spadaro

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Author name code: spadaro
ADS astronomy entries on 2022-09-14
author:"Spadaro, Daniele."

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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. 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. 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. 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. 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: Linking Small-scale Solar Wind Properties with Large-scale
Coronal Source Regions through Joint Parker Solar Probe-Metis/Solar
Orbiter Observations
Authors: Telloni, Daniele; Zank, Gary P.; Sorriso-Valvo, Luca;
D'Amicis, Raffaella; Panasenco, Olga; Susino, Roberto; Bruno, Roberto;
Perrone, Denise; Adhikari, Laxman; Liang, Haoming; Nakanotani, Masaru;
Zhao, Lingling; Hadid, Lina Z.; Sánchez-Cano, Beatriz; Verscharen,
Daniel; Velli, Marco; Grimani, Catia; Marino, Raffaele; Carbone,
Francesco; Mancuso, Salvatore; Biondo, Ruggero; Pagano, Paolo; Reale,
Fabio; Bale, Stuart D.; Kasper, Justin C.; Case, Anthony W.; de Wit,
Thierry Dudok; Goetz, Keith; Harvey, Peter R.; Korreck, Kelly E.;
Larson, Davin; Livi, Roberto; MacDowall, Robert J.; Malaspina, David
M.; Pulupa, Marc; Stevens, Michael L.; Whittlesey, Phyllis; Romoli,
Marco; Andretta, Vincenzo; Deppo, Vania Da; Fineschi, Silvano; Heinzel,
Petr; Moses, John D.; Naletto, Giampiero; Nicolini, Gianalfredo;
Spadaro, Daniele; Stangalini, Marco; Teriaca, Luca; Capobianco,
Gerardo; Capuano, Giuseppe E.; Casini, Chiara; Casti, Marta; Chioetto,
Paolo; Corso, Alain J.; Leo, Yara De; Fabi, Michele; Frassati,
Federica; Frassetto, Fabio; Giordano, Silvio; Guglielmino, Salvo L.;
Jerse, Giovanna; Landini, Federico; Liberatore, Alessandro; Magli,
Enrico; Massone, Giuseppe; Messerotti, Mauro; Pancrazzi, Maurizio;
Pelizzo, Maria G.; Romano, Paolo; Sasso, Clementina; Schühle, Udo;
Slemer, Alessandra; Straus, Thomas; Uslenghi, Michela; Volpicelli,
Cosimo A.; Zangrilli, Luca; Zuppella, Paola; Abbo, Lucia; Auchère,
Frédéric; Cuadrado, Regina Aznar; Berlicki, Arkadiusz; Ciaravella,
Angela; Lamy, Philippe; Lanzafame, Alessandro; Malvezzi, Marco;
Nicolosi, Piergiorgio; Nisticò, Giuseppe; Peter, Hardi; Solanki,
Sami K.; Strachan, Leonard; Tsinganos, Kanaris; Ventura, Rita; Vial,
Jean-Claude; Woch, Joachim; Zimbardo, Gaetano
2022ApJ...935..112T Altcode:
The solar wind measured in situ by Parker Solar Probe in the very
inner heliosphere is studied in combination with the remote-sensing
observation of the coronal source region provided by the METIS
coronagraph aboard Solar Orbiter. The coronal outflows observed near
the ecliptic by Metis on 2021 January 17 at 16:30 UT, between 3.5 and
6.3 R ⊙ above the eastern solar limb, can be associated
with the streams sampled by PSP at 0.11 and 0.26 au from the Sun,
in two time intervals almost 5 days apart. The two plasma flows
come from two distinct source regions, characterized by different
magnetic field polarity and intensity at the coronal base. It follows
that both the global and local properties of the two streams are
different. Specifically, the solar wind emanating from the stronger
magnetic field region has a lower bulk flux density, as expected,
and is in a state of well-developed Alfvénic turbulence, with low
intermittency. This is interpreted in terms of slab turbulence in the
context of nearly incompressible magnetohydrodynamics. Conversely,
the highly intermittent and poorly developed turbulent behavior of the
solar wind from the weaker magnetic field region is presumably due to
large magnetic deflections most likely attributed to the presence of
switchbacks of interchange reconnection origin.

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Title: The observed large scale equatorial UV corona: new perspectives
with 'recent', 'future' and 'old' data
Authors: Abbo, Lucia; Fineschi, Silvano; Parenti, Susanna; Romoli,
Marco; Pancrazzi, Maurizio; Andretta, Vincenzo; Auchère, Frédéric;
Susino, Roberto; Spadaro, Daniele; Nicolini, Gianalfredo; Giordano,
Silvio; Zangrilli, Luca
2022cosp...44.1327A Altcode:
In order to understand the sources and the physical mechanisms for the
propagation of the Slow Solar Wind (SSW), it is essential to analyze
solar data in the region which shapes the large scale structure in
corona where the SSW is accelerated, such as streamers and boundaries
coronal hole/streamer. The focus of this work is to trace the channels
where the SSW escapes from the solar disk up to 5 solar radii in
corona. We give an overview on how Solar Orbiter observations (remote
sensing and in-situ) together with other space missions (i.e. SPP and
PROBA-3) can give a major contribution to the study of the evolution
of the streamer belt and global corona, of the role of the coronal
magnetic field topology in controlling the solar wind dynamics and
abundance, and of abundance anomalies in streamers and in boundaries
CH/streamer. In particular, we study how to trace back some equatorial
features from the extended corona to the disk. We analyse recent Metis
observations in corona together with the Extreme Ultraviolet Imager
(EUI) observations on disk and corona (by using the occulter). We also
present results from SOHO observations in 1996-1997 (solar minimum),
during which was observed a stable equatorial streamer belt with a
typical dipole magnetic structure. We have analyzed data by UVCS,
SUMER, CDS to trace large scale features and also sub-structures at
very high spatial resolution from the disk up to 3 solar radii. This
comparison and overlapping is still unique in solar physics and it can
improve our knowledge about the origin, acceleration and propagation
of the solar wind.

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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.

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Title: Measuring the F-corona intensity through time correlation of
total and polarized visible light images
Authors: Burtovoi, A.; Naletto, G.; Dolei, S.; Spadaro, D.; Romoli,
M.; Landini, F.; De Leo, Y.
2022A&A...659A..50B Altcode: 2021arXiv211211930B
We present a new correlation method for deriving the F-corona intensity
distribution, which is based on the analysis of the evolution of the
total and polarized visible light (VL) images. We studied the one-month
variation profiles of the total and polarized brightness acquired with
Large Angle Spectrometric COronagraph and found that in some regions
they are highly correlated. Assuming that the F-corona does not vary
significantly on a timescale of one month, we estimated its intensity
in the high-correlation regions and reconstructed the corresponding
intensity maps both during the solar-minimum and solar-maximum
periods. Systematic uncertainties were estimated by performing
dedicated simulations. We compared the resulting F-corona images with
those determined using the inversion technique and found that the
correlation method provides a smoother intensity distribution. We also
obtained that the F-corona images calculated for consecutive months
show no significant variation. Finally, we note that this method can
be applied to the future high-cadence VL observations carried out with
the Metis/Solar Orbiter coronagraph.

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Title: Implications of spicule activity on coronal loop heating and
catastrophic cooling
Authors: Nived, V. N.; Scullion, E.; Doyle, J. G.; Susino, R.; Antolin,
P.; Spadaro, D.; Sasso, C.; Sahin, S.; Mathioudakis, M.
2022MNRAS.509.5523N Altcode: 2021arXiv211107967N; 2021MNRAS.tmp.3004N
We report on the properties of coronal loop foot-point heating
with observations at the highest resolution, from the CRisp Imaging
Spectro-Polarimeter located at the Swedish 1-m Solar Telescope and
co-aligned NASA Solar Dynamics Observatory observations, of Type II
spicules in the chromosphere and their signatures in the extreme
ultraviolet (EUV) corona. Here, we address one important issue,
as to why there is not always a one-to-one correspondence, between
Type II spicules and hot coronal plasma signatures, i.e. beyond
TR temperatures. We do not detect any difference in their spectral
properties in a quiet Sun region compared to a region dominated by
coronal loops. On the other hand, the number density close to the
foot-points in the active region is found to be an order of magnitude
higher than in the quiet Sun case. A differential emission measure
analysis reveals a peak at ~5 × 105 K of the order of
1022 cm-5 K-1. Using this result as
a constraint, we conduct numerical simulations and show that with an
energy input of 1.25 × 1024 erg (corresponding to ~10 RBEs
contributing to the burst) we manage to reproduce the observation very
closely. However, simulation runs with lower thermal energy input do not
reproduce the synthetic AIA 171 Å signatures, indicating that there
is a critical number of spicules required in order to account for the
AIA 171 Å signatures in the simulation. Furthermore, the higher energy
(1.25 × 1024 erg) simulations reproduce catastrophic cooling
with a cycle duration of ~5 h, matching a periodicity we observe in
the EUV observations.

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Title: On the Evolution of a Sub-C Class Flare: A Showcase for the
Capabilities of the Revamped Catania Solar Telescope
Authors: Romano, Paolo; Guglielmino, Salvo L.; Costa, Pierfrancesco;
Falco, Mariachiara; Buttaccio, Salvatore; Costa, Alessandro;
Martinetti, Eugenio; Occhipinti, Giovanni; Spadaro, Daniele; Ventura,
Rita; Capuano, Giuseppe E.; Zuccarello, Francesca
2022SoPh..297....7R Altcode: 2021arXiv211108972R
Solar flares are occasionally responsible for severe space-weather
events, which can affect space-borne and ground-based infrastructures,
endangering anthropic technological activities and even human health and
safety. Thus, an essential activity in the framework of space-weather
monitoring is devoted to the observation of the activity level on
the Sun. In this context, the acquisition system of the Catania
Solar Telescope has been recently upgraded in order to improve its
contribution to the European Space Agency (ESA) - Space Weather Service
Network through the ESA Portal, which represents the main asset for
space weather in Europe. Here, we describe the hardware and software
upgrades of the Catania Solar Telescope and the main data products
provided by this facility, which include full-disk images of the
photosphere and chromosphere, together with a detailed characterization
of sunspot groups. As a showcase of the observational capabilities of
the revamped Catania Solar Telescope, we report the analysis of a B5.4
class flare that occurred on 7 December 2020, simultaneously observed
by the Interface Region Imaging Spectrograph and the Solar Dynamics
Observatory satellites.

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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. 
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. 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. 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−1. 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. 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. Movies are available at <A
href="https://www.aanda.org/10.1051/0004-6361/202142407/olm">https://www.aanda.org</A>

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Title: Cosmic-ray flux predictions and observations for and with
Metis on board Solar Orbiter
Authors: Grimani, C.; Andretta, V.; Chioetto, P.; Da Deppo, V.; Fabi,
M.; Gissot, S.; Naletto, G.; Persici, A.; Plainaki, C.; Romoli, M.;
Sabbatini, F.; Spadaro, D.; Stangalini, M.; Telloni, D.; Uslenghi, M.;
Antonucci, E.; Bemporad, A.; Capobianco, G.; Capuano, G.; Casti, M.;
De Leo, Y.; Fineschi, S.; Frassati, F.; Frassetto, F.; Heinzel, P.;
Jerse, G.; Landini, F.; Liberatore, A.; Magli, E.; Messerotti, M.;
Moses, D.; Nicolini, G.; Pancrazzi, M.; Pelizzo, M. G.; Romano, P.;
Sasso, C.; Schühle, U.; Slemer, A.; Straus, T.; Susino, R.; Teriaca,
L.; Volpicelli, C. A.; Freiherr von Forstner, J. L.; Zuppella, P.
2021A&A...656A..15G Altcode: 2021arXiv210413700G
Context. The Metis coronagraph is one of the remote sensing instruments
hosted on board the ESA/NASA Solar Orbiter mission. Metis is devoted
to carry out the first simultaneous imaging of the solar corona in
both visible light (VL) and ultraviolet (UV). High-energy particles
can penetrate spacecraft materials and may limit the performance of
the on-board instruments. A study of the galactic cosmic-ray (GCR)
tracks observed in the first VL images gathered by Metis during the
commissioning phase is presented here. A similar analysis is planned
for the UV channel. Aims: We aim to formulate a prediction of
the GCR flux up to hundreds of GeV for the first part of the Solar
Orbiter mission to study the performance of the Metis coronagraph. Methods: The GCR model predictions are compared to observations
gathered on board Solar Orbiter by the High-Energy Telescope in the
range between 10 MeV and 100 MeV in the summer of 2020 as well as with
the previous measurements. Estimated cosmic-ray fluxes above 70 MeV
n−1 have been also parameterized and used for Monte Carlo
simulations aimed at reproducing the cosmic-ray track observations in
the Metis coronagraph VL images. The same parameterizations can also
be used to study the performance of other detectors. Results:
By comparing observations of cosmic-ray tracks in the Metis VL images
with FLUKA Monte Carlo simulations of cosmic-ray interactions in
the VL detector, we find that cosmic rays fire only a fraction, on
the order of 10−4, of the whole image pixel sample. We
also find that the overall efficiency for cosmic-ray identification
in the Metis VL images is approximately equal to the contribution
of Z ≥ 2 GCR particles. A similar study will be carried out during
the whole of the Solar Orbiter's mission duration for the purposes of
instrument diagnostics and to verify whether the Metis data and Monte
Carlo simulations would allow for a long-term monitoring of the GCR
proton flux.

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Title: First light observations of the solar wind in the outer corona
with the Metis coronagraph
Authors: Romoli, M.; Antonucci, E.; Andretta, V.; Capuano, G. E.; Da
Deppo, V.; De Leo, Y.; Downs, C.; Fineschi, S.; Heinzel, P.; Landini,
F.; Liberatore, A.; Naletto, G.; Nicolini, G.; Pancrazzi, M.; Sasso,
C.; Spadaro, D.; Susino, R.; Telloni, D.; Teriaca, L.; Uslenghi,
M.; Wang, Y. -M.; Bemporad, A.; Capobianco, G.; Casti, M.; Fabi, M.;
Frassati, F.; Frassetto, F.; Giordano, S.; Grimani, C.; Jerse, G.;
Magli, E.; Massone, G.; Messerotti, M.; Moses, D.; Pelizzo, M. -G.;
Romano, P.; Schühle, U.; Slemer, A.; Stangalini, M.; Straus, T.;
Volpicelli, C. A.; Zangrilli, L.; Zuppella, P.; Abbo, L.; Auchère,
F.; Aznar Cuadrado, R.; Berlicki, A.; 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...656A..32R Altcode: 2021arXiv210613344R
In this work, we present an investigation of the wind in the solar
corona that has been initiated by observations of the resonantly
scattered ultraviolet emission of the coronal plasma obtained with
UVCS-SOHO, designed to measure the wind outflow speed by applying
Doppler dimming diagnostics. Metis on Solar Orbiter complements the
UVCS spectroscopic observations that were performed during solar
activity cycle 23 by simultaneously imaging the polarized visible
light and the H I Lyman-α corona in order to obtain high spatial and
temporal resolution maps of the outward velocity of the continuously
expanding solar atmosphere. The Metis observations, taken on May 15,
2020, provide the first H I Lyman-α images of the extended corona
and the first instantaneous map of the speed of the coronal plasma
outflows during the minimum of solar activity and allow us to identify
the layer where the slow wind flow is observed. The polarized visible
light (580-640 nm) and the ultraviolet H I Lyα (121.6 nm) coronal
emissions, obtained with the two Metis channels, were combined in
order to measure the dimming of the UV emission relative to a static
corona. This effect is caused by the outward motion of the coronal
plasma along the direction of incidence of the chromospheric photons
on the coronal neutral hydrogen. The plasma outflow velocity was then
derived as a function of the measured Doppler dimming. The static
corona UV emission was simulated on the basis of the plasma electron
density inferred from the polarized visible light. This study leads
to the identification, in the velocity maps of the solar corona, of
the high-density layer about ±10° wide, centered on the extension
of a quiet equatorial streamer present at the east limb - the coronal
origin of the heliospheric current sheet - where the slowest wind
flows at about 160 ± 18 km s−1 from 4 R⊙
to 6 R⊙. Beyond the boundaries of the high-density layer,
the wind velocity rapidly increases, marking the transition between
slow and fast wind in the corona.

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Title: Exploring the Solar Wind from Its Source on the Corona into
the Inner Heliosphere during the First Solar Orbiter-Parker Solar
Probe Quadrature
Authors: Telloni, Daniele; Andretta, Vincenzo; Antonucci, Ester;
Bemporad, Alessandro; Capuano, Giuseppe E.; Fineschi, Silvano;
Giordano, Silvio; Habbal, Shadia; Perrone, Denise; Pinto, Rui F.;
Sorriso-Valvo, Luca; Spadaro, Daniele; Susino, Roberto; Woodham, Lloyd
D.; Zank, Gary P.; Romoli, Marco; Bale, Stuart D.; Kasper, Justin C.;
Auchère, Frédéric; Bruno, Roberto; Capobianco, Gerardo; Case,
Anthony W.; Casini, Chiara; Casti, Marta; Chioetto, Paolo; Corso,
Alain J.; Da Deppo, Vania; De Leo, Yara; Dudok de Wit, Thierry;
Frassati, Federica; Frassetto, Fabio; Goetz, Keith; Guglielmino,
Salvo L.; Harvey, Peter R.; Heinzel, Petr; Jerse, Giovanna; Korreck,
Kelly E.; Landini, Federico; Larson, Davin; Liberatore, Alessandro;
Livi, Roberto; MacDowall, Robert J.; Magli, Enrico; Malaspina, David
M.; Massone, Giuseppe; Messerotti, Mauro; Moses, John D.; Naletto,
Giampiero; Nicolini, Gianalfredo; Nisticò, Giuseppe; Panasenco,
Olga; Pancrazzi, Maurizio; Pelizzo, Maria G.; Pulupa, Marc; Reale,
Fabio; Romano, Paolo; Sasso, Clementina; Schühle, Udo; Stangalini,
Marco; Stevens, Michael L.; Strachan, Leonard; Straus, Thomas; Teriaca,
Luca; Uslenghi, Michela; Velli, Marco; Verscharen, Daniel; Volpicelli,
Cosimo A.; Whittlesey, Phyllis; Zangrilli, Luca; Zimbardo, Gaetano;
Zuppella, Paola
2021ApJ...920L..14T Altcode: 2021arXiv211011031T
This Letter addresses the first Solar Orbiter (SO)-Parker Solar
Probe (PSP) quadrature, occurring on 2021 January 18 to investigate
the evolution of solar wind from the extended corona to the inner
heliosphere. Assuming ballistic propagation, the same plasma volume
observed remotely in the corona at altitudes between 3.5 and 6.3
solar radii above the solar limb with the Metis coronagraph on SO
can be tracked to PSP, orbiting at 0.1 au, thus allowing the local
properties of the solar wind to be linked to the coronal source region
from where it originated. Thanks to the close approach of PSP to the
Sun and the simultaneous Metis observation of the solar corona, the
flow-aligned magnetic field and the bulk kinetic energy flux density
can be empirically inferred along the coronal current sheet with an
unprecedented accuracy, allowing in particular estimation of the Alfvén
radius at 8.7 solar radii during the time of this event. This is thus
the very first study of the same solar wind plasma as it expands from
the sub-Alfvénic solar corona to just above the Alfvén surface.

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Title: Effects of the chromospheric Lyα line profile shape on
the determination of the solar wind H I outflow velocity using the
Doppler dimming technique
Authors: Capuano, G. E.; Dolei, S.; Spadaro, D.; Guglielmino, S. L.;
Romano, P.; Ventura, R.; Andretta, V.; Bemporad, A.; Sasso, C.;
Susino, R.; Da Deppo, V.; Frassetto, F.; Giordano, S. M.; Landini,
F.; Nicolini, G.; Pancrazzi, M.; Romoli, M.; Zangrilli, L.
2021A&A...652A..85C Altcode: 2021arXiv210805957C
Context. The determination of solar wind H I outflow velocity is
fundamental to shedding light on the mechanisms of wind acceleration
occurring in the corona. Moreover, it has implications in various
astrophysical contexts, such as in the heliosphere and in cometary
and planetary atmospheres. Aims: We aim to study the effects
of the chromospheric Lyα line profile shape on the determination
of the outflow speed of coronal H I atoms via the Doppler dimming
technique. This is of particular interest in view of the upcoming
measurements of the Metis coronagraph aboard the Solar Orbiter
mission. Methods: The Doppler dimming technique exploits the
decrease of coronal Lyα radiation in regions where H I atoms flow out
in the solar wind. Starting from UV observations of the coronal Lyα
line from the Solar and Heliospheric Observatory (SOHO), aboard the
UltraViolet Coronagraph Spectrometer, and simultaneous measurements
of coronal electron densities from pB coronagraphic observations, we
explored the effect of the profile of the pumping chromospheric Lyα
line. We used measurements from the Solar UV Measurement of Emitted
Radiation, aboard SOHO, the Ultraviolet Spectrometer and Polarimeter,
aboard the Solar Maximum Mission, and the Laboratoire de Physique
Stellaire et Planetaire, aboard the Eight Orbiting Solar Observatory,
both from representative on-disc regions, such as coronal holes
and quiet Sun and active regions, and as a function of time during
the solar activity cycle. In particular, we considered the effect
of four chromospheric line parameters: line width, reversal depth,
asymmetry, and distance of the peaks. Results: We find that
the range of variability of the four line parameters is of about 50%
for the width, 69% for the reversal depth, and 35% and 50% for the
asymmetry and distance of the peaks, respectively. We then find that
the variability of the pumping Lyα profile affects the estimates of
the coronal H I velocity by about 9−12%. This uncertainty is smaller
than the uncertainties due to variations of other physical quantities,
such as electron density, electron temperature, H I temperature, and
integrated chromospheric Lyα radiance. Conclusions: Our work
suggests that the observed variations in the chromospheric Lyα line
profile parameters along a cycle and in specific regions negligibly
affect the determination of the solar wind speed of H I atoms. Due
to this weak dependence, a unique shape of the Lyα profile over
the solar disc that is constant in time can be adopted to obtain the
values of the solar wind H I outflow velocity. Moreover, the use of an
empirical analytical chromospheric profile of the Lyα, assumed uniform
over the solar disc and constant in time, is justifiable in order to
obtain a good estimate of the coronal wind H I outflow velocity using
coronagraphic UV images.

---------------------------------------------------------
Title: A journey of exploration to the polar regions of a star:
probing the solar poles and the heliosphere from high helio-latitude
Authors: Harra, Louise; Andretta, Vincenzo; Appourchaux, Thierry;
Baudin, Frédéric; Bellot-Rubio, Luis; Birch, Aaron C.; Boumier,
Patrick; Cameron, Robert H.; Carlsson, Matts; Corbard, Thierry;
Davies, Jackie; Fazakerley, Andrew; Fineschi, Silvano; Finsterle,
Wolfgang; Gizon, Laurent; Harrison, Richard; Hassler, Donald M.;
Leibacher, John; Liewer, Paulett; Macdonald, Malcolm; Maksimovic,
Milan; Murphy, Neil; Naletto, Giampiero; Nigro, Giuseppina; Owen,
Christopher; Martínez-Pillet, Valentín; Rochus, Pierre; Romoli,
Marco; Sekii, Takashi; Spadaro, Daniele; Veronig, Astrid; Schmutz, W.
2021ExA...tmp...93H Altcode: 2021arXiv210410876H
A mission to view the solar poles from high helio-latitudes (above 60°)
will build on the experience of Solar Orbiter as well as a long heritage
of successful solar missions and instrumentation (e.g. SOHO Domingo et
al. (Solar Phys. 162(1-2), 1-37 1995), STEREO Howard et al. (Space
Sci. Rev. 136(1-4), 67-115 2008), Hinode Kosugi et al. (Solar
Phys. 243(1), 3-17 2007), Pesnell et al. Solar Phys. 275(1-2),
3-15 2012), but will focus for the first time on the solar poles,
enabling scientific investigations that cannot be done by any other
mission. One of the major mysteries of the Sun is the solar cycle. The
activity cycle of the Sun drives the structure and behaviour of the
heliosphere and of course, the driver of space weather. In addition,
solar activity and variability provides fluctuating input into the
Earth climate models, and these same physical processes are applicable
to stellar systems hosting exoplanets. One of the main obstructions
to understanding the solar cycle, and hence all solar activity,
is our current lack of understanding of the polar regions. In this
White Paper, submitted to the European Space Agency in response to the
Voyage 2050 call, we describe a mission concept that aims to address
this fundamental issue. In parallel, we recognise that viewing the Sun
from above the polar regions enables further scientific advantages,
beyond those related to the solar cycle, such as unique and powerful
studies of coronal mass ejection processes, from a global perspective,
and studies of coronal structure and activity in polar regions. Not
only will these provide important scientific advances for fundamental
stellar physics research, they will feed into our understanding of
impacts on the Earth and other planets' space environment.

---------------------------------------------------------
Title: In-flight optical performance assessment for the Metis solar
coronagraph
Authors: Da Deppo, Vania; Chioetto, Paolo; Andretta, Vincenzo; Casini,
Chiara; Frassetto, Fabio; Slemer, Alessandra; Zuppella, Paola; Romoli,
Marco; Fineschi, Silvano; Heinzel, Petr; Naletto, Giampiero; Nicolini,
Gianalfredo; Spadaro, Daniele; Stangalini, Marco; Teriaca, Luca;
Bemporad, Alessandro; Casti, Marta; Fabi, Michele; Grimani, Catia;
Heerlein, Klaus; Jerse, Giovanna; Landini, Federico; Liberatore,
Alessandro; Magli, Enrico; Melich, Radek; Pancrazzi, Maurizio; Pelizzo,
Maria-G.; Romano, Paolo; Sasso, Clementina; Straus, Thomas; Susino,
Roberto; Uslenghi, Michela; Volpicelli, Cosimo Antonio
2021SPIE11852E..10D Altcode:
Metis is a multi-wavelength coronagraph onboard the European Space
Agency (ESA) Solar Orbiter mission. The instrument features an
innovative instrument design conceived for simultaneously imaging the
Sun's corona in the visible and ultraviolet range. The Metis visible
channel employs broad-band, polarized imaging of the visible K-corona,
while the UV one uses narrow-band imaging at the HI Ly 􀄮, i.e. 121.6
nm. During the commissioning different acquisitions and activities,
performed with both the Metis channels, have been carried out with the
aim to check the functioning and the performance of the instrument. In
particular, specific observations of stars have been devised to assess
the optical alignment of the telescope and to derive the instrument
optical parameters such as focal length, PSF and possibly check the
optical distortion and the vignetting function. In this paper, the
preliminary results obtained for the PSF of both channels and the
determination of the scale for the visible channel will be described
and discussed. The in-flight obtained data will be compared to those
obtained on-ground during the calibration campaign.

---------------------------------------------------------
Title: On-ground flat-field calibration of the Metis coronagraph
onboard the Solar Orbiter ESA mission
Authors: Casini, C.; Da Deppo, V.; Zuppella, P.; Chioetto, P.; Slemer,
A.; Frassetto, F.; Romoli, M.; Landini, F.; Pancrazzi, M.; Andretta,
V.; De Leo, Y.; Bemporad, A.; Fabi, M.; Fineschi, S.; Frassati, F.;
Grimani, C.; Jerse, G.; Heerlein, K.; Liberatore, A.; Magli, E.;
Naletto, G.; Nicolini, G.; Pelizzo, M. G.; Romano, P.; Sasso, C.;
Spadaro, D.; Stangalini, M.; Straus, T.; Susino, R.; Teriaca, L.;
Uslenghi, M.; Casti, M.; Heinzel, P.; Volpicelli, A.
2021SPIE11852E..5BC Altcode:
Solar Orbiter, launched on February 9th 2020, is an
ESA/NASA mission conceived to study the Sun. This work presents
the embedded Metis coronagraph and its on-ground calibration in the
580-640 nm wavelength range using a flat field panel. It provides
a uniform illumination to evaluate the response of each pixel of
the detector; and to characterize the Field of View (FoV) of the
coronagraph. Different images with different exposure times were
acquired during the on-ground calibration campaign. They were analyzed
to verify the linearity response of the instrument and the requirements
for the FoV: the maximum area of the sky that Metis can acquire.

---------------------------------------------------------
Title: Challenges during Metis-Solar Orbiter commissioning phase
Authors: Romoli, Marco; Andretta, Vincenzo; Bemporad, Alessandro;
Casti, Marta; Da Deppo, Vania; De Leo, Yara; Fabi, Michele; Fineschi,
Silvano; Frassetto, Fabio; Grimani, Catia; Heerlein, Klaus; Heinzel,
Petr; Jerse, Giovanna; Landini, Federico; Liberatore, Alessandro;
Magli, Enrico; Naletto, Giampiero; Nicolini, Gianalfredo; Pancrazzi,
Maurizio; Pelizzo, Maria Guglielmina; Romano, Paolo; Sasso, Clementina;
Schühle, Udo; Slemer, Alessandra; Spadaro, Daniele; Straus, Thomas;
Susino, Roberto; Teriaca, Luca; Uslenghi, Michela; Volpicelli, Cosimo
Antonio; Zupella, Paola
2021SPIE11852E..5AR Altcode:
Metis is the visible light and UV light imaging coronagraph on board
the ESA-NASA mission Solar Orbiter that has been launched February 10th,
2020, from Cape Canaveral. Scope of the mission is to study the Sun up
close, taking high-resolution images of the Sun's poles for the first
time, and understanding the Sun-Earth connection. Metis coronagraph
will image the solar corona in the linearly polarized broadband visible
radiation and in the UV HI Ly-α line from 1.6 to 3 solar radii when at
Solar Orbiter perihelion, providing a diagnostics, with unprecedented
temporal coverage and spatial resolution, of the structures and dynamics
of the full corona. Solar Orbiter commissioning phase big challenge was
Covid-19 social distancing phase that affected the way commissioning
of a spacecraft and its payload is typically done. Metis coronagraph
on-board Solar Orbiter had its additional challenges: to wake up and
check the performance of the optical, electrical and thermal subsystems,
most of them unchecked since Metis delivery to spacecraft prime, Airbus,
in May 2017. The roadmap to the fully commissioned coronagraph is here
described throughout the steps from the software functional test,
the switch on of the detectors of the two channels, UV and visible,
to the optimization of the occulting system and the characterization
of the instrumental stray light, one of the most challenging features
in a coronagraph.

---------------------------------------------------------
Title: In-flight calibration of Metis coronagraph on board of
Solar Orbiter
Authors: Liberatore, A.; Fineschi, S.; Casti, M.; Capobianco, G.;
Romoli, M.; Andretta, V.; Bemporad, A.; Da Deppo, V.; De Leo, Y.; Fabi,
M.; Frassetto, F.; Grimani, C.; Heerlein, K.; Heinzel, P.; Jerse,
G.; Landini, F.; Magli, E.; Naletto, G.; Nicolini, G.; Pancrazzi,
M.; Pelizzo, M. G.; Romano, P.; Sasso, C.; Slemer, A.; Spadaro, D.;
Straus, T.; Susino, R.; Teriaca, L.; Uslenghi, M.; Volpicelli, C. A.;
Zuppella, P.
2021SPIE11852E..48L Altcode:
Metis coronagraph is one of the remote-sensing instruments of the Solar
Orbiter mission launched at the begin of 2020. The mission profile will
allow for the first time the remote-sensing observation of the Sun
from a very close distance and increasing the latitude with respect
to the ecliptic plane. In particular, Metis is aimed at the overall
characterization and study of the solar corona and solar wind. Metis
instrument acquires images of the solar corona in two different
wavelengths simultaneously; ultraviolet (UV) and visible-light (VL). The
VL channel includes a polarimeter with an electro-optically modulating
Liquid Crystal Variable Retarder (LCVR) to measure the linearly
polarized brighness pB) of the K-corona. This paper presents part of
the in-flight calibration results for both wavelength channels together
with a comparison with on-ground calibrations. The orientation of the
K-corona linear polarization was used for the in-flight calibration
of the Metis polarimeter. This paper describes the correction of the
on-ground VL vignetting function after the in-flight adjustment of
the internal occulter. The same vignetting function was adaptated to
the UV channel.

---------------------------------------------------------
Title: The MDOR/PDOR on-line module for MISO, the planning software
of Solar Orbiter instruments
Authors: Volpicelli, Cosimo; Landini, Federico; Pancrazzi, Maurizio;
Straus, Thomas; Susino, Roberto; Nicolini, Gianalfredo; Sasso,
Clementina; Fabi, Michele; De Leo, Yara; Casini, Chiara; Naletto,
Giampiero; Nicolosi, Piergiorgio; Spadaro, Daniele; Andretta, Vincenzo;
Antonucci, Ester; Fineschi, Silvano; Da Deppo, Vania; Zuppella, Paola;
Frassetto, Fabio; Slemer, Alessandra; Mercier, Claude; Kouliche,
Dimitri; Caminade, Stephane; Picard, David; Buchlin, Eric; Auchère,
Frédéric; Romoli, Marco
2020SPIE11452E..0SV Altcode:
Solar Orbiter is a solar mission that will approach the Sun down to a
minimum perihelion of 0.28 AU and will increase its orbit inclination
with respect to the ecliptic up to a maximum angle of 34 deg. For
imagers aboard Solar Orbiter there will be three 10-days remote sensing
windows per orbit. Observations shall be carefully planned at least 6
months in advance. The Multi Instrument Sequence Organizer (MISO) is
a web based platform developed by the SPICE group and made available
to support Solar Orbiter instruments teams in planning observations
by assembling Mission Database sequences. Metis is the UV and visible
light coronagraph aboard Solar Orbiter. Metis is a complex instrument
characterized by a rich variety of observing modes, which required a
careful commissioning activity and will need support for potential
maintenance operations throughout the mission. In order to support
commissioning and maintenance activities, the Metis team developed
a PDOR (Payload Direct Operation Request) and MDOR (Memory Direct
Operation Request) module integrated in MISO and made available to all
Solar Orbiter instruments. An effort was made in order to interpret
the coding philosophy of the main project and to make the additional
module as homogeneous as possible both to the web interface and to the
algorithm logic, while integrating characteristics which are peculiar
to PDORs and MDORs. An user friendly web based interface allows the
operator to build the operation request and to successively modify or
integrate it with further or alternative information. In the present
work we describe the PDOR/MDOR module for MISO by addressing its logic
and main characteristics.

---------------------------------------------------------
Title: A Journey of Exploration to the Polar Regions of a Star:
Probing the Solar Poles and the Heliosphere from High Helio-Latitude
Authors: Finsterle, W.; Harra, L.; Andretta, V.; Appourchaux, T.;
Baudin, F.; Bellot Rubio, L.; Birch, A.; Boumier, P.; Cameron, R. H.;
Carlsson, M.; Corbard, T.; Davies, J. A.; Fazakerley, A. N.; Fineschi,
S.; Gizon, L. C.; Harrison, R. A.; Hassler, D.; Leibacher, J. W.;
Liewer, P. C.; Macdonald, M.; Maksimovic, M.; Murphy, N.; Naletto, G.;
Nigro, G.; Owen, C. J.; Martinez-Pillet, V.; Rochus, P. L.; Romoli,
M.; Sekii, T.; Spadaro, D.; Veronig, A.
2020AGUFMSH0110005F Altcode:
A mission to view the solar poles from high helio-latitudes (above
60°) will build on the experience of Solar Orbiter as well as a long
heritage of successful solar missions and instrumentation (e.g. SOHO,
STEREO, Hinode, SDO), but will focus for the first time on the solar
poles, enabling scientific investigations that cannot be done by
any other mission. One of the major mysteries of the Sun is the solar
cycle. The activity cycle of the Sun drives the structure and behaviour
of the heliosphere and is, of course, the driver of space weather. In
addition, solar activity and variability provides fluctuating input
into the Earth climate models, and these same physical processes
are applicable to stellar systems hosting exoplanets. One of the
main obstructions to understanding the solar cycle, and hence all
solar activity, is our current lack of understanding of the polar
regions. We describe a mission concept that aims to address this
fundamental issue. In parallel, we recognise that viewing the Sun
from above the polar regions enables further scientific advantages,
beyond those related to the solar cycle, such as unique and powerful
studies of coronal mass ejection processes, from a global perspective,
and studies of coronal structure and activity in polar regions. Not
only will these provide important scientific advances for fundamental
stellar physics research, they will feed into our understanding of
impacts on the Earth and other planets' space environment.

---------------------------------------------------------
Title: A Radiation Environmental Study for the Metis Coronagraph on
board Solar Orbiter
Authors: Grimani, C.; Andretta, V.; Chioetto, P.; Da Deppo, V.; Fabi,
M.; Gissot, S.; Naletto, G.; Plainaki, C.; Romoli, M.; Spadaro, D.;
Stangalini, M.; Telloni, D.; Uslenghi, M.
2020AGUFMSH038..08G Altcode:
The solar cycle 24 was the weakest of the last hundred years. All
predictions available in the literature for the solar cycle 25 indicate
a similar or even weaker period of solar activity. As a result,
the highest galactic cosmic-ray flux of the last century will strike
the Solar Orbiter spacecraft along its orbit. Conversely, only one
solar energetic particle event (SEP) per year (average predictions)
is expected during the cruise phase of the mission in the fluence range
106-107 protons cm-2 above 30 MeV.An
instrument dedicated radiation environmental study will be carried out
for Metis, the coronagraph on board Solar Orbiter. Pre-launch Monte
Carlo simulations aiming to estimate the overall dose absorbed by the
Cerium treated polarimeter lenses indicated an average dose absorption
of 2000 Gy for the extended mission, while the lenses showed a few %
transmittance loss with a 106 Gy of gamma radiation. Monte Carlo simulations will be also performed to study energetic
particle single hits and tracks in the images of the visible light and
ultraviolet detectors. On the other hand, dark images provide precious
clues for cosmic-ray monitoring and images background estimates for both
Metis and EUI (Extreme-Ultraviolet Imager) detectors. Collaboration with
the EPD (Energetic Particle Detector) instrument scientists and data
from cosmic-ray experiments in orbit during the Solar Orbiter mission
will allow us to study cosmic-ray variations along the spacecraft
orbit and their effects on the instrument performance.

---------------------------------------------------------
Title: Metis - Solar Orbiter Topical Team on "Modelling of CME
propagation/evolution in corona and solar wind in connection with
Space Weather"
Authors: Bemporad, A.; Banerjee, D.; Berlicki, A.; Biondo, R.; Boe,
B.; Calchetti, D.; Capuano, G.; De Leo, Y.; Del Moro, D.; Feng, L.;
Foldes, R.; Frassati, F.; Frazin, R. A.; Giovannelli, L.; Giunta,
A. S.; Heinzel, P.; Ippolito, A.; Janvier, M.; Jerse, G.; Kilpua,
K. E. J.; Laurenza, M.; Lloveras, D.; Magdalenic, J.; Mancuso, S.;
Messerotti, M.; Mierla, M.; Nandy, D.; Napoletano, G.; Nuevo, F.;
Pagano, P.; Pinto, R.; Plainaki, C.; Reale, F.; Romoli, M.; Rodriguez,
L.; Slemer, A.; Spadaro, D.; Susino, R.; Stangalini, M.; Vainio,
R. O.; Valori, G.; Vásquez, A. M.; West, M. J.
2020AGUFMSH0360027B Altcode:
Despite the current availability of multi-spacecraft observations of
Coronal Mass Ejections (CMEs) and their interplanetary counterpart
(ICMEs), at present we still don't understand which physical phenomena
are driving their expansion and propagation phases. This also limits
our understanding on how CMEs (observed with remote sensing data)
become ICMEs (observed in situ), how they interact with the background
solar wind, and how their final geo-effectiveness can be modified
during their interplanetary evolution. Such problems match some of
the scientific objectives of the Solar Orbiter Science Activity Plan
and of the Metis coronagraph. Thanks to its multi-channel capability,
Metis (acquiring images in the visible light and at the same time in
the UV HI Lyman-alpha emission) will really provide an unprecedented
view of CMEs and in particular of their thermodynamic evolution. At
closest approaches to the Sun (in the nominal mission), Metis will
acquire high spatial resolution and/or temporal cadence multi-channel
images of CMEs. Farther from the Sun, Metis will shed light on the
early Interplanetary propagation of CMEs. Later on (in the extended
mission) Metis will observe for the first time the CME/ICME propagation
out-of-ecliptic. These novelties will be combined with the unique
vantage point that will be offered by the Solar Orbiter spacecraft,
and supported with valuable data acquired by other on-board remote
sensing (e.g. SPICE, EUI, SoloHI) and in situ (e.g. EPD, MAG,
SWA, RPW) instruments. In this contribution we present the ongoing
activities of the Metis Topical Team on "CME/ICME propagation", (<A
href="http://metis.oato.inaf.it/topical_teams.html">http://metis.oato.inaf.it/topical_teams.html</A>),
an international working group recently established and gathering
scientists from different countries, experts of both in-situ and remote
sensing observations, as well as numerical simulations, and we summarize
the main science objectives discussed during the last months.

---------------------------------------------------------
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. 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. 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. 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: 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. 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. 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. 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. 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: 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.

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Title: Metis: the Solar Orbiter visible light and ultraviolet
coronal imager
Authors: Antonucci, Ester; Romoli, Marco; Andretta, Vincenzo; Fineschi,
Silvano; Heinzel, Petr; Moses, J. Daniel; Naletto, Giampiero; Nicolini,
Gianalfredo; Spadaro, Daniele; Teriaca, Luca; Berlicki, Arkadiusz;
Capobianco, Gerardo; Crescenzio, Giuseppe; Da Deppo, Vania; Focardi,
Mauro; Frassetto, Fabio; Heerlein, Klaus; Landini, Federico; Magli,
Enrico; Marco Malvezzi, Andrea; Massone, Giuseppe; Melich, Radek;
Nicolosi, Piergiorgio; Noci, Giancarlo; Pancrazzi, Maurizio; Pelizzo,
Maria G.; Poletto, Luca; Sasso, Clementina; Schühle, Udo; Solanki,
Sami K.; Strachan, Leonard; Susino, Roberto; Tondello, Giuseppe;
Uslenghi, Michela; Woch, Joachim; Abbo, Lucia; Bemporad, Alessandro;
Casti, Marta; Dolei, Sergio; Grimani, Catia; Messerotti, Mauro;
Ricci, Marco; Straus, Thomas; Telloni, Daniele; Zuppella, Paola;
Auchère, Frederic; Bruno, Roberto; Ciaravella, Angela; Corso,
Alain J.; Alvarez Copano, Miguel; Aznar Cuadrado, Regina; D'Amicis,
Raffaella; Enge, Reiner; Gravina, Alessio; Jejčič, Sonja; Lamy,
Philippe; Lanzafame, Alessandro; Meierdierks, Thimo; Papagiannaki,
Ioanna; Peter, Hardi; Fernandez Rico, German; Giday Sertsu, Mewael;
Staub, Jan; Tsinganos, Kanaris; Velli, Marco; Ventura, Rita; Verroi,
Enrico; Vial, Jean-Claude; Vives, Sebastien; Volpicelli, Antonio;
Werner, Stephan; Zerr, Andreas; Negri, Barbara; Castronuovo, Marco;
Gabrielli, Alessandro; Bertacin, Roberto; Carpentiero, Rita; Natalucci,
Silvia; Marliani, Filippo; Cesa, Marco; Laget, Philippe; Morea, Danilo;
Pieraccini, Stefano; Radaelli, Paolo; Sandri, Paolo; Sarra, Paolo;
Cesare, Stefano; Del Forno, Felice; Massa, Ernesto; Montabone, Mauro;
Mottini, Sergio; Quattropani, Daniele; Schillaci, Tiziano; Boccardo,
Roberto; Brando, Rosario; Pandi, Arianna; Baietto, Cristian; Bertone,
Riccardo; Alvarez-Herrero, Alberto; García Parejo, Pilar; Cebollero,
María; Amoruso, Mauro; Centonze, Vito
2020A&A...642A..10A Altcode: 2019arXiv191108462A
 Aims: Metis is the first solar coronagraph designed for a
space mission and is capable of performing simultaneous imaging of the
off-limb solar corona in both visible and UV light. The observations
obtained with Metis aboard the Solar Orbiter ESA-NASA observatory
will enable us to diagnose, with unprecedented temporal coverage and
spatial resolution, the structures and dynamics of the full corona
in a square field of view (FoV) of ±2.9° in width, with an inner
circular FoV at 1.6°, thus spanning the solar atmosphere from 1.7
R⊙ to about 9 R⊙, owing to the eccentricity
of the spacecraft orbit. Due to the uniqueness of the Solar Orbiter
mission profile, Metis will be able to observe the solar corona
from a close (0.28 AU, at the closest perihelion) vantage point,
achieving increasing out-of-ecliptic views with the increase of the
orbit inclination over time. Moreover, observations near perihelion,
during the phase of lower rotational velocity of the solar surface
relative to the spacecraft, allow longer-term studies of the off-limb
coronal features, thus finally disentangling their intrinsic evolution
from effects due to solar rotation. Methods: Thanks to a novel
occultation design and a combination of a UV interference coating of
the mirrors and a spectral bandpass filter, Metis images the solar
corona simultaneously in the visible light band, between 580 and 640
nm, and in the UV H I Lyman-α line at 121.6 nm. The visible light
channel also includes a broadband polarimeter able to observe the
linearly polarised component of the K corona. The coronal images in
both the UV H I Lyman-α and polarised visible light are obtained at
high spatial resolution with a spatial scale down to about 2000 km
and 15 000 km at perihelion, in the cases of the visible and UV light,
respectively. A temporal resolution down to 1 s can be achieved when
observing coronal fluctuations in visible light. Results: The
Metis measurements, obtained from different latitudes, will allow for
complete characterisation of the main physical parameters and dynamics
of the electron and neutral hydrogen/proton plasma components of the
corona in the region where the solar wind undergoes the acceleration
process and where the onset and initial propagation of coronal mass
ejections (CMEs) take place. The near-Sun multi-wavelength coronal
imaging performed with Metis, combined with the unique opportunities
offered by the Solar Orbiter mission, can effectively address crucial
issues of solar physics such as: the origin and heating/acceleration
of the fast and slow solar wind streams; the origin, acceleration,
and transport of the solar energetic particles; and the transient
ejection of coronal mass and its evolution in the inner heliosphere,
thus significantly improving our understanding of the region connecting
the Sun to the heliosphere and of the processes generating and driving
the solar wind and coronal mass ejections. Conclusions: This
paper presents the scientific objectives and requirements, the overall
optical design of the Metis instrument, the thermo-mechanical design,
and the processing and power unit; reports on the results of the
campaigns dedicated to integration, alignment, and tests, and to
the characterisation of the instrument performance; describes the
operation concept, data handling, and software tools; and, finally,
the diagnostic techniques to be applied to the data, as well as a brief
description of the expected scientific products. The performance of the
instrument measured during calibrations ensures that the scientific
objectives of Metis can be pursued with success. Metis website:
<A href="http://metis.oato.inaf.it">http://metis.oato.inaf.it</A>

---------------------------------------------------------
Title: Optical design of the multi-wavelength imaging coronagraph
Metis for the solar orbiter mission
Authors: Fineschi, S.; Naletto, G.; Romoli, M.; Da Deppo, V.;
Antonucci, E.; Moses, D.; Malvezzi, A. M.; Nicolini, G.; Spadaro,
D.; Teriaca, L.; Andretta, V.; Capobianco, G.; Crescenzio, G.;
Focardi, M.; Frassetto, F.; Landini, F.; Massone, G.; Melich, R.;
Nicolosi, P.; Pancrazzi, M.; Pelizzo, M. G.; Poletto, L.; Schühle,
U.; Uslenghi, M.; Vives, S.; Solanki, S. K.; Heinzel, P.; Berlicki,
A.; Cesare, S.; Morea, D.; Mottini, S.; Sandri, P.; Alvarez-Herrero,
A.; Castronuovo, M.
2020ExA....49..239F Altcode: 2020ExA...tmp...14F
This paper describes the innovative optical design of the Metis
coronagraph for the Solar Orbiter ESA-NASA mission. Metis is a
multi-wavelength, externally occulted telescope for the imaging
of the solar corona in both the visible and ultraviolet wavelength
ranges. Metis adopts a novel occultation scheme for the solar disk,
that we named "inverse external occulter", for reducing the extremely
high thermal load on the instrument at the spacecraft perihelion. The
core of the Metis optical design is an aplanatic Gregorian telescope
common to both the visible and ultraviolet channels. A suitable
dichroic beam-splitter, optimized for transmitting a narrow-band in
the ultraviolet (121.6 nm, HI Lyman-α) and reflecting a broadband
in the visible (580-640 nm) spectral range, is used to separate the
two optical paths. Along the visible light optical path, a liquid
crystal electro-optical modulator, used for the first time in space,
allows making polarimetric measurements.

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Title: Solar physics in the 2020s: DKIST, parker solar probe, and
solar orbiter as a multi-messenger constellation
Authors: Martinez Pillet, V.; Tritschler, A.; Harra, L.; Andretta, V.;
Vourlidas, A.; Raouafi, N.; Alterman, B. L.; Bellot Rubio, L.; Cauzzi,
G.; Cranmer, S. R.; Gibson, S.; Habbal, S.; Ko, Y. K.; Lepri, S. T.;
Linker, J.; Malaspina, D. M.; Matthews, S.; Parenti, S.; Petrie, G.;
Spadaro, D.; Ugarte-Urra, I.; Warren, H.; Winslow, R.
2020arXiv200408632M Altcode:
The National Science Foundation (NSF) Daniel K. Inouye Solar Telescope
(DKIST) is about to start operations at the summit of Haleakala
(Hawaii). DKIST will join the early science phases of the NASA
and ESA Parker Solar Probe and Solar Orbiter encounter missions. By
combining in-situ measurements of the near-sun plasma environment and
detail remote observations of multiple layers of the Sun, the three
observatories form an unprecedented multi-messenger constellation to
study the magnetic connectivity inside the solar system. This white
paper outlines the synergistic science that this multi-messenger
suite enables.

---------------------------------------------------------
Title: Metis: the Solar Orbiter Visible Light and Ultraviolet Coronal
Imager Scientific Objectives
Authors: Spadaro, D.
2019AGUFMSH24A..09S Altcode:
The Metis coronagraph onboard Solar Orbiter (Antonucci et al. 2019) will
image the full off-limb corona, with the purpose of tracing its dynamics
and evolution on a global-scale and at high temporal resolution. It will
acquire for the first time simultaneous images of the full off-limb
corona and inner heliosphere in broadband (580 - 640 nm) polarized
visible light (VL) and narrow-band (121.6 ± 10 nm) ultraviolet (UV)
H I Lyman-α line, with unprecedented temporal coverage and spatial
resolution. For instance, a spatial scale of about 2000 km is achieved
in visible light when the spacecraft is at the closest perihelion at
0.28 AU. The field of view (FoV) of the coronagraph spans over a wide
range of heliocentric distances owing to the eccentric orbit of the
spacecraft, thus permitting the study of the solar atmosphere from
1.7 to about 9 solar radii, during the nominal observation windows
along the orbit. Metis measurements allow a complete characterization
of the main properties and dynamics of the most important constituents
of the coronal and solar wind plasma, i.e., electrons and protons. For
instance, during the Remote Sensing Windows they will provide coronal
maps of the solar wind outflow velocity in a continuous way, also
giving the longitudinal distribution of the wind velocity in the
out-of-ecliptic phases. The Metis instrument versatility combined
with the characteristics of the Solar Orbiter mission, addresses all
the four key scientific questions of Solar Orbiter mission, by providing
unique contributions to investigating the following scientific issues:
Energy deposition and outflows in the expanding corona. Role of magnetic
field lines in channeling the coronal wind. Coronal fluctuations and
their role in the solar wind acceleration. Coronal mass ejection onset
and early propagation. Eruption of prominences and their propagation
in the corona. Global evolution of the streamer belt. Acceleration of
the solar energetic particles. Solar Orbiter remote sensing and
in situ instruments, as well as observations obtained by simultaneous
heliophysics space missions, will complement the Metis observations
and facilitate our understanding of the scientific questions being
addressed.

---------------------------------------------------------
Title: Comparing extrapolations of the coronal magnetic field
structure at 2.5 R⊙ with multi-viewpoint coronagraphic
observations
Authors: Sasso, C.; Pinto, R. F.; Andretta, V.; Howard, R. A.;
Vourlidas, A.; Bemporad, A.; Dolei, S.; Spadaro, D.; Susino, R.;
Antonucci, E.; Abbo, L.; Da Deppo, V.; Fineschi, S.; Frassetto, F.;
Landini, F.; Naletto, G.; Nicolini, G.; Nicolosi, P.; Pancrazzi, M.;
Romoli, M.; Telloni, D.; Ventura, R.
2019A&A...627A...9S Altcode: 2019arXiv190509005S
The magnetic field shapes the structure of the solar corona, but we
still know little about the interrelationships between the coronal
magnetic field configurations and the resulting quasi-stationary
structures observed in coronagraphic images (such as streamers,
plumes, and coronal holes). One way to obtain information on the
large-scale structure of the coronal magnetic field is to extrapolate
it from photospheric data and compare the results with coronagraphic
images. Our aim is to verify whether this comparison can be a fast
method to systematically determine the reliability of the many methods
that are available for modeling the coronal magnetic field. Coronal
fields are usually extrapolated from photospheric measurements that
are typically obtained in a region close to the central meridian on
the solar disk and are then compared with coronagraphic images at the
limbs, acquired at least seven days before or after to account for solar
rotation. This implicitly assumes that no significant changes occurred
in the corona during that period. In this work, we combine images from
three coronagraphs (SOHO/LASCO-C2 and the two STEREO/SECCHI-COR1) that
observe the Sun from different viewing angles to build Carrington maps
that cover the entire corona to reduce the effect of temporal evolution
to about five days. We then compare the position of the observed
streamers in these Carrington maps with that of the neutral lines
obtained from four different magnetic field extrapolations to evaluate
the performances of the latter in the solar corona. Our results show
that the location of coronal streamers can provide important indications
to distinguish between different magnetic field extrapolations.

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Title: OPSys: optical payload systems facility for space
instrumentation integration and calibration
Authors: Capobianco, Gerardo; Fineschi, Silvano; Massone, Giuseppe;
Landini, Federico; Casti, Marta; Bellomo, Alessandro; Deffacis,
Maurizio; Romoli, Marco; Antonucci, Ester; Andretta, Vincenzo; Naletto,
Giampiero; Nicolini, Gianalfredo; Spadaro, Daniele
2019SPIE11180E..7MC Altcode:
The Optical Payload System (OPSys) is an INAF (italian National
Institute for Astrophysics) facility hosted by Aerospace Logistics
Technology Engineering Company (ALTEC SpA) in Turin, Italy. The facility
is composed by three clean rooms having different cleanliness levels,
a thermo-vacuum chamber (SPOCC, Space Optics calibration Chamber)
with a motorized optical bench and several light sources covering the
range from the extreme ultraviolet to the red light wavelengths. The
SPOCC has been designed having in mind the very stringent requirements
of the calibration of solar coronagraphs and the suppression of
the stray-light. The facility and the optical performances will be
described here. The calibration campaign performed on Metis space
coronagraph will be reported as a case study.

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Title: Optical performance of the Metis coronagraph on the Solar
Orbiter ESA mission
Authors: Frassetto, Fabio; Da Deppo, Vania; Zuppella, Paola; Romoli,
Marco; Fineschi, Silvano; Antonucci, Ester; Nicolini, Giana; Naletto,
Giampiero; Nicolosi, Piergiorgio; Spadaro, Daniele; Andretta, Vincenzo;
Castronuovo, Marco; Casti, Marta; Capobianco, Gerardo; Massone,
Giuseppe; Susino, Roberto; Landini, Federico; Pancrazzi, Maurizio;
Teriaca, Luca; Schühle, Udo; Heerlein, Klaus; Uslenghi, Michela
2019SPIE11180E..6YF Altcode:
The Metis coronagraph aboard the Solar Orbiter ESA spacecraft is
expected to provide new insights into the solar dynamics. In detail,
it is designed to address three main questions: the energy deposition
mechanism at the poles (where the fast wind is originated), the
source of the slow wind at lower altitude, and how the global corona
evolves, in particular in relation to the huge plasma ejections that
occasionally are produced. To obtain the required optical performance,
not only the Metis optical design has been highly optimized, but the
alignment procedure has also been subjected to an accurate evaluation
in order to fulfill the integration specifications. The telescope
assembling sequence has been constructed considering all the subsystems
manufacturing, alignment and integration tolerances. The performance
verification activity is an important milestone in the instrument
characterization and the obtained results will assure the fulfillment
of the science requirements for its operation in space. The entire
alignment and verification phase has been performed by the Metis team in
collaboration with Thales Alenia Space Torino and took place in ALTEC
(Turin) at the Optical Payload System Facility using the Space Optics
Calibration Chamber infrastructure, a vacuum chamber especially built
and tested for the alignment and calibration of the Metis coronagraph,
and suitable for tests of future payloads. The goal of the alignment,
integration, verification and calibration processes is to measure
the parameters of the telescope, and the characteristics of the two
Metis channels: visible and ultraviolet. They work in parallel thanks
to the peculiar optical layout. The focusing and alignment performance
of the two channels must be well understood, and the results need to be
easily compared to the requirements. For this, a dedicated illumination
method, with both channels fed by the same source, has been developed;
and a procedure to perform a simultaneous through focus analysis has
been adopted. In this paper the final optical performance achieved by
Metis is reported and commented.

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Title: Alignment procedure for the Gregorian telescope of the Metis
coronagraph for the Solar Orbiter ESA mission
Authors: Da Deppo, Vania; Mottini, Sergio; Naletto, Giampiero;
Frassetto, Fabio; Zuppella, Paola; Sertsu, Mewael G.; Romoli, Marco;
Fineschi, Silvano; Antonucci, Ester; Nicolini, Gianalfredo; Nicolosi,
Piergiorgio; Spadaro, Daniele; Andretta, Vincenzo; Castronuovo, Marco;
Casti, Marta; Capobianco, Gerardo; Massone, Giuseppe; Susino, Roberto;
Landini, Federico; Pancrazzi, Maurizio; Casini, Chiara; Teriaca,
Luca; Uslenghi, Michela
2019SPIE11180E..76D Altcode:
Metis is a solar coronagraph mounted on-board the Solar Orbiter ESA
spacecraft. Solar Orbiter is scheduled for launch in February 2020
and it is dedicated to study the solar and heliospheric physics from a
privileged close and inclined orbit around the Sun. Perihelion passages
with a minimum distance of 0.28 AU are foreseen. Metis features two
channels to image the solar corona in two different spectral bands:
in the HI Lyman at 121.6 nm, and in the polarized visible light band
(580 - 640 nm). Metis is a solar coronagraph adopting an "inverted
occulted" configuration. The inverted external occulter (IEO) is a
circular aperture followed by a spherical mirror which back rejects
the disk light. The reflected disk light exits the instrument through
the IEO aperture itself, while the passing coronal light is collected
by the Metis telescope. Common to both channels, the Gregorian on-axis
telescope is centrally occulted and both the primary and the secondary
mirror have annular shape. Classic alignment methods adopted for on-axis
telescope cannot be used, since the on-axis field is not available. A
novel and ad hoc alignment set-up has been developed for the telescope
alignment. An auxiliary visible optical ground support equipment source
has been conceived for the telescope alignment. It is made up by four
collimated beams inclined and dimensioned to illuminate different
sections of the annular primary mirror without being vignetted by
other optical or mechanical elements of the instrument.

---------------------------------------------------------
Title: Metis/Solar Orbiter polarimetric visible light channel
calibration
Authors: Casti, M.; Fineschi, S.; Capobianco, G.; Romoli, M.;
Antonucci, E.; Nicolini, G.; Naletto, G.; Nicolosi, P.; Spadaro, D.;
Andretta, V.; Castronuovo, M.; Massone, G.; Susino, R.; Da Deppo, V.;
Frassetto, F.; Landini, F.; Pancrazzi, M.; Teriaca, L.; Uslenghi, M.
2019SPIE11180E..3CC Altcode:
Metis is the solar coronagraph of the ESA mission Solar Orbiter. For
the first time, Metis will acquire simultaneous images of the solar
corona in linearly polarized, broadband visible light (580-640 nm) and
in the narrow-band HI Ly-α line (121.6 nm). The visible light path
includes a polarimeter, designed to observe and analyse the K-corona
linearly polarized by Thomson scattering. The polarimeter comprises a
liquid crystal Polarization Modulation Package (PMP) together with a
quarter-wave retarder and a linear polarizer. The Metis PMP consists of
two Anti-Parallel Nematic Liquid Crystal Variable Retarders (LCVRs) with
their fast axis parallel with respect to each other and a pre-tilted
angle of the molecules in opposite direction. This configuration results
in an instrumental wide field of view (+/-7°). The LCVRs provide an
electro-optical modulation of the input polarized light by applying an
electric field to the liquid crystal molecules inside the cells. A given
optical retardance can be induced in the LCVRs by selecting a suitable
voltage value. This paper reports the polarimetric characterization of
the Visible-light channel for the Metis/Solar Orbiter coronagraph. The
retardance-to-voltage calibration of the electro-optical polarimeter was
characterized over the entire field of view of the coronagraph yielding
a complete "polarimetric flat-field" of the Metis Visible-light channel.

---------------------------------------------------------
Title: Stray light calibration for the Solar Orbiter/Metis solar
coronagraph
Authors: Landini, F.; Romoli, M.; Fineschi, S.; Casini, C.; Baccani,
C.; Antonucci, E.; Nicolini, G.; Naletto, G.; Nicolosi, P.; Spadaro,
D.; Andretta, V.; Castronuovo, M.; Casti, M.; Capobianco, G.; Massone,
G.; Susino, R.; Da Deppo, V.; Frassetto, F.; Pancrazzi, M.; Teriaca,
L.; Schuehle, U.; Heerlein, K.; Uslenghi, M.
2019SPIE11180E..2IL Altcode:
The Solar Orbiter/Metis visible and UV solar coronagraph redefines
the concept of external occultation in solar coronagraphy. Classical
externally occulted coronagraphs are characterized by an occulter in
front of the telescope entrance aperture. Solar Orbiter will approach
the Sun down to 0.28 AU: in order to reduce the thermal load, the
Metis design switches the positions of the entrance aperture and the
external occulter thus achieving what is called the inverted external
occultation. The inverted external occulter (IEO) consists of a circular
aperture on the Solar Orbiter thermal shield that acts as coronagraph
entrance pupil. A spherical mirror, located 800 mm behind the IEO, back
rejects the disklight through the IEO itself. To pursue the goal of
maximizing the reduction of the stray light level on the focal plane,
an optimization of the IEO shape was implemented. The stray light
calibration was performed in a clean environment in front of the OPSys
solar disk divergence simulator (at ALTEC, in Torino, Italy), which is
able to emulate different heliocentric distances. Ground calibrations
were a unique opportunity to map the Metis stray light level thanks to
a pure solar disk simulator without the solar corona. The stray light
calibration was limited to the visible light case, being the most
stringent. This work is focused on the description of the laboratory
facility that was used to perform the stray light calibration and on
the calibration results.

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Title: Effect of the non-uniform solar chromospheric Lyα radiation
on determining the coronal H I outflow velocity
Authors: Dolei, S.; Spadaro, D.; Ventura, R.; Bemporad, A.; Andretta,
V.; Sasso, C.; Susino, R.; Antonucci, E.; Da Deppo, V.; Fineschi,
S.; Frassetto, F.; Landini, F.; Naletto, G.; Nicolini, G.; Pancrazzi,
M.; Romoli, M.
2019A&A...627A..18D Altcode:
We derived maps of the solar wind outflow velocity of coronal
neutral hydrogen atoms at solar minimum in the altitude range
1.5-4.0 R⊙. We applied the Doppler dimming technique to
coronagraphic observations in the UV H I Lyα line at 121.6 nm. The
technique exploits the intensity reduction in the coronal line with
increasing velocities of the outflowing plasma to determine the
solar wind velocity by iterative modelling. The Lyα line intensity
is sensitive to the wind outflow velocity and also depends on the
physical properties of coronal particles and underlying chromospheric
emission. Measurements of irradiance by the chromospheric Lyα
radiation in the corona are required for a rigorous application of
the Doppler dimming technique, but they are not provided by past
and current instrumentations. A correlation function between the H
I 121.6 nm and He II 30.4 nm line intensities was used to construct
Carrington rotation maps of the non-uniform solar chromospheric Lyα
radiation and thus to compute the Lyα line irradiance throughout
the outer corona. Approximations concerning the temperature of
the scattering H I atoms and exciting solar disc radiation were
also adopted to significantly reduce the computational time and
obtain a faster procedure for a quick-look data analysis of future
coronagraphic observations. The effect of the chromospheric Lyα
brightness distribution on the resulting H I outflow velocities
was quantified. In particular, we found that the usual uniform-disc
approximation systematically leads to an overestimated velocity in
the polar and mid-latitude coronal regions up to a maximum of about
50-60 km s-1 closer to the Sun. This difference decreases at
higher altitudes, where an increasingly larger chromospheric portion,
including both brighter and darker disc features, contributes to
illuminate the solar corona, and the non-uniform radiation condition
progressively approaches the uniform-disc approximation.

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Title: Wide field of view liquid crystals-based modulator for the
polarimeter of the Metis/Solar Orbiter
Authors: Capobianco, Gerardo; Casti, Marta; Fineschi, Silvano;
Massone, Giuseppe; Sertsu, Mewael G.; Landini, Federico; Romoli,
Marco; Antonucci, Ester; Andretta, Vincenzo; Naletto, Giampiero;
Nicolini, Gianalfredo; Spadaro, Daniele; Alvarez Herrero, Alberto;
Garcia Parejo, Pilar; Marmonti, Matteo
2018SPIE10698E..30C Altcode:
Metis is an inverted occulted coronagraph on-board the ESA/Solar
Orbiter mission. The visible light path of the instrument will observe
the "white" light (580-640 nm) linearly-polarized emission from the
solar corona. The coronal polarized brightness allows retrieval of
physical parameters such as the electron density and temperature of
the K-corona. The Metis polarimeter comprises a quarter-wave retarder,
the liquid crystal polarization modulation package (PMP) and a linear
polarizer working as polarization analyser. The PMP consists of two
Anti-Parallel Nematic Liquid Crystal Variable Retarders (LCVRs) with
the fast axes parallels one to each other and a pre-tilted angle of the
molecules in opposite direction, in order to maximize the homogeneity of
the retardance across instrumental wide field of view: +/-7 deg. This
presentation reports the characterization of the PMP breadboard
(BB), fully representative of the optical/polarimetric performances
of the flight model. This characterization consisted in determining
the performances of the device in terms of retardance as function of
the applied voltage at different temperatures, angle of incidence and
the variation of the retardance as a function of the wavelength. The
calibrations were performed by measuring the complete Mueller matrix
of the PMP-BB. The experimental results have been compared with the
parameters of the theoretical model (e.g., depolarization, effective
retardance, cells misalignment).

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Title: Calibration of the liquid crystal visible-light polarimeter
for the Metis/Solar Orbiter coronagraph
Authors: Casti, M.; Fineschi, S.; Capobianco, G.; Landini, F.; Romoli,
M.; Antonucci, E.; Andretta, V.; Naletto, G.; Nicolini, G.; Spadaro,
D.; Alvarez-Herrero, A.; Garcia-Parejo, P.; Marmonti, M.
2018SPIE10698E..31C Altcode:
Metis is the solar coronagraph selected for the payload of the ESA
Solar Orbiter mission. Metis will acquire simultaneous imaging in
linearly polarized, broadband visible light (580-640 nm) and in the
narrow-band HI Ly-α line (121.6 nm). The METIS visible light path
includes a polarimeter, designed to observe and analyse the K-corona
linearly polarized by Thomson scattering. The polarimeter comprises a
liquid crystal Polarization Modulation Package (PMP) together with a
quarter-wave retarder and a linear polarizer. The Metis PMP consists of
two Anti-Parallel Nematic Liquid Crystal Variable Retarders (LCVRs) with
their fast axis parallel with respect to each other and a pre-tilted
angle of the molecules in opposite direction. The LCVRs provide an
electro-optical modulation of the input polarized light by applying
an electric field to the liquid crystal molecules inside the cells. A
given optical retardance can be induced in the LCVRs by selecting a
suitable voltage value. This presentation will report the polarimetric
characterization of the Flight Model of the Metis polarimeter and the
voltage-to-retardance calibration.

---------------------------------------------------------
Title: Mapping the solar wind HI outflow velocity in the inner
heliosphere by coronagraphic ultraviolet and visible-light
observations
Authors: Dolei, S.; Susino, R.; Sasso, C.; Bemporad, A.; Andretta,
V.; Spadaro, D.; Ventura, R.; Antonucci, E.; Abbo, L.; Da Deppo, V.;
Fineschi, S.; Focardi, M.; Frassetto, F.; Giordano, S.; Landini, F.;
Naletto, G.; Nicolini, G.; Nicolosi, P.; Pancrazzi, M.; Romoli, M.;
Telloni, D.
2018A&A...612A..84D Altcode:
We investigated the capability of mapping the solar wind outflow
velocity of neutral hydrogen atoms by using synergistic visible-light
and ultraviolet observations. We used polarised brightness images
acquired by the LASCO/SOHO and Mk3/MLSO coronagraphs, and synoptic Lyα
line observations of the UVCS/SOHO spectrometer to obtain daily maps
of solar wind H I outflow velocity between 1.5 and 4.0 R⊙
on the SOHO plane of the sky during a complete solar rotation (from
1997 June 1 to 1997 June 28). The 28-days data sequence allows us to
construct coronal off-limb Carrington maps of the resulting velocities
at different heliocentric distances to investigate the space and time
evolution of the outflowing solar plasma. In addition, we performed
a parameter space exploration in order to study the dependence of the
derived outflow velocities on the physical quantities characterising
the Lyα emitting process in the corona. Our results are important
in anticipation of the future science with the Metis instrument,
selected to be part of the Solar Orbiter scientific payload. It was
conceived to carry out near-sun coronagraphy, performing for the first
time simultaneous imaging in polarised visible-light and ultraviolet
H I Lyα line, so providing an unprecedented view of the solar wind
acceleration region in the inner corona. The movie (see Sect. 4.2)
is available at https://www.aanda.org

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Title: The optimization of the inverted occulter of the solar
orbiter/METIS coronagraph/spectrometer
Authors: Landini, F.; Vives, S.; Romoli, M.; Guillon, C.; Pancrazzi,
M.; Escolle, C.; Focardi, M.; Fineschi, S.; Antonucci, E.; Nicolini,
G.; Naletto, G.; Nicolosi, P.; Spadaro, D.
2017SPIE10564E..0FL Altcode:
The coronagraph/spectrometer METIS (Multi Element Telescope for Imaging
and Spectroscopy), selected to fly aboard the Solar Orbiter ESA/NASA
mission, is conceived to perform imaging (in visible, UV and EUV)
and spectroscopy (in EUV) of the solar corona. It is an integrated
instrument suite located on a single optical bench and sharing a
unique aperture on the satellite heat shield. As every coronagraph,
METIS is highly demanding in terms of stray light suppression. In
order to meet the strict thermal requirements of Solar Orbiter, METIS
optical design has been optimized by moving the entrance pupil at the
level of the external occulter on the S/C thermal shield, thus reducing
the size of the external aperture. The scheme is based on an inverted
external-occulter (IEO). The IEO consists of a circular aperture on
the Solar Orbiter thermal shield. A spherical mirror rejects back the
disk-light through the IEO. The experience built on all the previous
space coronagraphs forces designers to dedicate a particular attention
to the occulter optimization. Two breadboards were manufactured to
perform occulter optimization measurements: BOA (Breadboard of the
Occulting Assembly) and ANACONDA (AN Alternative COnfiguration for the
Occulting Native Design Assembly). A preliminary measurement campaign
has been carried on at the Laboratoire d'Astrophysique de Marseille. In
this paper we describe BOA and ANACONDA designs, the laboratory set-up
and the preliminary results.

---------------------------------------------------------
Title: Evaluation of the stray light from the diffraction of METIS
coronagraph external occulter
Authors: Romoli, M.; Landini, F.; Moses, D.; Fineschi, S.; Pancrazzi,
M.; Focardi, M.; Antonucci, E.; Nicolini, G.; Naletto, G.; Nicolosi,
P.; Spadaro, D.
2017SPIE10564E..37R Altcode:
METIS (Multi Element Telescope for Imaging and Spectroscopy) is an
externally occulted coronagraph part of the Solar Orbiter payload. METIS
innovative occulting system, called inverted externally occulter (IEO),
consists of a circular aperture, IEO, that acts also as the entrance
pupil of the instrument, and a solar disk rejection mirror (M0),
placed at the bottom end of the coronagraph boom. M0 reflects back
through IEO the solar disk radiation, letting the coronal radiation
enter the coronagraph telescope. Light diffracted by IEO enters the
telescope and has to be minimized with a proper shape of the IEO
edge. The paper describes the theoretical results of the diffraction
analysis extended to the scattered light by the primary mirror of the
telescope onto the primary focal plane. A summary of the entire stray
light reduction capabilities of METIS is also given.

---------------------------------------------------------
Title: Internal checkup illumination sources for METIS coronagraph
on solar orbiter
Authors: Frassetto, F.; Poletto, L.; Fineschi, S.; De Santi, C.;
Meneghini, M.; Meneghesso, G.; Antonucci, E.; Naletto, G.; Romoli,
M.; Spadaro, D.; Nicolini, G.
2017SPIE10563E..5JF Altcode:
METIS is one of the remote sensing instrument on the Solar Orbiter
mission. It will acquire coronal images from distances from the Sun
as close as 0.28 AU. The mission innovations rely not only in the
spacecraft orbit; METIS introduces many technical breakthroughs in the
optical layout and in many other areas, mainly the inverted external
occulter and the visible light (VL) polarimeter.

---------------------------------------------------------
Title: METIS, the Multi Element Telescope for Imaging and
Spectroscopy: an instrument proposed for the solar orbiter mission
Authors: Antonucci, E.; Andretta, V.; Cesare, S.; Ciaravella, A.;
Doschek, G.; Fineschi, S.; Giordano, S.; Lamy, P.; Moses, D.; Naletto,
G.; Newmark, J.; Poletto, L.; Romoli, M.; Solanki, S.; Spadaro, D.;
Teriaca, L.; Zangrilli, L.
2017SPIE10566E..0LA Altcode:
METIS, the Multi Element Telescope for Imaging and Spectroscopy,
is an instrument proposed to the European Space Agency to be part of
the payload of the Solar Orbiter mission. The instrument design has
been conceived for performing extreme ultraviolet (EUV) spectroscopy
both on the solar disk and off-limb, and near-Sun coronagraphy
and spectroscopy. The proposed instrument suite consists of three
different interconnected elements, COR, EUS and SOCS, sharing the
same optical bench, electronics, and S/C heat shield aperture. COR is
a visible-EUV multiband coronagraph based on a classical externally
occulted design. EUS is the component of the METIS EUV disk spectrometer
which includes the telescope and all the related mechanisms. Finally,
SOCS is the METIS spectroscopic component including the dispersive
system and the detectors. The capability of inserting a small telescope
collecting coronal light has been added to perform also EUV coronal
spectroscopy. METIS can simultaneously image the visible and ultraviolet
emission of the solar corona and diagnose, with unprecedented temporal
coverage and space resolution the structure and dynamics of the full
corona in the range from 1.2 to 3.0 (1.6 to 4.1) solar radii (R⊙,
measured from Sun centre) at minimum (maximum) perihelion during the
nominal mission. It can also perform spectroscopic observations of the
solar disk and out to 1.4 R⊙ within the 50-150 nm spectral region,
and of the geo-effective coronal region 1.7-2.7 R⊙ within the 30-125
nm spectral band.

---------------------------------------------------------
Title: METIS: the visible and UV coronagraph for solar orbiter
Authors: Romoli, M.; Landini, F.; Antonucci, E.; Andretta, V.;
Berlicki, A.; Fineschi, S.; Moses, J. D.; Naletto, G.; Nicolosi, P.;
Nicolini, G.; Spadaro, D.; Teriaca, L.; Baccani, C.; Focardi, M.;
Pancrazzi, M.; Pucci, S.; Abbo, L.; Bemporad, A.; Capobianco, G.;
Massone, G.; Telloni, D.; Magli, E.; Da Deppo, V.; Frassetto, F.;
Pelizzo, M. G.; Poletto, L.; Uslenghi, M.; Vives, S.; Malvezzi, M.
2017SPIE10563E..1MR Altcode:
METIS coronagraph is designed to observe the solar corona with an
annular field of view from 1.5 to 2.9 degrees in the visible broadband
(580-640 nm) and in the UV HI Lyman-alpha, during the Sun close
approaching and high latitude tilting orbit of Solar Orbiter. The
big challenge for a coronagraph is the stray light rejection. In
this paper after a description of the present METIS optical design,
the stray light rejection design is presented in detail together with
METIS off-pointing strategies throughout the mission. Data shown in this
paper derive from the optimization of the optical design performed with
Zemax ray tracing and from laboratory breadboards of the occultation
system and of the polarimeter.

---------------------------------------------------------
Title: Investigating the behaviour of neutral hydrogen Lyα spectral
line width in polar coronal holes at solar minimum
Authors: Spadaro, D.; Susino, R.; Dolei, S.; Ventura, R.; Antonucci, E.
2017A&A...603A..35S Altcode:
We investigate the behaviour of the H I Lyα spectral line widths
measured by UVCS/SOHO in polar coronal holes at minimum of solar
magnetic activity. The line widths are reported to significantly
increase up to 3 R⊙, while above 3 R⊙
there is observational evidence of either nearly constant or slightly
decreasing values. We adopt empirical models of polar coronal holes at
solar activity minimum reported in the literature and calculate the
characteristic timescales relevant to different processes coupling
neutral hydrogen atoms and protons, which are heated and accelerated
in the outflowing plasma. This analysis leads us to believe that
the progressive decoupling of the two sets of particles below 10
R⊙, caused by the decrease of the plasma density due
to the rapid expansion of the wind, cannot explain the behaviour
of the Lyα line profile observed in polar coronal holes. We also
synthesise the intensity and profile of the Lyα line as a function
of heliocentric distance from the coronal hole models, adopting H
I densities computed in non-equilibrium ionisation with the aim of
satisfactorily reproducing the UVCS Lyα observations reported in the
literature. Our analysis shows that the coronal Lyα emission decreases
with heliocentric distance, down to values below the interplanetary
Lyα emission, owing to the decrease of the plasma density and to
non-equilibrium ionisation effects in the expanding plasma. This
can lead to the predominance of the interplanetary emission, which
is characterised by H I velocity distributions corresponding to
temperatures about one order of magnitude lower than the coronal
temperatures, and to the narrowing of the resulting coronal profile
at higher heliocentric distances. This scenario can be a plausible
explanation for the behaviour of the Lyα line profile with height
observed in polar coronal holes at solar activity minimum.

---------------------------------------------------------
Title: A virtual appliance as proxy pipeline for the Solar
Orbiter/Metis coronagraph
Authors: Pancrazzi, M.; Straus, T.; Andretta, V.; Spadaro, D.; Haugan,
S. V.; de Groof, A.; Carr, R.; Focardi, M.; Nicolini, G.; Landini,
F.; Baccani, C.; Romoli, M.; Antonucci, E.
2016SPIE.9913E..4LP Altcode:
Metis is the coronagraph on board Solar Orbiter, the ESA mission devoted
to the study of the Sun that will be launched in October 2018. Metis is
designed to perform imaging of the solar corona in the UV at 121.6 nm
and in the visible range where it will accomplish polarimetry studies
thanks to a variable retarder plate. Due to mission constraints, the
telemetry downlink on the spacecraft will be limited and data will be
downloaded with delays that could reach, in the worst case, several
months. In order to have a quick overview on the ongoing operations
and to check the safety of the 10 instruments on board, a high-priority
downlink channel has been foreseen to download a restricted amount of
data. These so-called Low Latency Data will be downloaded daily and,
since they could trigger possible actions, they have to be quickly
processed on ground as soon as they are delivered. To do so, a proper
processing pipeline has to be developed by each instrument. This
tool will then be integrated in a single system at the ESA Science
Operation Center that will receive the downloaded data by the Mission
Operation Center. This paper will provide a brief overview of the on
board processing and data produced by Metis and it will describe the
proxy-pipeline currently under development to deal with the Metis
low-latency data.

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Title: Mapping the coronal hydrogen temperature in view of the
forthcoming coronagraph observations by Solar Orbiter
Authors: Dolei, S.; Spadaro, D.; Ventura, R.
2016A&A...592A.137D Altcode:
Context. Synergistic visible light and ultraviolet coronagraphic
observations are essential to investigate the link of the Sun to
the inner heliosphere through the study of the dynamic properties
of the solar wind. Aims: We perform spectroscopic mapping
of the outer solar corona to constitute a statistically significant
database of neutral hydrogen coronal temperatures, which is suitable
for overcoming the lack of spectrometric information in observations
performed by coronagraphs that are solely equipped for visible light and
ultraviolet imaging; these include the forthcoming Metis instrument on
board Solar Orbiter. Methods: We systematically analysed neutral
hydrogen Lyα line data that was obtained by UVCS/SOHO observations
of the extended solar corona relevant to a lot of polar, mid-latitude
and equatorial structures at different phases of solar activity,
and collected far longer than a whole solar cycle (1996-2012). 
Results: We created a database consisting in both the neutral hydrogen
temperature components, which are perpendicular and parallel to the
radially symmetric coronal magnetic field lines, as a function of the
heliocentric distance and polar angle and for different phases of the
solar activity cycle. We validated the reliability of the constituted
neutral hydrogen temperature database, investigating a new set of UVCS
Lyα data with the Doppler dimming technique. The solar wind outflow
velocities obtained by adopting both the neutral hydrogen temperature
distribution directly derived from the observed Lyα profiles and
those taken from our database well agree within the uncertainties.

---------------------------------------------------------
Title: Modelling low-lying, cool solar loops with optically thick
radiative losses
Authors: Sasso, C.; Andretta, V.; Spadaro, D.
2015A&A...583A..54S Altcode: 2015arXiv150805792S
 Aims: We investigate the increase of the differential emission
measure (DEM) towards the chromosphere due to small and cool magnetic
loops (height ≲8 Mm, T ≲ 105 K). In a previous paper,
we analysed the conditions of existence and stability of these loops
through hydrodynamic simulations, focussing on their dependence on the
details of the optically thin radiative loss function. Methods:
In this paper, we extend those hydrodynamic simulations to verify
if this class of loops exists and is stable when using an optically
thick radiative loss function. We study two cases: constant background
heating and a heating depending on the density. The contribution to the
transition region extreme-UV output of these loops is also calculated
and presented. Results: We find that stable, quasi-static cool
loops can be obtained using an optically thick radiative loss function
and a background heating depending on the density. The DEMs of these
loops, however, fail to reproduce the observed DEM for temperatures
between 4.6 &lt; log T &lt; 4.8. We also show the transient phase of
a dynamic loop obtained by considering constant heating rate and find
that its average DEM, interpreted as a set of evolving dynamic loops,
reproduces the observed DEM very well.

---------------------------------------------------------
Title: Stray-light analyses of the METIS coronagraph on Solar Orbiter
Authors: Fineschi, S.; Sandri, P.; Landini, F.; Romoli, M.; DaDeppo,
V.; Frassetto, F.; Verroi, E.; Naletto, G.; Morea, D.; Antonucci,
E.; Spadaro, D.; Andretta, V.
2015SPIE.9604E..0KF Altcode:
The METIS coronagraph on board the Solar Orbiter mission will have the
unique opportunity of observing the solar outer atmosphere as close
to the Sun as 0.28 A.U., and from up to 35° out-of-ecliptic. The
telescope design of the METIS coronagraph includes two optical paths:
i) broad-band imaging of the full corona in linearly polarized
visible-light (VL: 580-640 nm), ii) narrow-band imaging of the full
corona in the ultraviolet (UV) Lyman α (121.6 nm). This paper describes
the stray-light analyses performed on the UV and VL channels of the
METIS Telescope with the nonsequential modality of Zemax OpticStudio. A
detailed opto-mechanical model of the METIS Telescope is simulated
by placing the CAD parts of all the sub-assemblies at the nominal
position. Each surface, mechanical and optical, is provided with a
modelled coating and BSDF reproducing the optical and the diffusing
properties. The geometric model allows for the verification of the
correct functioning of the blocking elements inside the telescope
and for an evaluation of the stray-light level due to surface
roughness. The diffraction off the inner edge of the IEO on the plane
of the IO is modelled separately from the contributor of the surface
micro-roughness. The contributors due to particle contamination and
cosmetic defects are also analysed. The results obtained are merged
together and compared to the requirements of stray-light. The results
of this analysis together with those from two different analyses based
on a Montecarlo ray-trace and a semi-analytical model are consistent
with each other and indicate that the METIS design meets the stray-light
level requirements

---------------------------------------------------------
Title: Visible light and ultraviolet observations of coronal
structures: physical properties of an equatorial streamer and
modelling of the F corona
Authors: Dolei, S.; Spadaro, D.; Ventura, R.
2015A&A...577A..34D Altcode:
The present work studies the characteristics of an equatorial streamer
visible above the east limb of the Sun on March 2008, during the
most recent minimum of solar activity. We analysed the visible light
coronagraphic images of SOHO/LASCO and the ultraviolet observations
in the H I Lyα spectral line obtained by SOHO/UVCS, and exploited
the Doppler dimming effect of the coronal Lyα line to derive the
outflow velocity profile of the scattering neutral hydrogen atoms in
the streamer region. Taking advantage of the synergy between visible
light and ultraviolet observations, we were able to determine all
the properties of the coronal structure. In particular, the actual
extent of the streamer along the line of sight has been evaluated
for the first time. In so doing, the solar wind outflow velocity
turned out to be the only free parameter in the theoretical modelling
of the Lyα intensity. We found nearly static conditions below 3.5
R⊙ along the streamer axis, whereas the solar wind flows
at velocities from 40 km s-1 to 140 km s-1 in
the altitude range 2.5-5.0 R⊙ along the southern boundary
of the streamer. We also derived the intensity distribution of the F
coronal component in the LASCO C2 field of view, by combining total
and polarized brightness data. Finally, we investigated the dependence
of the Lyα resonant scattering process on the kinetic temperature of
the coronal neutral hydrogen atoms and found that the value of this
temperature mostly affects the scattering process at low heliocentric
distances, where the solar wind flows with low velocity.

---------------------------------------------------------
Title: Polarimetric calibrations and astronomical polarimetry in
the V-band with Solar Orbiter/METIS instrument
Authors: Capobianco, Gerardo; Fineschi, Silvano; Focardi, Mauro;
Andretta, Vincenzo; Massone, Giuseppe; Bemporad, Alessandro; Romoli,
Marco; Antonucci, Ester; Naletto, Giampiero; Nicolini, Gianalfredo;
Nicolosi, Piergiorgio; Spadaro, Daniele
2014SPIE.9143E..4VC Altcode:
METIS is one of the remote sensing instruments on board the ESA-
Solar Orbiter mission, that will be launched in July 2017. The Visible
Light Channel (VLC) of the instrument is composed by an achromatic
LC-based polarimeter for the study of the linearly polarized solar
K-corona in the 580-640 nm bandpass. The laboratory calibrations with
spectropolarimetric techniques and the in-flight calibrations of this
channel, using some well knows linearly polarized stars in the FoV
of the instrument with a degree of linear polarization DOLP &gt; 10%
are here discussed. The selection of the stars and the use of other
astronomical targets (i.e. planets, comets,…) and the opportunity
of measurements of the degree of linear polarization in the visible
bandpass of some astronomical objects (i.e. Earth, comets,…) are
also objects of this paper.

---------------------------------------------------------
Title: On-board CME detection algorithm for the Solar Orbiter-METIS
coronagraph
Authors: Bemporad, A.; Andretta, V.; Pancrazzi, M.; Focardi, M.;
Straus, T.; Sasso, C.; Spadaro, D.; Uslenghi, M.; Antonucci, E.;
Fineschi, S.; Abbo, L.; Nicolini, G.; Landini, F.; Romoli, M.; Naletto,
G.; Nicolosi, P.
2014SPIE.9152E..0KB Altcode:
The METIS coronagraph is one of the instruments part of the payload of
the ESA - Solar Orbiter mission to be launched in 2017. The spacecraft
will operate much like a planetary encounter mission, with the main
scientific activity taking place with the remote-sensing instruments
during three 10-days intervals per orbit: optimization of the different
instrument observing modes will be crucial. One of the key scientific
targets of METIS will be the study of transient ejections of mass
through the solar corona (Coronal Mass Ejections - CMEs) and their
heliospheric evolution. METIS will provide for the first time imaging of
CMEs in two different wavelengths: VL (visible light 580- 640 nm) and UV
(Lyman-α line of HI at 121.6 nm). The detection of transient phenomena
shall be managed directly by the METIS Processing and Power Unit (MPPU)
by means of both external triggers ("flags") coming from other Solar
Orbiter instruments, and internal "flags" produced directly by the METIS
on-board software. METIS on-board algorithm for the automatic detection
of CMEs will be based on running differences between consecutive images
re-binned to very low resolution and thresholded for significant changes
over a minimum value. Given the small relative variation of white light
intensity during CMEs, the algorithm will take advantage of VL images
acquired with different polarization angles to maximize the detection
capability: possible false detections should be automatically managed
by the algorithm. The algorithm will be able to provide the CME first
detection time, latitudinal direction of propagation on the plane
of the sky (within 45 degrees), a binary flag indicating whether a
"halo CME" has been detected.

---------------------------------------------------------
Title: Stereoscopic observations of the effects of a halo CME on
the solar coronal structure
Authors: Dolei, S.; Romano, P.; Spadaro, D.; Ventura, R.
2014A&A...567A...9D Altcode:
We investigated the substantial restructuring of the outer solar corona
in the aftermath of the halo CME that occurred on 9 March 2012. To
perform our analysis, we used SOHO/LASCO, STEREO/COR1 and SDO/AIA data,
which provide observations from different viewpoints. In particular, we
applied the polarization ratio technique to the COR1 calibrated images
to derive the three-dimensional structure of the CME and determine
its direction and speed of propagation. We also estimated the CME mass
from a sequence of four observations of the event and obtained values
of up to 2.2 × 1016 g. The COR1 images show a brightness
decrease in the coronal sector where the CME propagates. We verified
that this intensity reduction is due to a plasma depletion. Moreover,
the combined analysis performed by the two STEREO satellites allowed us
to deduce that a preexisting streamer is located along the propagation
direction of the CME and disappears after the passage of the event. The
coronal mass loss associated with the plasma depletion is much lower
than the mass expelled from the Sun in the COR1-B data. Conversely,
the COR1-A obsevations allowed us to infer that the mass of the streamer
carried away from the outer corona corresponds to about half of the CME
mass. The results highlight the importance of stereoscopic observations
in the study of corona restructuring in the aftermath of a CME event. The movie associated with Fig. 3 is available in electronic form at <A
href="http://www.aanda.org/10.1051/0004-6361/201423449/olm">http://www.aanda.org</A>

---------------------------------------------------------
Title: In-flight UV and polarized-VL radiometric calibrations of
the solar orbiter/METIS imaging coronagraph
Authors: Focardi, M.; Capobianco, G.; Andretta, V.; Sasso, C.; Romoli,
M.; Landini, F.; Fineschi, S.; Pancrazzi, M.; Bemporad, A.; Nicolini,
G.; Pucci, S.; Uslenghi, M.; Naletto, G.; Nicolosi, P.; Spadaro, D.;
Teriaca, L.; SchuÌhle, U. H.; Antonucci, E.
2014SPIE.9144E..09F Altcode:
METIS is an innovative inverted occulted solar coronagraph capable of
obtaining for the first time simultaneous imaging of the full corona
in linearly polarized visible-light (580-640 nm) and narrow-band
(+/- 10 nm) ultraviolet H I Ly-α (121.6 nm). It has been selected to
fly aboard the Solar Orbiter1 spacecraft, whose launch is
foreseen in July 2017. Thanks to its own capabilities and exploiting
the peculiar opportunities offered by the Solar Orbiter planned orbit,
METIS will address some of the still open issues in understanding the
physical processes in the corona and inner heliosphere. The Solar
Orbiter Nominal Mission Phase (NMP) will be characterized by three
scientific observing windows per orbit and METIS will perform at least
one in-flight calibration per observing window. The two imaging channels
of METIS will be calibrated on ground and periodically checked, verified
and re-calibrated in-flight. In particular, radiometric calibration
images will be needed to determine the absolute brightness of the solar
corona. For UV radiometric calibration a set of targets is represented
by continuum-emitting early type bright stars (e.g. A and B spectral
types) whose photospheres produce a bright far-ultraviolet continuum
spectrum stable over long timescales. These stars represent an important
reference standard not only for METIS in-flight calibrations but
also for other Solar Orbiter instruments and they will be crucial for
instruments cross-calibrations as well. For VL radiometric calibration,
a set of linearly polarized stars will be used. These targets shall
have a minimum degree of linear polarization (DoLP &gt; 5%) and a
detectable magnitude, compatible with the instrument integration times
constrained by the desired S/N ratio and the characteristics of the
spacecraft orbit dynamics.

---------------------------------------------------------
Title: Hardware and software architecture on board solar
orbiter/METIS: an update
Authors: Pancrazzi, M.; Focardi, M.; Nicolini, G.; Andretta, V.;
Uslenghi, M.; Magli, E.; Ricci, M.; Bemporad, A.; Spadaro, D.; Landini,
F.; Romoli, M.; Antonucci, E.; Fineschi, S.; Naletto, G.; Nicolosi,
P.; Teriaca, L.
2014SPIE.9144E..3FP Altcode:
METIS, is one of the ten instruments selected to be part of the Solar
Orbiter payload; it is a coronagraph that will investigate the inner
part of the heliosphere performing imaging in the visible band and in
the hydrogen Lyman α line @ 121.6 nm. METIS has recently undergone
throughout a revision to simplify the instrument design. This paper
will provide an overview of the updated hardware and software design of
the coronagraph as presented at the Instrument Delta-Preliminary Design
Review occurred in April 2014. The current configuration foresees two
detectors, an Intensified APS for the UV channel and an APS for the
visible light equipped with a Liquid Crystal Variable Retarder (LCVR)
plate to perform broadband visible polarimetry. Each detector has a
proximity electronics generating the control and readout signals for
the sensor but the operations of the two devices are in charge of a
centralized unit, the METIS Processing and Power Unit (MPPU). The MPPU
operates the remaining electrical subsystems supplying them with power
and providing on board storage and processing capabilities. Its design
foresees the redundancy of the most critical parts, thus mitigating the
effects of possible failures of the electronics subsystems. The central
monitoring unit is also in charge of providing the communication with
the S/C, handling the telemetry and telecommand exchange with the
platform. The data acquired by the detectors shall undergo through
a preliminary on-board processing to maximize the scientific return
and to provide the necessary information to validate the results on
ground. Operations as images summing, compression and cosmic rays
monitoring and removal will be fundamental not only to mitigate the
effects of the main sources of noise on the acquired data, but also to
maximize the data volume to be transferred to the spacecraft in order to
fully exploit the limited bandwidth telemetry downlink. Finally, being
Solar Orbiter a deep-space mission, some METIS procedures have been
designed to provide the instrument an efficient autonomous behavior
in case of an immediate reaction is required as for the arising of
transient events or the occurrence of safety hazards conditions.

---------------------------------------------------------
Title: On-board detection and removal of cosmic ray and solar
energetic particle signatures for the Solar Orbiter-METIS coronagraph
Authors: Andretta, V.; Bemporad, A.; Focardi, M.; Grimani, C.;
Landini, F.; Pancrazzi, M.; Sasso, C.; Spadaro, D.; Straus, T.;
Uslenghi, M. C.; Antonucci, E.; Fineschi, S.; Naletto, G.; Nicolini,
G.; Nicolosi, P.; Romoli, M.
2014SPIE.9152E..2QA Altcode:
METIS is part of the science payload of Solar Orbiter. It is a
coronagraph designed to obtain images of the outer solar corona both in
the visible 580-640 nm band and in the UV, in a narrow band centered
around the hydrogen Lyman-α line. We describe the main features of
the procedures to remove signatures due to cosmic rays (CRs) and to
solar energetic particles (SEPs) comparing them with alternatives in
other contexts and in other solar coronagraphic missions. Our analysis
starts from a realistic assessment of the radiation environment where
the instrument is expected to operate, which is characteristic of the
interplanetary space of the inner solar system, but quite unusual for
most solar missions.

---------------------------------------------------------
Title: Stereoscopic investigation on plasma density fluctuations in
the outer solar corona
Authors: Telloni, D.; Antonucci, E.; Dolei, S.; Romano, P.; Spadaro,
D.; Ventura, R.
2014A&A...565A..22T Altcode:
This research note extends a previous work focused on the 2D
reconstruction of the spatial distribution and temporal evolution of
the plasma density fluctuations in the outer solar corona and based
on STEREO COR1-A white-light observations. By using the corresponding
total brightness images obtained in the same observational period with
the coronagraph COR1-B onboard the "Behind" twin STEREO-B spacecraft,
and adopting the same methodological approach as for COR1-A data, it
was possible to confirm the results of the previous work and argue for
the 3D configuration of the fluctuations of the coronal plasma. This
provides further evidence in support of a scenario in which the
fluctuating features, which are recurrent and spatially coherent, are
localized along the magnetic field lines and points out the crucial
role played by the 3D magnetic field topology in the confinement and
evolution of the plasma density fluctuations.

---------------------------------------------------------
Title: Measurements with STEREO/COR1 data of drag forces acting on
small-scale blobs falling in the intermediate corona
Authors: Dolei, S.; Bemporad, A.; Spadaro, D.
2014A&A...562A..74D Altcode: 2014arXiv1401.7984D
In this work we study the kinematics of three small-scale (0.01
R⊙) blobs of chromospheric plasma falling back to the
Sun after the huge eruptive event of June 7, 2011. From a study of
3D trajectories of blobs made with the Solar TErrestrial RElations
Observatory (STEREO) data, we demonstrate the existence of a significant
drag force acting on the blobs and calculate two drag coefficients, in
the radial and tangential directions. The resulting drag coefficients
CD are between 0 and 5, comparable in the two directions,
making the drag force only a factor of 0.45-0.75 smaller than the
gravitational force. To obtain a correct determination of electron
densities in the blobs, we also demonstrate how, by combining
measurements of total and polarized brightness, the Hα contribution
to the white-light emission observed by the COR1 telescopes can be
estimated. This component is significant for chromospheric plasma,
being between 95 and 98% of the total white-light emission. Moreover,
we demonstrate that the COR1 data can be employed even to estimate
the Hα polarized component, which turns out to be in the order of a
few percent of Hα total emission from the blobs. If the drag forces
acting on small-scale blobs reported here are similar to those that
play a role during the CME propagation, our results suggest that the
magnetic drag should be considered even in the CME initiation modelling.

---------------------------------------------------------
Title: Identification, physical structure and variability of the
coronal sources of the fast and slow solar wind
Authors: Spadaro, Daniele
2014cosp...40E3181S Altcode:
In spite of the numerous and continuous improvements in our
understanding of the mechanisms governing the solar corona and its
dynamics, none of the previous missions to the Sun have been able to
fully explore the interface region where the solar wind originates
and heliospheric structures are formed with sufficient observational
capabilities to link solar wind structures back to their source regions
at the Sun. Thanks to the powerful combination of in-situ and
remote-sensing instruments and the unique inner-heliospheric mission
design, the upcoming solar and heliospheric missions will definitely
contribute to address the central scientific question: how does the Sun
create and control the heliosphere? Answering this fundamental question
means to address, in particular, the interrelated question: how and
where do the solar wind plasma streams originate in the corona? To
answer these questions it is essential to perform in-situ measurements
of the solar wind plasma, magnetic fields, waves and energetic particles
close enough to the Sun to prevent any modification of the observed
properties due to the subsequent transport and propagation processes. The Solar Orbiter spacecraft will approach the Sun to within 0.28 AU,
leading also to a significant improvement in spatial resolution of the
remote-sensing instruments. Simultaneous high-resolution imaging and
spectroscopic observations of the Sun in and out of the ecliptic plane
will allow to relate in-situ measurements by the Solar Orbiter itself,
as well as by the Solar Probe Plus, back to their source regions and
structures on the Sun, also providing unprecedented close-up views
of the Sun's polar regions at solar latitudes higher than 30(°)
. This proximity to the Sun will also give the advantage of flying
in near synchronization with the Sun's rotation allowing observations
of the solar surface and heliosphere from a near co-rotating vantage
point. In these observations, both the on-disc inner corona and the
outer corona will be nearly frozen for several days in the plane of
the sky, and this can be used to disentangle the evolution of coronal
structures and solar rotation effects on medium-term scales. This
presentation will discuss the capability of remote-sensing instruments
to provide information on the physical properties, fine structure and
variability of different coronal regions, with both closed and open
magnetic configuration, that can help to get a firmer identification
of the source regions of the fast and slow solar wind streams.

---------------------------------------------------------
Title: Detection of Plasma Fluctuations in White-light Images of
the Outer Solar Corona: Investigation of the Spatial and Temporal
Evolution
Authors: Telloni, D.; Ventura, R.; Romano, P.; Spadaro, D.;
Antonucci, E.
2013ApJ...767..138T Altcode: 2013arXiv1302.3382T
This work focuses on the first results from the identification and
characterization of periodic plasma density fluctuations in the outer
corona, observed in STEREO-A COR1 white-light image time series. A
two-dimensional reconstruction of the spatial distribution and temporal
evolution of the coronal fluctuation power has been performed over
the whole plane of the sky, from 1.4 to 4.0 R ⊙. The
adopted diagnostic tool is based on wavelet transforms. This technique,
with respect to the standard Fourier analysis, has the advantage of
localizing non-persistent fluctuating features and exploring variations
of the relating wavelet power in both space and time. The map of
the variance of the coronal brightness clearly outlines intermittent
spatially coherent fluctuating features, localized along, or adjacent
to, the strongest magnetic field lines. In most cases, they do not
correspond to the visible coronal structures in the brightness maps. The
results obtained provide a scenario in which the solar corona shows
quasi-periodic, non-stationary density variations characterized by
a wide range of temporal and spatial scales and strongly confined
by the magnetic field topology. In addition, structures fluctuating
with larger power are larger in size and evolve more slowly. The
characteristic periodicities of the fluctuations are comparable
to their lifetimes. This suggests that plasma fluctuations lasting
only one or two wave periods and initially characterized by a single
dominant periodicity either rapidly decay into a turbulent mixed flow
via nonlinear interactions with other plasma modes, or they are damped
by thermal conduction. The periodic non-stationary coronal fluctuations
outlined by the closed field lines at low and mid latitudes might be
associated with the existence of slow standing magneto-acoustic waves
excited by the convective supergranular motion. The fluctuating ray-like
structures observed along open field lines appear to be linked either
to the intermittent nature of the processes underlying the generation
of magnetic reconnection in the polar regions or to the oscillatory
transverse displacements of the coronal ray itself.

---------------------------------------------------------
Title: Properties of multistranded, impulsively heated hydrodynamic
loop models
Authors: Susino, R.; Spadaro, D.; Lanzafame, A. C.; Lanza, A. F.
2013A&A...552A..17S Altcode:
 Aims: We investigate the capability of multistranded loop models
subject to nanoflare heating to reproduce the properties recently
observed in coronal loops at extreme ultraviolet (EUV) wavelengths. Methods: One-dimensional hydrodynamic simulations of magnetic loop
strands were performed with an impulsive, footpoint-localised heating,
with a moderate asymmetry between the two loop halves that was produced
either by a sequence of identical nanoflares with a given cadence time
tC or by a single energy pulse. The temporal evolution of the
emission of a multistranded loop was modelled by simply combining the
results of independent single-strand simulations, neglecting any spatial
interaction among the strands, and was compared with TRACE and SDO/AIA
light curves. The density excess with respect to hydrostatic equilibrium
(the ψ factor) was evaluated with the filter-ratio technique. Results: Both loop models exhibit a density excess compared with
hydrostatic equilibrium models, which agrees well with the observed
values (1 ≲ ψ ≲ 12). However, in the single-pulse model the light
curve and density excess maxima do not match. On the other hand, the
models with a sequence of nanoflares predict strong emission at lower
temperatures that cannot be reconciled with the available observations.

---------------------------------------------------------
Title: LEMUR: Large European module for solar Ultraviolet
Research. European contribution to JAXA's Solar-C mission
Authors: Teriaca, Luca; Andretta, Vincenzo; Auchère, Frédéric;
Brown, Charles M.; Buchlin, Eric; Cauzzi, Gianna; Culhane, J. Len;
Curdt, Werner; Davila, Joseph M.; Del Zanna, Giulio; Doschek, George
A.; Fineschi, Silvano; Fludra, Andrzej; Gallagher, Peter T.; Green,
Lucie; Harra, Louise K.; Imada, Shinsuke; Innes, Davina; Kliem,
Bernhard; Korendyke, Clarence; Mariska, John T.; Martínez-Pillet,
Valentin; Parenti, Susanna; Patsourakos, Spiros; Peter, Hardi; Poletto,
Luca; Rutten, Robert J.; Schühle, Udo; Siemer, Martin; Shimizu,
Toshifumi; Socas-Navarro, Hector; Solanki, Sami K.; Spadaro, Daniele;
Trujillo-Bueno, Javier; Tsuneta, Saku; Dominguez, Santiago Vargas;
Vial, Jean-Claude; Walsh, Robert; Warren, Harry P.; Wiegelmann,
Thomas; Winter, Berend; Young, Peter
2012ExA....34..273T Altcode: 2011ExA...tmp..135T; 2011arXiv1109.4301T
The solar outer atmosphere is an extremely dynamic environment
characterized by the continuous interplay between the plasma and the
magnetic field that generates and permeates it. Such interactions play a
fundamental role in hugely diverse astrophysical systems, but occur at
scales that cannot be studied outside the solar system. Understanding
this complex system requires concerted, simultaneous solar observations
from the visible to the vacuum ultraviolet (VUV) and soft X-rays, at
high spatial resolution (between 0.1” and 0.3”), at high temporal
resolution (on the order of 10 s, i.e., the time scale of chromospheric
dynamics), with a wide temperature coverage (0.01 MK to 20 MK,
from the chromosphere to the flaring corona), and the capability of
measuring magnetic fields through spectropolarimetry at visible and
near-infrared wavelengths. Simultaneous spectroscopic measurements
sampling the entire temperature range are particularly important. These
requirements are fulfilled by the Japanese Solar-C mission (Plan B),
composed of a spacecraft in a geosynchronous orbit with a payload
providing a significant improvement of imaging and spectropolarimetric
capabilities in the UV, visible, and near-infrared with respect to
what is available today and foreseen in the near future. The Large
European Module for solar Ultraviolet Research (LEMUR), described
in this paper, is a large VUV telescope feeding a scientific payload
of high-resolution imaging spectrographs and cameras. LEMUR consists
of two major components: a VUV solar telescope with a 30 cm diameter
mirror and a focal length of 3.6 m, and a focal-plane package composed
of VUV spectrometers covering six carefully chosen wavelength ranges
between 170 Å and 1270 Å. The LEMUR slit covers 280” on the Sun with
0.14” per pixel sampling. In addition, LEMUR is capable of measuring
mass flows velocities (line shifts) down to 2 km s - 1 or
better. LEMUR has been proposed to ESA as the European contribution
to the Solar C mission.

---------------------------------------------------------
Title: Multi Element Telescope for Imaging and Spectroscopy (METIS)
coronagraph for the Solar Orbiter mission
Authors: Antonucci, Ester; Fineschi, Silvano; Naletto, Giampiero;
Romoli, Marco; Spadaro, Daniele; Nicolini, Gianalfredo; Nicolosi,
Piergiorgio; Abbo, Lucia; Andretta, Vincenzo; Bemporad, Alessandro;
Auchère, Frédéric; Berlicki, Arkadiusz; Bruno, Roberto; Capobianco,
Gerardo; Ciaravella, Angela; Crescenzio, Giuseppe; Da Deppo, Vania;
D'Amicis, Raffaella; Focardi, Mauro; Frassetto, Fabio; Heinzel,
Peter; Lamy, Philippe L.; Landini, Federico; Massone, Giuseppe;
Malvezzi, Marco A.; Moses, J. Dan; Pancrazzi, Maurizio; Pelizzo,
Maria-Guglielmina; Poletto, Luca; Schühle, Udo H.; Solanki, Sami K.;
Telloni, Daniele; Teriaca, Luca; Uslenghi, Michela
2012SPIE.8443E..09A Altcode:
METIS, the “Multi Element Telescope for Imaging and Spectroscopy”,
is a coronagraph selected by the European Space Agency to be part of
the payload of the Solar Orbiter mission to be launched in 2017. The
unique profile of this mission will allow 1) a close approach to the
Sun (up to 0.28 A.U.) thus leading to a significant improvement in
spatial resolution; 2) quasi co-rotation with the Sun, resulting in
observations that nearly freeze for several days the large-scale outer
corona in the plane of the sky and 3) unprecedented out-of-ecliptic
view of the solar corona. This paper describes the experiment concept
and the observational tools required to achieve the science drivers
of METIS. METIS will be capable of obtaining for the first time: •
simultaneous imaging of the full corona in polarized visible-light
(590-650 nm) and narrow-band ultraviolet HI Lyman α (121.6 nm); •
monochromatic imaging of the full corona in the extreme ultraviolet
He II Lyman α (30.4 nm); • spectrographic observations of the HI
and He II Ly α in corona. These measurements will allow a complete
characterization of the three most important plasma components of
the corona and the solar wind, that is, electrons, hydrogen, and
helium. This presentation gives an overview of the METIS imaging and
spectroscopic observational capabilities to carry out such measurements.

---------------------------------------------------------
Title: Optimization of the occulter for the Solar Orbiter/METIS
coronagraph
Authors: Landini, Federico; Vivès, Sébastien; Romoli, Marco; Guillon,
Christophe; Pancrazzi, Maurizio; Escolle, Clement; Focardi, Mauro;
Antonucci, Ester; Fineschi, Silvano; Naletto, Giampiero; Nicolini,
Gianalfredo; Nicolosi, Piergiorgio; Spadaro, Daniele
2012SPIE.8442E..27L Altcode:
METIS (Multi Element Telescope for Imaging and Spectroscopy
investigation), selected to fly aboard the Solar Orbiter ESA/NASA
mission, is conceived to perform imaging (in visible, UV and EUV) and
spectroscopy (in EUV) of the solar corona, by means of an integrated
instrument suite located on a single optical bench and sharing the
same aperture on the satellite heat shield. As every coronagraph, METIS
is highly demanding in terms of stray light suppression. Coronagraphs
history teaches that a particular attention must be dedicated to the
occulter optimization. The METIS occulting system is of particular
interest due to its innovative concept. In order to meet the strict
thermal requirements of Solar Orbiter, METIS optical design has been
optimized by moving the entrance pupil at the level of the external
occulter on the S/C thermal shield, thus reducing the size of the
external aperture. The scheme is based on an inverted external-occulter
(IEO). The IEO consists of a circular aperture on the Solar Orbiter
thermal shield. A spherical mirror rejects back the disk-light
through the IEO. A breadboard of the occulting assembly (BOA) has
been manufactured in order to perform stray light tests in front of
two solar simulators (in Marseille, France and in Torino, Italy). A
first measurement campaign has been carried on at the Laboratoire
d'Astrophysique de Marseille. In this paper we describe the BOA design,
the laboratory set-up and the preliminary results.

---------------------------------------------------------
Title: The processing and power unit of the METIS coronagraph aboard
the Solar Orbiter space mission
Authors: Focardi, M.; Pancrazzi, M.; Uslenghi, M.; Nicolini, G.;
Magli, E.; Landini, F.; Romoli, M.; Antonucci, E.; Fineschi, S.;
Naletto, G.; Nicolosi, P.; Spadaro, D.; Andretta, V.; Gennaro, C.;
Zoppo, G. P.; Stevoli, A.; Battistelli, E.; Rusconi, A.
2012SPIE.8442E..4IF Altcode:
The Multi Element Telescope for Imaging and Spectroscopy (METIS) is the
coronagraph selected for the Solar Orbiter payload, adopted in October
2011 by ESA for the following Implementation Phase. The instrument
design has been conceived by a team composed by several research
institutes with the aim to perform both VIS and EUV narrow-band
imaging and spectroscopy of the solar corona. METIS, owing to its
multi-wavelength capability, will address some of the major open issues
in understanding the physical processes in the corona and the solar
wind origin and properties, exploiting the unique opportunities offered
by the SO mission profile. The METIS Processing and Power Unit (MPPU)
is the Instrument's power supply and on-board data handling modular
electronics, designed to address all the scientific requirements of
the METIS Coronagraph. MPPU manages data and command flows, the timing
and power distribution networks and its architecture reflects several
trade-off solutions with respect to the allocated resources in order
to reduce any possible electronics single-point failure. This paper
reports on the selected HW and SW architectures adopted after the
Preliminary Design Review (PDR), performed by ESA in early 2012.

---------------------------------------------------------
Title: METIS: a novel coronagraph design for the Solar Orbiter mission
Authors: Fineschi, Silvano; Antonucci, Ester; Naletto, Giampiero;
Romoli, Marco; Spadaro, Daniele; Nicolini, Gianalfredo; Abbo, Lucia;
Andretta, Vincenzo; Bemporad, Alessandro; Berlicki, Arkadiusz;
Capobianco, Gerardo; Crescenzio, Giuseppe; Da Deppo, Vania; Focardi,
Mauro; Landini, Federico; Massone, Giuseppe; Malvezzi, Marco A.;
Moses, J. Dan; Nicolosi, Piergiorgio; Pancrazzi, Maurizio; Pelizzo,
Maria-Guglielmina; Poletto, Luca; Schühle, Udo H.; Solanki, Sami K.;
Telloni, Daniele; Teriaca, Luca; Uslenghi, Michela
2012SPIE.8443E..3HF Altcode:
METIS (Multi Element Telescope for Imaging and Spectroscopy) METIS,
the “Multi Element Telescope for Imaging and Spectroscopy”,
is a coronagraph selected by the European Space Agency to be part
of the payload of the Solar Orbiter mission to be launched in
2017. The mission profile will bring the Solar Orbiter spacecraft
as close to the Sun as 0.3 A.U., and up to 35° out-of-ecliptic
providing a unique platform for helio-synchronous observations of
the Sun and its polar regions. METIS coronagraph is designed for
multi-wavelength imaging and spectroscopy of the solar corona. This
presentation gives an overview of the innovative design elements of
the METIS coronagraph. These elements include: i) multi-wavelength,
reflecting Gregorian-telescope; ii) multilayer coating optimized for
the extreme UV (30.4 nm, HeII Lyman-α) with a reflecting cap-layer
for the UV (121.6 nm, HI Lyman-α) and visible-light (590-650); iii)
inverse external-occulter scheme for reduced thermal load at spacecraft
peri-helion; iv) EUV/UV spectrograph using the telescope primary mirror
to feed a 1st and 4th-order spherical varied
line-spaced (SVLS) grating placed on a section of the secondary mirror;
v) liquid crystals electro-optic polarimeter for observations of the
visible-light K-corona. The expected performances are also presented.

---------------------------------------------------------
Title: Solar magnetism eXplorer (SolmeX). Exploring the magnetic
field in the upper atmosphere of our closest star
Authors: Peter, Hardi; Abbo, L.; Andretta, V.; Auchère, F.; Bemporad,
A.; Berrilli, F.; Bommier, V.; Braukhane, A.; Casini, R.; Curdt,
W.; Davila, J.; Dittus, H.; Fineschi, S.; Fludra, A.; Gandorfer, A.;
Griffin, D.; Inhester, B.; Lagg, A.; Landi Degl'Innocenti, E.; Maiwald,
V.; Sainz, R. Manso; Martínez Pillet, V; Matthews, S.; Moses, D.;
Parenti, S.; Pietarila, A.; Quantius, D.; Raouafi, N. -E.; Raymond, J.;
Rochus, P.; Romberg, O.; Schlotterer, M.; Schühle, U.; Solanki, S.;
Spadaro, D.; Teriaca, L.; Tomczyk, S.; Trujillo Bueno, J.; Vial, J. -C.
2012ExA....33..271P Altcode: 2011arXiv1108.5304P; 2011ExA...tmp..134P
The magnetic field plays a pivotal role in many fields of
Astrophysics. This is especially true for the physics of the solar
atmosphere. Measuring the magnetic field in the upper solar atmosphere
is crucial to understand the nature of the underlying physical
processes that drive the violent dynamics of the solar corona—that
can also affect life on Earth. SolmeX, a fully equipped solar space
observatory for remote-sensing observations, will provide the first
comprehensive measurements of the strength and direction of the
magnetic field in the upper solar atmosphere. The mission consists
of two spacecraft, one carrying the instruments, and another one in
formation flight at a distance of about 200 m carrying the occulter to
provide an artificial total solar eclipse. This will ensure high-quality
coronagraphic observations above the solar limb. SolmeX integrates two
spectro-polarimetric coronagraphs for off-limb observations, one in
the EUV and one in the IR, and three instruments for observations on
the disk. The latter comprises one imaging polarimeter in the EUV for
coronal studies, a spectro-polarimeter in the EUV to investigate the low
corona, and an imaging spectro-polarimeter in the UV for chromospheric
studies. SOHO and other existing missions have investigated the emission
of the upper atmosphere in detail (not considering polarization),
and as this will be the case also for missions planned for the near
future. Therefore it is timely that SolmeX provides the final piece of
the observational quest by measuring the magnetic field in the upper
atmosphere through polarimetric observations.

---------------------------------------------------------
Title: Solar low-lying cool loops and their contribution to the
transition region EUV output
Authors: Sasso, C.; Andretta, V.; Spadaro, D.; Susino, R.
2012A&A...537A.150S Altcode: 2011arXiv1112.0309S
 Aims: We aim to investigate the increase of the differential
emission measure (DEM) towards the chromosphere. In the past 30 years,
small and cool magnetic loops (height ≲ 8 Mm, T ≲ 105 K)
have been proposed as an explanation for this effect. Methods:
We present hydrodynamic simulations of low-lying cool loops in which
we studied the loops' conditions of existence and stability, and their
contribution to the transition region EUV output. Results:
We find that stable, quasi-static cool loops (with velocities &lt;1
km s-1) can be obtained under different and more realistic
assumptions on the radiative loss function with respect to previous
works. A mixture of the DEMs of these cool loops plus intermediate
loops with temperatures between 105 and 106
K can reproduce the observed emission of the lower transition region
at the critical turn-up temperature point (T ~ 2 × 105 K)
and below T = 105 K.

---------------------------------------------------------
Title: Physical structure of solar cool loops.
Authors: Sasso, C.; Susino, R.; Andretta, V.; Spadaro, D.
2012MSAIS..19...81S Altcode:
Recently, studies and observations focused on the solar transition
region and the low corona have shown the importance of small and
cool magnetic loops in producing most of the solar EUV output at
temperatures below 1 MK. This kind of structures has remained only
poorly characterized in terms of physical properties. We study the
possibility of obtaining cool loops using unidimensional hydrodynamic
simulations, performed with a state-of-the-art numerical code with a
fully adaptive grid. The dependence of their physical structures on
the form of the radiative losses function has been explored. We find,
as a first result, that the shape of the radiative losses function for
T&lt;105 K imposes restrictive conditions on the existence
and the stability of such cool loops.

---------------------------------------------------------
Title: The solar orbiter METIS coronagraph data signal processing
chain
Authors: Pancrazzi, M.; Focardi, M.; Uslenghi, M.; Nicolini, G.;
Magli, E.; Landini, F.; Romoli, M.; Bemporad, A.; Antonucci, E.;
Fineschi, S.; Naletto, G.; Nicolosi, P.; Spadaro, D.; Andretta, V.
2011SPIE.8167E..2CP Altcode: 2011SPIE.8167E..66P
METIS, the Multi Element Telescope for Imaging and Spectroscopy,
is one of the instruments selected in 2009 by ESA to be part of the
payload of the Solar Orbiter mission. The instrument design has been
conceived to perform both multiband imaging and UV spectroscopy of
the solar corona. The two sensors of the detecting system will produce
images in visible light and in two narrow UV bands, at 121.6 and 30.4
nm. The instrument is constituted by several subunits that have to be
properly controlled and synchronized in order to provide the expected
performances. Moreover, the large amount of data collected by METIS has
to be processed by the on board electronics to reduce the data volume
to be delivered to ground by telemetry. These functionalities will be
realized by a dedicated electronics, the Main Power and Processing Unit
(MPPU). This paper will provide an overview of the METIS data handling
system and the expected on board data processing.

---------------------------------------------------------
Title: CME evolution and 3D reconstruction with STEREO Data
Authors: Orlando, A.; Zuccarello, F.; Romano, P.; Zuccarello, F. P.;
Mierla, M.; Spadaro, D.; Ventura, R.
2011IAUS..274..165O Altcode:
We describe a CME event, occurred in NOAA 11059 on April 3 2010,
using STEREO and MDI/SOHO data. We analyze the CME evolution using
data provided by SECCHI-EUVI and COR1 onboard STEREO satellites,
and we perform a 3D reconstruction of the CME using the LCT-TP
method. Using MDI/SOHO line-of-sight magnetograms we analyze the
magnetic configuration of NOAA 11059 and we determine the magnetic
helicity trend.

---------------------------------------------------------
Title: Trend of photospheric magnetic helicity flux in active regions
generating halo coronal mass ejections
Authors: Smyrli, A.; Zuccarello, F.; Romano, P.; Zuccarello, F. P.;
Guglielmino, S. L.; Spadaro, D.; Hood, A. W.; Mackay, D.
2010A&A...521A..56S Altcode:
Context. Coronal mass ejections (CMEs) are very energetic events (~
1032 erg) initiated in the solar atmosphere, resulting
in the expulsion of magnetized plasma clouds that propagate into
interplanetary space. It has been proposed that CMEs can play an
important role in shedding magnetic helicity, avoiding its endless
accumulation in the corona. Aims: The aim of this work is to
investigate the behavior of magnetic helicity accumulation in sites
where the initiation of CMEs occurred to determine whether and how
changes in magnetic helicity accumulation are temporally correlated
with CME occurrence. Methods: We used MDI/SOHO line-of-sight
magnetograms to calculate magnetic flux evolution and magnetic
helicity injection in 10 active regions that gave rise to halo CMEs
observed during the period 2000 February to 2003 June. Results:
The magnetic helicity injection does not have a unique trend in the
events analyzed: in 40% of the cases it shows a large sudden and abrupt
change that is temporally correlated with a CME occurrence, while in
the other cases it shows a steady monotonic trend, with a slight change
in magnetic helicity at CME occurrence. Conclusions: The results
obtained from the sample of events that we have analyzed indicate that
major changes in magnetic helicity flux are observed in active regions
characterized by emergence of new magnetic flux and/or generating halo
CMEs associated with X-class flares or filament eruptions. In some of
the analyzed cases the changes in magnetic helicity flux follow the
CME events and can be attributed to a process of restoring a torque
balance between the subphotospheric and the coronal domain of the
flux tubes. Appendix is only available in electronic form at <A
href="http://www.aanda.org">http://www.aanda.org</A>

---------------------------------------------------------
Title: Signatures of Impulsive Localized Heating in the Temperature
Distribution of Multi-Stranded Coronal Loops
Authors: Susino, R.; Lanzafame, A. C.; Lanza, A. F.; Spadaro, D.
2010ApJ...709..499S Altcode: 2009arXiv0912.2592S
We study the signatures of coronal heating on the differential emission
measure (DEM) by means of hydrodynamic simulations capable of resolving
the chromospheric-corona transition region sections of multi-stranded
coronal loops and following their evolution. We consider heating
either uniformly distributed along the loop or localized close to the
chromospheric footpoints, in both steady and impulsive regimes. Our
simulations show that condensation at the top of the loop forms
when the impulsive heating, with a pulse cadence lower than the
plasma cooling time, is localized at the loop footpoints, and the
pulse energy is below a threshold above which the heating balances
the radiative losses, thus preventing the catastrophic cooling which
triggers the condensation. A condensation does not produce observable
signatures in the DEM because it does not redistribute the plasma over
a sufficiently large temperature range. On the other hand, the DEM
coronal peak is found sensitive to the pulse cadence time when this
is longer or comparable to the plasma cooling time. In this case, the
heating pulses produce large oscillations in temperature in the bulk
of the coronal plasma, which effectively smears out the coronal DEM
structure. The pronounced DEM peak observed in active regions would
indicate a predominance of conditions in which the cadence time is
shorter or of the order of the plasma cooling time, whilst the structure
of the quiet-Sun DEM suggests a cadence time longer than the plasma
cooling time. Our simulations give an explanation of the warm overdense
and hot underdense loops observed by TRACE, SOHO, and Yohkoh. However,
they are unable to reproduce both the transition region and the coronal
DEM structure with a unique set of parameters, which outlines the need
for a more realistic description of the transition region.

---------------------------------------------------------
Title: Trend of photospheric helicity flux in active regions
generating halo CMEs
Authors: Smyrli, Aimilia; Zuccarello, Francesco; Zuccarello, Francesca;
Romano, Paolo; Guglielmino, Salvatore Luigi; Spadaro, Daniele; Hood,
Alan; Mackay, Duncan
2010cosp...38.1860S Altcode: 2010cosp.meet.1860S
Coronal Mass Ejections (CMEs) are very energetic events initiated
in the solar atmosphere, re-sulting in the expulsion of magnetized
plasma clouds that propagate into interplanetary space. It has been
proposed that CMEs can play an important role in shedding magnetic
helicity, avoiding its endless accumulation in the corona. We therefore
investigated the behavior of magnetic helicity accumulation in sites
where the initiation of CMEs occurred, in order to de-termine whether
and how changes in magnetic helicity accumulation are temporally
correlated with CME occurrence. After identifying the active
regions (AR) where the CMEs were ini-tiated by means of a double
cross-check based on the flaring-eruptive activity and the use of
SOHO/EIT difference images, we used MDI magnetograms to calculate
magnetic flux evolu-tion, magnetic helicity injection rate and
magnetic helicity injection in 10 active regions that gave rise to
12 halo CMEs observed during the period February 2000 -June 2003. No
unique behavior in magnetic helicity injection accompanying halo CME
occurrence is found. In fact, in some cases there is an abrupt change
in helicity injection timely correlated with the CME event, while
in some others no significant variation is recorded. However, our
analysis show that the most significant changes in magnetic flux and
magnetic helicity injection are associated with impulsive CMEs rather
than gradual CMEs. Moreover, the most significant changes in mag-netic
helicity are observed when X-class flares or eruptive filaments occur,
while the occurrence of flares of class C or M seems not to affect
significantly the magnetic helicity accumulation.

---------------------------------------------------------
Title: Morphological and dynamical properties of small-scale
chromospheric features deduced from IBIS observations
Authors: Contarino, L.; Zuccarello, F.; Romano, P.; Spadaro, D.;
Ermolli, I.
2009A&A...507.1625C Altcode:
Context: In the past, chromospheric features were mostly studied by
analyzing observations performed along the Hα profile, but several
aspects related to their formation and dynamics remained uncertain
and poorly understood. Recently, new investigations have been carried
out using data obtained along the Ca II line at 854.21 nm, providing
new inputs for clarification of some of these aspects. Aims:
In order to give a further contribution to the comprehension of the
physical processes occurring in small-scale chromospheric features,
we analyzed high spatial and temporal resolution images, acquired along
the Ca II (λ = 854.21 nm) line with the Interferometric Bidimensional
Spectrometer (IBIS). We studied four chromospheric structures such
as mottles and arches belonging to an arch filament system (AFS)
inside a bipolar region, observed on October 3, 2006. Methods:
We evaluated the plasma velocity along the line of sight (LOS) using
two methods: the Doppler shift of the centroid of the line profile and
the cloud model. Also, we deduced the mean temperature, the Doppler
width, the optical thickness and the source function in the structures
to which we could apply the cloud model. Results: The pattern
of the LOS velocity in the four mottles showed different behaviors. A
mottle, initially, showed positive and negative velocities in eastern
and western endpoints, respectively, then the plasma motion seems
to reverse over a period of about 4 mn. In another mottle a motion
characterized by alternate upward and downward plasma flow along the
main axis was recorded. Irregular upward and downward motions along
the other two mottles confirm previous results. The LOS velocities
measured in the AFS, observed during the decay phase of the region,
are of the same order of magnitude as those measured in short-lived
active regions during their emergence phase. Conclusions:
The observations carried out in the Ca II line allowed us to obtain
information on small-scale magnetic features, like mottles and AFS,
observed in the chromosphere. These results, on one hand, confirm
previous results obtained using data acquired in the Hα line, and on
the other hand, provide new clues to the dynamic similarities between
mottles and dynamic fibrils. Moreover, this study allowed us to single
out the presence of an AFS during a phase characterized by decreasing
magnetic flux and the approach of the opposite polarities.

---------------------------------------------------------
Title: Emergence and evolution of active and ephemeral regions:
Comparison between observations and models
Authors: Zuccarello, Francesca; Guglielmino, Salvatore L.; Battiato,
Viviana; Contarino, Lidia; Spadaro, Daniele; Romano, Pado
2009AcGeo..57...15Z Altcode: 2008AcGeo.tmp...44Z
This work aims to describe some aspects relevant to the emergence
of magnetic structures on the solar surface. Using high resolution
photospheric and chromospheric data, besides than EUV images acquired
by space telescopes, the dynamics of rising flux tubes is studied. It
is shown that, for both long-lived and short-lived magnetic regions, the
flux tubes are initially characterized by a high rising velocity, which
eventually decreases as the region develops. Other results concern the
timeline of the active regions appearance in the atmospheric layers and
the asymmetries in plasma downflows between preceding and following
legs of the flux tubes. These results are briefly discussed in the
light of most recent models.

---------------------------------------------------------
Title: POLAR investigation of the Sun—POLARIS
Authors: Appourchaux, T.; Liewer, P.; Watt, M.; Alexander, D.;
Andretta, V.; Auchère, F.; D'Arrigo, P.; Ayon, J.; Corbard, T.;
Fineschi, S.; Finsterle, W.; Floyd, L.; Garbe, G.; Gizon, L.; Hassler,
D.; Harra, L.; Kosovichev, A.; Leibacher, J.; Leipold, M.; Murphy,
N.; Maksimovic, M.; Martinez-Pillet, V.; Matthews, B. S. A.; Mewaldt,
R.; Moses, D.; Newmark, J.; Régnier, S.; Schmutz, W.; Socker, D.;
Spadaro, D.; Stuttard, M.; Trosseille, C.; Ulrich, R.; Velli, M.;
Vourlidas, A.; Wimmer-Schweingruber, C. R.; Zurbuchen, T.
2009ExA....23.1079A Altcode: 2008ExA...tmp...40A; 2008arXiv0805.4389A
The POLAR Investigation of the Sun (POLARIS) mission uses a combination
of a gravity assist and solar sail propulsion to place a spacecraft
in a 0.48 AU circular orbit around the Sun with an inclination of 75°
with respect to solar equator. This challenging orbit is made possible
by the challenging development of solar sail propulsion. This first
extended view of the high-latitude regions of the Sun will enable
crucial observations not possible from the ecliptic viewpoint or from
Solar Orbiter. While Solar Orbiter would give the first glimpse of
the high latitude magnetic field and flows to probe the solar dynamo,
it does not have sufficient viewing of the polar regions to achieve
POLARIS’s primary objective: determining the relation between the
magnetism and dynamics of the Sun’s polar regions and the solar cycle.

---------------------------------------------------------
Title: Flare forecasting based on sunspot-groups characteristics
Authors: Contarino, Lidia; Zuccarello, Francesca; Romano, Paolo;
Spadaro, Daniele; Guglielmino, Salvatore L.; Battiato, Viviana
2009AcGeo..57...52C Altcode: 2008AcGeo.tmp...51C
Our comprehension of solar flares is still lacking in many aspects
and the possibility of observing active regions during the first
phases of flare occurrence is limited by our capability of doing
accurate flare forecasting. In order to give a contribution to this
aspect, we focused our attention on the characteristics that must
be fulfilled by sunspot-groups in order to be flare-productive. We
addressed this problem using a statistical approach: first, we analyzed
sunspot-groups parameters (i.e., Zürich class, magnetic configuration,
area, morphology of the penumbra) and evolution; then, we performed
a flare forecasting campaign, based on the results obtained in the
first phase and on real-time observations. The results obtained by
comparing the flare forecasting probability with the number of flares
that have actually occurred are quite encouraging; we plan to improve
this procedure by including a bigger statistical sampling.

---------------------------------------------------------
Title: What are the prospects for the study of the Sun and
solar-terrestrial relations?
Authors: Spadaro, D.
2009MmSAI..80..233S Altcode:
The aim of this paper is to introduce shortly the main open
questions in the knowledge of physical processes occurring in the
Sun and heliosphere and of their effects on the interplanetary
and circumterrestrial environment. Starting from the considerable
developments in the last decade, particularly owing to the availability
of new and more effective, both ground- and space-based, instruments
of investigation, that were also characterised by a significant
contribution of the Italian scientific community, the paper will
describe some researches which attempt to address these questions. A
special attention will be devoted to the prospects opening up with
the currently available instruments and their possible sinergies,
as well as to the opportunities that should be provided by the new
instruments planned for the next decade.

---------------------------------------------------------
Title: Studying the decay phase of a short-lived active region
with coordinated DST/IBIS, Hinode/EIS+SOT+XRT, SOHO/MDI and TRACE
observations
Authors: Zuccarello, F.; Berrilli, F.; Centrone, M.; Contarino, L.;
Criscuoli, S.; Del Moro, D.; Ermolli, I.; Giorgi, F.; Guglielmino,
L. S.; Salerno, C.; Spadaro, D.; Romano, P.
2008ESPM...12.2.56Z Altcode:
This study concerns the physical processes occurring during the decay
phase of the short-lived active region NOAA 10977, as evaluated from
analysis of data gathered using ground- (DST/IBIS) and space-based
(Hinode/EIS+SOT+XRT, SOHO/MDI and TRACE) facilities. The coordinated
observing campaign was performed from December 1st to 9th, 2007,
covering several spectral ranges, with unprecedented spatial and
spectral resolution. We present preliminary results of the Doppler
analysis of plasma motions evaluated from monochromatic images taken
along the Ca II (8542 Å) and the Fe I (7049 Å) spectral lines with
IBIS. We also report results concerning the horizontal displacements of
photospheric magnetic structures and advection flows as obtained from
application of Local Correlation Tracking (LCT) and Two-Level Structure
Tracking (TST) techniques to both the LoS magnetograms taken by MDI
and to high resolution intensity maps obtained by IBIS at DST/NSO. Further contributions to understanding the mechanisms at the base
of the magnetic field diffusion are provided from the inversion of
the Stokes profiles of the photospheric Fe I lines at 6301.5 Å and
6302.5 Å, obtained with SOT/SP, and the analysis of filtergrams in
the core of the Ca II H line (3968.5 ± 3 Å) and images in G-band
(4305 ± 8 Å) taken by SOT/BFI, as well as EIS data and images taken
by the thin Be of XRT, and by TRACE at 171 Å and 1600 Å.

---------------------------------------------------------
Title: Physical parameters along the boundaries of a mid-latitude
streamer and in its adjacent regions
Authors: Susino, R.; Ventura, R.; Spadaro, D.; Vourlidas, A.; Landi, E.
2008A&A...488..303S Altcode:
Context: Coronal streamers appear to be strictly associated with the
generation of the slow solar wind, even if a firm identification of
the sources of the particle flux within these structures is still an
unresolved issue. Aims: The purpose of this work is to contribute
to a better knowledge of the physical characteristics of streamers and
of their surroundings in a wide range of heliocentric distances and
at both high radial and latitudinal resolutions. Methods: The
analysis is based on spectral observations of a narrow, mid-latitude
streamer performed with UVCS/SOHO during one week in May 2004: H i
Lyα and O vi resonance doublet line intensities and profiles were
obtained at different heliocentric distances and latitudes. In addition,
white-light polarized brightness images were taken in the same days
of observation, through the LASCO/SOHO C2 coronagraph. Results:
The radial variations in electron density and temperature, H i and O
vi kinetic temperatures, and outflow velocities were derived from the
observed line intensities, profiles, and O vi line intensity ratios
between 1.6 and 5.0 R_⊙, in two regions, 2-3 arcmin wide, located
along the boundaries and in a narrow strip (5-10 arcmin) outside
the streamer structure. Significantly high kinetic temperatures and
outflow velocities were found in the out-of-streamer region above 3.0
R_⊙ for the O vi ions and, for the first time, H i atoms, compared
to those obtained along the streamer boundaries. Moreover, the O vi
kinetic temperatures and velocities turn out much higher than the H
i ones at any heliocentric distance in all the observed regions. A
higher anisotropy is also noticed for the O vi kinetic temperature
in the region flanking the streamer. Conclusions: The slow
coronal wind is found to flow with significantly different speeds and
kinetic temperatures along the boundaries of the streamer and in the
out-of-streamer regions at all heights, above 3.0-3.5 R_⊙. This fact,
consistent with previous studies, indicates that two components of
slow wind probably form in the observed regions: one originates just
above the streamer cusp and flows with velocities a little higher than
100 km s-1, while the other flows along the open magnetic
field lines flanking the streamer with velocities slightly lower than
the slow wind asymptotic heliospheric value of ~400 km s-1,
around 5.0 R_⊙.

---------------------------------------------------------
Title: A C-level flare observed in an arch filament system:
reconnection between pre-existing and emerging field lines?
Authors: Zuccarello, F.; Battiato, V.; Contarino, L.; Guglielmino,
S.; Romano, P.; Spadaro, D.
2008A&A...488.1117Z Altcode:
Context: Observations show that solar flares are often caused by the
emergence of new magnetic flux from subphotospheric layers and by
the interaction of the rising field lines with the ambient magnetic
field. In this framework, recent theoretical models of magnetic
flux emergence have investigated the effectiveness of magnetic
reconnection as a function of the old and new flux system relative
orientations. Aims: We aim to compare phenomena that occurred in
an active region, before and during a small flare, with the effects of
magnetic reconnection between nearly parallel magnetic field lines,
foreseen by these models. Methods: We analyzed high resolution
photospheric and chromospheric data acquired during a coordinated
observational campaign performed with the THEMIS telescope in IPM
mode, as well as MDI magnetograms and TRACE 1600 and 171 Å images, to
investigate the dynamics and the magnetic configuration of the active
region hosting the flare. Results: An emerging arch filament
system (AFS) was observed in the area between the two main sunspots:
it showed typical upward motion at the arch tops and plasma downward
motion at the footpoints. A C-level flare, characterized by a factor
of 3 peak enhancement in the GOES X-ray emission with respect to the
pre-event background, occurred in this zone, where the configuration of
the emerging magnetic field lines showed a small (∼ 12°) relative
inclination with respect to the old flux system. Conclusions:
In an active region (age ≥6 days) a new magnetic flux bundle emerged
between the two main polarity spots. It gave rise to the formation
of pores in the photosphere and to an AFS in the chromosphere. The
interaction between the new and the pre-existing field lines,
characterized by a small relative inclination, might have caused a
weak reconnection process and given rise to the C-level flare. This
result is in broad agreement with numerical simulations predicting
very limited reconnection when the two flux systems have an almost
parallel orientation.

---------------------------------------------------------
Title: Search for photospheric footpoints of quiet Sun transition
region loops
Authors: Sánchez Almeida, J.; Teriaca, L.; Sütterlin, P.; Spadaro,
D.; Schühle, U.; Rutten, R. J.
2007A&A...475.1101S Altcode: 2007arXiv0709.3451S
Context: The footpoints of quiet Sun Transition Region (TR) loops
do not seem to coincide with the photospheric magnetic structures
appearing in traditional low-sensitivity magnetograms. Aims: We
look for the so-far unidentified photospheric footpoints of TR loops
using G-band bright points (BPs) as proxies for photospheric magnetic
field concentrations. Methods: We compare TR measurements with
SoHO/SUMER and photospheric magnetic field observations obtained with
the Dutch Open Telescope. Results: Photospheric BPs are associated
with bright TR structures, but they seem to avoid the brightest parts
of the structure. BPs appear in regions that are globally redshifted,
but they avoid extreme velocities. TR explosive events are not clearly
associated with BPs. Conclusions: The observations are not
inconsistent with the BPs being footpoints of TR loops, although we
have not succeeded to uniquely identify particular BPs with specific
TR loops.

---------------------------------------------------------
Title: Physical parameters of a mid-latitude streamer during the
declining phase of the solar cycle
Authors: Spadaro, D.; Susino, R.; Ventura, R.; Vourlidas, A.; Landi, E.
2007A&A...475..707S Altcode:
Context: Investigating the physical properties of solar coronal
streamers is important for understanding their role in the global
magnetic structure of the extended solar atmosphere, as well as in the
generation of the slow solar wind. Aims: We hope to contribute as
completely as possible to the ongoing SOHO instruments campaign devoted
to the study of the physical characteristics of coronal streamers at
various heliocentric distances. Methods: We analyzed ultraviolet
H I Lyα and O VI resonance doublet lines observed by UVCS/SOHO in
a narrow, mid-latitude streamer structure along different lines
of sight during a week in May 2004 and made nearly simultaneous
white-light polarized brightness measurements from the LASCO/SOHO C2
coronagraph. Results: Electron densities and temperatures, H
I and O VI kinetic temperatures, and outflow velocities were derived
from the line intensities and widths, as well as from the O VI line
intensity ratio in the 1.6-5 R⊙ range of heights, limited
to the central region of the streamer. To our knowledge, the H I outflow
velocities obtained in this work are the first ones determined inside a
streamer structure. They are significantly lower than those of the O VI
ions. This, together with the O VI kinetic temperatures that are much
higher than the H I ones, suggest that the absorption of Alfvén waves
at the ion cyclotron frequency might also occur inside streamers. Conclusions: In comparison with other streamers described in the
literature, the structure examined in this work generally exhibits lower
electron density and neutral hydrogen kinetic temperature. Conversely,
the O VI kinetic temperature and outflow velocity radial profiles are
consistent with the results for the other examined streamers.

---------------------------------------------------------
Title: Study of the interface between coronal holes and streamers
Authors: Noci, Giancarlo; Gavryuseva, Elena; Spadaro, Daniele;
Susino, Roberto
2007AIPC..934..111N Altcode:
A technique to determine slow outflow speeds in the solar corona by
means of the line ratio of the OVI resonance doublet was described in
a previous paper [19]. The application of this technique to a streamer
structure was also described in that paper. We extend here those results
by analyzing two more streamers, both present at the west limb, one on
May 4, 1996, the other on June 5, 1996. We find results which confirm
the previous ones.

---------------------------------------------------------
Title: Plasma motions in a short-lived filament related to a magnetic
flux cancellation
Authors: Zuccarello, F.; Battiato, V.; Contarino, L.; Romano, P.;
Spadaro, D.
2007A&A...468..299Z Altcode:
Context: In recent years the mechanisms responsible for filament
formation and evolution have been investigated by many authors. In
particular, the role played by the processes of magnetic flux
cancellation in building up or destroying filaments is still a matter
of debate. Aims: In this paper we analyze the evolution of an
active region filament that formed in NOAA 10 407 on 14 July 2003,
to investigate the phenomena responsible for its destabilization
and short lifetime (~12 h). Methods: This analysis is based on
high-resolution Hα data acquired by THEMIS operating in IPM mode,
on Hα data acquired at Big Bear Solar Observatory, and on MDI/SOHO
magnetograms. Using these data, we determined the morphological,
dynamical, and magnetic evolution of the filament. Results: The
chromospheric images show two dark surges occurring sequentially in the
northern part of the filament, besides two bright Hα patches located
in the same area; from analysis of the photospheric magnetograms,
we could infer that a magnetic flux cancellation had occurred in
this area. Conclusions: The presence of a cancelling magnetic
feature (CMF) in the same area where the dark Hα surges occurred,
the temporal behavior of the velocity fields in the surges, and the
presence of bright Hα patches in the CMF area, suggest a scenario
where the coronal arcade initially sustaining the filament might have
undergone consecutive reconnection processes. From the concurrence of
these events with the filament activation and successive disappearance,
we believe that the arcade field lines, after the reconnection events,
changed such that the plasma filament was no longer confined in the
arcade: this led to its destabilization and disappearance.

---------------------------------------------------------
Title: Chromospheric and Transition Regions Features in Solar
Like Stars
Authors: Pagano, I.; De Martino, C.; Lanza, A. F.; Spadaro, D.;
Linsky, J. L.
2006ESASP.617E..91P Altcode: 2006soho...17E..91P
No abstract at ADS

---------------------------------------------------------
Title: A Transient Heating Model for the Structure and Dynamics of
the Solar Transition Region
Authors: Spadaro, D.; Lanza, A. F.; Karpen, J. T.; Antiochos, S. K.
2006ApJ...642..579S Altcode:
Understanding the structure and dynamics of the Sun's transition
region has been a major challenge to scientists since the Skylab
era. In particular, the characteristic shape of the emission measure
distribution and the Doppler shifts observed in EUV emission lines
have thus far resisted all theoretical and modeling efforts to explain
their origin. Recent observational advances have revealed a wealth
of dynamic fine-scale structure at transition-region temperatures,
validating earlier theories about the existence of such cool structure
and explaining in part why static models focusing solely on hot,
large-scale loops could not match observed conditions. In response
to this newly confirmed picture, we have investigated numerically the
hydrodynamic behavior of small, cool magnetic loops undergoing transient
heating spatially localized near the chromospheric footpoints. For
the first time we have successfully reproduced both the observed
emission measure distribution over the entire range logT=4.7-6.1 and
the observed temperature dependence of the persistent redshifts. The
closest agreement between simulations and observations is obtained with
heating timescales of the order of 20 s every 100 s, a length scale of
the order of 1 Mm, and energy deposition within the typical range of
nanoflares. We conclude that small, cool structures can indeed produce
most of the quiet solar EUV output at temperatures below 1 MK.

---------------------------------------------------------
Title: SINERGIES (Sun, INterplanetary, EaRth Ground-based InstrumEntS)
or the potential of the Italian Network for Ground-Based Observations
of Sun-Earth Phenomena.
Authors: Amata, E.; Candidi, M.; Centrone, M.; Consolini, G.;
Contarino, L.; Criscuoli, S.; De Lauretis, M.; Diego, P.; Ermolli,
I.; Francia, P.; Giorgi, F.; Laurenza, M.; Magrí, M.; Marcucci, F.;
Massetti, S.; Messerotti, M.; Oliviero, M.; Penza, V.; Perna, C.;
Pietropaolo, E.; Romano, P.; Severino, G.; Spadaro, D.; Storini, M.;
Vellante, M.; Villante, U.; Zlobec, P.; Zuccarello, F.
2006MSAIS...9...82A Altcode:
The Italian Network for Ground-Based Observations of Sun-Earth
Phenomena, whose instruments monitor the Sun, the Interplanetary
Space, and the Earth's Magnetosphere, has recently started to operate
in a coordinated scheme. In this paper, we describe few significant
examples of this coordination effort. 1) During the year 2003, several
coordinated observational campaigns were carried out in order to study
the solar photospheric dynamics. 2) Reconstruction of TSI in time, for
periods spanning from a solar rotation up to the whole current solar
cycle. 3) Extreme solar events occurring during the late October -
early November 2003.

---------------------------------------------------------
Title: From the solar core to the terrestrial magnetosphere:
a progress report on the study of the Sun and solar-terrestrial
relations .
Authors: Spadaro, D.
2006MSAIS...9...43S Altcode:
The knowledge of physical processes occurring in the Sun and heliosphere
has considerably developed in the last decade, particularly owing to the
availability of new and more effective, both ground- and space-based,
instruments of investigation. The Italian contribution in this field
is widely recognized within the international scientific community. The
most recent results have evidenced the crucial role played by magnetic
fields in structuring the solar atmosphere and causing its dynamic
behaviour. Moreover, a considerable interest in studying the alterations
of the terrestrial environment due to interplanetary perturbations
induced by the most energetic phenomena of the magnetic solar activity
(flares, prominence eruptions, coronal mass ejections) has risen in
the last years. The aim of this paper is to review shortly the studies
on the Sun, the heliosphere and the solar-terrestrial relations being
carried out in Italy at the present time, and to outline their future
prospects.

---------------------------------------------------------
Title: Dynamics and evolution of emerging active regions .
Authors: Battiato, V.; Billotta, S.; Contarino, L.; Romano, P.;
Spadaro, D.; Zuccarello, F.
2006MSAIS...9...85B Altcode:
In the framework of the study on active region emergence, we report
the results obtained from the analysis of two ARs (NOAA 10050 and NOAA
10407), characterized by different lifetimes: recurrent the former and
short-lived (7 days) the latter. The data used were acquired during
two observational campaigns carried out at THEMIS telescope in IPM
mode, coordinated with other instruments (IOACT, DOT, BBSO, MDI/SOHO,
EIT/SOHO, TRACE). The results obtained have provided indications on the
atmospheric layers where the first manifestations of the emerging AR
are evidenced, on the rate of emergence of magnetic flux, on the upward
velocity of AFS, on asymmetries in downward motions in the AFS legs.

---------------------------------------------------------
Title: SINERGIES, the Italian Network for Ground-Based Observations
of Sun-Earth Phenomena .
Authors: Amata, E.; Berrilli, F.; Candidi, M.; Cantarano, S.; Centrone,
M.; Consolini, G.; Contarino, L.; Criscuoli, S.; De Lauretis, M.;
Del Moro, D.; Egidi, A.; Ermolli, I.; Francia, P.; Giordano, S.;
Giorgi, F.; Oliviero, M.; Magrí, M.; Marcucci, F.; Massetti, S.;
Messerotti, M.; Parisi, M.; Perna, C.; Pietropaolo, E.; Romano, P.;
Severino, G.; Spadaro, D.; Storini, M.; Vellante, M.; Villante, U.;
Zlobec, P.; Zuccarello, F.
2006MSAIS...9...79A Altcode:
Since many years, the complex phenomena occurring on the Sun have
been continuously monitored by different and complementary ground
based instruments managed by groups of the Italian Astrophysics
Community. Recently some of these instruments have started to operate in
a coordinated scheme, the Italian Network for Ground-Based Observations
of Sun-Earth Phenomena. In this paper, we describe the characteristics
of the nodes belonging to the Network, called SINERGIES, the scientific
objectives, the facilities and the data storage system of the Network
itself. Due to its capabilities, the Network allows the Italian Solar
Terrestrial Physics Community to monitor solar activity and its effect
on the Earth.

---------------------------------------------------------
Title: SOLARNET-Italian Solar Archive Federation. The First Italian
Virtual Observatory Application
Authors: Volpicelli, C. A.; Antonucci, E.; Cora, A.; Giordano, S.;
Messerotti, M.; Santin, A.; Zlobec, P.; Severino, G.; Oliviero, M.;
DeMarino, I.; Alvino, R.; Straus, T.; Ermolli, I.; Centrone, C.;
Perna, C.; Zuccarello, F.; Romano, P.; Spadaro, D.; Contarino, L.
2006MSAIS...9..129V Altcode:
We describe the implementation of the national project SOLARNET (SOLar
ARchive NETwork) aimed at federating the heterogeneous Italian solar
data archives into a VO (Virtual Observatory) framework as a single
integrated database, and providing users with tools to search and
retrieve specific data sets. It interoperates using the SOAP/XML
Web Services exposed by each single node and managed via a unified
Portal.This project is the first real Italian Virtual Observatory
application using the standard defined by the IVOA (International
Virtual Observatory Alliance) working groups.

---------------------------------------------------------
Title: Atmospheric Pressure Anomalies Recorded on Italian Volcanoes:
Possible Relationships With Solar Activity
Authors: Madonia, P.; Gurrieri, S.; Inguaggiato, S.; Giugliano, P.;
Romano, P.; Spadaro, D.; Zuccarello, F.
2005AGUFM.A43C0118M Altcode:
Hourly data of atmospheric pressure are normally recorded in Italian
active volcanoes (Etna, Vesuvius, Stromboli), for environmental and
volcanic hazard monitoring purposes, in ground station networks managed
by the Italian National Institute for Geophysics and Volcanology
(INGV) and Vesuvius National Park. The common characteristic of the
three networks is the presence of two stations, located the lower
in the altitude range 0-300, the higher in the range 1000-1300 m,
that in the cases of Vesuvius and Stromboli coincide with the top of
the volcanoes. Data recorded during the years 2003-2004 have been
first analyzed in order to looking for anomalies due to volcanic
activities. The main result of the preliminary data analysis was
the identification of two main anomalies, not directly linked to
volcanic activity, occurred at the same time on the three volcanoes
at least in two different episodes in the periods September-October,
2003 and July-August, 2004. The main characteristics of the anomalies
was a decoupling of the signal recorded at sea level respect that
one recorded at higher altitudes, evidenced by a dramatic lowering of
the correlation coefficients calculated, on weekly basis, between the
hourly values of atmospheric pressure. These anomalies appear to be
strongly correlated with the level of solar activity, as determined
by the values of the electromagnetic index Kp and of the Wolf number,
the latter one calculated from the sunspot data daily acquired at the
Catania Astrophysical Observatory of the Italian National Institute
for Astrophysics.

---------------------------------------------------------
Title: AFS dynamics in a short-lived active region
Authors: Zuccarello, F.; Battiato, V.; Contarino, L.; Romano, P.;
Spadaro, D.; Vlahos, L.
2005A&A...442..661Z Altcode:
In the framework of the study on active region emergence, we report the
results obtained from the analysis of the short-lived (7 days) active
region NOAA 10407. The data used were acquired during an observational
campaign carried out with the THEMIS telescope in IPM mode in July 2003,
coordinated with other ground- and space-based instruments (INAF-OACT,
DOT, BBSO, MDI/SOHO, EIT/SOHO, TRACE). We determined the morphological
and magnetic evolution of NOAA 10407, as well as the velocity fields
associated with its magnetic structures. Within the limits imposed by
the spatial and temporal resolution of the images analyzed, the first
evidence of the active region formation is initially observed in the
transition region and lower corona, and later on (i.e. after about 7
h) in the inner layers, as found in a previous analysis concerning a
long-lived, recurrent active region. The results also indicate that
the AFS formed in the active region shows typical upward motion at
the AFS's tops and downward motion at the footpoints. The velocity
values relevant to the upward motions decrease over the evolution
of the region, similarly to the case of the recurrent active region,
while we notice an increasing trend in the downflow velocity during
the early phases of the time interval analyzed by THEMIS. On the other
hand, the AFS preceding legs show a higher downflow than the following
ones, a result in contrast with that found in the long-lived active
region. The chromospheric area overhanging the sunspot umbra shows an
upward motion of ∼ 2 km s-1, while that above the pores
shows a downward motion of ~4 km s-1.

---------------------------------------------------------
Title: Streamers and adjacent regions observed by UVCS/SOHO: A
comparison between different phases of solar activity
Authors: Ventura, R.; Spadaro, D.; Cimino, G.; Romoli, M.
2005A&A...430..701V Altcode:
UVCS/SOHO observations of the O VI resonance doublet and H I Lyα
line intensities and profiles, together with measurements of the
visible linearly polarized radiance, have been performed during
two MEDOC campaigns in 1997 and 2000, i.e. near solar minimum and
approaching the solar maximum phase, respectively. During both
observational runs mid-latitude coronal regions in the West limb
of the Sun have been scanned over a range of heliocentric distance
from 1.39 to 4.1 R⊙, to study the plasma properties
of streamers and adjacent regions, such as ion kinetic temperature,
electron density and outflow velocity, paying particular attention
to comparing plasma conditions deduced for different ions in coronal
structures observed on different days and during different phases
of solar activity. Besides confirming some previous findings on
significant differences between open and closed field-line structures
at solar minimum, our results provide some evidence for differences
in kinetic temperature among mid-latitude solar minimum streamers
observed on different days from about 2 R⊙ outwards,
as well as in their dynamical conditions at heliocentric distances
greater than 3.6 R⊙. For observations carried out in 2000,
conversely, the mid-latitude coronal streamers and their surroundings
are about 3 times, and more than one order of magnitude brighter,
respectively, than their solar minimum counterparts and exhibit very
similar kinetic and dynamical conditions. The kinetic temperatures
in adjacent regions are higher than in streamers (by about a factor
of 2) only within 2 R⊙, while at greater heights such
differences vanish, making it difficult to discriminate between open
and closed structures. This is opposite to the behaviour detected at
solar minimum, when adjacent regions appear to be characterized by
kinetic temperatures progressively higher and higher than in streamers
with increasing height, from 2 R⊙ outwards. Therefore, a
clear characterization of open and closed configurations near the solar
maximum might be quite difficult, probably due both to the intrisically
more complex magnetic configuration of the corona in this phase of
the solar activity and the line-of-sight contamination effects that
in a highly structured solar corona may strongly mix background and
foreground plasma with different properties. The transition from the
solar minimum to maximum also seems characterized by a global increase
in the electron density inside streamers of about a factor of 4 at
1.7 R⊙ and then it progressively decreases with height.

---------------------------------------------------------
Title: UVCS/SOHO investigation of the interface between streamers
and coronal holes
Authors: Spadaro, D.; Ventura, R.; Cimino, G.; Romoli, M.
2005A&A...429..353S Altcode:
We investigated the properties of the interface between streamers and
coronal holes at low heliocentric distances, observing the extended
solar corona in the North-West quadrant by UVCS/SOHO. We measured
the line profiles of the H I Lyα and O VI resonance doublet and the
visible linearly polarized radiance at heliocentric distances ranging
from 1.4 to 2.5 R⊙, and colatitudes spanning from the
North pole to the West equator with steps of ∼10°. The results
show that both the line intensities and the line widths, in particular
those of O VI, exhibit sharp variations across the streamer boundaries,
with a clear anticorrelation between intensities and widths. We also
notice a positive correlation for Lyα in the region close to the
equator. The steep changes in O VI line profiles occur in a narrow
transition region (5°- 10°), right at the borders of the streamers,
from 1.5 R⊙ onwards. The O VI resonance doublet line ratio
steeply increases outside of the streamer as well, but this occurs
at higher heliocentric distances (above 2 R⊙). Hence
the marked broadening of the O VI lines and the considerable rise of
their intensity ratio are an evident signature of the transition from
closed to open field lines in streamer magnetic field topologies. This
behaviour also implies that a strong and preferential non-thermal
heating of O VI ions in the direction coinciding with the line of sight
and the turn-on of a significant outflow occur in the open magnetic
field region near or just outside of the streamer edges. Figures
\ref{Fig2}, \ref{Fig4}-\ref{Fig6} and \ref{Fig8}-\ref{Fig10} are only
available in electronic form at http://www.edpsciences.org

---------------------------------------------------------
Title: AFS dynamic evolution during the emergence of an active region
Authors: Spadaro, D.; Billotta, S.; Contarino, L.; Romano, P.;
Zuccarello, F.
2004A&A...425..309S Altcode:
Using data acquired during an observational campaign carried out at
the THEMIS telescope in IPM mode, coordinated with other ground- and
space-based instruments (IOACT, TRACE, EIT/SOHO, MDI/SOHO), we have
analyzed the first evolutionary phases of a recurrent active region
(NOAA 10050), in order to study the morphology and dynamics of its
magnetic structures during their emergence and early development. The
main result obtained from this analysis concerns the dynamic evolution
of the arch filament system (AFS) crossing the polarity inversion line:
the line of sight velocities determined from Doppler measurements
confirm that the loops forming the AFS show an upward motion at their
tops and a downward motion at their extremities, but also indicate that
the upward motion decreases while the active region develops. Moreover,
it has been found that, within the limits of the temporal cadence
and spatial resolution of the instruments used, the first evidence of
the active region formation is initially observed in the transition
region and lower corona, and later on (i.e. after about 6 h) in the
inner layers (chromosphere and photosphere). Another interesting
result concerns the analysis of the magnetograms, indicating that the
initial increase in the magnetic flux seems to be synchronous with the
appearance od the active region appearance in the transition region
and lower corona, and that the rate of increase of the magnetic flux
during the formation of the active region is not constant, but is
steeper at the beginning (i.e. during the first 150 h) than in the
following period. All these results may indicate the presence of some
mechanism that decelerates the magnetic flux emergence as more and
more flux tubes rise towards higher atmospheric layers. Finally, we
would like to stress the observed asymmetries between the preceding
and the following sides of NOAA 10050: the p-side is more extented
than the f-side, the p-side moves forward from the initial outbreak
position much faster than the f-side recedes; the AFS f-side exhibits
higher downflows than the p-side.

---------------------------------------------------------
Title: Structure and dynamics of magnetic loops in the solar corona
Authors: Spadaro, D.
2003MSAIS...3...30S Altcode:
This paper is a short review of the principal results obtained by the
investigations concerning the physical structure and the dynamics
of coronal magnetic loops, and put into particular evidence the
interesting contribution given to these studies by the most recent
space missions. It also indicates the principal constraints on the
theoretical/numerical models of magnetic loops that arise from these
new findings.

---------------------------------------------------------
Title: Simulations of transiently heated solar coronal loops
Authors: Spadaro, D.; Lanza, A. F.
2003MmSAI..74..687S Altcode:
This is a short summary of a paper recently published in The
Astrophysical Journal. We investigate the hydrodynamic behaviour
of coronal loops undergoing transient heating. We adopt a 1-D loop
model with space- and time-dependent heating, concentrated near the
chromospheric footpoints. The timescale of heating variations is
comparable with the radiative cooling time of the coronal plasma ( ~
103 s). We describe the temporal behaviour of the various
physical quantities (plasma density, temperature, flow velocity)
along some modelled loops with different heating terms.

---------------------------------------------------------
Title: A Transient Heating Model for Coronal Structure and Dynamics
Authors: Spadaro, D.; Lanza, A. F.; Lanzafame, A. C.; Karpen, J. T.;
Antiochos, S. K.; Klimchuk, J. A.; MacNeice, P. J.
2003ApJ...582..486S Altcode:
A wealth of observational evidence for flows and intensity variations in
nonflaring coronal loops leads to the conclusion that coronal heating
is intrinsically unsteady and concentrated near the chromosphere. We
have investigated the hydrodynamic behavior of coronal loops undergoing
transient heating with one-dimensional numerical simulations in which
the timescale assumed for the heating variations (3000 s) is comparable
to the coronal radiative cooling time and the assumed heating location
and scale height (10 Mm) are consistent with the values derived from
TRACE studies. The model loops represent typical active region loops:
40-80 Mm in length, reaching peak temperatures up to 6 MK. We use ARGOS,
our state-of-the-art numerical code with adaptive mesh refinement, in
order to resolve adequately the dynamic chromospheric-coronal transition
region sections of the loop. The major new results from our work are
the following: (1) During much of the cooling phase, the loops exhibit
densities significantly larger than those predicted by the well-known
loop scaling laws, thus potentially explaining recent TRACE observations
of overdense loops. (2) Throughout the transient heating interval,
downflows appear in the lower transition region (T~0.1 MK) whose key
signature would be persistent, redshifted UV and EUV line emission,
as have long been observed. (3) Strongly unequal heating in the two
legs of the loop drives siphon flows from the more strongly heated
footpoint to the other end, thus explaining the substantial bulk flows
in loops recently observed by the Coronal Diagnostic Spectrometer and
the Solar Ultraviolet Measurement of Emission Radiation instrument. We
discuss the implications of our studies for the physical origins of
coronal heating and related dynamic phenomena.

---------------------------------------------------------
Title: EUV Line Emission from Coronal Loop Models in Thermal
Non-equilibrium
Authors: Lanza, A. F.; Spadaro, D.; Lanzafame, A. C.; Karpen, J. T.
2002ASPC..277..521L Altcode: 2002sccx.conf..521L
No abstract at ADS

---------------------------------------------------------
Title: Hydrodynamics of coronal loops undergoing transient heating
Authors: Spadaro, D.; Lanza, A. F.; Lanzafame, A. C.; Karpen, J. T.;
Antiochos, S. K.; MacNeice, P. J.
2002ASPC..277..597S Altcode: 2002sccx.conf..597S
No abstract at ADS

---------------------------------------------------------
Title: Erratum: UV line intensity and flow velocity distributions
in two coronal mass ejections as deduced by UVCS-SOHO observations
Authors: Ventura, R.; Spadaro, D.; Uzzo, M.; Suleiman, R.
2002A&A...395..975V Altcode:
This article has been misprinted. Following this page the article will
be printed again with its original page numbers.

---------------------------------------------------------
Title: Hydrodynamic models of transiently heated coronal loops
Authors: Spadaro, D.; Lanza, A. F.; Lanzafame, A. C.; Karpen, J. T.;
Antiochos, S. K.; Klimchuk, J. A.; MacNeice, P. J.
2002ESASP.505..583S Altcode: 2002solm.conf..583S; 2002IAUCo.188..583S
We investigate the hydrodynamic behaviour of coronal loops
undergoing transient heating. We adopt a 1-D loop model with space-
and time-dependent heating, concentrated near the chromospheric
footpoints. The timescale of heating variations is comparable with the
radiative cooling time of the coronal plasma (~103s). We
use a new numerical code that has a fully adaptive grid, in order to
properly resolve the chromospheric-coronal transition region sections of
the loop. We simulate here the hydrodynamics of a loop with different
effective gravity (i.e., loop geometry) and heating terms. We describe
the temporal behaviour of the various physical quantities along the
loop (plasma density, temperature, flow velocity), showing that the
increase in heating produces a chromospheric evaporation, or a siphon
flow if the loop heating is taken to be significantly different at
the two footpoints, followed by long-lasting downflows with velocities
of a few km s-1 during the quiescent phases in between the
episodic heatings. Moreover, in the case of considerable increase in
heating, a catastrophic cooling of the loop plasma can occur, giving
rise to downflows of several tens of km s-1.

---------------------------------------------------------
Title: Hydrodynamic simulations of coronal loops subject to transient
heating
Authors: Spadaro, D.; Lanza, A. F.; Lanzafame, A. C.; Karpen, J. T.;
MacNeice, P. J.; Antiochos, S. K.; Klimchuk, J. A.
2002ESASP.508..331S Altcode: 2002soho...11..331S
We investigate the hydrodynamic behaviour of coronal loops
undergoing transient heating. We adopt a 1-D loop model with space-
and time-dependent heating, concentrated near the chromospheric
footpoints. The timescale of heating variations is comparable with the
radiative cooling time of the coronal plasma (~103s). We
use a new numerical code that has a fully adaptive grid, in order to
properly resolve the chromospheric-coronal transition region sections of
the loop. We simulate here the hydrodynamics of a loop with different
effective gravity (i.e., loop geometry) and heating terms. We describe
the temporal behaviour of the various physical quantities along the loop
(plasma density,temperature, flow velocity), showing that the increase
in heating produces a chromospheric evaporation, or a siphon flow if
the loop heating is taken to be significantly different at the two
footpoints, followed by long-lasting downflows with velocities of a few
km s-1 during the quiescent phases in between the episodic
heatings. Moreover, in the case of considerable increase in heating,
a thermal instability can occur during the cooling phase of the loop
plasma, giving rise to downflows of several tens of km s-1.

---------------------------------------------------------
Title: UV line intensity and flow velocity distributions in two
coronal mass ejections as deduced by UVCS-SOHO observations
Authors: Ventura, R.; Spadaro, D.; Uzzo, M.; Suleiman, R.
2002A&A...383.1032V Altcode:
The Ultraviolet Coronagraph Spectrometer (UVCS) instrument onboard the
SOHO satellite observed two coronal mass ejections on November 2 and
3, 2000, related to the eruptions of a large filament structure in an
active region close to the West limb of the Sun, and of a prominence
near the South Pole, respectively. Intensity and profile of the O
VI resonance doublet lines at 1032 and 1037 Å and of Lybeta (1026
Å) line, together with the intensity of some other minor ions, were
observed using the O VI channel of UVCS. We analysed these spectroscopic
observations in order to get information about the distributions
of ionic densities and flow velocities in the solar coronal plasma
ejected during these transient events. Emission in ions ranging from
C II to O VI indicates a temperature range between 104.5
and 105.5 K. The morphology of the bright emission regions
suggests the development of several strands of plasma irregularly
distributed inside the CME structures, whose temporal evolution is
significantly different from each other. The velocities determined
for each bright element also give a complex picture of the plasma
kinematics characterizing these coronal mass ejections.

---------------------------------------------------------
Title: The Helium Focusing Cone of the Local Interstellar Medium
Close to the Sun
Authors: Michels, J. G.; Raymond, J. C.; Bertaux, J. L.; Quémerais,
E.; Lallement, R.; Ko, Y. -K.; Spadaro, D.; Gardner, L. D.; Giordano,
S.; O'Neal, R.; Fineschi, S.; Kohl, J. L.; Benna, C.; Ciaravella,
A.; Romoli, M.; Judge, D.
2002ApJ...568..385M Altcode:
The Solar and Heliospheric Observatory (SOHO) Ultraviolet Coronagraph
Spectrometer is used to observe the interplanetary He focusing cone
within 1 AU. Taken over 2 yr and from differing orbit positions, the
series of observations includes measurements of He I 584 Å and Lyβ
intensities. The cone itself is spatially well defined, and the He I
intensity within the cone was ~45 R in 1996 December, compared with
~1 R for lines of sight outward from 1 AU. Between 1996 December and
1998 June, the focusing cone dimmed by a factor of 3.3 as the level of
solar activity rose. This is the first time that interstellar helium
is observed so near the Sun. Measured intensities are compared to a
detailed temperature and density model of interstellar helium in the
solar system. The model includes EUV ionization but does not include
ionization by electron impact from solar wind electrons. There are
several features in the data model comparison that we attribute to
the absence of electron impact ionization in the model. The absolute
maximum intensity of 45 R first measured in 1996 December calls for
an ionization 45% more intense than the EUV photoionization alone as
measured by the Solar EUV Monitor/Charge, Element, and Isotope Analysis
System (SEM/CELIAS) on SOHO. Important day-to-day variations of the
intensity are observed, as well as a general decrease as the solar
activity rises (both absolute and divided by a model with a constant
ionization). This general decrease is even larger than predicted by a
model run with the SEM/CELIAS photoionization rate alone, in spite of a
factor of 1.5 increase of this rate from 1996 December to 1998 June. At
this time, an additional ionization rate of 0.56×10-7
s-1 (compared with 1.00×10-7 s-1 from
solar EUV) is required to fit the measured low intensity. We attribute
this additional rate to solar wind electron impact ionization of the
atoms. This shows that the helium intensity pattern is a very sensitive
indicator of the electron density and temperature near the Sun.

---------------------------------------------------------
Title: Hydrodynamics of coronal loops subject to transient heating
Authors: Spadaro, D.; Lanza, A. F.; Lanzafame, A. C.; Karpen, J. T.;
MacNeice, P. J.; Antiochos, S. K.
2001ESASP.493..367S Altcode: 2001sefs.work..367S
No abstract at ADS

---------------------------------------------------------
Title: Extreme-Ultraviolet Transition-Region Line Emission during
the Dynamic Formation of Prominence Condensations
Authors: Lanza, Antonino F.; Spadaro, Daniele; Lanzafame, Alessandro
C.; Antiochos, Spiro K.; MacNeice, Peter J.; Spicer, Daniel S.;
O'Mullane, Martin G.
2001ApJ...547.1116L Altcode:
We calculated the emission expected in EUV transition-region lines
during the process of dynamic formation of prominence condensations
in coronal loops, as predicted by the thermal nonequilibrium model of
Antiochos et al. We selected some lines emitted by ions of carbon and
oxygen because they are among the most intense and representative
in the temperature range corresponding to the solar transition
region. We present and discuss the principal characteristics of
the line intensities and profiles synthesized from the hydrodynamic
model at different times during the loop evolution. The ionization
balance is computed in detail and the deviations from the ionization
equilibrium caused by plasma flows and variations of temperature
and density are accounted for. The atomic physics is treated
using the latest atomic coefficients and the collisional-radiative
theory approach. The synthesized carbon and oxygen lines exhibit
a behavior significantly dependent on the variations of the plasma
parameters inside the magnetic flux tube and therefore are suitable
observational signatures of the processes giving rise to prominence
condensations. In particular, a sizeable increase of line intensity as
well as small blueshifts are expected from the loop footpoints during
the first part of the evaporation phase that fills the loop with the
material which subsequently condenses into the prominence. Once the
condensation appears, line intensities decrease in the footpoints and
simultaneously increase at the transition regions between the cool
plasma of the condensation and the coronal portion of the loop. Line
shifts are quite small in our symmetric model, and during most of
the condensation's lifetime, the nonthermal widths are relatively
small. These results can be compared with detailed ultraviolet
observations of filament/prominence regions obtained by recent space
missions in order to test the model proposed for the formation of
solar prominences.

---------------------------------------------------------
Title: Velocity Fields in an Active Region Loop System Observed on
the Solar Disc with SUMER/SOHO (CD-ROM Directory: contribs/lanzafam)
Authors: Lanzafame, A. C.; Spadaro, D.; Consoli, L.; Marsch, E.;
Brooks, D. H.
2001ASPC..223..691L Altcode: 2001csss...11..691L
No abstract at ADS

---------------------------------------------------------
Title: EUV line emission during the dynamic formation of prominence
condensations
Authors: Spadaro, D.; Lanza, A. F.; Lanzafame, A. C.; Antiochos,
S. K.; O'Mullane, M. G.
2001MmSAI..72..591S Altcode:
This contribution is a short summary of a paper recently submitted
to Astrophysical Journal. We calculated the emission expected in
EUV transition region lines during the process of dynamic formation
of prominence condensations in coronal loops, as predicted by the
thermal non-equilibrium model proposed by Antiochos et al. We present
and discuss the principal characteristics of the line intensities and
profiles synthesized from the hydrodynamic model at different times
during the loop evolution.

---------------------------------------------------------
Title: Structure and dynamics of an active region loop system observed
on the solar disc with SUMER on SOHO
Authors: Spadaro, D.; Lanzafame, A. C.; Consoli, L.; Marsch, E.;
Brooks, D. H.; Lang, J.
2000A&A...359..716S Altcode:
In this paper we present and discuss spectra obtained by SUMER on SOHO
from an active region loop system observed on the solar disc, close to
the central meridian, on July 26th, 1996. The region was observed with a
spatial resolution of about 2arcsec by 2arcsec in emission lines forming
in the transition region and inner corona, with the aim of investigating
the physical structure and dynamical behaviour of the plasma in active
region magnetic loops. To this purpose we have reduced and analysed the
spectral observations in order to determine the values of intensity,
Doppler shift and line profile width for the selected emission lines
in all the spatially resolved elements of the examined area of the
solar disc. By comparing intensity, velocity maps and photospheric
magnetic fields obtained by MDI on SOHO, several magnetic loops have
been identified, some of which contemporarily appear over a range of
temperatures, while others are compact and only visible in a limited
temperature range. A few loops exhibit velocity fields typical of siphon
flows, the siphon-like velocities being higher in compact loops. Two
compact loops seen in the transition region lines show asymmetric
siphon-like velocity fields and high non-thermal velocities at the
upflowing footpoint. High non-thermal velocities are also associated
with the falling footpoint of a larger loop. Besides such loops, other
bright features are observed in the transition region lines, whose
morphology cannot be identified as arch-like. They have no coronal
counterpart, are red-shifted with respect to the median line centroid
position and exhibit high non-thermal velocities.

---------------------------------------------------------
Title: Waves and Plasma Motions in the Transition Region and Corona:
the Observational Point of View
Authors: Spadaro, D.
1999ESASP.448..157S Altcode: 1999ESPM....9..157S; 1999mfsp.conf..157S
No abstract at ADS

---------------------------------------------------------
Title: Fast solar wind acceleration by Alfvén waves: observable
effects on the EUV lines detected by SOHO/UVCS
Authors: Ventura, R.; Orlando, S.; Peres, G.; Spadaro, D.
1999A&A...352..670V Altcode:
SOHO/UVCS observations of the most intense EUV spectral lines emitted by
the solar corona have been providing us a good opportunity to study in
detail the acceleration regions of the solar wind. In this work we aim
at deriving useful diagnostics and identifying possible signatures of
Alfvén waves momentum deposition. More specifically we investigate,
with the help of a detailed wind model (Orlando et al. 1996), the
insight and the constraints that these observations give on the presence
of Alfvén waves, as deduced from the influence of the waves on the
solar wind structure and dynamics. The model developed by Orlando et
al. (1996) accounts for the momentum deposition by a spectrum of non-WKB
Alfvén waves, generated in the Sun's lower atmosphere and undergoing
significant reflection across the transition region. We compute a
set of wind solutions characterized by different physical conditions,
synthesize, from them, the emission in the Lyalpha , Lybeta and O VI
doublet (1032 Ä, 1038 Ä) lines and derive possible diagnostics. We
finally compare our results with the most recent SOHO/UVCS data.

---------------------------------------------------------
Title: Working Group 2: Structure and Role of the Transition Region
Authors: Spadaro, D.
1999ESASP.446...75S Altcode: 1999soho....8...75S
No abstract at ADS

---------------------------------------------------------
Title: Dynamical Properties Of An Active Region Loop System Observed
On The Solar Disc With SUMER/SOHO
Authors: Lanzafame, A. C.; Spadaro, D.; Consoli, L.; Marsch, E.;
Brooks, D. H.
1999ESASP.446..429L Altcode: 1999soho....8..429L
In this paper we present and discuss spectra obtained by SUMER from
an active region loop system observed on the solar disc, close to
the central meridian. This region has been observed with a spatial
resolution of about 2” by 2” in emission lines formed in the
transition region and inner corona. Our aim is to investigate the
physical structure and dynamical behaviour of the plasma in the
transition region portion of the magnetic loops. To this purpose,
we have reduced and analysed the spectral observations in order to
determine the values of intensity, Doppler shift and line profile
width for the selected emission lines in all the spatially resolved
elements of the examined area of the solar disc. These data have
been used to locate the coronal structures within the observed active
region and to identify their morphology. They have also been used to
include a study of the spatial relationship between loops as seen in
spectral lines formed at different temperatures. As far as the data
relating to the line profiles are concerned, they have been analysed
with the purpose of examining indications of the presence of resolved
mass motions inside the active region and also for investigating the
non-thermal broadening of the lines, which is usually attributed to
microturbulence and probably related to the heating mechanisms working
in these layers of the solar atmosphere. We have also explored the
possibility of correlations amongst the line intensities, Doppler
shifts and microturbulence velocities, which might help us to gain
insight into the physical processes occurring in active regions,
particularly in the transition region portion of magnetic loops.

---------------------------------------------------------
Title: The Study of the Solar Atmosphere in the UV Band: the Italian
Contribution
Authors: Spadaro, D.
1999MmSAI..70..391S Altcode:
No abstract at ADS

---------------------------------------------------------
Title: An Empirical Model of a Polar Coronal Hole at Solar Minimum
Authors: Cranmer, S. R.; Kohl, J. L.; Noci, G.; Antonucci, E.;
Tondello, G.; Huber, M. C. E.; Strachan, L.; Panasyuk, A. V.;
Gardner, L. D.; Romoli, M.; Fineschi, S.; Dobrzycka, D.; Raymond,
J. C.; Nicolosi, P.; Siegmund, O. H. W.; Spadaro, D.; Benna, C.;
Ciaravella, A.; Giordano, S.; Habbal, S. R.; Karovska, M.; Li, X.;
Martin, R.; Michels, J. G.; Modigliani, A.; Naletto, G.; O'Neal,
R. H.; Pernechele, C.; Poletto, G.; Smith, P. L.; Suleiman, R. M.
1999ApJ...511..481C Altcode:
We present a comprehensive and self-consistent empirical model
for several plasma parameters in the extended solar corona above
a polar coronal hole. The model is derived from observations
with the SOHO Ultraviolet Coronagraph Spectrometer (UVCS/SOHO)
during the period between 1996 November and 1997 April. We compare
observations of H I Lyα and O VI λλ1032, 1037 emission lines
with detailed three-dimensional models of the plasma parameters and
iterate for optimal consistency between measured and synthesized
observable quantities. Empirical constraints are obtained for
the radial and latitudinal distribution of density for electrons,
H0, and O5+, as well as the outflow velocity
and unresolved anisotropic most probable speeds for H0 and
O5+. The electron density measured by UVCS/SOHO is consistent
with previous solar minimum determinations of the white-light coronal
structure; we also perform a statistical analysis of the distribution
of polar plumes using a long time series. From the emission lines we
find that the unexpectedly large line widths of H0 atoms
and O5+ ions at most heights are the result of anisotropic
velocity distributions. These distributions are not consistent with
purely thermal motions or the expected motions from a combination of
thermal and transverse wave velocities. Above 2 Rsolar,
the observed transverse most probable speeds for O5+ are
significantly larger than the corresponding motions for H0,
and the outflow velocities of O5+ are also significantly
larger than the corresponding velocities of H0. Also, the
latitudinal dependence of intensity constrains the geometry of the
wind velocity vectors, and superradial expansion is more consistent
with observations than radial flow. We discuss the constraints and
implications on various theoretical models of coronal heating and
acceleration.

---------------------------------------------------------
Title: Wavelength shifts of emission line profiles due to velocity
fields in the solar corona
Authors: Ventura, R.; Spadaro, D.
1999A&A...341..264V Altcode:
We have investigated the dependence of the wavelength shift of the
coronal emission line profiles on the line of sight velocity of the
emitting plasma. The results of our numerical calculations point out
that, while the wavelength shift of the collisionally excited component
of the line is related to the line of sight velocity by the usual
formula for the Doppler effect, that of the resonantly scattered
component also depends on the angle of scatter and on the angle
between the velocity vector and the line of sight. For the same outflow
velocity, the absolute value of the resonantly scattered component shift
is significantly smaller than that of the collisional component. Since
both mechanisms generally contribute to the formation of a coronal
line, we conclude that the results of this work should be taken into
account when deducing line of sight velocities from the analysis of
emission line profiles observed in the extended solar corona.

---------------------------------------------------------
Title: UVCS/SOHO Empirical Determinations of Anisotropic Velocity
Distributions in the Solar Corona
Authors: Kohl, J. L.; Noci, G.; Antonucci, E.; Tondello, G.; Huber,
M. C. E.; Cranmer, S. R.; Strachan, L.; Panasyuk, A. V.; Gardner,
L. D.; Romoli, M.; Fineschi, S.; Dobrzycka, D.; Raymond, J. C.;
Nicolosi, P.; Siegmund, O. H. W.; Spadaro, D.; Benna, C.; Ciaravella,
A.; Giordano, S.; Habbal, S. R.; Karovska, M.; Li, X.; Martin, R.;
Michels, J. G.; Modigliani, A.; Naletto, G.; O'Neal, R. H.; Pernechele,
C.; Poletto, G.; Smith, P. L.; Suleiman, R. M.
1998ApJ...501L.127K Altcode:
We present a self-consistent empirical model for several plasma
parameters of a polar coronal hole near solar minimum, derived from
observations with the Solar and Heliospheric Observatory Ultraviolet
Coronagraph Spectrometer. The model describes the radial distribution of
density for electrons, H0, and O5+ and the outflow
velocity and unresolved most probable velocities for H0
and O5+ during the period between 1996 November and 1997
April. In this Letter, we compare observations of H I Lyα and O
VI λλ1032, 1037 emission lines with spatial models of the plasma
parameters, and we iterate for optimal consistency between measured and
synthesized observable quantities. The unexpectedly large line widths
of H0 atoms and O5+ ions at most radii are the
result of anisotropic velocity distributions, which are not consistent
with purely thermal motions or the expected motions from a combination
of thermal and transverse wave velocities. Above 2 Rsolar,
the observed transverse, most probable speeds for O5+ are
significantly larger than the corresponding motions for H0,
and the outflow velocities of O5+ are also significantly
larger than the corresponding velocities of H0. We discuss
the constraints and implications on various theoretical models of
coronal heating and acceleration.

---------------------------------------------------------
Title: Effects of gravity in the models of siphon-flow stationary
loops
Authors: Arcifa, D.; Spadaro, D.; Zappalà, R. A.
1998MmSAI..69..711A Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Momentum deposition by a spectrum of Alfvén waves in fast
solar wind: effects on the emission lines observed by SOHO/UVCS
Authors: Orlando, S.; Ventura, R.; Peres, G.; Spadaro, D.
1998MmSAI..69..777O Altcode:
No abstract at ADS

---------------------------------------------------------
Title: An analysis of the unresolved fine structure model for the
solar transition region
Authors: Lanza, A. F.; Spadaro, D.; Antiochos, S. K.
1998MmSAI..69..695L Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Space observations of the source regions of the solar wind:
implications for the acceleration mechanisms
Authors: Spadaro, D.
1998MmSAI..69..677S Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Emission line wavelength shift dependence on velocity fields
in the solar corona
Authors: Ventura, R.; Spadaro, D.
1998MmSAI..69..707V Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Velocity Fields in the Solar Corona during Mass Ejections as
Observed with UVCS-SOHO
Authors: Antonucci, E.; Kohl, J. L.; Noci, G.; Tondello, G.; Huber,
M. C. E.; Gardner, L. D.; Nicolosi, P.; Giordano, S.; Spadaro, D.;
Ciaravella, A.; Raymond, C. J.; Naletto, G.; Fineschi, S.; Romoli, M.;
Siegmund, O. H. W.; Benna, C.; Michels, J.; Modigliani, A.; Panasyuk,
A.; Pernechele, C.; Smith, P. L.; Strachan, L.; Ventura, R.
1997ApJ...490L.183A Altcode:
This Letter presents the observations of the first two coronal mass
ejections (CMEs) obtained with the Ultraviolet Coronagraph Spectrometer
of SOHO. Both CMEs were observed at high spectral resolution in the
ultraviolet domain. The first event on 1996 June 6-7 was observed in H I
Lyα λ1216 and Lyβ λ1026, O VI λλ1032 and 1037, Si XII λλ499 and
521 and imaged within 1.5 and 5 Rsolar. The second event on
1996 December 23 was observed in several H I lines and cool lines such
as C III λ977, N III λλ990-992, and O V λ630. The analysis of line
profiles has allowed us to determine the line-of-sight velocities of the
extended corona during a mass ejection. In particular there is evidence
for mass motions consistent with untwisting magnetic fields around an
erupted flux tube in one of the events and line of sight velocities of
200 km s-1 in the early phase of the second event presumably
related to the expansion of the leading arch of the transient.

---------------------------------------------------------
Title: Composition of Coronal Streamers from the SOHO Ultraviolet
Coronagraph Spectrometer
Authors: Raymond, J. C.; Kohl, J. L.; Noci, G.; Antonucci, E.;
Tondello, G.; Huber, M. C. E.; Gardner, L. D.; Nicolosi, P.; Fineschi,
S.; Romoli, M.; Spadaro, D.; Siegmund, O. H. W.; Benna, C.; Ciaravella,
A.; Cranmer, S.; Giordano, S.; Karovska, M.; Martin, R.; Michels, J.;
Modigliani, A.; Naletto, G.; Panasyuk, A.; Pernechele, C.; Poletto,
G.; Smith, Peter L.; Suleiman, R. M.; Strachan, L.
1997SoPh..175..645R Altcode:
The Ultraviolet Coronagraph Spectrometer on the SOHO satellite covers
the 940-1350 Å range as well as the 470-630 Å range in second
order. It has detected coronal emission lines of H, N, O, Mg, Al, Si,
S, Ar, Ca, Fe, and Ni, particularly in coronal streamers. Resonance
scattering of emission lines from the solar disk dominates the
intensities of a few lines, but electron collisional excitation produces
most of the lines observed. Resonance, intercombination and forbidden
lines are seen, and their relative line intensities are diagnostics
for the ionization state and elemental abundances of the coronal gas.

---------------------------------------------------------
Title: First Results from the SOHO Ultraviolet Coronagraph
Spectrometer
Authors: Kohl, J. L.; Noci, G.; Antonucci, E.; Tondello, G.; Huber,
M. C. E.; Gardner, L. D.; Nicolosi, P.; Strachan, L.; Fineschi, S.;
Raymond, J. C.; Romoli, M.; Spadaro, D.; Panasyuk, A.; Siegmund,
O. H. W.; Benna, C.; Ciaravella, A.; Cranmer, S. R.; Giordano, S.;
Karovska, M.; Martin, R.; Michels, J.; Modigliani, A.; Naletto, G.;
Pernechele, C.; Poletto, G.; Smith, P. L.
1997SoPh..175..613K Altcode:
The SOHO Ultraviolet Coronagraph Spectrometer (UVCS/SOHO) is being
used to observe the extended solar corona from 1.25 to 10 R⊙ from
Sun center. Initial observations of polar coronal holes and equatorial
streamers are described. The observations include measurements of
spectral line profiles for HI Lα and Lβ, Ovi 1032 Å and 1037 Å,
Mgx 625 Å, Fexii 1242 Å and several others. Intensities for Mgx
610 Å, Sixii 499 Å, and 520 Å, Sx 1196 Å, and 22 others have been
observed. Preliminary results for derived H0, O5+,
Mg9+, and Fe11+ velocity distributions and initial
indications of outflow velocities for O5+ are described. In
streamers, the H0 velocity distribution along the line of
sight (specified by the value at e-1, along the line of
sight) decreases from a maximum value of about 180 km s-1
at 2 R⊙ to about 140 km s-1 at 8 R⊙. The value for
O5+ increases with height reaching a value of 150 km
s-1 at 4.7 R⊙. In polar coronal holes, the O5+
velocity at e-1 is about equal to that of H0
at 1.7 R⊙ and significantly larger at 2.1 R⊙. The O5+
in both streamers and coronal holes were found to have anisotropic
velocity distributions with the smaller values in the radial direction.

---------------------------------------------------------
Title: Evidence of untwisting magnetic fields in the Coronal Mass
Ejections of June 7, 1996
Authors: Antonucci, E.; Giordano, S.; Noci, G.; Kohl, J. K.; Spadaro,
D.; Benna, C.
1997BAAS...29R1120A Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Optical performances of the Ultraviolet Coronagraph
Spectrometer of the Solar Heliospheric Observatory
Authors: Pernechele, Claudio; Naletto, Giampiero; Nicolosi,
Piergiorgio; Tondello, Giuseppe; Fineschi, Silvano; Romoli, Marco;
Noci, Giancarlo; Spadaro, Daniele; Kohl, John L.
1997ApOpt..36..813P Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Measurements of H I and O VI velocity distributions in the
extended solar corona with UVCS/SOHO and UVCS/Spartan 201
Authors: Kohl, J. H.; Noci, G.; Antonucci, E.; Tondello, G.; Huber,
M. C. E.; Gardner, L. D.; Nicolosi, P.; Fineschi, S.; Raymond, J. C.;
Romoli, M.; Spadaro, D.; Siegmund, O. H. W.; Benna, C.; Ciaravella,
A.; Cranmer, S. R.; Giordano, S.; Karovska, M.; Martin, R.; Michels,
J.; Modigliani, A.; Naletto, G.; Panasyuk, A.; Pernechele, C.; Poletto,
G.; Smith, P. L.; Strachan, L.
1997AdSpR..20....3K Altcode:
The Ultraviolet Coronagraph Spectrometer on the Solar and Heliospheric
Observatory, UVCS/SOHO, and the Ultraviolet Coronal Spectrometer on
the Spartan 201 satellite, UVCS/Spartan, have been used to measure
H I 1215.67 A˚ line profiles in polar coronal holes of the Sun at
projected heliocentric heights between 1.5 and 3.0 R_solar. UVCS/SOHO
also measured line profiles for H I 1025.72 A˚, O VI 1032/1037 A˚,
and Mg X 625 A˚. The reported UVCS/SOHO observations were made between
5 April and 21 June 1996 and the UVCS/Spartan observations were made
between 11 and 12 April 1993. Both sets of measurements indicate that a
significant fraction of the protons along the line of sight in coronal
holes have velocities larger than those for a Maxwellian velocity
distribution at the expected electron temperature. Most probable
speeds for O^5+ velocity distributions along the lines of sight are
smaller than those of H^0 at 1.5 R_solar, are comparable at about 1.7
R_solar and become significantly larger than the H^0 velocities above
2 R_solar. There is a tendency for the O^5+ line of sight velocity
distribution in concentrations of polar plumes to be more narrow than
those in regions away from such concentrations. UVCS/SOHO has identified
31 spectral lines in the extended solar corona.

---------------------------------------------------------
Title: First Results from UVCS: Dynamics of the Extended Corona
Authors: Antonucci, E.; Noci, G.; Kohl, J. L.; Tondello, G.; Huber,
M. C. E.; Giordano, S.; Benna, C.; Ciaravella, A.; Fineschi, S.;
Gardner, L. D.; Martin, R.; Michels, J.; Naletto, G.; Nicolosi, P.;
Panasyuk, A.; Raymond, C. J.; Romoli, M.; Spadaro, D.; Strachan, L.;
van Ballegooijen, A.
1997ASPC..118..273A Altcode: 1997fasp.conf..273A
The Ultraviolet Coronagraph Spectrometer (UVCS) started to observe
the Sun at the end of January 1996. Here we present a selection of
results obtained with the UVCS in the first months of operation. UV
spectral line profiles in coronal holes, and in general in regions
with open magnetic field lines, are much broader than in closed
field line regions; that is, line-of-sight velocities are much
larger in open field lines . Polar plumes have narrower profiles
than interplume regions. The O VI ratio diagnostics indicates that in
polar coronal holes the outflow velocity is progressively increasing
with heliodistance and exceeds 100 km/sec near 2--2.5 solar radii. A
coronal mass ejection observation has revealed line--of--sight plasma
motions of 100 km/sec and a complex dynamics.

---------------------------------------------------------
Title: First results from UVCS/SOHO
Authors: Noci, G.; Kohl, J. L.; Antonucci, E.; Tondello, G.; Huber,
M. C. E.; Fineschi, S.; Gardner, L. D.; Naletto, G.; Nicolosi, P.;
Raymond, J. C.; Romoli, M.; Spadaro, D.; Siegmund, O. H. W.; Benna, C.;
Ciaravella, A.; Giordano, S.; Michels, J.; Modigliani, A.; Panasyuk,
A.; Pernechele, C.; Poletto, G.; Smith, P. L.; Strachan, L.
1997AdSpR..20.2219N Altcode:
We present here the first results obtained by the Ultraviolet
Coronagraph Spectrometer (UVCS) operating on board the SOHO
satellite. The UVCS started to observe the extended corona at the end
of January 1996; it routinely obtains coronal spectra in the 1145 A˚ -
1287 A˚, 984 A˚ - 1080 A˚ ranges, and intensity data in the visible
continuum. Through the composition of slit images it also produces
monocromatic images of the extended corona. The performance of the
instrument is excellent and the data obtained up to now are of great
interest. We briefly describe preliminary results concerning polar
coronal holes, streamers and a coronal mass ejection, in particular: the
very large r.m.s. velocities of ions in polar holes (hundreds km/sec
for OVI and MgX); the puzzling difference between the HI Ly-alpha
image and that in the OVI resonance doublet, for most streamers; the
different signatures of the core and external layers of the streamers
in the width of the ion lines and in the OVI doublet ratio, indicating
larger line-of-sight (l.o.s.) and outflow velocities in the latter.

---------------------------------------------------------
Title: The quiescent corona and slow solar wind
Authors: Noci, G.; Kohl, J. L.; Antonucci, E.; Tondello, G.; Huber,
M. C. E.; Fineschi, S.; Gardner, L. D.; Korendyke, C. M.; Nicolosi,
P.; Romoli, M.; Spadaro, D.; Maccari, L.; Raymond, J. C.; Siegmund,
O. H. W.; Benna, C.; Ciaravella, A.; Giordano, S.; Michels, J.;
Modigliani, A.; Naletto, G.; Panasyuk, A.; Pernechele, C.; Poletto,
G.; Smith, P. L.; Strachan, L.
1997ESASP.404...75N Altcode: 1997cswn.conf...75N; 1997soho....5...75N
No abstract at ADS

---------------------------------------------------------
Title: Stray light, radiometric, and spectral characterization of
UVCS/SOHO: laboratory calibration and flight performance
Authors: Gardner, Larry D.; Kohl, J. L.; Daigneau, P. S.; Dennis,
E. F.; Fineschi, Silvano; Michels, J.; Nystrom, George U.;
Panasyuk, Alexander; Raymond, John C.; Reisenfeld, D. J.; Smith,
Peter L.; Strachan, Leonard; Suleiman, R.; Noci, G. C.; Romoli, Marco;
Ciaravella, A.; Modigliani, A.; Huber, Martin C.; Antonucci, E.; Benna,
C.; Giordano, S.; Tondello, Giuseppe; Nicolosi, Piergiorgio; Naletto,
Giampiero; Pernechele, Claudio; Spadaro, D.; Siegmund, Oswald H.;
Allegra, A.; Carosso, Paolo A.; Jhabvala, Murzy D.
1996SPIE.2831....2G Altcode:
The Ultraviolet Coronagraph Spectrometer is one of the instruments
on board the Solar and Heliospheric Observatory spacecraft, which
was launched in December, 1995. The instrument is designed to make
ultraviolet spectrometric measurements and visible polarimetric
measurements of the extended solar corona. Prior to launch laboratory
measurements were carried out to determine system level values for
many of the key performance parameters. Further measurements on
instrument performance have been carried out since launch. Presented
are descriptions of measurement techniques and representative results.

---------------------------------------------------------
Title: In-Flight Performance of the SOHO Ultraviolet Coronagraph
Spectrometer
Authors: Gardner, L. D.; Kohl, J. L.; Noci, G.; Antonucci, E.;
Tondello, G.; Huber, M. C. E.; Ciaravella, A.; Fineschi, S.; Giordano,
S.; Moran, T.; Naletto, G.; Nicolosi, P.; Romoli, M.; Strachan,
L.; Benna, C.; Pernechele, C.; Raymond, J. C.; Siegmund, O. H. W.;
Spadaro, D.; Smith, P. L.
1996AAS...188.3705G Altcode: 1996BAAS...28..878G
The in-flight performance of the SOHO Ultraviolet Coronagraph
Spectrometer (UVCS/SOHO) is consistent with the pre-launch
characterization and meets all planned observational
requirements. Measurements of the key UVCS/SOHO performance
characteristics have been performed. This paper describes the
measurement techniques and the results. In-flight values for the
spectral and spatial resolutions, wavelength scales, the flat
fields, the geometric distortions, radiometric calibrations,
and stray light levels for the two ultraviolet channels have been
determined. Comparisons will be made to pre-flight measurements at both
the component level and system level. This work is supported by NASA
under contract NAS5-31250 to the Smithsonian Astrophysical Observatory,
by the Italian Space Agency and by Switzerland.

---------------------------------------------------------
Title: Spectroscopic Diagnostic Techniques with the SOHO Ultraviolet
Coronagraph Spectrometer
Authors: Romoli, M.; Kohl, J. L.; Noci, G.; Antonucci, E.; Tondello,
G.; Huber, M. C. E.; Fineschi, S.; Karovska, M.; Moran, T.; Strachan,
L.; Ciaravella, A.; Benna, C.; Gardner, L. D.; Giordano, S.; Naletto,
G.; Nicolosi, P.; Raymond, J. C.; Siegmund, O. H. W.; Spadaro, D.;
Smith, P. L.
1996AAS...188.3703R Altcode: 1996BAAS...28R.877R
The SOHO Ultraviolet Coronagraph Spectrometer (UVCS/SOHO) uses
spectroscopic diagnostic techniques and polarimetry to determine
velocity distributions, temperatures, outflow velocities and densities
of protons, electrons, and several minor ions in the extended solar
corona. This paper describes the initial use of these techniques with
UVCS/SOHO. Velocity distributions are derived from the observed spectral
line profiles. In some cases, grating scans are used to improve the
spectral resolution. The Doppler dimming method is used to determine
radial outflow velocities and spectral line shifts are used for line of
sight velocity measurements. The electron densities are derived from
visible polarized radiance measurements. The status of attempts to
derive electron temperatures from observations of electron scattered
HI Lyman-alpha will be presented. This research is supported by NASA
Contract NAS5-31250 to the Smithsonian Astrophysical Observatory,
by the Italian Space Agency and by Switzerland.

---------------------------------------------------------
Title: Ultraviolet Imaging of the Extended Solar Corona with the
SOHO Ultraviolet Coronagraph Spectrometer
Authors: Noci, G.; Kohl, J. L.; Antonucci, E.; Tondello, G.; Huber,
M. C. E.; Strachan, L.; Giordano, S.; Panasyuk, A.; Benna, C.;
Ciaravella, A.; Fineschi, S.; Gardner, L. D.; Naletto, G.; Nicolosi,
P.; Raymond, J. C.; Romoli, M.; Siegmund, O. H. W.; Spadaro, D.;
Smith, P. L.
1996AAS...188.3701N Altcode: 1996BAAS...28..877N
Spectroscopic observations of the extended solar corona with the SOHO
Ultraviolet Coronagraph Spectrometer (UVCS/SOHO) can be used to produce
images of the extended solar corona in several ultraviolet spectral
lines. The images are produced by scanning coronal images across the
spectrometer entrance slits. The slits intercept a 40 arcminute slice of
the corona parallel to the limb tangent. Telescope mirror motions can
be used to scan from about 1.25 to 10 R_⊙. The instrument is rolled
about its Sun-center axis to obtain images of the full corona. The
spatial resolution depends on the selected slit width and the combined
resolution of the spectrometer and XDL detectors. It is limited by
diffraction for observations near the Sun where only a narrow strip of
the telescope mirror is unvignetted by the external occulter. Images
of equatorial streamers in HI Lyman-alpha and beta, and in O VI 103.2
nm will be presented. Ultraviolet images of polar plumes will also be
provided. In some cases, interpolation techniques are used to fill-in
gaps in the raster pattern. This research is supported by NASA Contract
NAS5-31250 to the Smithsonian Astrophysical Observatory, by the Italian
Space Agency and by Switzerland.

---------------------------------------------------------
Title: Expected Spectroscopic Signatures of Siphon Flows on Coronal
Loops - Doppler Dimming and Doppler Shifts
Authors: Kopp, R.; Spadaro, D.; Ventura, R.
1996AAS...188.3707K Altcode: 1996BAAS...28Q.878K
Coronal magnetic loops may display a wide variety of flow
configurations, depending upon their geometries and the plasma
conditions at their footpoints, as well as upon the distribution of
nonthermal heating along them. Existing models of steady state loop
flows ("siphon" flows, such as may exist in the closed-field regions
of large, long-lived helmet streamers) show that the bulk plasma
streaming velo- city at the top of a loop can easily reach values of
order the acoustic speed, i.e., in excess of 100 km/s, and may be even
higher in the supersonic (descending) leg of the loop. In this paper
we consider some of the observational con- sequences of such siphon
flows. Using a simple polytropic model to describe the variation of
plasma parameters along a typical coronal loop, we have calculated the
expected frequency-dependent emissivities of the resonance-scattered
H I Lyman-alpha and O VI emission lines as functions of position
on the loop and of the loop orientation relative to the viewing
direction. Comparison with similar calculations for a static plasma
with the same temperature and density provides the degree of Doppler
dimming to be expected at various points along the loop. This Doppler
dimming, and the related Doppler shift, comprise important diagnostic
signatures of loop flows which are potentially observable with the UVCS
instrument on SOHO. Surprisingly, Doppler dimming, which is ordinarily
regarded as an indicator of radial outflow from the Sun, does not vanish
entirely for the horizontal flow at the top of a loop. For a hot (T 2
MK), nearly isothermal loop extending less than, say, 1 solar radius
above the limb, the Doppler dimming there can achieve values of more
than 10 per cent at the loop's summit.

---------------------------------------------------------
Title: Coordinated SOHO Observations of Polar Plumes: Ultraviolet
Spectroscopy with UVCS
Authors: Fineschi, S.; Kohl, J. L.; Noci, G.; Antonucci, E.;
Tondello, G.; Huber, M. C. E.; Gardner, L. D.; Giordano, S.; Romoli,
M.; Benna, C.; Ciaravella, A.; Naletto, G.; Nicolosi, P.; Raymond,
J. C.; Siegmund, O. H. W.; Spadaro, D.; Smith, P. L.; Strachan, L.
1996AAS...188.3704F Altcode: 1996BAAS...28..877F
The SOHO Ultraviolet Coronagraph Spectrometer (UVCS/SOHO) observed polar
plumes at the south polar coronal hole on 7 March 1996. Observations
were made in H I Ly-alpha, Ly-beta and O VI 103.2 and 103.7
nm. Heliocentric heights from 1.5 to 3.2 R_⊙ were observed. In
addition, HI Ly-alpha observations with 60 sec time resolution were
obtained at a heliocentric height of 1.6 solar radii. The polar plumes
are clearly distinguishable in both H I Ly-alpha and O VI. These
measurements were made in coordination with time resolved magnetograms
by the Michelson Doppler Imager (MDI) and time resolved XUV images
by the Extreme-Ultraviolet Imaging Telescope (EIT). This work is
supported by NASA Contract NAS5-31250 to the Smithsonian Astrophysical
Observatory, by the Italian Space Agency and by Switzerland.

---------------------------------------------------------
Title: A Study of the Unresolved Fine-Structure Model for the Solar
Transition Region
Authors: Spadaro, D.; Lanza, A. F.; Antiochos, S. K.
1996ApJ...462.1011S Altcode:
The unresolved fine-structure (UFS) model for the lower transition
region was proposed by Feldman as an explanation for a number of
puzzling observational results: specifically, the small filling factor
of this region, the inability of the observations to resolve the
temperature structure, and the observation of persistent redshifted
UV emission lines even near the solar limb. It was hypothesized that
opacity effects may be able to explain the redshift observations. We
consider a simple model for the UFS consisting of a plasma sphere
undergoing expansion and contraction due to a time-varying heating. We
calculate in detail the line profile of the well-observed C IV 1548
Å line. Our calculations include the effects of both nonequilibrium
ionization and radiative transfer. We find that although the model can
reproduce some of the features of the observations, such as the line
widths, the effect of finite optical depth is to produce a blueshifted
peak for the emission line, contrary to observations. The physical
origins of this blueshift are discussed. We conclude that unless
the pressures of the UFS are significantly higher than the typical
pressures assumed for the lower transition region, opacity effects
are unlikely to explain the observations.

---------------------------------------------------------
Title: First Results from the SOHO Ultraviolet Coronagraph
Spectrometer
Authors: Kohl, J. L.; Noci, G.; Antonucci, E.; Tondello, G.; Huber,
M. C. E.; Benna, C.; Ciaravella, A.; Fineschi, S.; Gardner, L. D.;
Giordano, S.; Karovska, M.; Michels, J.; Naletto, G.; Nicolosi, P.;
Poletto, G.; Pernechele, C.; Raymond, J. C.; Romoli, M.; Siegmund,
O. H. W.; Spadaro, D.; Smith, P. L.; Strachan, L.
1996AAS...188.4906K Altcode: 1996BAAS...28R.897K
The SOHO Ultraviolet Coronagraph Spectrometer (UVCS/SOHO) is being used
to observe the extended solar corona from 1.25 to 10 R_⊙ from Sun
center. Initial observations of polar coronal holes, polar plumes,
equatorial streamers and the diffuse mid-latitude corona will be
presented. The observations include measurements of spectral line
profiles for HI Lyman alpha and beta, and O VI 103.2 and 103.7
nm. Line intensities for Mg X 61.0 nm, Si XII 49.9 and 52.0 nm,
S X 119.6 nm, Fe XII 124.2 nm and several other minor ions have been
observed. Observations with moderate time resolution (about 1 minute) at
one strip of the corona will also be presented. Preliminary results for
derived proton and O VI velocity distributions and initial indications
of outflow velocities for protons, and O VI will be discussed as
well as preliminary results for other spectroscopic diagnostics
techniques. This research is supported by NASA Contract NAS5-31250 to
the Smithsonian Astrophysical Observatory, by the Italian Space Agency
and by Switzerland.

---------------------------------------------------------
Title: Coronal Emission Lines with UVCS
Authors: Raymond, J. C.; Noci, G.; Kohl, J. L.; Antonucci, E.;
Tondello, G.; Huber, M. C. E.; Benna, C.; Ciaravella, A.; Fineschi, S.;
Gardner, L. D.; Giordano, S.; Naletto, G.; Nicolosi, P.; Romoli, M.;
Siegmund, O. H. W.; Spadaro, D.; Smith, P. L.; Strachan, L.; Martin, R.
1996AAS...188.3702R Altcode: 1996BAAS...28Q.877R
The Ultraviolet Coronagraph Spectrometer aboard the SOHO satellite has
observed the extended solar corona in H I Lyalpha and O VI lines for
coronal diagnostics, but other, fainter, lines are also present. We
discuss a spectral atlas obtained from emission in equatorial streamers
and above solar active regions, pointing out lines which are especially
useful for determining the elemental abundances, ionization state,
and density of the emitting plasma. This work is supported by NASA
under contract NAS5-31250 to the Smithsonian Astrophysical Observatory.

---------------------------------------------------------
Title: Intercalibration and Co-Registration of the LASCO, UVCS and
SUMER instruments on SOHO
Authors: Michels, J.; Kohl, J. L.; Noci, G.; Antonucci, E.; Tondello,
G.; Huber, M. C. E.; Curdt, W.; Hollandt, J.; Lemaire, P.; Schuhle,
U.; Wilhelm, K.; Korendyke, C.; Moran, T.; Raymond, J. C.; Romoli,
M.; Benna, C.; Ciaravella, A.; Fineschi, S.; Gardner, L. D.; Giordano,
S.; Naletto, G.; Nicolosi, P.; Siegmund, O. H. W.; Spadaro, D.; Smith,
P. L.; Strachan, L.
1996AAS...188.3706M Altcode: 1996BAAS...28..878M
Joint observations of equatorial streamers by three SOHO instruments
have been used for radiometric intercalibration, co-registration and
other spectroscopic comparisons. The results are used to track the
stability of the radiometric calibrations of the Ultraviolet Coronagraph
Spectrometer (UVCS) and the Solar Ultraviolet Measurements of Emitted
Radiation (SUMER) experiment at overlapping wavelenghs. Observations
of equatorial streamers at heliocentric heights from 1.25 to 1.5
R_⊙ are used for the intercalibrations. The results are compared to
pre-launch laboratory calibrations and to observations of stars. The
first stellar observation was for 38 AQI. These UV observations are
compared to coronal green line (Fe XIV) observations obtained with the
Large Angle Spectrometric Coronagraph (LASCO) C1 coronagraph obtained
in the same time frame. Intercomparisons of spectral line profiles
among LASCO, SUMER, and UVCS are also planned. The LASCO research is
supported by NASA Grant NDPR S92835D; the UVCS research is supported by
NASA Contract NAS5-31250 to the Smithsonian Astrophysical Observatory,
by the Italian Space Agency and by Switzerland, and SUMER is financially
supported by BMFT/DARA, CNES, NASA and PRODEX (Swiss Contribution).

---------------------------------------------------------
Title: Elemental abundances in the solar network and cell centers
from EUV spectra.
Authors: Spadaro, D.; Zuccarello, F.; Zappala, R. A.
1996A&A...308..970S Altcode:
In order to search for empirical evidences in the transition region
and corona explaining the observed variability of the chemical
composition in the solar wind, we have used a set of EUV average
spectra in the 296-1350A wavelength range (Vernazza &amp; Reeves
1978), to determine the relative abundances of C, N, O, Ne, Mg, Si,
S in the cell centers and the network within a coronal hole and a
quiet region, respectively. Moreover, we have determined the relative
abundances in an active region during two periods characterized by
different activity levels. The analysis has shown that the elemental
abundances appear in broad agreement with the photospheric ones for
all the different regions examined. Moreover, within the coronal hole
and the quiet region, the chemical composition in the cell centers
does not differ appreciably from that in the network. Further, no
differences in the elemental abundances have been found in the active
region during the two considered phases. Nevetherless, we point out
that the data used in this analysis for a given kind of structures,
are composed by spectra taken at various times and positions within
the same region, so that eventual differences may be smoothed out
by temporal and spatial averages. We discuss the implications of the
results concerning the cell centers and the network for the ion-neutral
separation model suggested by Meyer (1991).

---------------------------------------------------------
Title: EUV spectral lines from solar wind source regions: The
resonance doublets of N V, MG X and SI XII, and the Fe XII λ1242
forbidden line.
Authors: Spadaro, D.; Ventura, R.
1996A&AS..115..531S Altcode:
We present numerical simulations of intensities and profiles of
the N V λ1239 and λ 1243, Mg X λ610 and λ625, Si XII λ499 and
λ521, and Fe XII λ1242 lines expected from an equatorial and polar
coronal hole at solar minimum, when observed on the plane of the sky
in the 1.2Rsun_-8Rsun_ range of heliocentric
distance. The radial variations of coronal temperatures, densities
and outflow speeds inside these structures are those determined by
Withbroe (1988) through a one-fluid steady-state radiative energy
balance model. We discuss how the spectral features depend on the
physical parameters of the examined structures, in order to evaluate
to which extent they can put constraints on empirical models of the
extended corona. We also investigate the effects of the deviations
from ionization equilibrium occurring in the plasma outflowing from
the considered coronal structures on the intensity and profile of the
spectral lines examined. Such effects become significant at heliocentric
distances higher than 3Rsun_. These results may contribute
to prepare and interpret UVCS/SOHO future observations.

---------------------------------------------------------
Title: The Ultraviolet Coronagraph Spectrometer for the Solar and
Heliospheric Observatory
Authors: Kohl, J. L.; Esser, R.; Gardner, L. D.; Habbal, S.; Daigneau,
P. S.; Dennis, E. F.; Nystrom, G. U.; Panasyuk, A.; Raymond, J. C.;
Smith, P. L.; Strachan, L.; Van Ballegooijen, A. A.; Noci, G.;
Fineschi, S.; Romoli, M.; Ciaravella, A.; Modigliani, A.; Huber,
M. C. E.; Antonucci, E.; Benna, C.; Giordano, S.; Tondello, G.;
Nicolosi, P.; Naletto, G.; Pernechele, C.; Spadaro, D.; Poletto, G.;
Livi, S.; Von Der Lühe, O.; Geiss, J.; Timothy, J. G.; Gloeckler,
G.; Allegra, A.; Basile, G.; Brusa, R.; Wood, B.; Siegmund, O. H. W.;
Fowler, W.; Fisher, R.; Jhabvala, M.
1995SoPh..162..313K Altcode:
The SOHO Ultraviolet Coronagraph Spectrometer (UVCS/SOHO) is composed of
three reflecting telescopes with external and internal occultation and
a spectrometer assembly consisting of two toric grating spectrometers
and a visible light polarimeter. The purpose of the UVCS instrument is
to provide a body of data that can be used to address a broad range
of scientific questions regarding the nature of the solar corona and
the generation of the solar wind. The primary scientific goals are
the following: to locate and characterize the coronal source regions
of the solar wind, to identify and understand the dominant physical
processes that accelerate the solar wind, to understand how the coronal
plasma is heated in solar wind acceleration regions, and to increase the
knowledge of coronal phenomena that control the physical properties of
the solar wind as determined byin situ measurements. To progress toward
these goals, the UVCS will perform ultraviolet spectroscopy and visible
polarimetry to be combined with plasma diagnostic analysis techniques
to provide detailed empirical descriptions of the extended solar corona
from the coronal base to a heliocentric height of 12 solar radii.

---------------------------------------------------------
Title: Ultraviolet Coronagraph Spectrometer for the Solar and
Heliospheric Observatory: instrument description and calibration
overview
Authors: Kohl, J. L.; Esser, R.; Gardner, Larry D.; Habbal, S.;
Daigneau, P. S.; Nystrom, George U.; Raymond, John C.; Strachan,
Leonard; van Ballegooijen, A. A.; Noci, G.; Fineschi, Silvano; Romoli,
Marco; Ciaravella, A.; Modigliani, A.; Huber, Martin C.; Antonucci, E.;
Benna, C.; Giordano, S.; von der Luehe, Oskar; Tondello, Giuseppe;
Nicolosi, Piergiorgio; Naletto, Giampiero; Pernechele, Claudio;
Geiss, J.; Gloeckler, G.; Poletto, G.; Spadaro, D.; Allegra, A.;
Basile, G.; Brusa, R.; Wood, B.; Siegmund, Oswald H.
1995SPIE.2517...40K Altcode:
The SOHO ultraviolet coronagraph spectrometer (UVCS/SOHO) is
composed of three reflecting telescopes with external and internal
occultation and a spectrometer assembly consisting of two toric grating
spectrometers and a visible light polarimeter. The UVCS will perform
ultraviolet spectroscopy and visible polarimetry to be combined with
plasma diagnostic analysis techniques to provide detailed empirical
descriptions of the extended solar corona from the coronal base to a
heliographic height of 12 R. In this paper, the salient features of
the design of the UVCS instrument are described. An overview of the
UVCS test and calibration activities is presented. The results from
the calibration activity have demonstrated that the UVCS can achieve
all its primary scientific observational goals.

---------------------------------------------------------
Title: Effects of flows and non-equilibrium ionization on some C IV
line ratios on the Sun.
Authors: Spadaro, D.; Orlando, S.; Peres, G.; Leto, P.
1995A&A...302..285S Altcode:
We investigate the deviations from ionization equilibrium occurring in
coronal loops hosting steady-state siphon flows, and their effects on
the EUV emission line ratios of C IV recently considered by Keenan et
al. (1992) and found discrepant with observations of highly dynamics
events. We use the same electron impact excitation rates adopted by
Keenan et al. and two independent siphon flow models. The C IV line
ratios predicted by our models do not differ appreciably between
equilibrium and non-equilibrium conditions, and therefore indicate
that the discrepancy found by Keenan et al. (1992) cannot be solved
by steady flows. We discuss alternative solutions, also in view of
forthcoming observations by CDS/SOHO.

---------------------------------------------------------
Title: The Ultraviolet Coronagraph Spectrometer for the Solar and
Hellospheric Observatory
Authors: Raymond, J. C.; Kohl, J. L.; Esser, R.; Gardner, L. D.;
Habbal, S.; Strachan, L.; van Ballegooijen, A. A.; Noci, G.; Fineschi,
S.; Romoli, M.; Huber, M. C. E.; Antonucci, E.; Benna, C.; von der
Luhe, O.; Naletto, G.; Nicolosi, P.; Pernechele, C.; Tondello, G.;
Geiss, J.; Gloeckler, G.; Spadaro, D.; Daigneau, P. S.; Nystrom,
G. U.; Allegra, A.; Basile, G.; Brusa, R.; Wood, B.; Siegmund, O. H. W.
1995SPD....26..720R Altcode: 1995BAAS...27..970R
No abstract at ADS

---------------------------------------------------------
Title: The Ultraviolet Coronagraph Spectrometer
Authors: Noci, G.; Kohl, J. L.; Huber, M. C. E.; Antonucci, E.;
Fineschi, S.; Gardner, L. D.; Naletto, G.; Nicolosi, P.; Raymond,
J. C.; Romoli, M.; Spadaro, D.; Strachan, L.; Tondello, G.; van
Ballegooijen, A.
1995LNP...444..261N Altcode: 1995cmer.conf..261N
The Ultraviolet Coronagraph Spectrometer (UVCS) is an instrument onboard
the Solar and Heliospheric (SOHO) spacecraft, a joint ESA/NASA mission
to be launched in 1995. The UVCS will provide ultraviolet spectroscopic
measurements to determine the primary plasma parameters of the solar
corona (temperatures, densities, velocities), from its base to as high
as 10 R⊙. We review briefly, here, its science objectives
and give an instrument description.

---------------------------------------------------------
Title: UVCS Science from SOHO
Authors: Antonucci, E.; Kohl, J. L.; Noci, G.; Huber, M. C. E.;
Fineschi, S.; Gardner, L. D.; Naletto, G.; Nicolosi, P.; Pernechele,
C.; Raymond, J. C.; Romoli, M.; Spadaro, Daniele; Strachan, L.;
Tondello, G.; van Ballegooijen, A.
1995jena.conf...80A Altcode:
The ultraviolet Coronagraph Spectrometer (UVCS), to be launched on
board SOHO in 1995, has been designed to determine the primary plasma
parameters in order to obtain a far more complete description of the
coronal plasma than presently exists. This will be accomplished by
obtaining ultraviolet spectroscopic observations in some EUV lines (HI
Ly Alpha, O VI, Mg X, Si XII, Fe XII) and in the visible continuum,
form the base of the solar corona to as high as 12 solar radii. The
profiles and intensities of the measured UV lines are sensitive
to effective temperature of protons, minor ions and electrons; ion
densities; chemical abundances; and outflow velocities of protons and
ions into the solar wind. The electron density is determined by means
of white light observations. The UVCS data will be used to address a
broad range of scientific questions concerning the nature of the solar
corona and the generation of the solar wind. The primary scientific
objectives are in fact those of identifying the source regions of the
slow and fast solar wind, understanding the dominant processes that
accelerate the solar wind, and the mechanisms for heating the coronal
plasma in the extended corona.

---------------------------------------------------------
Title: Properties and Variability of the Stellar Wind from P Cygni
Authors: Scuderi, S.; Bonanno, G.; Spadaro, D.; Panagia, N.; Lamers,
H. J. G. L. M.; de Koter, A.
1994ApJ...437..465S Altcode:
We present the results of a study of the wind of the luminous blue
variable star P Cyg. We obtained spectroscopy of P Cyg in the H-alpha
line region in the period 1988 June through 1991 July. We also used
UBV photometric data to obtain information on the variations of the
radius and of the effective temperature of the star. The properties
of the wind of P Cyg at the different epochs of observations were
determined by fitting theoretical H-alpha profiles to the observed
ones. The computation of the theoretical profiles was done using the
method of Scuderi et al. (1992), enhanced to include the effect of
Thomson scattering by free electrons on the H-alpha profile. We found
that the wind velocity field displays both systematic and irregular
variations which match the variability of the stellar radius and
effective temperature. On the other hand, the mass-loss rate is
virtually constant, at a level of (1.9 +/- 0.2) x 10-5
solar mass/yr, and so is the bolometric luminosity of the star. These
results suggest that the mass-loss rate of P Cyg is determined entirely
by internal properties of the star and is connected with its energy
output whereas the wind velocity structure is also sensitive to even
small changes of the photosphere conditions.

---------------------------------------------------------
Title: Modelling UV spectral lines from solar coronal transients
Authors: Kosovichev, A. G.; Spadaro, D.; Stepanova, T. V.; Ventura, R.
1994ESASP.373..159K Altcode: 1994soho....3..159K
No abstract at ADS

---------------------------------------------------------
Title: UV spectral lines from coronal transients
Authors: Spadaro, D.; Ventura, R.; Martin, R.
1994SSRv...70..365S Altcode:
We investigated the UV emission expected from solar coronal transients,
selecting some spectral lines which will be observed with the UVCS
spectrocoronagraph onboard the SOHO spacecraft. The line intensities
were calculated starting from a representative, simplified model of
coronal transient. We discuss how the considered intensities depend on
the physical parameters of the examined structures. This work is aimed
to give a contribution in defining and preparing the future observations
of coronal transients and coronal mass ejections by the UVCS/SOHO.

---------------------------------------------------------
Title: Observational evidence for non-equilibrium ionization in the
solar corona
Authors: Spadaro, D.; Leto, P.; Antiochos, S. K.
1994SSRv...70..207S Altcode:
We investigate whether temperature sensitive EUV line ratios can be
used as observational signatures for the presence of non-equilibrium
ionization in transition region plasma. We compute the total
intensity of some EUV lines of carbon and oxygen expected from
coronal loop models with a steady-state flow and which are known to
have significant departures from ionization equilibrium, selecting
lines whose intensity ratios are useful for deducing the electron
temperature in the coronal plasma. We calculate the intensity ratios
with and without the approximation of ionization equilibrium, in order
to determine the effects of any deviations from equilibrium on the
numerical values of the line ratios examined.

---------------------------------------------------------
Title: Ultraviolet coronagraph spectrometer (UVCS) for the solar
and heliospheric (SOHO) mission
Authors: Fineschi, Silvano; Naletto, Giampiero; Nicolosi, Piergiorgio;
Noci, G.; Pernechele, Claudio; Romoli, Marco; Spadaro, D.; Tondello,
Giuseppe
1994SPIE.2209..348F Altcode:
The optical performances of the Ultraviolet Coronagraph Spectrometer
(UVCS) of the Solar and Heliospheric Observatory (SOHO) mission have
been tested. A laboratory evaluation unit (LEU) of the spectrometer
assembly (SPA) consisting of the structure equipped with breadboard
models of the entrance slit assembly (ESA), a grating drive mechanism
(GDM) mounting a toroidal grating for the Ly(alpha) channel and a
multi-anode microchannel array (MAMA) detector has been integrated
and aligned. Both tests with visible and UV radiation have been
performed. Aberration and stray light measurements have shown
satisfactory performances of the instrument almost in compliance
with the scientific requirements. A LEU and a flight unit of the
White Light Channel (WLC) have been integrated and aligned in a
proper light-tight housing and in the flight spectrometer assembly
respectively. Measurements of the polarimeter modulation curve and
the relative error have shown performances within the specificated
requirements.

---------------------------------------------------------
Title: The effect of non-equilibrium ionization on the H I Lyman-α
line originating in the solar wind source regions.
Authors: Spadaro, D.; Ventura, R.
1994A&A...289..279S Altcode:
We investigated the effects of the deviations from ionization
equilibrium occurring in the plasma outflowing from the solar wind
source regions on the intensity and profile of the H I Lyman-α
line. In particular, we computed the densities of the ions of
Hydrogen along a coronal hole model, with and without the assumption
of ionization equilibrium. Analogously, we computed the ion densities
in the unstructured quiet corona surrounding the coronal hole. These
density values were used to calculate the intensity and profile of the
Lyman-α line expected from the coronal structures considered, both
in equilibrium and non-equilibrium conditions. The comparison between
non-equilibrium and equilibrium results shows only some differences at
heliocentric distances higher than 5 Rsun_. The importance
of these results for the analysis of the Lyman-α emission from the
solar wind source regions has been discussed.

---------------------------------------------------------
Title: Observational Tests for Nonequilibrium Ionization in the
Solar Corona
Authors: Spadaro, D.; Leto, P.; Antiochos, S. K.
1994ApJ...427..453S Altcode:
Nonequilibrium ionization may be produced by a variety of processes
in the solar corona, for example, by mass flows through the large
temperature gradients of the transition region or by impulsive heating
and cooling. Any deviation from equilibrium ionization would have a
strong effect on the radiation from the corona and on the interpretation
of solar observations; hence, it is important to determine observational
signatures of nonequilibrium. The temperature-sensitive line ratios can
be used as such signatures. We examine the line ratios: C IV I(1548.2
A)/I(312.4 A), O IV I(789.4 A)/I(554.4 A), O V I(629.7 A)/I(172.2 A),
O VI I(1031.9 A)/I(173.0 A) and O VI I(1031.9 A)/I(150.1 A). These
line ratios are calculated for four coronal loop models that have
a steady flow and that are known to have significant departures
from equilibrium ionization. Our results indicate that, in general,
nonequilibrium causes a considerable reduction in the line ratios,
more than an order of magnitude in the downflowing leg of the loop
model with the largest mass flows. We find that the C IV line ratio is
the most sensitive to nonequilibrium. We discuss the implications of
our results for observations, specifically, the observations expected
from the upcoming SOHO mission.

---------------------------------------------------------
Title: The effect of non-equilibrium ionization on the O VI resonance
doublet lines originating in the solar wind source regions
Authors: Spadaro, D.; Ventura, R.
1994A&A...281..245S Altcode:
We investigated the effects of the deviations from ionization
equilibrium occurring in the plasma outflowing from the solar wind
source regions on the intensity and profile of the O VI resonance
doublet lines. In particular, we computed the densities of the
ions of oxygen along the coronal hole models considered by Spadaro
&amp; Ventura (1993, hereafter Paper I), dropping the assumption of
ionization equilibrium. These density values were used to calculate
the intensity and profile of the O VI lines expected from the coronal
structures considered, adopting the same procedure described in Paper
I. The results have been compared to those obtained assuming ionization
equilibrium. The comparison shows differences which become significant
at heliocentric distances larger than 3-4 solar radii. The importance
of these results for the analysis of the O VI emission from the solar
wind source regions has been discussed.

---------------------------------------------------------
Title: Numerical Simulations of the O VI λ 1032 and λ 1038 Emission
from Source Regions of the Solar Wind
Authors: Spadaro, D.; Ventura, R.
1994emsp.conf..163S Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Spectral lines from source regions of the solar wind: the O
VI resonance doublet
Authors: Spadaro, D.; Ventura, R.
1993A&A...276..571S Altcode:
We present numerical simulations of intensities and profiles of the
O VI λ1O32 and λ1O38 lines expected from an equatorial and polar
coronal hole at solar minimum, when observed on the plane of the sky
in the 1.2 Rsun-8 Rsun range of heliocentric
distance. The radial variations of coronal temperatures, densities and
outflow speeds inside these structures are those n}} Withbroe (1988)
through a one-fluid steady-state energy balance model. We discuss
how the spectral features depend on the physical parameters of the
examined structures, in order to evaluate to which extent they can put
constraints on empirical models of the extended solar corona. These
results may contribute to prepare and interpret SPARTAN and UVCS/SOHO
future observations.

---------------------------------------------------------
Title: Scientific objectives with UVCS/SOHO (invited paper)
Authors: Spadaro, D.
1993MmSAI..64..403S Altcode:
No abstract at ADS

---------------------------------------------------------
Title: Lyalpha radiation from coronal transients
Authors: Spadaro, Daniele; Ventura, R.; Martin, R.; Wu, S. T.; Wang,
A. H.
1992ESASP.348..105S Altcode: 1992cscl.work..105S
The intensity and profile of the Lyman alpha spectral line expected
from the extended coronal plasma evolving during a coronal transient,
when observed in the plane of the sky in the range of heliocentric
distance 1.5 to 4 solar radii, are calculated. The numerical values of
temperature, density and outflow speed inside the coronal transient
are those determined by Wu and Wang under the assumption of a single
fluid, three dimensional, time dependent magnetohydrodynamic model of
the outer solar atmosphere. The dependence of the Lyman alpha line on
the physical parameters of the examined structure is discussed. These
results may help in preparing and interpreting UVCS/SOHO (Ultraviolet
Coronagraph/Solar and Heliospheric Observatory) observations of
coronal transients.

---------------------------------------------------------
Title: H alpha Observations of Early-Type Stars
Authors: Scuderi, S.; Bonanno, G.; di Benedetto, R.; Spadaro, D.;
Panagia, N.
1992ApJ...392..201S Altcode:
Results are presented of a first session of a program run at the
Catania Astrophysical Observatory to study and monitor the H-alpha
emission from early-type stars, and the properties of their mass loss
are determined. Twelve early-type supergiants in the Cygnus region were
observed repeatedly in 1988 July. From these observations, evidence
is found for short-term variability of the mass-loss rate. Also, a
comparison with literature data reveals strong long-term variations
for some of the stars. In addition, simplified models were developed
to describe the H-alpha profile resulting from the combination of
photospheric absorption with emission and scattering in the wind. By
fitting the observed profiles with the models, the mass-loss rates
and the velocity fields are determined for all stars with accuracies
generally better than 25 percent.

---------------------------------------------------------
Title: Steady Siphon Flows in Closed Coronal Structures: Comparison
with Extreme-Ultraviolet Observations
Authors: Peres, G.; Spadaro, D.; Noci, G.
1992ApJ...389..777P Altcode:
Models of steady siphon flow in solar coronal loops are computed and the
intensities of some EUV transition region emission lines synthesized
from these models are compared with representative obsevations of
typical solar regions. It is found that siphon flow models of active
region loops are in better agreement with observations of EUV transition
region lines, while for large loops interconnecting different active
regions, static models work slightly better. The role of siphon flows
in determining the structure of the outer solar atmosphere is discussed
based on these results.

---------------------------------------------------------
Title: On VI extreme ultraviolet radiation from source regions of
solar wind
Authors: Spadaro, D.; Ventura, R.
1992sws..coll..113S Altcode:
Numerical simulations are presented for the O VI 1032 and 1036 A line
intensities from several coronal hole configurations observed in the
1.1-10.0 solar radius range. Attention is given to the dependence of
observables on the physical parameters of the structures in question,
in order to evaluate the degree to which they may furnish constraints
for empirical models of the extended corona.

---------------------------------------------------------
Title: Modelling of open and closed coronal structures - Comparison
with detailed EUV observations
Authors: Peres, G.; Spadaro, D.
1992sws..coll...87P Altcode:
We consider the modelling and EUV diagnostics of plasma in steady
state motion both within closed coronal structures (siphon flows) and
outflowing from coronal holes toward interplanetary space. We take into
account nonequilibrium ionization in the synthesis of emission lines
originating from the modelled closed structures and compare the computed
line intensities with detailed EUV observations, in order to constrain
significantly the model. We evaluate the importance of nonequilibrium
ionizations effects for some published coronal hole models.

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Title: Angular momentum transport by Reynolds stresses determined
from the analysis of 100-year sunspot motions and its variations
with solar cycle
Authors: Paterno, L.; Zuccarello, F.; Spadaro, D.; Zappala, R. A.
1991A&A...252..337P Altcode:
Some aspects of the latitudinal momentum transport by Reynolds
stresses, as deduced from the analysis of the Greenwich sunspot data
for the period 1874-1976 by using only very young sunspot groups (age
equal to or less than 3 d), were investigated in order to study the
equatorial acceleration maintenance and its possible correlations with
the equatorial angular velocity time variations and the solar cycle. The
results, which are consistent with those of previous authors, indicate
the presence of a net angular momentum flux toward the equator which
is more vigorous at higher latitudes, and sufficient on average to
maintain the observed equatorial acceleration. The angular momentum
transport time variations show a significant periodicity correlated
with the solar cycle. Also, the equatorial velocity time variations
show significant periodicities, which in turn may depend on the
angular momentum transport time variations. The scenario which emerges
from these results is discussed in the framework of the theories of
differential rotation and activity cycle.

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Title: Nonequilibrium Ionization Effects in Asymmetrically Heated
Loops
Authors: Spadaro, D.; Antiochos, Spiro K.; Mariska, J. T.
1991ApJ...382..338S Altcode:
The effects of nonequilibrium ionization on magnetic loop models with
a steady siphon flow that is driven by a nonuniform heating rate are
investigated. The model developed by Mariska (1988) to explain the
observed redshifts of transition region emission lines is examined,
and the number densities of the ions of carbon and oxygen along the
loop are computed, with and without the approximation of ionization
equilibrium. Considerable deviations from equilibrium were found. In
order to determine the consequences of these nonequilibrium effects
on the characteristics of the EUV emission from the loop plasma, the
profiles and wavelength positions of all the important emission lines
due to carbon and oxygen were calculated. The calculations are in broad
agreement with Mariska's conclusions, although they show a significant
diminution of the Doppler shifts, as well as modifications to the line
widths. It is concluded that the inclusion of nonequilibrium effects
make it more difficult to reproduce the observed characteristics of
the solar transition region by means of the asymmetric-heating models.

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Title: UV observational techniques for the extended solar corona
Authors: Kohl, J. L.; Gardner, L. D.; Huber, M. C. E.; Nicolosi,
P.; Noci, G.; Naletto, G.; Romoli, M.; Spadaro, D.; Tondello, G.;
Weiser, H.
1991AdSpR..11a.359K Altcode: 1991AdSpR..11..359K
The SOHO Ultraviolet Coronagraph Spectrometer is being developed for
spectroscopic determinations of temperatures, densities and flow
velocities in the extended solar corona. Determinations of plasma
parameters for the primary particles (electrons and protons) and for
several minor ions are planned. The techniques and instrumentation
to be used must overcome the relatively low intensity levels and
potentially high stray light levels intrinsic to observations of the
extended corona while also providing high radiometric and spectrometric
accuracy and relatively high spectral and spatial resolution. This
paper concentrates on the instrument characteristics that are required
to observe the resonantly scatter HI Lyman-alpha line at heliocentric
heights from 1 to 10 solar radii.

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Title: Non-equilibrium ionization as a consequence of flows in
coronal loops
Authors: Spadaro, D.
1991AdSpR..11a.221S Altcode: 1991AdSpR..11..221S
Observations of the solar corona suggest the existence of a family
of coronal loops characterized by plasma flows. The effects of these
mass flows on the ionization state of the loop plasma have recently
been investigated by a number of authors, in order to check the
validity of a current assumption in the analysis of EUV and X-ray
solar emission, the ionization equilibrium. These studies have shown
that considerable deviations from the ionization equilibrium occur
in the plasma flowing inside closed magnetic loops. The deviations
are larger in the transition region segment of the loop, due to the
steep temperature gradient there, whilst are smaller in the coronal
segment. The importance of these results for the analysis of EUV and
X-ray solar emission, from which most information on the physical
conditions of the outer solar atmosphere has been deduced, is discussed.

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Title: The Effects of Nonequilibrium Ionization on the Radiative
Losses of the Solar Corona
Authors: Spadaro, D.; Zappala, R. A.; Antiochos, S. K.; Lanzafame,
G.; Noci, G.
1990ApJ...362..370S Altcode: 1990ApJ...362R.370S
The emissivity of the ions of carbon and oxygen has been recalculated
for a set of solar coronal loop models with a steady state siphon
flow. The ion densities were calculated from the plasma velocities,
temperatures, and densities of the models, and large departures from
equilibrium were found. For purposes of comparison, the emissivity
was calculated with and without the approximation of ionization
equilibrium. Considerable differences in the radiative loss function
Lambda(T) curve between equilibrium and nonequilibrium conditions
were found. The nonequilibrium Lambda(T) function was then used to
solve again the steady state flow equations of the loop models. The
differences in the structure of these models with respect to the models
calculated adopting the Lambda(T) curve in equilibrium are discussed.

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Title: The Effect of Nonequilibrium Ionization on Ultraviolet Line
Shifts in the Solar Transition Region
Authors: Spadaro, D.; Noci, G.; Zappala, R. A.; Antiochos, S. K.
1990ApJ...355..342S Altcode:
The line profiles and wavelength positions of all the important
emission lines due to carbon were computed for a variety of steady
state siphon flow loop models. For the lines from the lower ionization
states (C II-C IV) a preponderance of blueshifts was found, contrary
to the observations. The lines from the higher ionization states can
show either a net red- or blueshift, depending on the position of the
loop on the solar disk. Similar results are expected for oxygen. It
is concluded that the observed redshifts cannot be explained by the
models proposed here.

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Title: Mass Flows and the Ionization States of Coronal Loops: Erratum
Authors: Noci, G.; Spadaro, D.; Zappala, R. A.; Antiochos, S. K.
1990ApJ...349..678N Altcode:
No abstract at ADS

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Title: Hα observations of O and B type stars.
Authors: Scuderi, Salvatore; Bonanno, Giovanni; Spadaro, Daniele;
Panagia, Nino
1990ASPC....7..253S Altcode: 1990phls.work..253S
This paper reports on the progress of an observational program to study
and monitor the Hα emission from early type stars and determine the
properties of their mass loss.

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Title: Mass Flows and the Ionization State of Coronal Loops
Authors: Noci, G.; Spadaro, D.; Zappala, R. A.; Antiochos, S. K.
1989ApJ...338.1131N Altcode:
A basic assumption in the analysis of EUV and X-ray solar emission
is that the plasma is in ionization equilibrium. The effects of mass
flows on the ionization state of solar plasma have been investigated
in order to check the validity of ionization equilibrium. Solar
coronal loop models with a steady state flow as described by Antiochos
(1984) are considered. The number densities of carbon ions have been
determined for four loop models that cover a range of densities and
flow velocities. The results show evidence of nonequilibrium ionization
effects even for velocities of only a few km/s at the loop top and
10 times less at the base, with densities ranging from 10 to the
8th to 10 to the 10th/cu cm between the top and the footpoints. The
importance of these results for the analysis of EUV and X-ray solar
emission is discussed.

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Title: Solar observations made at Catania Astrophysical Observatory
during 1987.
Authors: Ternullo, M.; Spadaro, D.
1989PCat..174.....T Altcode:
Contents: 1. Introduction. 2. Sunspots. 3. Hα faculae. 4. Hα
flares. 5. Hα quiescent prominences. 6. Hα active prominences on
disc and at limb. 7. Hα patrol coverage times.

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Title: Sub-sonic mass flows and ionization state in coronal loops
Authors: Noci, G.; Spadaro, D.; Zappala, R. A.; Antiochos, S. K.
1989MmSAI..60...55N Altcode:
The effects of subsonic mass flows on the ionization state of the
solar plasma inside magnetic loops are studied. Motions along the
magnetic field lines from one footpoint of the loop to the other are
considered in order to investigate the effects of the motion through
positive and negative temperature gradients. The number densities of
carbon ions are determined for some loop models that cover a range of
densities and flow velocities. The results show that deviations from
ionization equilibrium can occur in coronal loops with a steady-state
subsonic flow from one footpoint to the other. The deviations depend
on the electron density and flow velocity. The importance of these
results for the analysis of EUV and X-ray solar emission is discussed.

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Title: Elemental abundances in different solar regions from EUV
observations
Authors: Noci, G.; Spadaro, D.; Zappala, R. A.; Zuccarello, F.
1988A&A...198..311N Altcode:
The relative abundances of C, N, O, Ne, Mg, Si, S in different regions
of the solar transition zone (a coronal hole, a quiet and an active
region) have been determined from the analysis of average EUV spectra
in the range 296-1350 A. The methodology described by Pottasch (1964)
and later on improved (Dupree, 1972; Withbroe, 1981) has been used;
moreover, the role played by the population of the metastable levels
of the emitting ions has been taken into account. The abundances found
in different regions and those found at the photospheric level do not
differ more than the errors, except for oxygen, whose abundances seem
to be lower for values of T less than 10 exp 5.2 K, particularly in
the active region. The comparison between quiet region and coronal
hole shows that their chemical compositions differ by values much
lower than the estimated uncertainty, which suggests that the errors
affecting the abundance determinations are lower than estimated. This
could imply that differences in the chemical composition between active
region and other coronal regions exist.

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Title: Venti stellari.
Authors: Spadaro, D.
1986GAst...12....9S Altcode:
No abstract at ADS