M.
2011ApJ...740...90V Altcode:
We analyze light curves from the LYRA irradiance experiment on
board PROBA2 during the flare of 2010 February 8. We see both long-
and short-period oscillations during the flare. The long-period
oscillation is interpreted in terms of standing slow sausage modes;
the short-period oscillation is thought to be a standing fast sausage
mode. The simultaneous presence of two oscillation modes in the same
flaring structure allows for new coronal seismological applications. The
periods are used to find seismological estimates of the plasma-β and
the density contrast of the flaring loop. Also the wave mode number
is estimated from the observed periods.
---------------------------------------------------------
Title: Validation of CME Detection Software (CACTus) by Means of
Simulated Data, and Analysis of Projection Effects on CME Velocity
Measurements
Authors: Bonte, K.; Jacobs, C.; Robbrecht, E.; De Groof, A.; Berghmans,
D.; Poedts, S.
2011SoPh..270..253B Altcode: 2011SoPh..tmp...52B; 2011SoPh..tmp...72B
In the context of space weather forecasting, an automated detection
of coronal mass ejections (CMEs) becomes more and more important
for efficiently handling a large data flow which is expected from
recently-launched and future solar missions. In this paper we validate
the detection software package "CACTus" by applying the program to
synthetic data from our 3D time-dependent CME simulations instead of
observational data. The main strength of this study is that we know
in advance what should be detected. We describe the sensitivities
and strengths of automated detection, more specific for the CACTus
program, resulting in a better understanding of CME detection on one
hand and the calibration of the CACTus software on the other hand,
suggesting possible improvements of the package. In addition, the
simulation is an ideal tool to investigate projection effects on CME
velocity measurements.
---------------------------------------------------------
Title: SWAP-SECCHI Observations of a Mass-loading Type Solar Eruption
Authors: Seaton, Daniel B.; Mierla, Marilena; Berghmans, David;
Zhukov, Andrei N.; Dolla, Laurent
2011ApJ...727L..10S Altcode: 2010arXiv1011.1144S
We present a three-dimensional reconstruction of an eruption that
occurred on 2010 April 3 using observations from SWAP on board PROBA2
and SECCHI on board STEREO. The event unfolded in two parts: an initial
flow of cooler material confined to a height low in the corona, followed
by a flux rope eruption higher in the corona. We conclude that mass
off-loading from the first part triggered a rise and, subsequently,
catastrophic loss of equilibrium of the flux rope.
---------------------------------------------------------
Title: SWAP: An EUV Imager for Solar Monitoring on Board of the
PROBA2 Micro-Satellite
Authors: Katsiyannis, A. C.; Berghmans, D.; Swap Consortium
2010ASPC..424..104K Altcode:
PROBA2 is a ESA technology demonstration mission successfully launched
in November 2<SUP>nd</SUP> 2009. The prime instrument on board of
PROBA2 is SWAP (Sun Watcher using Active Pixel System detector and
Image Processing), a full disk solar imager with a narrow bandpass
filter centered at 17.4 nm (Fe IX - XI) and a fast cadence of ≍1
min. The telescope is an extreme ultraviolet (EUV), high cadence
(of up to 1 frame per minute) imager based on an enchanted APS CMOS
detector. The field of view will be wider than EIT’s by ≍20%
allowing SWAP to observe a larger portion of the lower corona and
bridge the gap between EIT and LASCO-C2.
---------------------------------------------------------
Title: The technical challenges of the Solar-Orbiter EUI instrument
Authors: Halain, Jean-Philippe; Rochus, Pierre; Appourchaux, Thierry;
Berghmans, David; Harra, Louise; Schühle, Udo; Auchère, Frédéric;
Zhukov, Andrei; Renotte, Etienne; Defise, Jean-Marc; Rossi, Laurence;
Fleury-Frenette, Karl; Jacques, Lionel; Hochedez, Jean-François;
Ben Moussa, Ali
2010SPIE.7732E..0RH Altcode: 2010SPIE.7732E..20H
The Extreme Ultraviolet Imager (EUI) onboard Solar Orbiter consists of
a suite of two high-resolution imagers (HRI) and one dual-band full
Sun imager (FSI) that will provide EUV and Lyman-α images of the
solar atmospheric layers above the photosphere. The EUI instrument is
based on a set of challenging new technologies allowing to reach the
scientific objectives and to cope with the hard space environment of
the Solar Orbiter mission. The mechanical concept of the EUI instrument
is based on a common structure supporting the HRI and FSI channels,
and a separated electronic box. A heat rejection baffle system is
used to reduce the Sun heat load and provide a first protection level
against the solar disk straylight. The spectral bands are selected by
thin filters and multilayer mirror coatings. The detectors are 10μm
pitch back illuminated CMOS Active Pixel Sensors (APS), best suited
for the EUI science requirements and radiation hardness. This paper
presents the EUI instrument concept and its major sub-systems. The
current developments of the instrument technologies are also summarized.
---------------------------------------------------------
Title: First light of SWAP on-board PROBA2
Authors: Halain, Jean-Philippe; Berghmans, David; Defise, Jean-Marc;
Renotte, Etienne; Thibert, Tanguy; Mazy, Emmanuel; Rochus, Pierre;
Nicula, Bogdan; de Groof, Anik; Seaton, Dan; Schühle, Udo
2010SPIE.7732E..0PH Altcode: 2010SPIE.7732E..18H
The SWAP telescope (Sun Watcher using Active Pixel System detector
and Image Processing) is an instrument launched on 2nd November 2009
on-board the ESA PROBA2 technological mission. SWAP is a space weather
sentinel from a low Earth orbit, providing images at 174 nm of the
solar corona. The instrument concept has been adapted to the PROBA2
mini-satellite requirements (compactness, low power electronics and
a-thermal opto-mechanical system). It also takes advantage of the
platform pointing agility, on-board processor, Packetwire interface
and autonomous operations. The key component of SWAP is a radiation
resistant CMOS-APS detector combined with onboard compression and
data prioritization. SWAP has been developed and qualified at the
Centre Spatial de Liège (CSL) and calibrated at the PTBBessy
facility. After launch, SWAP has provided its first images on 14th
November 2009 and started its nominal, scientific phase in February
2010, after 3 months of platform and payload commissioning. This
paper summarizes the latest SWAP developments and qualifications,
and presents the first light results.
---------------------------------------------------------
Title: Space Weather data and services at SIDC / RWC Belgium
Authors: van der Linden, Ronald; Ben Moussa, Ali; Berghmans, David;
Boulvin, Olivier; Boyes, David; Cabanas Parada, Carlos; Callebaut,
Benoit; Clette, Frédéric; Dammasch, Ingolf; Delouille, Veronique;
D'Huys, Elke; Dolla, Laurent; Dominique, Marie; Dufond, Jean-Luc;
Ergen, Aydin; Giordanengo, Boris; Gissot, Samuel; Goryaev, Farid;
Hochedez, Jean-Francois; Lemaâtre, Olivier; Lisnichenko, Pavel;
Magdalenic, Jas-Mina; Mampaey, Benjamin; Marque, Christophe; Nicula,
Bogdan; Podladchikova, Elena; Pylyser, Erik; Raynal, Sophie; Rodriguez,
Luciano; Seaton, Daniël; van der Linden, Ronald; Vandersyppe, Anne;
Vanlommel, Petra; Vanraes, Stéphane; Verbeeck, Cis; Verdini, Andrea;
Wauters, Laurence; West, Matthew; Willems, Sarah; Zhukov, Andrei
2010cosp...38.4202V Altcode: 2010cosp.meet.4202V
The SIDC of the Royal Observatory of Belgium is a very active center
for solar physics research, but also provides an operational service
for data and services related to solar activity and space weather. In
this poster we present the currently available data sets and products,
with a focus on recent additions and new developments.
---------------------------------------------------------
Title: Solar observations from PROBA2: ready for space weather
operations
Authors: Berghmans, David; Hochedez, Jean-François
2010cosp...38.4184B Altcode: 2010cosp.meet.4184B
The ESA micro satellite PROBA2 was launched on November 2, 2009. It
carries two solar instruments, the radiometer LYRA and the coronal
imager SWAP whose commissioning ended in March 2010. LYRA (PI:
J.-F. Hochedez) observes the solar irradiance in 4 wavelengths
chosen for their relevance to space weather, solar physics and Earth
aeronomy. LYRA is able to follow the time evolution of solar flares
at very high temporal resolution. SWAP (PI: D. Berghmans) takes an
image of the EUV corona of the sun every minute in an extended field of
view. SWAP is able to image all space weather significant events such
as flares, coronal holes, dimmings, etc. We will present the technical
capabilities of the two instruments and show their complementarity
with e.g. SDO. We will discuss the SWAP and LYRA data products and
how to make use of them in an operational space weather context. More
information is available at http://proba2.sidc.be.
---------------------------------------------------------
Title: On 3D Reconstruction of Coronal Mass Ejections: I. Method
Description and Application to SECCHI-COR Data
Authors: Mierla, M.; Inhester, B.; Marqué, C.; Rodriguez, L.; Gissot,
S.; Zhukov, A. N.; Berghmans, D.; Davila, J.
2009SoPh..259..123M Altcode:
The data from SECCHI-COR1 and SECCHI-COR2 coronagraphs onboard the
STEREO mission, which was launched in October 2006, provide us with the
first-ever stereoscopic images of the Sun's corona. These observations
were found to be useful in inferring the three-dimensional structure
of coronal mass ejections (CMEs) and their propagation direction in
space. We apply four methods for reconstructing CMEs: i) Forward
modeling technique; ii) Local correlation tracking (to identify
the same feature in COR Ahead and COR Behind images) plus tie-point
reconstruction technique; iii) Center of mass of the structures in
a given epipolar plane plus tie-point reconstruction technique; iv)
Polarization ratio technique. The four techniques are applied to three
structured CMEs observed by COR1 and COR2 instruments, respectively,
on 15 May 2007, 31 August 2007, and 25 March 2008. A comparison of
the results obtained from the application of the four reconstruction
algorithms is presented and discussed.
---------------------------------------------------------
Title: On 3D Reconstruction of Coronal Mass Ejections using
SECCHI-COR Data
Authors: Mierla, M.; Inhester, B.; Marque, C.; Rodriguez, L.; Gissot,
S.; Zhukov, A.; Berghmans, D.; Davila, J.
2009EGUGA..11.1145M Altcode:
The data from SECCHI-COR1 and SECCHI-COR2 coronagraphs onboard STEREO
mission which was launched in October 2006 provided us with the
first-ever stereoscopic images of the Sun's corona. These observations
were found to be extremely useful in reconstructing the 3D structure of
coronal mass ejections (CMEs). We apply four methods for reconstructing
the CMEs: 1) Local correlation tracking (to identify the same feature
in COR Ahead and COR Behind images) plus tie-point reconstruction
technique; 2) Center of mass of the structures along the line of
sight (i.e. along each epipolar lines) plus tie-point reconstruction
technique; 3) Polarization ratio technique (see for e.g. Moran and
Davila 2004); 4) Forward modelling technique (see Thernisien et
al. 2006). The four techniques are applied on three structured CMEs
observed by COR1 and COR2 instruments on 15 May 2007, 31 August 2007
and 25 March 2008. A comparison of results obtained from the application
of the four reconstruction algorithms is presented and discussed.
---------------------------------------------------------
Title: Automated LASCO CME Catalog for Solar Cycle 23: Are CMEs
Scale Invariant?
Authors: Robbrecht, E.; Berghmans, D.; Van der Linden, R. A. M.
2009ApJ...691.1222R Altcode: 2008arXiv0810.1252R
In this paper, we present the first automatically constructed LASCO
coronal mass ejection (CME) catalog, a result of the application of
the Computer Aided CME Tracking software (CACTus) on the LASCO archive
during the interval 1997 September-2007 January. We have studied the CME
characteristics and have compared them with similar results obtained
by manual detection (CDAW CME catalog). On average, CACTus detects
less than two events per day during solar minimum, up to eight events
during maximum, nearly half of them being narrow (<20°). Assuming
a correction factor, we find that the CACTus CME rate is surprisingly
consistent with CME rates found during the past 30 years. The CACTus
statistics show that small-scale outflow is ubiquitously observed in the
outer corona. The majority of CACTus-only events are narrow transients
related to previous CME activity or to intensity variations in the slow
solar wind, reflecting its turbulent nature. A significant fraction
(about 15%) of CACTus-only events were identified as independent
events, thus not related to other CME activity. The CACTus CME width
distribution is essentially scale invariant in angular span over a
range of scales from 20° to 120° while previous catalogs present a
broad maximum around 30°. The possibility that the size of coronal
mass outflows follow a power-law distribution could indicate that
no typical CME size exists, i.e., that the narrow transients are not
different from the larger well defined CMEs.
---------------------------------------------------------
Title: Meeting contribution: The history of the Sunspot Index
Authors: Berghmans, D.
2008JBAA..118..348B Altcode:
No abstract at ADS
---------------------------------------------------------
Title: SWAP onboard PROBA2: An Innovative EUV Imager Designed for
Space Weather
Authors: de Groof, A.; Berghmans, D.; Defise, J. M.; Nicula, B.;
Schuehle, U.
2008ESPM...122.116D Altcode:
PROBA2 (PRoject for OnBoard Autonomy) is an ESA micro-satellite
that is being prepared for launch in 2009. Its primary goal is the
demonstration of new technologies in the space environment. Furthermore,
the satellite carries an ambitious suite of both in-situ and
remote sensing instruments for monitoring space weather, despite
the modest onboard resources. Both the spacecraft and the remote
sensing instruments are mainly developed within Belgium. <P />One of
the main instruments, SWAP (Sun Watcher with APS detectors and image
Processing), is a compact EUV imager. It carries the first APS detector
with an EUV sensitive scintillator coating to be flown in orbit. In
addition to the new detector, the PROBA2/SWAP design is innovative
in the sense that the instrument will make heavy use of on-board data
processing and autonomous operations. These will range from automatic
off-pointing and tracking of appropriate solar events, to pre-downlink
data prioritisation, and feature and event recognition procedures. <P
/>We discuss the first results of the SWAP pre-flight calibration and
the strengths and weaknesses of the instrument [2]. With a narrow
spectral bandpass centred around 17.4nm, a FOV of 54 arcmin and an
image cadence of 1 min, its design is ideal for monitoring most CME
associated phenomena on the solar disk and close to the limb. <P />[1]
Defise J., Halain J., Berghmans D., et al. 2007, In: Proc. SPIE, 6689,
66890S <P />[2] De Groof A., Berghmans D., Nicula B., et al. 2008,
Solar Phys. 249, 147-163
---------------------------------------------------------
Title: Du nombre de Wolf á l'indice international des taches
solaires: 25 ans de SIDC (2<SUP>e</SUP> partie)
Authors: Clette, Frédéric; Berghmans, David; Vanlommel, Petra;
van der Linden, Ronald A. M.; Koeckelenbergh, André; Wauters, Laurence
2008C&T...124...98C Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Du nombre de Wolf á l'indice international des taches
solaires: 25 ans de SIDC (1<SUP>e</SUP> partie)
Authors: Clette, Frédéric; Berghmans, David; Vanlommel, Petra;
van der Linden, Ronald A. M.; Koeckelenbergh, André; Wauters, Laurence
2008C&T...124...66C Altcode:
No abstract at ADS
---------------------------------------------------------
Title: CMOS-APS Detectors for Solar Physics: Lessons Learned during
the SWAP Preflight Calibration
Authors: De Groof, A.; Berghmans, D.; Nicula, B.; Halain, J. -P.;
Defise, J. -M.; Thibert, T.; Schühle, U.
2008SoPh..249..147D Altcode: 2008SoPh..tmp...62D
CMOS-APS imaging detectors open new opportunities for remote sensing
in solar physics beyond what classical CCDs can provide, offering
far less power consumption, simpler electronics, better radiation
hardness, and the possibility of avoiding a mechanical shutter. The
SWAP telescope onboard the PROBA2 technology demonstration satellite
of the European Space Agency will be the first actual implementation
of a CMOS-APS detector for solar physics in orbit. One of the goals
of the SWAP project is precisely to acquire experience with the
CMOS-APS technology in a real-live space science context. Such a
precursor mission is essential in the preparation of missions such as
Solar Orbiter where the extra CMOS-APS functionalities will be hard
requirements. The current paper concentrates on specific CMOS-APS
issues that were identified during the SWAP preflight calibration
measurements. We will discuss the different readout possibilities that
the CMOS-APS detector of SWAP provides and their associated pros and
cons. In particular we describe the "image lag" effect, which results in
a contamination of each image with a remnant of the previous image. We
have characterised this effect for the specific SWAP implementation
and we conclude with a strategy on how to successfully circumvent the
problem and actually take benefit of it for solar monitoring.
---------------------------------------------------------
Title: Visualization of Distributed Solar Data and Metadata with
the Solar Weather Browser
Authors: Nicula, B.; Marqué, C.; Berghmans, D.
2008SoPh..248..225N Altcode: 2008SoPh..tmp....7N
The Solar Weather Browser (SWB) is a standalone, open-source software
tool designed to display solar images with context overlays. It was
originally developed for the space-weather forecast activities of the
Solar Influence Data analysis Center (SIDC) but it is more generally
well suited to display the output of solar-feature recognition
methods. The SWB is also useful in the context of distributed
solar-image archives, where it could play the role of a quick-look
viewer. The SWB allows the user to visually browse large solar data sets
and investigate the solar activity for a given date. It has a client -
server design that minimizes the bandwidth from the network to the
user's monitor. The server processes the data using the SolarSoft
library and distributes them through a Web server to which the SWB
client connects. The client is readily available for Linux, Mac OS X,
and Windows at http://sidc.be/SWB. We discuss the software technology
embedded in the SWB as well as its use for solar physics and space
weather.
---------------------------------------------------------
Title: SWAP: a novel EUV telescope for space weather
Authors: Defise, Jean-Marc; Halain, Jean-Philippe; Berghmans,
David; Denis, François; Mazy, Emmanuel; Thibert, Tanguy; Lecat,
Jean-Hervé; Rochus, Pierre; Nicula, Bogdan; De Groof, Anik; Hochedez,
Jean-François; Schühle, Udo; Ravet, Marie-Françoise; Delmotte, Frank
2007SPIE.6689E..0SD Altcode: 2007SPIE.6689E..24D
The SWAP telescope (Sun Watcher using Active Pixel System detector and
Image Processing) is being developed to be part of the PROBA2 payload,
an ESA technological mission to be launched in early 2008. SWAP
is directly derived from the concept of the EIT telescope that we
developed in the '90s for the SOHO mission. Several major innovations
have been introduced in the design of the instrument in order to
be compliant with the requirements of the PROBA2 mini-satellite:
compactness with a new of-axis optical design, radiation resistance
with a new CMOS-APS detector, a very low power electronics, an athermal
opto-mechanical system, optimized onboard compression schemes combined
with prioritization of collected data, autonomy with automatic
triggering of observation and off-pointing procedures in case of
Solar event occurrence, ... All these new features result from the low
resource requirements (power, mass, telemetry) of the mini-satellite,
but also take advantage of the specificities of a modern technological
platform, such as quick pointing agility, new powerful on-board
processor, Packetwire interface and autonomous operations. These
new enhancements will greatly improve the operations of SWAP as
a space weather sentinel from a low Earth orbit while the downlink
capabilities are limited. This paper summarizes the conceptual design,
the development and the qualification of the instrument, the autonomous
operations and the expected performances for science exploitation.
---------------------------------------------------------
Title: Helio-informatics: Preparing For The Future Of Heliophysics
Research.
Authors: Schrijver, Carolus J.; Hurlburt, N. E.; Cheung, M. C.; Title,
A. M.; Delouille, V.; Hochedez, J.; Berghmans, D.
2007AAS...210.2514S Altcode: 2007BAAS...39..133S
The rapidly growing data volumes for space- and ground-based
observatories for Sun and heliosphere will soon make it impractical,
costly, and perhaps effectively impossible for researchers to download
and locally inspect substantial portions of the data archives. By
the end of 2008, for example, the Solar Dynamics Observatory will
downlink over 2TB/day of compressed data; such a large volume would
readily saturate internet connections to the archive site if it were
exported to a handful of researchers around the world. We envision a
revolution in research methodology towards a mode in which researchers
run autonomous event-finding algorithms at a primary data archive in
order to pre-select relatively small subsets of the data that can
subsequently be inspected and analyzed in detail at a researcher's
home institution. Teams from the SDO, Hinode, STEREO, and TRACE
missions are developing the infrastructure that is needed to make this
into a useful research tool: we are (1) defining standardized event
attributes compatible with the Virtual Observatory and EGSO concepts,
(2) developing a knowledge base supported by a web-based tool for
compound queries based on the contents of solar and heliospheric
observations, and (3) assembling a group of researchers who are
interested in helping us develop a prototype system while beta-testing
it in real scientific studies. We invite you to contact us (a) if you
have feature-finding algorithms that you would like to see applied to
existing data archives, (b) if you would like to contribute expertise
in developing the knowledge-base system, or (c) if you would like
to participate in the testing of the system for scientific use. More
information on our plans, target dates, and contact information can
be found at http://www.lmsal.com/helio-informatics/hpkb/. <P />The
helio-informatics project is being developed with support from
the HINODE/SOT (NNM07AA01C), SDO/AIA (NNG04EA00C), STEREO/SECCHI
(N00173-02-C-2035), and TRACE (NAS5-38099) science investigations.
---------------------------------------------------------
Title: From the Wolf number to the International Sunspot Index:
25 years of SIDC
Authors: Clette, Frédéric; Berghmans, David; Vanlommel, Petra;
Van der Linden, Ronald A. M.; Koeckelenbergh, André; Wauters, Laurence
2007AdSpR..40..919C Altcode:
By encompassing four centuries of solar evolution, the sunspot number
provides the longest available record of solar activity. Nowadays,
it is widely used as the main reference solar index on which hundreds
of published studies are based, in various fields of science. In this
review, we will retrace the history of this crucial solar index, from
its roots at the Zürich Observatory up to the current multiple indices
established and distributed by the Solar Influences Data Analysis Center
(SIDC), World Data Center for the International Sunspot Index, which
was founded in 1981, exactly 25 years ago. We describe the principles
now in use for the statistical processing of input data coming from
the worldwide observing network (∼80 stations). Among the various
SIDC data products and innovations, we highlight some recent ones,
including the daily Estimated International Sunspot Number. Taking a
wider perspective, we show how the sunspot index stands the test of
time versus more recent quantitative indices, but we also consider
the prospects and possible options for a future transition from
the visual sunspot index heritage towards an equivalent global
activity index. Based on past historical flaws, we conclude on the
key requirements involved in the maintenance of any robust long-term
solar activity index.
---------------------------------------------------------
Title: Current and future space weather services and products from
the SIDC- Brussels
Authors: Lawrence, G.; Kretzschmar, M.; Berghmans, D.; Clete,
F.; Hochedez, J.; van der Linden, R.; Delouille, V.; Gissot, S.;
Marque, C.; Nicula, B.; Patoul, J.; Podladchikova, E.; Robbrecht,
E.; Vanlommel, P.; Dehant, V.
2006AGUFMSA51A..04L Altcode:
The SIDC-Brussels, as WDC for the sunspot index and European RWC of the
ISES, is the European hub for solar data and forecasts. Its services
and products, while long established and widely recognised and used,
are continuously being enhanced and supplemented. We present in
detail the current status and outline the imminent improvements and
additions. The Solar Weather Browser (SWB) is a free, downloadable,
multi-platform visualisation package for real-time browsing of processed
solar images from a variety of space and ground based sources, combined
with context information (events, regions IDs, etc.) via a wide choice
of overlay combinations. The Estimated International Sunspot Number
(EISN) has been produced and distributed daily since January 2006 by the
SIDC. Intended to support operational model predictions of ionospheric
radio propagation, we present some early statistical results. CACTus,
the operational Computer-Aided CME Tracking algorithm, now freely
available to the community via the SSW software framework, is being
tested for its real-time application to the STEREO/SECCHI COR-2 "space
weather beacon" coronagraph telemetry stream. Also NEMO, a software
package for the automated detection and morphological analysis of EIT
waves presently being tested, details the relation between coronal EUV
wave fronts and dimmings and characterizes their evolution; we present
sample results of both developments. The Velociraptor software processes
and interprets movies of the EUV solar corona, an algorithm identifying
outstanding motions such as loop openings that are associated to
space weather events. Sample results using EIT and TRACE data will be
shown. A new flare catalog called B2X is presented, compliled via a
method to detect automatically, and characterise according to time,
localization, size, EUV flares belonging to classes B to X anywhere
on the solar disc and at the limb. In addition we present a summary
of the full range of products available from SIDC which can be chosen
in any combination tailored to the individual, or group's needs. All
products are available via the revamped SIDC website, http://www.sidc.be
---------------------------------------------------------
Title: A Broad Perspective on Automated CME Tracking: Towards Higher
Level Space Weather Forecasting
Authors: Robbrecht, Eva; Berghmans, David
2006GMS...165...33R Altcode:
We discuss our current capabilities to deliver the CME parameters
required for the space weather forecasting process. The ever
growing importance of space weather has lead to new requirements
on the timeliness and objectiveness of CME detection. It has become
indispensable to report the occurrence of Earth-directed CMEs and to
predict their possible impact on the geospace environment. Early 2005,
we are on the eve of a new era in space weather forecasting. We point
out the restricted accuracy on the current forecasts and discuss a
chance for amelioration. This invokes data-driven models (empirical
and numerical), triggered by a real-time CME disturbance, simulating
the propagation and interaction of the ejection with the ambient solar
wind. We discuss the link between the direct observable parameters
(like the CME projected speed and angle around the occulter) and the
required input parameters (like radial speed, direction, …). The only
way to guarantee the real-time value of the simulations is by employing
software which autonomously detect CME parameters in a variety of
data. This paper focusses on the automated CME detection algorithms
that are currently available. Automated CME tracking is yet in its
infancy, therefore this `review' will be an outlook on the potential
of this field rather than looking back on already achieved milestones.
---------------------------------------------------------
Title: A broad Perspective on Automated CME Tracking: towards higher
level space weather forecasting
Authors: Robbrecht, E.; Berghmans, D.
2006GMS...165.....R Altcode:
We discuss our current capabilities to deliver the CME parameters
required for the space weather forecasting process. The ever
growing importance of space weather has lead to new requirements
on the timeliness and objectiveness of CME detection. It has become
indispensable to report the occurrence of Earth-directed CMEs and to
predict their possible impact on the geospace environment. Early 2005,
we are on the eve of a new era in space weather forecasting. We point
out the restricted accuracy on the current forecasts and discuss a
chance for amelioration. This invokes data-driven models (empirical
and numerical), triggered by a real-time CME disturbance, simulating
the propagation and interaction of the ejection with the ambient solar
wind. We discuss the link between the direct observable parameters
(like the CME projected speed and angle around the occulter) and the
required input parameters (like radial speed, direction, ...). The only
way to guarantee the real-time value of the simulations is by employing
software which autonomously detect CME parameters in a variety of
data. This paper focusses on the automated CME detection algorithms
that are currently available. Automated CME tracking is yet in its
infancy, therefore this `review' will be an outlook on the potential
of this field rather than looking back on already achieved milestones.
---------------------------------------------------------
Title: SWAP: An EUV imager for solar monitoring on board of PROBA2
Authors: Katsiyannis, A. C.; Berghmans, D.; Nicula, B.; Defise,
J. -M.; Lawrence, G.; Lecat, J. -H.; Hochedez, J. -F.; Slemzin, V.
2006AIPC..848..847K Altcode:
PROBA2 is an ESA technology demonstration mission to be launched in
2007. The prime instrument on board of Proba2 is SWAP (Sun Watcher
using Active Pixel System detector and Image Processing), a full disk
solar imager with a bandpass filter centred at 17.5 nm (Fe IX-XI)
and a fast cadence of ~ 1 min. The telescope is based on an off-axis
Ritchey Chretien design while an extreme ultraviolet (EUV) enhanced
APS CMOS will be used as a detector. As the prime goal of the SWAP is
solar monitoring and advance warning of Coronal Mass Ejections (CME),
on-board intelligence will be implemented. Image recognition software
using experimental algorithms will be used to detect CMEs during the
first phase of eruption so the event can be tracked by the spacecraft
without human intervention.
---------------------------------------------------------
Title: History of the Sunspot Index: 25 years SIDC
Authors: Berghmans, D.; van der Linden, R. A. M.; Vanlommel, P.;
Clette, F.; Robbrecht, E.
2006BGGKP...7..288B Altcode:
The sunspot number is the oldest solar activity index. For a long time,
it was the only index representative of the solar cycle, and many
studies on the cyclical behavior of the Sun were performed using the
sunspot number. The Sunspot Index Data Center (SIDC) was founded in
January 1981 to continue the work of the Swiss Federal Observatory ,
when this institution decided to stop computing and publishing the
sunspot number. The SIDC now also provides daily activity reports and
forecasts of the status of the space environment. This 'space weather'
activity is part of the International Space Environment Services (ISES,
a permanent service of the FAGS) that co-ordinates 10 regional warning
centers (RWC). In this paper we will give an overview of the history
of the sunspot number, as well as a short overview of the 25-year
history of the SIDC.
---------------------------------------------------------
Title: LYRA and SWAP aboard PROBA2 - heralding future solar VUV
observations
Authors: Hochedez, J. -F.; Berghmans, D.; Defise, J. -M.
2006cosp...36.3272H Altcode: 2006cosp.meet.3272H
Two novel solar VUV instruments will be launched with the PROBA2
mission in the end of 2007 SWAP is a EUV solar imaging telescope and
LYRA is a VUV filter radiometer We will discuss the interest of the
new observations that can be expected from each of them and show in
which sense LYRA and SWAP address the technological and scientific
questions of future solar VUV observations
---------------------------------------------------------
Title: Objective CME detection over the solar cycle: A first attempt
Authors: Robbrecht, E.; Berghmans, D.; van der Linden, R. A. M.
2006AdSpR..38..475R Altcode:
We recently developed a software package to autonomously detect
coronal mass ejections (CMEs) in image sequences from large angle
spectrometric coronagraph (LASCO). The detection is not done in the
original images, instead we detect bright ridges in (time, height) plots
using a modified version of the Hough transform. Experimental results
on real-time data have shown that the developed technique can achieve
excellent results in measuring starting time and principal angle and
good results for the angular width and velocity measurement compared to
the CMEs listed in the manually assembled catalog. The real-time output
of the software can be found online at www.sidc.oma.be/cactus. With
the present paper, we report on the first large scale application of
the software to the LASCO archive. In an ongoing work, we have applied
the software on a first sample of 29 months selected from archive data
in the period July 1997 to December 2002. The results in this paper
show that relevant characteristics of CMEs over the solar cycle are
successfully recovered with the automated procedure. This proves that
a completely automatically produced CME catalog is within reach.
---------------------------------------------------------
Title: LYRA, a solar UV radiometer on Proba2
Authors: Hochedez, J. -F.; Schmutz, W.; Stockman, Y.; Schühle, U.;
Benmoussa, A.; Koller, S.; Haenen, K.; Berghmans, D.; Defise, J. -M.;
Halain, J. -P.; Theissen, A.; Delouille, V.; Slemzin, V.; Gillotay, D.;
Fussen, D.; Dominique, M.; Vanhellemont, F.; McMullin, D.; Kretzschmar,
M.; Mitrofanov, A.; Nicula, B.; Wauters, L.; Roth, H.; Rozanov, E.;
Rüedi, I.; Wehrli, C.; Soltani, A.; Amano, H.; van der Linden, R.;
Zhukov, A.; Clette, F.; Koizumi, S.; Mortet, V.; Remes, Z.; Petersen,
R.; Nesládek, M.; D'Olieslaeger, M.; Roggen, J.; Rochus, P.
2006AdSpR..37..303H Altcode:
LYRA is the solar UV radiometer that will embark in 2006 onboard
Proba2, a technologically oriented ESA micro-mission. LYRA is
designed and manufactured by a Belgian Swiss German consortium (ROB,
PMOD/WRC, IMOMEC, CSL, MPS and BISA) with additional international
collaborations. It will monitor the solar irradiance in four UV
passbands. They have been chosen for their relevance to Solar Physics,
Aeronomy and Space Weather: (1) the 115 125 nm Lyman-α channel,
(2) the 200 220 nm Herzberg continuum range, (3) the Aluminium
filter channel (17 70 nm) including He II at 30.4 nm and (4) the
Zirconium filter channel (1 20 nm). The radiometric calibration will
be traceable to synchrotron source standards (PTB and NIST). The
stability will be monitored by onboard calibration sources (LEDs),
which allow to distinguish between potential degradations of the
detectors and filters. Additionally, a redundancy strategy maximizes
the accuracy and the stability of the measurements. LYRA will benefit
from wide bandgap detectors based on diamond: it will be the first space
assessment of a pioneering UV detectors program. Diamond sensors make
the instruments radiation-hard and solar-blind: their high bandgap
energy makes them insensitive to visible light and, therefore, make
dispensable visible light blocking filters, which seriously attenuate
the desired ultraviolet signal. Their elimination augments the effective
area and hence the signal-to-noise, therefore increasing the precision
and the cadence. The SWAP EUV imaging telescope will operate next to
LYRA on Proba2. Together, they will establish a high performance solar
monitor for operational space weather nowcasting and research. LYRA
demonstrates technologies important for future missions such as the
ESA Solar Orbiter.
---------------------------------------------------------
Title: A Complete LASCO CME-Catalog based on Automated Detection
Authors: Robbrecht, E.; Berghmans, D.; van der Linden, R. A. M.
2006cosp...36.3564R Altcode: 2006cosp.meet.3564R
We present our new CME catalog a result of the large scale application
of our software CACTus on the LASCO archive We recently improved the
algorithm and upgraded the test-version of the catalog available online
at www sidc be cactus The automatic detection of a CME is done in two
steps and is applied simultaneously on c2 and c3 running difference
images 1 detection of bright features moving radially outward 2
clustering detections into CMEs The recent improvements are undertaken
in the second step of this process Unique for our detection method
is that we use the condition moving radially outward as part of the
detection criterion The detection itself is done using the stroboscopic
method i e in height time slices where height means radial distance
from the sun An outwardly moving feature appears then as a bright ridge
extracted by a modified version of the Hough transform Per month the
output consists of a table containing the CME characteristics and an
overview map in a angle time -coordinate system that clearly shows all
detected CMEs As a result of our method we also have for each CME a
linear speed profile along the angular width of the CME We studied the
characteristics of the CMEs detected with CACTus over the solar cycle
and compared them with results obtained from other catalogs This paper
shows that relevant characteristics of CMEs over the solar cycle are
successfully recovered with the automated procedure Recent tests prove
that in general automated procedures detect far more small features
than human
---------------------------------------------------------
Title: SWAP onboard PROBA 2, a new EUV imager for solar monitoring
Authors: Berghmans, D.; Hochedez, J. F.; Defise, J. M.; Lecat, J. H.;
Nicula, B.; Slemzin, V.; Lawrence, G.; Katsyiannis, A. C.; van der
Linden, R.; Zhukov, A.; Clette, F.; Rochus, P.; Mazy, E.; Thibert,
T.; Nicolosi, P.; Pelizzo, M. -G.; Schühle, U.
2006AdSpR..38.1807B Altcode:
SWAP (Sun Watcher using Active Pixel system detector and image
processing) is a solar imager in the extreme ultraviolet (EUV)
that has been selected to fly in 2007 on the PROBA 2 technological
platform, an ESA program. SWAP will use an off-axis Ritchey Chrétien
telescope equipped with an EUV enhanced active pixel sensor detector
(coated APS). This type of detector has advantages that promise to
be very profitable for solar EUV imaging. SWAP will provide solar
coronal images at a 1-min cadence in a bandpass centered on 17.5
nm. Observations with this specific wavelength allow detecting
phenomena, such as solar flares or EIT-waves, associated with the
early phase of coronal mass ejections. Image processing software will
be developed that automatically detects these phenomena and sends out
space weather warnings. Together with its sister instrument LYRA, also
onboard PROBA 2, SWAP will serve as a high performance solar monitoring
tool to be used in operational space weather forecasting. The SWAP
data will complement the solar observations provided by instruments
like SOHO-EIT, and STEREO-SECCHI.
---------------------------------------------------------
Title: Detailed comparison of downflows seen both in EIT 30.4 nm
and Big Bear Hα movies
Authors: de Groof, A.; Bastiaensen, C.; Müller, D. A. N.; Berghmans,
D.; Poedts, S.
2005A&A...443..319D Altcode:
An EIT shutterless campaign was conducted on 11 July 2001 and provided
120 high-cadence (68 s) 30.4 nm images of the north-eastern quarter
of the Sun. Systematic intensity variations are seen which appear
to propagate along an off-disk loop-like structure. In this paper we
study the nature of these intensity variations by confronting the EIT
observations studied in De Groof et al. (2004, A&A, 415, 1141)
with simultaneous Hα images from Big Bear Solar Observatory. With
the goal to carefully co-register the two image sets, we introduce a
technique designed to compare data of two different instruments. The
image series are first co-aligned and later overplotted in order to
visualize and compare the behaviour of the propagating disturbances
in both data sets. Since the same intensity variations are seen in
the EIT 30.4 nm and in the Hα images, we confirm the interpretation
of De Groof et al. (2004, A&A, 415, 1141) that we are observing
downflows of relatively cool plasma. The origin of the downflows is
explained by numerical simulations of "catastrophic cooling" in a
coronal loop which is heated predominantly at its footpoints.
---------------------------------------------------------
Title: Solar weather monitoring
Authors: Hochedez, J. -F.; Zhukov, A.; Robbrecht, E.; van der Linden,
R.; Berghmans, D.; Vanlommel, P.; Theissen, A.; Clette, F.
2005AnGeo..23.3149H Altcode:
Space Weather nowcasting and forecasting require solar observations
because geoeffective disturbances can arise from three types of solar
phenomena: coronal mass ejections (CMEs), flares and coronal holes. For
each, we discuss their definition and review their precursors in terms
of remote sensing and in-situ observations. The objectives of Space
Weather require some specific instrumental features, which we list
using the experience gained from the daily operations of the Solar
Influences Data analysis Centre (SIDC) at the Royal Observatory of
Belgium. Nowcasting requires real-time monitoring to assess quickly and
reliably the severity of any potentially geoeffective solar event. Both
research and forecasting could incorporate more observations in order
to feed case studies and data assimilation respectively. Numerical
models will result in better predictions of geomagnetic storms
and solar energetic particle (SEP) events. We review the data types
available to monitor solar activity and interplanetary conditions. They
come from space missions and ground observatories and range from
sequences of dopplergrams, magnetograms, white-light, chromospheric,
coronal, coronagraphic and radio images, to irradiance and in-situ
time-series. Their role is summarized together with indications about
current and future solar monitoring instruments.
---------------------------------------------------------
Title: Solar activity: nowcasting and forecasting at the SIDC
Authors: Berghmans, D.; van der Linden, R. A. M.; Vanlommel, P.;
Warnant, R.; Zhukov, A.; Robbrecht, E.; Clette, F.; Podladchikova,
O.; Nicula, B.; Hochedez, J. -F.; Wauters, L.; Willems, S.
2005AnGeo..23.3115B Altcode:
The Solar Influences Data analysis Center (SIDC) is the World Data
Center for the production and the distribution of the International
Sunspot Index, coordinating a network of about 80 stations
worldwide. From this core activity, the SIDC has grown in recent years
to a European center for nowcasting and forecasting of solar activity
on all timescales. This paper reviews the services (data, forecasts,
alerts, software) that the SIDC currently offers to the scientific
community. The SIDC operates instruments both on the ground and in
space. The USET telescope in Brussels produces daily white light and
Hα images. Several members of the SIDC are co-investigators of the
EIT instrument onboard SOHO and are involved in the development of the
next generation of Europe's solar weather monitoring capabilities. While
the SIDC is staffed only during day-time (7 days/week), the monitoring
service is a 24 h activity thanks to the implementation of autonomous
software for data handling and analysis and the sending of automated
alerts. We will give an overview of recently developed techniques for
visualization and automated analysis of solar images and detection of
events significant for space weather (e.g. CMEs or EIT waves). As part
of the involvement of the SIDC in the ESA Pilot Project for Space
Weather Applications we have developed services dedicated to the
users of the Global Positioning System (GPS). As a Regional Warning
Center (RWC) of the International Space Environment Service (ISES),
the SIDC produces daily forecasts of flaring probability, geomagnetic
activity and 10.7 cm radio flux. The accuracy of these forecasts will
be investigated through an in-depth quality analysis.
---------------------------------------------------------
Title: Swap: AN EUV Imager for Solar Monitoring on Board of PROBA2
Authors: Katsiyannis, A. C.; Berghmans, D.; Nicula, B.; Defise,
J. -M.; Lawrence, G.; Lecat, J. -H.; Hochedez, J. -F.; Slemzin, V.
2005ESASP.596E..70K Altcode: 2005ccmf.confE..70K
No abstract at ADS
---------------------------------------------------------
Title: Energetic Dymanics of EIT Wave Structure Analyzed by EIT
Wave Detector
Authors: Podladchikova, O.; Berghmans, D.
2005ESASP.592..751P Altcode: 2005soho...16E.153P; 2005ESASP.592E.153P
No abstract at ADS
---------------------------------------------------------
Title: Space Weather with ESA's PROBA2 Mission
Authors: Lawrence, G.; Berghmans, D.; Hochedez, J. -F.; Ben-Moussa,
A.; Defise, J. -M.; Delouille, V.; Dominique, M.; Katsitannis, A.;
Lecat, J. -H.; Nicula, B.; Schmutz, W.; Slemzin, V.; Theissen, A.
2005ESASP.592..685L Altcode: 2005ESASP.592E.137L; 2005soho...16E.137L
No abstract at ADS
---------------------------------------------------------
Title: Interaction of EIT Wave With Active Regions on the Sun
Authors: Podladchikova, O.; Berghmans, D.
2005ESASP.592..535P Altcode: 2005soho...16E.100P; 2005ESASP.592E.100P
No abstract at ADS
---------------------------------------------------------
Title: SWAP: an EUV imager for solar monitoring on board of PROBA2
Authors: Katsiyannis, Athanassios C.; Berghmans, David; Hochedez,
Jean-Francois; Nicula, Bogdan; Lawrence, Gareth; Defise, Jean-Marc;
Ben-Moussa, Ali; Delouille, Veronique; Dominique, Marie; Lecat,
Jean-Herve; Schmutz, W.; Theissen, Armin; Slemzin, Vladimir
2005SPIE.5901..236K Altcode:
PROBA2 is an ESA technology demonstration mission to be launched in
early 2007. The two primary scientific instruments on board of PROBA2
are SWAP (Sun Watcher using Active Pixel System detector and Image
Processing) and the LYRA VUV radiometer. SWAP provides a full disk
solar imaging capability with a bandpass filter centred at 17.5 nm
(FeIX-XI) and a fast cadence of ≈1 min. The telescope is based on
an off-axis Ritchey Chretien design while an extreme ultraviolet (EUV)
enhanced APS CMOS will be used as a detector. As the prime goal of the
SWAP is solar monitoring and advance warning of Coronal Mass Ejections
(CME), on-board intellige nce will be implemented. Image recognition
software using experimental algorithms will be used to detect CMEs
during the first phase of eruption so the event can be tracked by
the spacecraft without huma n intervention. LYRA will monitor solar
irradiance in four different VUV passbands with a cadence of up to
100 Hz. The four channels were chosen for their relevance to solar
physics, aeronomy and space weather: 115-125 nm (Lyman-α), 200-220
nm Herzberg continuum, the 17-70 nm Aluminium filter channel (that
includes the HeII line at 30.4 nm) and the 1-20 nm Zirconium filter
channel. On-board calibration sources will monitor the stability of
the detectors and the filters throughout the duration of the mission.
---------------------------------------------------------
Title: Poisson Recoding Of Solar Images For Enhanced Compression
Authors: Nicula, Bogdan; Berghmans, David; Hochedez, Jean-François
2005SoPh..228..253N Altcode:
The amount of useful scientific data that a space-borne telescope
produces is often limited by the available telemetry of the
platform. General purpose image compression schemes are usually used
to compress the image either lossy or losslessly. These schemes do not
take into account the fact that pixel values of typical solar images
are only known to within a certain uncertainty range. We present a
preprocessing method to enhance the performance (compression ratio) of
any subsequent image compression scheme. The method uses estimates of
the photon shot and thermal noises to compute a recoding look-up table
that maps the initial data into uncertainty intervals. The recoding
method is lossy in a mathematical sense but lossless in a physical
sense, since the image alterations are guaranteed to be smaller than
the Poisson noise. The performance of any further compression algorithm
is enhanced while achieving a known guaranteed maximum absolute error
for each pixel in the case of lossless compression.
---------------------------------------------------------
Title: Foreword
Authors: Gallagher, Peter; Berghmans, David; Aschwanden, Markus
2005SoPh..228....1G Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Automated Detection Of Eit Waves And Dimmings
Authors: Podladchikova, Olena; Berghmans, David
2005SoPh..228..265P Altcode:
Studies of the onset of Earth-directed coronal mass ejections (CMEs)
rely on solar disk observations where CME structures are difficult
to disentangle because of the diversity and transient character of
the phenomena involved. Dimmings and coronal waves are among the
best evidence of the large-scale reorganization of coronal magnetic
fields associated with the onset of CMEs. The physical mechanism
behind EIT waves is still unclear: they are considered as MHD waves
and/or as a consequence of plasma compression on the extending border
of a dimming. In this paper, we address the problem of automatically
detecting and analyzing EIT waves and dimmings in EUV images. This
paper presents a "proof of principle" that automated detection of EIT
wave and dimmings is indeed possible. At the current stage of work,
the method can unambiguously detect dimmings and EIT waves when applied
on a typical test-case event. Moreover, we propose a way to extract
these events from the data, and determine such parameters as life
time, depth, area and volume of dimmings for future catalogs. For EIT
waves we unambiguously define, in near solar minimum conditions, the
eruption center, the front of EIT wave and its propagation velocity. In
addition, we show that the presented methods yield new insights about
the geometrical shape of dimmings and the connection with the EIT wave
front properties, and the apparent angular rotation of the EIT wave
under study.
---------------------------------------------------------
Title: Entering The Era Of Automated Cme Recognition: A Review Of
Existing Tools
Authors: Robbrecht, E.; Berghmans, D.
2005SoPh..228..239R Altcode:
We consider the problem of the observational identification of CMEs. The
ever growing importance of space weather has led to new requirements on
the timeliness and objectiveness of CME detection. It is not sufficient
any more to simply detect CMEs, a complete set of characteristics
(speed, direction, mass, chirality) must be reported as soon as
possible to estimate its geoeffectiveness. Recent developments in
(solar) feature recognition greatly improved the ability to address
these new needs. Progress was achieved in automating the detection of
CMEs in coronagraphic data. This has led to near-real-time messages
alerting the space weather community day and night. In attempting to
generate ever-prompter alerts, we can employ a far broader set of solar
observations than coronagraphic data alone. At present an extensive
set of automatic recognition tools exists for a number of CME-related
phenomena occurring in the lower corona. This paper deals with detection
techniques for disappearing filaments in Hα images, dimmings, EIT waves
and erupting prominences in radio data. We believe that incorporating
all automatically generated alerts into one report per CME can provide
valuable CME information, especially when no coronagraphic images are
available. This paper is thus a quest to reach a maximal success rate
with the help of an integrated system of tools acting on a variety of
data. Future grid-technology systems will greatly facilitate this.
---------------------------------------------------------
Title: Automated recognition of coronal mass ejections (CMEs) in
near-real-time data
Authors: Robbrecht, E.; Berghmans, D.
2004A&A...425.1097R Altcode:
This paper presents a new method and first applications of software that
we have developed to autonomously detect CMEs in image sequences from
LASCO (Large Angle Spectrometric Coronagraph). The crux of the software
is the detection of CMEs as bright ridges in (time, height) maps using
the Hough transform. The next step employs clustering and morphological
closing operations to mark out different CMEs. The output is a list of
events, similar to the classic catalogs, with starting time, principle
angle, angular width and velocity estimation for each CME. In addition
we present a new type of CME overview map that clearly shows all
detected CMEs in a (principal angle, time of occurrence) coordinate
system. In contrast to catalogs assembled by human operators, these CME
detections can be done without any human interference on real-time data
24 h per day (see http://sidc.oma.be/cactus for the real-time output
with data covering the last 4 days). Therefore the detection is not
only more immediate, but, more importantly, also more objective. In
this paper we describe the software and validate its performance by
comparing its output with the SOHO LASCO CME catalog. Experimental
results on real-time data show that the developed technique can achieve
excellent results in measuring starting time and principal angle and
good results for the angular width and velocity measurement compared to
the CMEs listed in the catalog. Its overall success rate is presently
about 94%. The software also reveals CMEs or other features that have
not been listed in the catalog. Such unreported cases might influence
CME statistics and they demonstrate that also the present catalogs do
not have a 100% success rate. This inevitably leads to a discussion
on the definition of a CME. Prospects for improvement and exploitation
are discussed.
---------------------------------------------------------
Title: The Sidc: World Data Center for the Sunspot Index
Authors: Vanlommel, P.; Cugnon, P.; Linden, R. A. M. Van Der;
Berghmans, D.; Clette, F.
2004SoPh..224..113V Altcode: 2005SoPh..224..113V
Since January 1981, the Royal Observatory of Belgium (ROB) has operated
the Sunspot Index Data Center (SIDC), the World Data Center for the
Sunspot Index. From 2000, the SIDC obtained the status of Regional
Warning Center (RWC) of the International Space Environment Service
(ISES) and became the "Solar Influences Data analysis Center". As a
data analysis service of the Federation of Astronomical and Geophysical
data analysis Services (FAGS), the SIDC collects monthly observations
from worldwide stations in order to calculate the International Sunspot
Number, R<SUB>i</SUB>. The center broadcasts the daily, monthly, yearly
sunspot numbers, with middle-range predictions (up to 12 months). Since
August 1992, hemispheric sunspot numbers are also provided.
---------------------------------------------------------
Title: SWAP: Sun watcher with a new EUV telescope on a technology
demonstration platform
Authors: Defise, Jean-Marc; Lecat, Jean-Hervé; Mazy, Emmanuel;
Rochus, Pierre; Rossi, Laurence; Thibert, Tanguy; Gillis, Jean-Marie;
Berghmans, David; Hochedez, Jean-François; Schühle, Udo
2004ESASP.554..257D Altcode: 2004icso.conf..257D
SWAP (SWAP (Sun Watcher using Active Pixel System detector and Image
Processing) is an instrument that has been selected to fly on the
PROBA-2 technology demonstration platform, a program of the European
Space Agency (ESA) to be launched in 2006. SWAP is based on an off-axis
degraded Ritchey Chretien telescope that will image the EUV solar
corona at 19.5 nm on a specifically fabricated extreme ultraviolet
(EUV) sensitivity enhanced CMOS APS detector. The optical design and
the optical coatings are derived from the Extreme Ultraviolet Imaging
Telescope (EIT) operating on-board SOHO since 1995. It has been adapted
for a single wavelength telescope with off-axis optics. It allows to
use smaller optics and filters, with simple internal baffles avoiding
external protruding parts. The superpolished optics will receive a
multilayer coating that provides spectral selection centred on 19.5
nm and EUV reflectivity in normal incidence. This compact design is
specifically adapted for accommodation on PROBA-2, where mass and
envelope requirements are very stringent The SWAP PROBA-2 program will
be an opportunity to demonstrate this new optical concept, while it
will also validate space remote sensing with APS detectors, as well as
on-board image processing capabilities. On the science outcomes, SWAP
will provide solar corona images in the Fe XII line on a baselined 2-min
cadence. Observations with this specific wavelength allow detecting
phenomena, such as solar flares or 'EIT-waves', associated with the
early phase of coronal mass ejections. The SWAP data will complement
the observations provided by SOHO-EIT, and STEREO-SECCHI.
---------------------------------------------------------
Title: Intensity variations in EIT shutterless mode: Waves or flows?
Authors: De Groof, A.; Berghmans, D.; van Driel-Gesztelyi, L.;
Poedts, S.
2004A&A...415.1141D Altcode:
On 11 July 2001 an EIT shutterless campaign was conducted which provided
120 high-cadence (68 s) 304 Å images of the north eastern quarter of
the Sun. The most interesting feature seen in the data is an off-limb
half loop structure along which systematic intensity variations are
seen which appear to propagate from the top of the loop towards its
footpoint. We investigate the underlying cause of these propagating
disturbances, i.e. whether they are caused by waves or by plasma
flows. First we identify 7 blobs with the highest intensities and
follow them along the loop. By means of a location-time plot, bulk
velocities can be measured at several locations along the loop. The
velocity curve found this way is then compared with characteristic
wave speeds and with the free-fall speed in order to deduce the nature
of the intensity variations. Additional information on density and
temperature is derived by measuring the relative intensity enhancements
and comparing the EIT 304 Å sequence with Big Bear data and 171 Å
data (TRACE/EIT). The combination of all these constraints gives us an
insight on the nature and origin of these intensity variations. The
idea of slow magneto-acoustic waves is rejected, and we find several
arguments supporting that these intensity variations are due to
flowing/falling plasma blobs.
---------------------------------------------------------
Title: SWAP: Sun watcher using APS detector on-board PROBA-2, a new
EUV off-axis telescope on a technology demonstration platform
Authors: Defise, Jean-Marc; Berghmans, David; Hochedez, Jean-Francois
E.; Lecat, Jean-Herve M.; Mazy, Emmanuel; Rochus, Pierre L.; Thibert,
Tanguy; Nicolosi, Piergiorgio; Pelizzo, Maria G.; Schuehle, Udo H.;
Van der Linden, Ronald A. M.; Zhukov, Andrei N.
2004SPIE.5171..143D Altcode:
SWAP (Sun Watcher using Active Pixel System detector and Image
Processing) is an instrument that has been selected to fly on the
PROBA-II technology demonstration platform, a program of the European
Space Agency (ESA) to be launched in 2006. This paper presents the
instrument concept and its scientific goals. SWAP uses an off-axis
Ritchey Chretien telescope that will image the EUV solar corona at 19.5
nm on a specifically fabricated extreme ultraviolet (EUV) sensitivity
enhanced CMOS APS detector. This type of detector has advantages that
promise to be very profitable for solar EUV imaging. The SWAP design
is built on a similar concept as the MAGRITTE instrument suite for
the NASA Solar Dynamics Observatory (SDO) mission to be launched in
2007. The optics have been adapted to the detector size. The SWAP
PROBA-2 program will be an opportunity to demonstrate and validate
the optical concept of MAGRITTE, while it will also validate space
remote sensing with APS detectors. On the science outcomes, SWAP will
provide solar corona images in the Fe XII line on a baselined 1-min
cadence. Observations with this specific wavelength allow detecting
phenomena, such as solar flares or 'EIT-waves", associated with the
early phase of coronal mass ejections. Image recognition software will
be developed that automatically detects these phenomena and sends out
space weather warnings. Different modules of this software will run
both on the ground system as well as on the onboard computer of PROBA
II. The SWAP data will complement the observations provided by SOHO-EIT,
and STEREO-SECCHI.
---------------------------------------------------------
Title: MAGRITTE: an instrument suite for the solar atmospheric
imaging assembly (AIA) aboard the Solar Dynamics Observatory
Authors: Rochus, Pierre L.; Defise, Jean-Marc; Halain, Jean-Philippe;
Jamar, Claude A. J.; Mazy, Emmanuel; Rossi, Laurence; Thibert,
Tanguy; Clette, Frederic; Cugnon, Pierre; Berghmans, David; Hochedez,
Jean-Francois E.; Delaboudiniere, Jean-Pierre; Auchere, Frederic;
Mercier, Raymond; Ravet, Marie-Francoise; Delmotte, Franck; Idir,
Mourad; Schuehle, Udo H.; Bothmer, Volker; Fineschi, Silvano; Howard,
Russell A.; Moses, John D.; Newmark, Jeffrey S.
2004SPIE.5171...53R Altcode:
The Solar Atmospheric Imaging Assembly (AIA) aboard the Solar Dynamics
Observatory will characterize the dynamical evolution of the solar
plasma from the chromosphere to the corona, and will follow the
connection of plasma dynamics with magnetic activity throughout the
solar atmosphere. The AIA consists of 7 high-resolution imaging
telescopes in the following spectral bandpasses: 1215Å. Ly-a,
304 Å He II, 629 Å OV, 465 Å Ne VII, 195 Å Fe XII (includes Fe
XXIV), 284 Å Fe XV, and 335 Å Fe XVI. The telescopes are grouped
by instrumental approach: the MAGRITTE Filtergraphs (R. MAGRITTE,
famous 20th Century Belgian Surrealistic Artist), five multilayer EUV
channels with bandpasses ranging from 195 to 1216 Å, and the SPECTRE
Spectroheliograph with one soft-EUV channel at OV 629 Å. They will be
simultaneously operated with a 10-second imaging cadence. These two
instruments, the electronic boxes and two redundant Guide Telescopes
(GT) constitute the AIA suite. They will be mounted and coaligned on a
dedicated common optical bench. The GTs will provide pointing jitter
information to the whole SHARPP assembly. This paper presents the
selected technologies, the different challenges, the trade-offs to be
made in phase A, and the model philosophy. From a scientific viewpoint,
the unique combination high temporal and spatial resolutions with the
simultaneous multi-channel capability will allow MAGRITTE / SPECTRE
to explore new domains in the dynamics of the solar atmosphere, in
particular the fast small-scale phenomena. We show how the spectral
channels of the different instruments were derived to fulfill the
AIA scientific objectives, and we outline how this imager array will
address key science issues, like the transition region and coronal waves
or flare precursors, in coordination with other SDO experiments. We
finally describe the real-time solar monitoring products that will be
made available for space-weather forecasting applications.
---------------------------------------------------------
Title: The expanding space weather services of the SIDC at the Royal
Observatory of Belgium
Authors: van der Linden, R. A. M.; Berghmans, D.; Vanlommel, P.;
Robbrecht, E.; Cugnon, P.; Clette, F.; Wauters, L.; Zhukov, A.
2004cosp...35.2781V Altcode: 2004cosp.meet.2781V
Originally founded in 1981 as the World Data Centre for the Sunspot
Index, the SIDC (Solar Influences Data analysis Centre) shifted to
a higher gear in 2000, when it became a Regional Warning Centre of
the ISES (taking over this activity from Meudon). The obvious link
between space weather and solar activity - a prime research topic of
the solar physics department of the Royal Observatory of Belgium -
and the equally obvious relevance of continuous long-term monitoring
of solar activity have made the SIDC well-placed to embark on this new
future. Thanks to becoming one of the Service Development Activities in
the Space Weather Applications Pilot Project recently set up by ESA, the
SIDC has been able to further improve and expand these activities. In
this paper we discuss some of the new tools, models and data that have
been or will be developed to this purpose. It will also be detailed how
the scientific and operational involvement of the Royal Observatory of
Belgium in many future space missions oriented towards solar physics
and solar monitoring will help the SIDC become an independent European
space weather monitoring and forecasting centre.
---------------------------------------------------------
Title: Intensity Variations in EIT Shutterless Mode: Waves or Flows?
Authors: de Groof, A.; Berghmans, D.; van Driel-Gesztelyi, L.;
Poedts, S.
2004ESASP.547..245D Altcode: 2004soho...13..245D
On 11 July 2001 an EIT shutterless campaign was conducted which provided
120 high-cadence (68s) 304 Å images of the north eastern quarter of the
Sun. The most interesting feature seen in the data is an off-limb half
loop structure along which systematic intensity variations appear to
propagate from the top of the loop towards its footpoint. We investigate
the underlying cause of these propagating disturbances, i.e. whether
they are caused by waves or by plasma flows. First we identify 7 blobs
with the highest intensities and follow them along the loop. By means
of a location-time plot, bulk velocities can be measured at several
locations along the loop. The velocity curve found this way is then
compared with characteristic wave speeds and with the free-fall speed
in order to deduce the nature of the intensity variations. Additional
information is derived by measuring the relative intensity enhancements
and comparing the EIT 304 Å sequence with Big Bear and 171 Å data. The
idea of slow magneto-acoustic waves is rejected, and we find several
arguments supporting that these intensity variations are due to
flowing/falling plasma blobs.
---------------------------------------------------------
Title: Objective CME detection over the solar cycle
Authors: Robbrecht, E.; Berghmans, D.
2004cosp...35.2702R Altcode: 2004cosp.meet.2702R
We have developed a software package for 'Computer Aided CME Tracking'
(CACTus), that autonomously detects CMEs in image sequences from
LASCO. The crux of the CACTus software is the detection of CMEs as
bright ridges in [height, time] maps using the Hough transform. The
output is a list of events, similar to the classic catalogs,
with principle angle, angular width and velocity estimation for
each CME. In contrast to catalogs assembled by human operators,
these CME detections by software can be faster and possibly also
more objective, as the detection criterion is written explicitly
in a program. Especially on the timescale of a solar cycle, it is
questionnable whether human, visual CME detection is stable, as the
operator gains experience or personnel is replaced. In this paper we
overview the latest improvements of CACTUS and validate its performance
by comparing the CACTus output with the classical, visually assembled
CME catalogs. Discrepancies between the classical catalogs and the
CACTUS catalogs are discussed. Such discrepancies highlight not
only the performance of CACTUS but also the caveats of the classical
catalogs. Indeed, CACTUS sometimes finds CMEs that are not listed in
the catalogs or interpreted differently (eg halo CME or not). It is
important to know these caveats when using the CME catalogs as input for
statistical CME studies over the solar cycle. The near realtime output
of the software is available on the web(http://sidc.oma.be/cactus)
and is updated daily.
---------------------------------------------------------
Title: SWAP onboard PROBA-2, a new EUV imager for solar monitoring
Authors: Berghmans, D.; Swap Consortium
2004cosp...35.2747B Altcode: 2004cosp.meet.2747B
SWAP (Sun Watcher using Active Pixel System detector and Image
Processing) is a solar EUV imager that has been selected to fly in 2006
on the PROBA-2 technological platform, an ESA program. SWAP will use an
off-axis Ritchey Chretien telescope equipped with a specifically EUV
enhanced CMOS APS detector. This type of detector has advantages that
promise to be very profitable for solar EUV imaging. SWAP will provide
solar corona images in the Fe XII line (19.5 nm) on a baselined 1-min
cadence. Observations with this specific wavelength allow detecting
phenomena, such as solar flares or EIT-waves, associated with the
early phase of coronal mass ejections. Image recognition software
will be developed that automatically detects these phenomena and sends
out space weather warnings. Together with its sister instrument LYRA
(Lyman-alpha Radiometer) onboard PROBA-2, SWAP will serve as a high
performance solar monitoring tool to be used in operational space
weather forecasting. The SWAP data will complement the observations
provided by SOHO-EIT, and STEREO-SECCHI.
---------------------------------------------------------
Title: Extracting the apparent motion from two successive EIT images
Authors: Gissot, Samuel F.; Hochedez, J. -F.; Dibos, F.; Brajša,
R.; Jacques, L.; Berghmans, D.; Zhukov, A.; Clette, F.; Wöhl, H.;
Antoine, J. -P.
2003ESASP.535..853G Altcode: 2003iscs.symp..853G
The EIT observations cover more than seven years of the 23rd solar
cycle. The main synoptic dataset, usually refered to as the "CME
Watch", is a nearly uninterrupted sequence of images taken in the Fe
XII bandpass at a cadence of four images per hour. In this work we
study motion tracking methods in order to estimate displacements from
frame to frame. We have implemented a novel optical flow algorithm,
and tested it on a couple of successive images. We have linked the
apparent motion occurring between two frames to the expected rotation
rate. On this short time scale (20 minutes), we are able to retrieve
the global parameters of the solar differential rotation. A strategy
for the extraction of region with reliable motion will be discussed.
---------------------------------------------------------
Title: MAGRITTE / SPECTRE : the Solar Atmospheric Imaging Assembly
(AIA) aboard the Solar Dynamics Observatory
Authors: Rochus, P.; Defise, J. M.; Halain, J. P.; Mazy, E.; Jamar, C.;
Clette, F.; Cugnon, P.; Berghmans, D.; Hochedez, J. F.; Delaboudiniere,
J. P.; Artzner, G.; Auchere, F.; Mercier, R.; Ravet, M. F.; Delmotte,
M.; Idir, M.; Fineschi, S.; Antonucci, E.; Harrison, R. A.; Howard,
R. A.; Moses, J. D.; Newmark, J. S.
2002AGUFMSH21C..05R Altcode:
The Solar Atmospheric Imaging Assembly (AIA) aboard the Solar
Dynamics Observatory will characterize the dynamical evolution of
the solar plasma from the chromosphere to the corona, and will follow
the connection of plasma dynamics with magnetic activity throughout
the solar atmosphere. The AIA consists of 7 high resolution imaging
telescopes in the following spectral bandpasses: 1215 \x8F Ly-a, 304
\x8F He II, 629 \x8F OV, 465 \x8F Ne VII, 195 \x8F Fe XII (includes Fe
XXIV), 284 \x8F Fe XV, and 335 \x8F Fe XVI. The telescopes are grouped
by instrumental approach: the Magritte Filtergraphs (R. Magritte,
famous 20th Century Belgian Surrealistic Artist), five multilayer EUV
channels with bandpasses ranging from 195 to 1216 \x8F, and the SPECTRE
Spectroheliograph with one soft-EUV channel at OV 629 \x8F. They will
be simultaneously operated with a 10-second imaging cadence. These two
instruments, the electronic boxes and two redundant Guide Telescopes
(GT) constitute the AIA suite. They will be mounted and coaligned on a
dedicated common optical bench. The GTs will provide pointing jitter
information to the whole SHARPP assembly. This poster presents the
selected technologies, the different challenges, the trade-offs to be
made in phase A, and the model philosophy. From a scientific viewpoint,
the unique combination high temporal and spatial resolutions with the
simultaneous multi-channel capability will allow Magritte/SPECTRE
to explore new domains in the dynamics of the solar atmosphere, in
particular the fast small-scale phenomena. We show how the spectral
channels of the different instruments were derived to fulfill the
AIA scientific objectives, and we outline how this imager array will
address key science issues, like the transition region and coronal waves
or flare precursors, in coordination with other SDO experiments. We
finally describe the real-time solar monitoring products that will be
made available for space-weather forecasting applications.
---------------------------------------------------------
Title: The Solar Influences Data Analysis Center: current status of
expanding activities
Authors: Clette, F.; van der Linden, R.; Cugnon, P.; Berghmans,
D.; Foullon, C.; Wouters, L.; Verwichte, E.; Hochedez, J. -F.;
Vanlommel, P.
2002ESASP.506..125C Altcode: 2002ESPM...10..125C; 2002svco.conf..125C
Over the last 24 months, the activities of the SIDC, which is the
European Regional Warning Center of the ISES, have steadily expanded. A
7-day/week service has been implemented, the SIDC Web interface has
been reworked and expanded and the number of registered users increased
further. New image data have been added, including new photospheric
and chromospheric CCD images from the Uccle Station. We summarize here
the new services provided to the community and some statistics about
the success rate of our forecasts. We also outline the orientations
of the future SIDC development.
---------------------------------------------------------
Title: Getting hot by nanoflares
Authors: Berghmans, David
2002ESASP.506..501B Altcode: 2002svco.conf..501B; 2002ESPM...10..501B
We review the current status of the 'Parker hypothesis' which
suggests that the solar corona is heated by a multitude of small
flare-like events called nanoflares. Space-borne coronal imagers
such as SXT, EIT or TRACE have allowed to test Parker's hypothesis
observationally. Combining the results from different authors it
seems that we are close to falsifying the hypothesis, i.e. there are
not enough nanoflares to heat the corona. The only remaining hope
for nanoflare-adepts is the transition region which contains various
types of impulsive events such as explosive events or blinkers whose
role and mutual relation is not sufficiently understood yet to make
a final verdict on Parker's hypothesis.
---------------------------------------------------------
Title: Automated detection of CMEs
Authors: Berghmans, D.
2002ESASP.506...85B Altcode: 2002ESPM...10...85B; 2002svco.conf...85B
We have developed a shoftware package for 'Computer Aided CME Tracking'
(CACTus), that autonomously detects CMEs in image sequences from
LASCO. The crux of the CACTus software is the detection of CMEs as
bright ridges in [height, time] maps using the Hough transform. The
output is a list of events, similar to the classic catalogs, with
principle angle, angular width and velocity estimation for each CME. In
contrast to catalogs assembled by human operators, these CME detections
by software can be faster and possibly also more objective, as the
detection criterion is written explicitly in a program. In this paper
we discuss two applications of the software. In a first application,
we validate the performance by comparing the CACTus output with the
classical, visually assembled CME catalogs. We discuss its present
success rate (about 75%) and prospects for improvement. By giving
an example we show that the software can also reveal CMEs that have
been not been listed in the catalogs. Such unreported cases might
be of influence on CME stastistics and prove that also the present
catalogs do not have a 100% success rate. The second application,
is an operational version of CACTus that scans in real time, the last
available LASCO images for recent CMEs.
---------------------------------------------------------
Title: The new instrumentation of the SIDC/Uccle station
Authors: Clette, F.; Cugnon, P.; Berghmans, D.; van der Linden, R.;
Wauters, L.
2002ESASP.506..935C Altcode: 2002svco.conf..935C; 2002ESPM...10..935C
New digital 1K×1K CCD cameras have been installed on the solar
telescope of the Royal Observatory of Belgium (ROB, Uccle, Brussels),
in addition to the visual telescope used for the classical sunspot
observations. One camera provides full-disk images of the photosphere
and uses an image-selection algorithm to compensate the effects
of the seeing. The other camera produces full-disk images of the
chromosphere in the Hα line, and will be used for an automated flare
patrol work. After completion of the instrument commissioning (August
2002), those images will be made available in near real-time through
the SIDC Regional Warning Center web pages (http://sidc.oma.be) and
in the form of a FITS file archive. We describe here the instruments
and their capabilities.
---------------------------------------------------------
Title: Automated detection of CMEs in LASCO data
Authors: Berghmans, D.; Foing, B. H.; Fleck, B.
2002ESASP.508..437B Altcode: 2002soho...11..437B
We have developed software that autonomously detects CMEs in image
sequences from LASCO. the crux of the software is the detection of CMEs
as bright ridges in (height, time) maps using the Hough transform. The
output is a list of events, similar to the classic catalogs, with
principle angle, angular width and velocity estimation for each
CME. In contrast to catalogs assembled by human operators, these CME
detections by software can be faster, which is especially important in
the context of space weather, and possibly also more objective, as the
detection criterion is written explicitly in a program. In this paper
we describe the software and validate its performance by comparing its
output with the visually assembled CME catalogs. We discuss its present
success rate (about 75%) and prospects for improvement. Finally, we
show that the software can also reveal CMEs that have not been listed
in the catalogs. Such unreported cases might be of influence on CME
statistics and prove that also the present catalogs do not have a 100%
success rate.
---------------------------------------------------------
Title: Space weather
Authors: Glover, Alexi; Daly, Eamonn; Hilgers, Alain; Berghmans, David
2002EuRv...10..249G Altcode:
Space weather is caused by conditions on the Sun and in the solar wind,
the magnetosphere, ionosphere and thermosphere that can influence
the performance and reliability of space-borne and ground-based
technological systems and can affect human life or health. It affects
man-made systems such as satellite electronics, terrestrial power
grids and radio communications. This paper provides an overview of how
space weather arises in the solar terrestrial system and how physical
processes are able to cause space weather effects. We also discuss
European perspectives and activities geared towards the possible
initiation of a European Space Weather programme.
---------------------------------------------------------
Title: Multiscale activity observed by EIT/SoHO
Authors: Hochedez, J. -F.; Jacques, L.; Verwichte, E.; Berghmans,
D.; Wauters, L.; Clette, F.; Cugnon, P.
2002ESASP.477..115H Altcode: 2002scsw.conf..115H
The Extreme ultraviolet Imaging Telescope (EIT) of SoHO provides a
high-resolution and large sampling of the solar corona in time, space
and brightness. To extract the wealth of its physics, it is valuable to
adopt a multiscale approach. The Mexican Hat (MH) Continuous Wavelet
Transform (CWT) is used for the first time to derive statistically
the distribution of scales over 4 Mm. The global behaviour of the
small scales offers a powerful way to monitor coronal activity. This
is demonstrated with the May 1998 "CME Watch" data. This benefit
is of space weather relevance and could improve forecasting of the
solar activity.
---------------------------------------------------------
Title: The solar influences data analysis centre
Authors: Berghmans, D.; Clette, F.; Cugnon, P.; Gabryl, J. -R.;
Hochedez, J. -F.; Van der Linden, R. A. M.; Verwichte, E.
2002JASTP..64..757B Altcode: 2002JATP...64..757B
Since 1981, the Royal Observatory of Belgium has operated the
Sunspot Index Data Centre, the World Data Centre for the Sunspot
Index. Recently, the Space Weather Forecast Centre of Paris-Meudon
was transferred and added to the activities of the SIDC. Moreover,
a complete archive of all images of the SOHO instrument EIT has
become available at the SIDC. Given all these extensions, the new
style SIDC has become a `Solar Influences Data Centre' that analyses
solar activity and provides services on three different time scales:
1. Fast warnings and real time monitoring. As the Regional Warning
Centre (RWC) for Western Europe of the International Space Environment
Service (ISES), the SIDC collects and redistributes solar, geomagnetic,
and ionospheric data in Western Europe. Short-term predictions (3 days)
and alerts are produced on a daily basis. 2. Forecasts and middle term
analysis. The SIDC takes care of the calculation of a sunspot index,
called the International Sunspot Number. We compute and broadcast the
daily, monthly, yearly international sunspot numbers, with middle range
predictions (up to 12 months). 3. Post-event analysis and long-term
solar cycle analysis. Since the launch of SOHO, EIT offers a global view
of the EUV corona over the whole rising phase of the solar activity
cycle. Such a long-duration data series is unprecedented and allows
the study of the evolution over the solar cycle of objects classes
such as active regions, coronal holes, coronal mass ejections or flares.
---------------------------------------------------------
Title: Slow magneto-acoustic waves in coronal loops
Authors: Verwichte, E.; Nakariakov, V. M.; Berghmans, D.; Hochedez,
J. -F.
2001ESASP.493..395V Altcode: 2001sefs.work..395V
No abstract at ADS
---------------------------------------------------------
Title: Slow magnetoacoustic waves in coronal loops: EIT and TRACE
Authors: Robbrecht, E.; Verwichte, E.; Berghmans, D.; Hochedez, J. F.;
Poedts, S.; Nakariakov, V. M.
2001A&A...370..591R Altcode:
On May 13, 1998 the EIT (Extreme ultraviolet Imaging Telescope) on board
of SoHO (Solar and Heliospheric Observatory) and TRACE (Transition
Region And Coronal Explorer) instruments produced simultaneous high
cadence image sequences of the same active region (AR 8218). TRACE
achieved a 25 s cadence in the Fe Ix (171 Å) bandpass while EIT
achieved a 15 s cadence (operating in “shutterless mode”, SoHO JOP
80) in the Fe Xii (195 Å) bandpass. These high cadence observations
in two complementary wavelengths have revealed the existence of weak
transient disturbances in an extended coronal loop system. These
propagating disturbances (PDs) seem to be a common phenomenon in
this part of the active region. The disturbances originate from small
scale brightenings at the footpoints of the loops and propagate along
the loops. The projected propagation speeds roughly vary between 65
and 150 km s<SUP>-1</SUP> for both instruments which is close to and
below the expected sound speed in the coronal loops. The measured slow
magnetoacoustic propagation speeds seem to suggest that the transients
are sound (or slow) wave disturbances. This work differs from previous
studies in the sense that it is based on a multi-wavelength observation
of an entire loop bundle at high cadence by two EUV imagers. The
observation of sound waves along the same path shows that they propagate
along the same loop, suggesting that loops contain sharp temperature
gradients and consist of either concentric shells or thin loop threads,
at different temperatures.
---------------------------------------------------------
Title: Active region transient brightenings. A simultaneous view by
SXT, EIT and TRACE
Authors: Berghmans, D.; McKenzie, D.; Clette, F.
2001A&A...369..291B Altcode:
This paper reports on a qualitative study on the weakest flarelike
brightenings in active region that can be observed with current
coronal imagers. Specificallly, we investigate the correspondence of
the “active region transient brightenings” (ARTB) first observed
almost a decade ago with SXT with similar brightenings in the EUV
that are now observed by EIT and TRACE. For this goal, exceptionally
high cadence image sequences were acquired of a small but rapidly
evolving active region (NOAA 8218), simultaneously by SXT, EIT, and
TRACE. Within the timeframe of this coordinated campaign, we detected
41 soft X-ray brightenings and 373 EUV brightenings. We find that the
strongest brightenings observed by EIT are indeed the EUV counterparts
of the ARTBs seen by SXT. Weaker brightenings seen by EIT often do not
have an X-ray counterpart. Among the brightenings detected with SXT we
discover a new subpopulation, consisting of events that brighten in soft
X-rays only, at a footpoint of a pre-existing SXT loop shortly after
an ARTB occurred at the other footpoint. The propagation speed of the
perturbation suggests an interpretation in terms of slow mode MHD waves.
---------------------------------------------------------
Title: Long Term Variations in the Extreme UV Corona: the EIT/SoHO
perspective
Authors: Hochedez, J. -F.; Clette, F.; Verwichte, E.; Berghmans, D.;
Cugnon, P.
2001IAUS..203..501H Altcode:
Since the start of the SOHO mission, EIT offered a global view of
the extreme ultraviolet corona constinuously over the whole rising
phase of the solar activity cycle. Such a long-duration data serie
is unprecedented. We present here the current results of an ongoing
investigation of the entire EIT data set. In this process, numerous
classes of magnetic regions of all sizes (active regions, coronal
holes, bright points, plumes, transition region network, filaments)
as well as many different classes of dynamic events (CME's, flares,
jets, blinkers, macrospicules) will be identified in EIT images made
in its four bandpasses. The changes in the class properties (location,
size, area, topology, lifetime, integrated flux) or in the relationship
between different object classes can then be monitored over the fast
rise of magnetic activity towards the current maximum. We describe here
the image processing techniques developed for this search as well as
early results.
---------------------------------------------------------
Title: Slow magnetoacoustic waves in coronal loops
Authors: Nakariakov, V. M.; Verwichte, E.; Berghmans, D.; Robbrecht, E.
2000A&A...362.1151N Altcode:
A theoretical model interpreting propagating disturbances of EUV
emission intensity, recently observed in coronal loops, is constructed
in terms of slow magnetoacoustic waves. The model is one-dimensional
and incorporates effects of nonlinearity, dissipation due to finite
viscosity and thermal conduction, and gravitational stratification of
plasma in the loop. It has been found that, for the observationally
detected parameters of the waves, the main factors influencing the
wave evolution are dissipation and stratification. The upwardly
propagating waves of observed periods (5-20 min) are found to decay
significantly in the vicinity of the loop apex, explaining the rarity
of observational detection of downwardly propagating waves. The model
provides a theoretical basis for development of MHD seismology of the
coronal loops.
---------------------------------------------------------
Title: Slow magnetoacoustic waves in coronal loops: EIT vs TRACE
Authors: Robbrecht, E.; Verwichte, E.; Berghmans, D.; Hochedez, J. F.;
Poedts, S.
2000AIPC..537..271R Altcode: 2000wdss.conf..271R
On May 13, 1998 the EIT (Extreme-Ultraviolet Imaging Telescope) and
TRACE (Transition Region And Coronal Explorer) instruments produced
simultaneous high cadence image sequences of the same active region
(AR 8218). TRACE achieved a 25 sec cadence in the Fe IX/X (171 Å)
bandpass while EIT achieved a 15 sec cadence (operating in `shutterless
mode,' SOHO JOP 80) in the Fe XII (195 Å) bandpass. These high
cadence observations in two complementary wavelengths have revealed
the existence of weak transient disturbances in an extended coronal
loop system. These propagating disturbances (PDs) seem to be a
common phenomenon in this part of the active region. The disturbances
originate from small scale brightenings at the footpoints of the loops
and propagate along the loops. The apparent propagation speeds roughly
vary between 65 and 150 km s<SUP>-1</SUP> which is close to the expected
sound speed of the coronal loops. The measured propagation speeds seem
to suggest that the transients are sound (or slow) wave disturbances. .
---------------------------------------------------------
Title: Observations of solar wave/instability phenomena as imaged
by EIT/SOHO, TRACE and Yohkoh/SXT
Authors: Berghmans, D.; McKenzie, D.
2000AIPC..537..168B Altcode: 2000wdss.conf..168B
On May 13 1998, active region NOAA 8218 was observed in the context
of the SOHO/JOP80 campaign by an array of 8 different ground-based and
space-born instruments. The emphasis was set on imaging of small-scale
dynamics in this relatively small but rapidly evolving AR. In
particular, SOHO/EIT (195 Å), TRACE (171 Å) and YOHKOH/SXT produced
subfield image sequences at their respective highest possible rates. We
searched for wave and instability phenomena by using an automated
recognition scheme. This result in a wide inventory of propagating
disturbances and localized transient brightenings. By comparing the
soft X-ray signature as recorded by SXT with the EUV-signature as
collected by EIT and TRACE, we are able to distinguish between various
types of active region transients. As such we find that the strongest
brightenings observed by EIT are indeed the EUV counterparts of the
previously reported ARTBs seen by SXT. Weaker brightenings seen by
EIT do often not have an X-ray counterpart. Moreover, in an extended
system of faint quasi-open loops, we find propagating disturbances, with
speeds of the order of 100 km/s, both in EIT and TRACE images. These are
interpreted as sonic perturbations. The brightenings will be discussed
in this paper while the propagating disturbances are described in the
presentation by Eva Robbrecht at this conference. .
---------------------------------------------------------
Title: Mid-Term Variations in the Extreme UV Corona: the EIT/SOHO
Perspective
Authors: Hochedez, J. F.; Clette, Frederic; Verwichte, Erwin;
Berghmans, David; Cugnon, Pierre
2000ESASP.463...79H Altcode: 2000sctc.proc...79H
No abstract at ADS
---------------------------------------------------------
Title: Multi-Imager Study of Transients and Propagating Disturbances
in Active Region Loops (SOHO JOP80 Campaign)
Authors: Berghmans, D.; Clette, F.; Robbrecht, E.; McKenzie, D.
1999ESASP.448..575B Altcode: 1999ESPM....9..575B; 1999mfsp.conf..575B
No abstract at ADS
---------------------------------------------------------
Title: Slow Magnetoacoustic Waves in Coronal Loops?
Authors: Robbrecht, E.; Berghmans, D.; Nakariakov, V.; Poedts, S.
1999ESASP.446..575R Altcode: 1999soho....8..575R
On May 13, 1998 the EIT and TRACE instruments produced simultaneous
high cadence image sequences of the same active region (AR 8218). TRACE
achieved a 25 sec cadence in the 171 deg passband while EIT achieved
a 15 sec cadence (operating in 'shutterless mode', SOHO JOP 80) in the
195 deg passband. These high cadence observations in two complementary
wavelengths have revealed the existence of weak disturbances in an
extended coronal loop system. The disturbances originate from small
scale brightenings at the footpoints of the loops and propagate along
the loops at an apparant speed of the order of 150 km/s which is close
to the expected sound speed. To conclude whether these propagating
disturbances should be interpreted as slow magnetoacoustic waves or as
mass motions ('microflows'), we compare our observational findings with
theoretical models. Our results suggest that the recent discovery of
DeForest and Gurman (1998) of slow MHD waves in polar plumes, are in
fact not typical of polar plumes but occur also in extended coronal
structures elsewhere.
---------------------------------------------------------
Title: Active Region Transient Brightenings : EIT Versus SXT
Authors: Berghmans, D.; McKenzie, D.; Clette, F.
1999ESASP.446..173B Altcode: 1999soho....8..173B
On May 13, 1998, the Extreme-Ultraviolet Imaging Telescope (EIT,
on board SOHO) has produced a unique image sequence operating in
'shutterless mode' (SOHO JOP 80). In JOP 80, EIT is the leading
instrument, followed by several space born instruments (SXT, TRACE,
MDI, CDS, SUMER), as well as two observatories on the ground (in La
Palma and Sac Peak). The target of the campaign was a relatively small
but rapidly evolving active region (AR 8218). For the EIT contribution,
a 15 s cadence was achieved in the Fe XII bandpass at 195 deg by leaving
EIT's shutter open for 1 hour and operating the CCD in frame transfer
mode. We have started the analysis of the huge data set, by making an
inventory of the transients observed in the EIT image sequence. These
transients range from a B3.5 flare producing a large plasma flow along
pre-existing loops, to smaller EUV brightenings of active region
loops. In addition, a new class of weaker footpoint brightenings
was discovered that produce wave-like disturbances propagating along
quasi-open field lines (see the presentation by Eva Robbrecht at this
workshop). In this paper we take the opportunity provided by JOP 80,
to investigate the correspondence of the transient brightenings observed
by EIT in this active region, with the ARTB previously observed by SXT
and studied by Shimizu (1992). Within the simultaneous high cadence
SOHO JOP 80 image sequences, both EIT and SXT accummulated a few tens
of brightening events. At the time of the writing of this abstract,
we can say that most of the SXT events have indeed 1 or more EIT
counterparts. Typically the SXT events are somewhat bigger than the EIT
events where the latter are ussualy located toward the point of origin
of the SXT events. Whereas a few brightenings exist in one dataset
without any trace in the other dataset (in both directions), we have
additionally for a few brightenings in the SXT data, a corresponding
EIT darkening as if the plasma is suddenly heated and dissappears from
the EIT passband.
---------------------------------------------------------
Title: EIT Micro-Variability Studies : Preliminary Results from the
SOHO JOP 80 Campaign
Authors: Clette, F.; Berghmans, D.
1999ASPC..184..217C Altcode:
The first results from the high-cadence imaging campaign run in May 98,
by several space-based instruments with ground support (SOHO JOP80), are
presented. General properties and scaling laws are deduced for a fairly
large sample of small-amplitude short-lived impulsive brightenings
occuring locally in active region loops. From these, we derive some
conclusions about similarities with soft-X ray microflares. Several
classes of minor transients are distinguished, such as loop-like and
twin brightenings. We find also evidence for propagating compressive
waves in extended field lines rooted near one magnetic pole of the
active region. This study provides a first inventory of small-scale
variabilities in view of the full analysis of this huge and rich
data set.
---------------------------------------------------------
Title: Active region EUV transient brightenings - First Results by
EIT of SOHO JOP 80
Authors: Berghmans, D.; Clette, F.
1999SoPh..186..207B Altcode:
On 13 May 1998, the Extreme-Ultraviolet Imaging Telescope (EIT, on board
SOHO) has produced a unique image sequence operating in 'shutterless
mode' (SOHO JOP 80). In JOP 80, EIT is the lead instrument, followed by
several space-born instruments (SXT, TRACE, MDI, CDS, SUMER), as well
as two observatories on the ground (in La Palma and Sac Peak). The
target of the campaign was a relatively small but rapidly evolving
active region (AR 8218). For the EIT contribution, a 15 s cadence was
achieved in the Fe xii bandpass at 195 Å by leaving EIT's shutter open
for 1 h and operating the CCD in frame-transfer mode. In this paper, we
start the analysis of the huge data set, by making an inventory of the
transients observed in the EIT image sequence. Besides scatter plots of
duration, size and radiative output of the detected EUV brightenings,
we discuss in full detail the morphology and evolution of several
typical events. These transients range from a B3.5 flare producing a
large plasma flow along pre-existing loops, to EUV versions of active
region transient brightenings as previously observed by SXT on board
Yohkoh. In addition, a new class of weaker footpoint brightenings
is discussed that produce wave-like disturbances propagating along
quasi-open field lines. This new class of propagating disturbances
extends the wide variety of transient phenomena that we discovered in
the EIT data, and makes the potential for inter-instrumental studies of
the JOP 80 data all the more exciting. We stress the necessity of such
forthcoming studies to reach an instrument-independent classification
of small-scale solar transients.
---------------------------------------------------------
Title: Quiet Sun EUV transient brightenings and turbulence. A
panoramic view by EIT on board SOHO
Authors: Berghmans, D.; Clette, F.; Moses, D.
1998A&A...336.1039B Altcode:
Since January 1996, the Extreme-Ultraviolet Imaging Telescope (EIT,
onboard SOHO) has produced unique image sequences covering a wide field
of view with a high temporal resolution, in the He Ii transition region
line and in several Fe coronal emission lines. Using two sequences
acquired with cadences of the order of one minute and with durations
ranging from one hour to several hours, we analyse the dynamical
properties of the transition region and corona. We find evidence of
turbulence both in spatial and in temporal power spectra suggesting
that the plasma of the quiet solar atmosphere is in a permanent state
of turbulence. As predicted by numerical simulations, this turbulence
has an highly intermittent nature. We find an unexpectedly large number
of small-scale brightenings. The coronal brightenings are identified as
the low energy counterparts of “X-ray network flares” observed with
SXT on board Yohkoh. The thousands of brightenings observed by EIT in
the transition region include many that are similar to “blinkers”
observed with CDS, though we find a larger variety. Thanks to EIT's
wide spatial coverage, we can perform a large scale statistical study,
complementing spectroscopic studies which give access to only a very
small subsample of events. We present occurrence distributions of
duration, size and radiative output of the brightenings as well as
various correlations between these parameters. The energy injected by
the brightenings into the solar atmosphere is insufficient to be in
itself responsible for coronal heating. We discuss the importance of
the ubiquitous small brightenings as perhaps the most visible aspect
of yet undetected heating events higher up in the quiet corona.
---------------------------------------------------------
Title: Impulsive Coronal Dynamics as Revealed by EIT
Authors: Clette, F.; Berghmans, D.
1998ASPC..155..356C Altcode: 1998sasp.conf..356C
No abstract at ADS
---------------------------------------------------------
Title: Quiet Sun EUV Transient Brightenings and Turbulence
Authors: Berghmans, D.; Clette, F.; Moses, D.
1998ESASP.417..229B Altcode: 1998cesh.conf..229B
No abstract at ADS
---------------------------------------------------------
Title: EIT Observations of Small-Scale Dynamics in the Transition
Region and Corona
Authors: Clette, F.; Berghmans, D.
1997ESASP.415...95C Altcode: 1997cpsh.conf...95C
No abstract at ADS
---------------------------------------------------------
Title: EIT Observations of the Extreme Ultraviolet Sun
Authors: Moses, D.; Clette, F.; Delaboudinière, J. -P.; Artzner,
G. E.; Bougnet, M.; Brunaud, J.; Carabetian, C.; Gabriel, A. H.;
Hochedez, J. F.; Millier, F.; Song, X. Y.; Au, B.; Dere, K. P.; Howard,
R. A.; Kreplin, R.; Michels, D. J.; Defise, J. M.; Jamar, C.; Rochus,
P.; Chauvineau, J. P.; Marioge, J. P.; Catura, R. C.; Lemen, J. R.;
Shing, L.; Stern, R. A.; Gurman, J. B.; Neupert, W. M.; Newmark,
J.; Thompson, B.; Maucherat, A.; Portier-Fozzani, F.; Berghmans, D.;
Cugnon, P.; Van Dessel, E. L.; Gabryl, J. R.
1997SoPh..175..571M Altcode:
The Extreme Ultraviolet Imaging Telescope (EIT) on board the SOHO
spacecraft has been operational since 2 January 1996. EIT observes
the Sun over a 45 x 45 arc min field of view in four emission line
groups: Feix, x, Fexii, Fexv, and Heii. A post-launch determination
of the instrument flatfield, the instrument scattering function, and
the instrument aging were necessary for the reduction and analysis
of the data. The observed structures and their evolution in each
of the four EUV bandpasses are characteristic of the peak emission
temperature of the line(s) chosen for that bandpass. Reports on the
initial results of a variety of analysis projects demonstrate the range
of investigations now underway: EIT provides new observations of the
corona in the temperature range of 1 to 2 MK. Temperature studies of
the large-scale coronal features extend previous coronagraph work
with low-noise temperature maps. Temperatures of radial, extended,
plume-like structures in both the polar coronal hole and in a low
latitude decaying active region were found to be cooler than the
surrounding material. Active region loops were investigated in detail
and found to be isothermal for the low loops but hottest at the loop
tops for the large loops.
---------------------------------------------------------
Title: Wave heating of coronal loops driven by azimuthally polarised
footpoint motions. I. Stationary behaviour in dissipative MHD.
Authors: Berghmans, D.; Tirry, W. J.
1997A&A...325..318B Altcode:
We study the heating of coronal loops by linear resonant Alfven waves
that are excited by photospheric footpoint motions of the magnetic
field lines. The analysis is restricted to azimuthally polarised
footpoint motions so that Alfven waves are excited. At the radii where
Alfven waves, travelling back and forth along the loop, are in phase
with the footpoint motions the oscillations grow unbounded in ideal
MHD. Inclusion of dissipation prevents singular growth and we can
look at the steady state in which the energy input at the photosphere
is balanced by the energy dissipated at the resonance. The crux of
our study is that the azimuthal wave number is taken non-zero which
means that also fast waves, including quasi-modes, can be excited
by the purely azimuthally polarised footpoint motions. In this case
resonant Alfven waves are not only excited directly by the footpoint
motions but also indirectly through coupling to fast waves. For some
footpoint motions these contributions counteract each other leading to
virtually no heating (anti-resonance) while for values corresponding to
a quasi-mode the two contributions act in concert leading to enhanced
heating. This dramatic influence of the quasi-mode is unexpected since,
in contrast to a sideways driven loop, a loop driven at the footpoints
by azimuthally polarised footpoint motions does not need quasi-modes
as energy carrier waves. In this paper a stationary state is assumed
which allows us to determine the optimal footpoint characteristics
for heating, but does not give any information on the time scales
involved. This item is adressed in a companion paper where an identical
system is studied time dependently using ideal MHD. This twin study
investigates the attainability of the heating scenarios and provides
an enhanced insight in the results of the present paper.
---------------------------------------------------------
Title: Wave heating of coronal loops driven by azimuthally polarised
footpoint motions. II. The time-dependent behaviour in ideal MHD.
Authors: Tirry, W. J.; Berghmans, D.
1997A&A...325..329T Altcode:
We study the heating of coronal loops by linear resonant Alfven waves
that are excited by photospheric footpoint motions of the magnetic field
lines. The analysis is restricted to azimuthally polarised footpoint
motions so that Alfven waves are excited directly. At the radii where
Alfven waves, travelling back and forth along the length of the loop,
are in phase with the footpoint motions, the oscillations grow unbounded
in ideal MHD. In the companion paper (Paper I) dissipation is included
and we looked at the steady state in which the energy injected at the
photospheric part of the loop is balanced by the energy dissipated
in the dissipative layer around the resonance. In this paper we make
an analysis in time-dependent ideal linear MHD in order to get more
physical insight in the results of Paper I and to get information
about the time scales involved. In the present study the azimuthal
wave number is taken to be non-zero so that Alfven and fast wave do
not exist independently. In this case the heating in the resonance
layer becomes a complicated interplay of the influence of the Alfven
waves excited directly at the photospheric base of the resonant layer
and the influence of the quasi-modes excited indirectly. We find that
the presence of these quasi-modes influence the resonance development
dramatically. This is unexpected, since in contrast to a sideways
driven loop, a loop driven at the footpoints by azimuthally footpoint
motions does not need quasi-modes as energy carrier waves.
---------------------------------------------------------
Title: Temporal evolution of resonant absorption in coronal
loops. Excitation by footpoint motions normal to the magnetic
surfaces.
Authors: Tirry, W. J.; Berghmans, D.; Goossens, M.
1997A&A...322..329T Altcode:
In this paper we study the temporal evolution of linear MHD waves
excited by footpoint motions using an ideal, pressureless slab model
for coronal loops. We choose the footpoint motions to be polarised
normal to the magnetic flux surfaces such that only fast waves
are driven directly, including the so-called quasi-modes. We have
derived a formal analytical solution as a superposition of eigenmodes
describing the system as a function of time. The corresponding
eigenvalue problem is solved numerically. This enables us to study
the influence of the characteristics of the footpoint motion on the
excitation of the quasi-modes. On the magnetic flux surface where the
frequency of these quasi-modes equals the local Alfven frequency,
wave energy is transferred from the quasi-modes towards Alfven
waves. We investigate the time evolution of this process in which
small scale dissipative features are generated which can be relevant
in the context of coronal heating. Special attention is given to the
question whether this generation of small scale dissipative features
takes place on time scales shorter than typical life times of coronal
loops. Expressing the dissipation time scale as function of the length
scale corresponding to the resonances, an estimate for the time when
dissipation becomes important and when our ideal MHD simulation stops
to be valid, can be derived. For typical dissipation coefficients and
length scales, dissipation becomes important in the resonance layer
in a time comparable to the life time of coronal loops.
---------------------------------------------------------
Title: Direct excitation of resonant torsional Alfven waves by
footpoint motions.
Authors: Ruderman, M. S.; Berghmans, D.; Goossens, M.; Poedts, S.
1997A&A...320..305R Altcode:
The present paper studies the heating of coronal loops by linear
resonant Alfven waves that are excited by the motions of the
photospheric footpoints of the magnetic field lines. The analysis
is restricted to torsionally polarised footpoint motions in an
axially symmetric system so that only torsional Alfven waves are
excited. For this subclass of footpoint motions, the Alfven and cusp
singularities are absent from the analysis which means that resonant
coupling between global modes of the loop and localised oscillations
is avoided. Instead, the focus is on the resonances due to the finite
extent of the loop in the longitudinal direction: at the radii where
Alfven waves travelling back and forth along the length of the loop are
in phase with the footpoint motions, the oscillations grow unbounded
in ideal MHD. Inclusion of electrical resistivity and viscosity as
dissipation mechanisms prevents singular growth and we can look at the
steady state in which the energy injected at the photospheric part
of the loop is balanced by the energy dissipated at the dissipative
layer around the resonance. In this sense, we show that the direct
excitation of Alfven waves by torsionally polarised footpoint motions
leads to a very efficient heating mechanism for coronal loops, even
without resonant coupling to global modes.
---------------------------------------------------------
Title: Heating of Coronal Loops by MHD Waves Driven by Photospheric
Motions
Authors: Berghmans, D.
1997ESASP.404..199B Altcode: 1997cswn.conf..199B
No abstract at ADS
---------------------------------------------------------
Title: Wave and Small-Scale Dynamics Study Using High-Cadence EIT
Image Sequences
Authors: Clette, F.; Berghmans, D.
1997ESASP.404..283C Altcode: 1997cswn.conf..283C
No abstract at ADS
---------------------------------------------------------
Title: MHD wave heating of coronal loops
Authors: Poedts, S.; Tirry, W.; Berghmans, D.; Goossens, M.
1997jena.confE..54P Altcode:
The possibility of heating coronal loops by phase-mixing and resonant
absorption of MHD waves is discussed. The focus is on the efficiency and
time scales of the conversion of the wave energy to heat for typical
coronal loop parameter values. Both the sideways excitation of loops
by incident waves and the footpoint driving by convective motions are
discussed. First, the mechanisms of phase-mixing and resonant absorption
are explained in a simple set-up. Next, linear MHD results on solar
coronal loop applications are reviewed. In sideways excited loops
(by incident waves), `quasi-modes' (or `collective modes') play the
crucial role of energy carrier from the external region {through the
flux surfaces} to the resonant layers. The quasi-modes are required
to obtain a reasonable efficiency unless the resonances are located
in the outer region of the loop. In footpoint driven loops, on the
other hand, resonant Alfven can be excited directly and the efficiency
depends of the polarization of the driving source. Recent results take
the variation of plasma density and magnetic field strength {along the
loop} into account. For typical coronal loop parameters, the MHD wave
heating mechanism turns out to be very efficient, i.e. the coupling
of the loop plasma to the external driver is very good and the time
scales for dissipation are much smaller than the typical life time of
a loop. However, the dynamics in the resonant layers is very nonlinear
in the hot (very well conducting) coronal plasma. Computer simulations
show that the shear flow in these layers can become unstable. It will
be shown that the Kelvin-Helmholtz-like instabilities may destroy
the resonant layers and lead to a turbulent state. Finally, some
observational results and consequences are discussed. This brings
us to the problems of the discrepancy between the observed and the
required power spectrum of MHD waves and the distinction between
different candidate heating mechanisms. Scientific visualization of
the observational consequences of the computer simulated results
may lead to different observable features for different candidate
heating mechanisms and, hence, to the identification of the mechanism
responsible for the heating of the coronal loops.
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Title: The role of the quasi-modes in the wave-heating of line-tied
coronal loops
Authors: Tirry, W.; Berghmans, D.
1997jena.confE..58T Altcode:
We study the heating of coronal loops by linear resonant Alfven waves
that are excited by photospheric footpoint motions of the magnetic
field lines. For azimuthally polarised footpoint motions Alfven waves
are excited directly. At the radii where Alfven waves, travelling back
and forth along the loop, are in phase with the footpoint motions
the oscillations grow unbounded in ideal MHD. However, inclusion of
dissipation prevents singular growth and we can look at the steady
state in which the energy input at the photosphere is balanced by
the energy dissipated at the resonance. The crux of our study is
that the azimuthal wave number is taken non-zero which means that
also fast waves, including quasi-modes, can be excited by the purely
azimuthally polarised footpoint motions. In this case resonant Alfven
waves are not only excited directly by the footpoint motions but also
indirectly through coupling to fast waves. For some footpoint motions
these contributions counteract each other leading to virtually no
heating (anti-resonance) while for parameter values corresponding to
a quasi-mode the two contributions act in concert leading to enhanced
heating. In a first study a steady state is assumed, which allows us
to determine the optimal footpoint characteristics for heating. In
order to get information on the time scales involved we studied the
same coronal loop model using a time-dependent ideal approach. This
approach also provides us with the physical insight in the phenomena
of anti-resonances.
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Title: The Footpoint-driven Coronal Sausage Wave
Authors: Berghmans, David; de Bruyne, Peter; Goossens, Marcel
1996ApJ...472..398B Altcode:
We study the excitation of MHD waves in a coronal loop as its field
line footpoints are forced to follow the photo spheric convective
motions. By focussing on the specific case of cylindrically symmetric
footpoint motions, the original problem is reduced to one in which
fast waves and Alfvén waves are decoupled. This allows for a full
analytical treatment of the photo spheric excitation of both sausage
waves and of torsional Alfvén waves. Previously, Berghmans & De
Bruyne considered the case of torsional Alfvén waves. In the present
paper we extend that analysis to sausage waves that are excited by
radially polarized footpoint motions (e.g., typical for granules). The
time-dependent solution that we obtain is written as a superposition
of body and leaky eigenmodes whose excitation is easily determined
from the imposed footpoint motion. This provides analytical insight
into the dynamics and energetics of both impulsively and periodically
driven sausage waves. In each case, we explain the time evolution
of the generated waves and discuss typical "signatures" that can be
looked for in numerical simulations and possibly in solar observations.
---------------------------------------------------------
Title: Coronal Loop Oscillations Driven by Footpoint Motions:
Analytical Results for a Model Problem
Authors: Berghmans, D.; de Bruyne, P.
1996ApL&C..34..157B Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Coronal Loop Oscillations Driven by Footpoint Motions:
Analytical Results for a Model Problem
Authors: Berghmans, David; de Bruyne, Peter
1995ApJ...453..495B Altcode:
We study the excitation of MHD waves in a coronal loop as its
field-line footpoints are forced to follow the photospheric convective
motions. Due to the large photo spheric-coronal density ratio, these
waves are reflected back and forth in the loop and thus build up a
global oscillation. By focusing on a specific case the problem is
reduced to the simplest situation conceivable which still contains
the relevant physics of wave propagation, reflections, resonances,
and phase mixing. This model problem allows for a fully analytical
treatment which greatly helps to understand earlier results found in the
literature. It is shown that the classical asymptotic state assumption,
in which all perturbed quantities have the same frequency as the driver,
is justified only when a wave damping mechanism, such as leakage, is
present. Special attention is given to footpoint motions with resonant
frequencies and to footpoint motions with finite lifetimes.
