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ADS astronomy entries on 2022-09-14
author:"Livingston, William C."
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Title: A Remarkable Recent Transition in the Solar Dynamo
Authors: de Jager, C.; Akasofu, S. -I.; Duhau, S.; Livingston, W. C.;
Nieuwenhuijzen, H.; Potgieter, M. S.
2016SSRv..201..109D Altcode: 2016SSRv..tmp...64D
We summarize the major aspects of the remarkable, fairly long lasting
period (∼ 2005 to ∼ 2010) of low solar activity, that we will call
the Transition. It is the transitional stage between the Grand Maximum
of the 20th century and a forthcoming (most probably Regular) episode
of solar activity. The various kinds of activity in the functioning
of the equatorial components of the solar dynamo before and during
the Transition are summarized. While the behavior of unipolar magnetic
regions and their rest-latitudes already gave very early indications -
mid 20th century - of the forthcoming Transition, more such indications
became available around 1995 and the main part of it occurred between
2005 and 2010. Some of the inferences are discussed. We submit the
hypothesis that the solar tachocline undergoes pulsations and we
present some helioseismic evidences. In that scenario we find that its
equatorial part has moved downward over a fairly small semi-amplitude
(∼ 0.03 solar radii) during the time of the Transition. There are
several indications, apart from this `pulsation', that the tachocline
may even be pulsating with still smaller amplitudes in more modes. We
speculate about the physical mechanism(s).
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Title: Variation of the Mn I 539.4 nm line with the solar cycle
Authors: Danilovic, S.; Solanki, S. K.; Livingston, W.; Krivova, N.;
Vince, I.
2016A&A...587A..33D Altcode: 2015arXiv151101286D
Context. As a part of the long-term program at Kitt Peak National
Observatory (KPNO), the Mn I 539.4 nm line has been observed for
nearly three solar cycles using the McMath telescope and the 13.5 m
spectrograph in double-pass mode. These full-disk spectrophotometric
observations revealed an unusually strong change of this line's
parameters over the solar cycle. <BR /> Aims: Optical pumping by the Mg
II k line was originally proposed to explain these variations. More
recent studies have proposed that this is not required and that
the magnetic variability (I.e., the changes in solar atmospheric
structure due to faculae) might explain these changes. Magnetic
variability is also the mechanism that drives the changes in total
solar irradiance variations (TSI). With this work we investigate this
proposition quantitatively by using the same model that was earlier
successfully employed to reconstruct the irradiance. <BR /> Methods:
We reconstructed the changes in the line parameters using the model
SATIRE-S, which takes only variations of the daily surface distribution
of the magnetic field into account. We applied exactly the same model
atmospheres and value of the free parameter as were used in previous
solar irradiance reconstructions to now model the variation in the Mn
I 539.4 nm line profile and in neighboring Fe I lines. We compared
the results of the theoretical model with KPNO observations. <BR />
Results: The changes in the Mn I 539.4 nm line and a neighbouring Fe
I 539.52 nm line over approximately three solar cycles are reproduced
well by the model without additionally tweaking the model parameters,
if changes made to the instrument setup are taken into account. The
model slightly overestimates the change for the strong Fe I 539.32 nm
line. <BR /> Conclusions: Our result confirms that optical pumping
of the Mn II 539.4 nm line by Mg II k is not the main cause of its
solar cycle change. It also provides independent confirmation of solar
irradiance models which are based on the assumption that irradiance
variations are caused by the evolution of the solar surface magnetic
flux. The result obtained here also supports the spectral irradiance
variations computed by these models.
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Title: Cross-Calibrating Sunspot Magnetic Field Strength Measurements
from the McMath-Pierce Solar Telescope and the Dunn Solar Telescope
Authors: Watson, Fraser T.; Beck, Christian; Penn, Matthew J.;
Tritschler, Alexandra; Pillet, Valentín Martinez; Livingston,
William C.
2015SoPh..290.3267W Altcode: 2015arXiv151107315W; 2015SoPh..tmp..158W
In this article we describe a recent effort to cross-calibrate data
from an infrared detector at the McMath-Pierce Solar Telescope and
the Facility InfraRed Spectropolarimeter (FIRS) at the Dunn Solar
Telescope. A synoptic observation program at the McMath-Pierce has
measured umbral magnetic field strengths since 1998, and this data set
has recently been compared with umbral magnetic field observations from
SOHO/MDI and SDO/HMI. To further improve on the data from McMath-Pierce,
we compared the data with measurements taken at the Dunn Solar Telescope
with far greater spectral resolution than has been possible with
space instrumentation. To minimise potential disruption to the study,
concurrent umbral measurements were made so that the relationship
between the two datasets can be most accurately characterised. We find
that there is a strong agreement between the umbral magnetic field
strengths recorded by each instrument, and we reduced the FIRS data
in two different ways to successfully test this correlation further.
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Title: A new solar signal: Average maximum sunspot magnetic fields
independent of activity cycle
Authors: Livingston, William; Watson, Fraser
2015GeoRL..42.9185L Altcode: 2016arXiv160403050L
Over the past 5 years, 2010 to April 2015, we observed 4176 sunspot
umbrae in the infrared (IR) to measure maximum magnetic field strengths
from the Zeeman splitting of Fe 15,648.5 Å. Herein we distinguish
"field strengths" from "field flux." Field strengths range from 1500 G
in pores to 3500+ in large spots. We made one observation per spot per
observing day, ignoring spot size. We show that in the IR no activity
cycle dependence on average maximum field strength (2070 ± 20 G) has
been found. A similar analysis of 17,450 spots observed in space by the
Helioseismic and Magnetic Imager reveals a similar cycle independence
(2050 ± 0.18 G). We conclude that the average maximum umbral fields
are constant with time and independent of the activity cycle within
our time coverage.
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Title: The photospheric solar oxygen project. IV. 3D-NLTE
investigation of the 777 nm triplet lines
Authors: Steffen, M.; Prakapavičius, D.; Caffau, E.; Ludwig, H. -G.;
Bonifacio, P.; Cayrel, R.; Kučinskas, A.; Livingston, W. C.
2015A&A...583A..57S Altcode: 2015arXiv150803487S
Context. The solar photospheric oxygen abundance is still widely
debated. Adopting the solar chemical composition based on the "low"
oxygen abundance, as determined with the use of three-dimensional (3D)
hydrodynamical model atmospheres, results in a well-known mismatch
between theoretical solar models and helioseismic measurements
that is so far unresolved. <BR /> Aims: We carry out an independent
redetermination of the solar oxygen abundance by investigating the
center-to-limb variation of the O i IR triplet lines at 777 nm in
different sets of spectra. <BR /> Methods: The high-resolution and high
signal-to-noise solar center-to-limb spectra are analyzed with the
help of detailed synthetic line profiles based on 3D hydrodynamical
CO5BOLD model atmospheres and 3D non-LTE line formation calculations
with NLTE3D. The idea is to exploit the information contained in the
observations at different limb angles to simultaneously derive the
oxygen abundance, A(O), and the scaling factor S<SUB>H</SUB> that
describes the cross-sections for inelastic collisions with neutral
hydrogen relative to the classical Drawin formula. Using the same
codes and methods, we compare our 3D results with those obtained from
the semi-empirical Holweger-Müller model atmosphere as well as from
different one-dimensional (1D) reference models. <BR /> Results: With
the CO5BOLD 3D solar model, the best fit of the center-to-limb variation
of the triplet lines is obtained when the collisions by neutral hydrogen
atoms are assumed to be efficient, i.e., when the scaling factor
S<SUB>H</SUB> is between 1.2 and 1.8, depending on the choice of the
observed spectrum and the triplet component used in the analysis. The
line profile fits achieved with standard 1D model atmospheres (with
fixed microturbulence, independent of disk position μ) are clearly
of inferior quality compared to the 3D case, and give the best match
to the observations when ignoring collisions with neutral hydrogen
(S<SUB>H</SUB> = 0). The results derived with the Holweger-Müller model
are intermediate between 3D and standard 1D. <BR /> Conclusions: The
analysis of various observations of the triplet lines with different
methods yields oxygen abundance values (on a logarithmic scale where
A(H) = 12) that fall in the range 8.74 <A(O) < 8.78, and our
best estimate of the 3D non-LTE solar oxygen abundance is A(O) = 8.76
± 0.02. All 1D non-LTE models give much lower oxygen abundances,
by up to -0.15 dex. This is mainly a consequence of the assumption
of a μ-independent microturbulence. An independent determination of
the relevant collisional cross-sections is essential to substantially
improve the accuracy of the oxygen abundance derived from the O i IR
triplet. <P />Appendices E and F are available in electronic form at <A
href="http://www.aanda.org/10.1051/0004-6361/201526406/olm">http://www.aanda.org</A>
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Title: The photospheric solar oxygen project. III. Investigation of
the centre-to-limb variation of the 630 nm [O I]-Ni I blend
Authors: Caffau, E.; Ludwig, H. -G.; Steffen, M.; Livingston, W.;
Bonifacio, P.; Malherbe, J. -M.; Doerr, H. -P.; Schmidt, W.
2015A&A...579A..88C Altcode: 2015arXiv150600931C
Context. The solar photospheric abundance of oxygen is still a matter
of debate. For about ten years some determinations have favoured a
low oxygen abundance which is at variance with the value inferred by
helioseismology. Among the oxygen abundance indicators, the forbidden
line at 630 nm has often been considered the most reliable even
though it is blended with a Ni i line. In Papers I and II of this
series we reported a discrepancy in the oxygen abundance derived
from the 630 nm and the subordinate [O I] line at 636 nm in dwarf
stars, including the Sun. <BR /> Aims: Here we analyse several,
in part new, solar observations of the centre-to-limb variation
of the spectral region including the blend at 630 nm in order to
separate the individual contributions of oxygen and nickel. <BR />
Methods: We analyse intensity spectra observed at different limb
angles in comparison with line formation computations performed on a
CO5BOLD 3D hydrodynamical simulation of the solar atmosphere. <BR />
Results: The oxygen abundances obtained from the forbidden line at
different limb angles are inconsistent if the commonly adopted nickel
abundance of 6.25 is assumed in our local thermodynamic equilibrium
computations. With a slightly lower nickel abundance, A(Ni) ≈ 6.1,
we obtain consistent fits indicating an oxygen abundance of A(O) = 8.73
± 0.05. At this value the discrepancy with the subordinate oxygen
line remains. <BR /> Conclusions: The derived value of the oxygen
abundance supports the notion of a rather low oxygen abundance in the
solar photosphere. However, it is disconcerting that the forbidden
oxygen lines at 630 and 636 nm give noticeably different results,
and that the nickel abundance derived here from the 630 nm blend is
lower than expected from other nickel lines.
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Title: A Spectro-polarimetric Analysis of Sunspot Umbrae
Authors: Watson, Fraser; Tritschler, Alexandra; Penn, Matthew J.;
Beck, Christian; Livingston, William; Martinez Pillet, Valentin
2014AAS...22411202W Altcode:
The recent quiet solar cycle has invited new questions as to
the nature of the solar magnetic field and how it changes over
time. To investigate this, we use the National Solar Observatory’s
McMath-Pierce Solar Telescope Facility (McMP) and Dunn Solar Telescope
(DST) to compare measurements of sunspots from five active regions
observed in 2013. Both BABO at the McMP and FIRS at the DST were
used to provide spectra of the Fe 1564.8nm line, which is affected
by the presence of magnetic fields. The magnetic field is derived
from Zeeman splitting in Stokes-I by BABO, and by inversion of the
Stokes parameters from FIRS data allowing for comparisons of sunspot
properties between the two instruments.. We present the first results
from this study including the magnetic fields in sunspot umbrae from
five active regions measured simultaneously by BABO and FIRS.
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Title: A Multi-instrument Analysis of Sunspot Umbrae
Authors: Watson, F. T.; Penn, M. J.; Livingston, W.
2014ApJ...787...22W Altcode: 2015arXiv151107300W
The recent solar minimum and rise phase of solar cycle 24 have been
unlike any period since the early 1900s. This article examines some
of the properties of sunspot umbrae over the last 17 yr with three
different instruments on the ground and in space: MDI, HMI and BABO. The
distribution of magnetic fields and their evolution over time is shown
and reveals that the field distribution in cycle 24 is fundamentally
different from that in cycle 23. The annual average umbral magnetic
field is then examined for the 17 yr observation period and shows a
small decrease of 375 G in sunspot magnetic fields over the period
1996-2013, but the mean intensity of sunspot umbrae does not vary
significantly over this time. A possible issue with sample sizes in a
previous study is then explored to explain disagreements in data from
two of the source instruments. All three instruments show that the
relationship between umbral magnetic fields and umbral intensity agrees
with past studies in that the umbral intensity decreases as the field
strength increases. This apparent contradiction can be explained by the
range of magnetic field values measured for a given umbral intensity
being larger than the measured 375 G change in umbral field strength
over time.
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Title: A Systematic Look At Sunspots From Space: 1996 - 2013
Authors: Watson, Fraser; Penn, M. J.; Livingston, W.
2013SPD....4420401W Altcode:
Space based measurements of sunspots are still relatively new when
compared with the long visual record that is available from ground based
observatories, but they can provide many advantages that ground based
measurements cannot. Sunspots are automatically detected from SOHO/MDI
and SDO/HMI continuum images using the Sunspot Tracking And Recognition
Algorithm (STARA). A self consistent sunspot catalogue is created using
the same criteria for detecting sunspots throughout time, eliminating
effects seen by ground observatories such as changing observers or the
effect of an observers eyesight as they age. This catalogue is then
analysed to determine how sunspots evolve and what their population
is in a number of physical parameters, which is of great importance
for simulations of magnetic flux emergence and the solar dynamo. In
particular, the change in sunspot parameters between solar cycles 23
and 24 is of great interest as the cycles appear vastly different in
activity, and sunspots are a primary indicator of the activity of the
Sun. The catalogue is also freely available for use by the community.
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Title: New Synoptic Measurements of Umbral Magnetic Fields
Authors: Harvey, J. W.; Hughes, A.; Marble, A.; Livingston, W. C.;
Pevtsov, A.; SOLIS Team
2013SPD....44..112H Altcode:
Apparent cyclic and secular changes of sunspot umbral intensities and
magnetic field strengths have been reported for many decades. Monthly
measurements since 1998 show changes that have been interpreted
as a decline in sunspot vigor that, if continued, may lead to very
few visible sunspots in forthcoming cycles (Livingston, Penn, and
Svalgaard 2012, ApJ 757, L8). This dramatic notion is controversial
(e.g. Nagovitsyn, Pevtsov, and Livingston 2012, ApJ 758, L20),
and additional observational evidence is needed based on a minimum
of interpretational steps and selection effects. The SOLIS vector
spectromagnetograph has recorded photospheric spectra around 630.2
nm over the full solar disk daily since late 2003 with spatial and
spectral pixel dimensions of about one arc second and 2.3 pm. We fit
the unpolarized intensity spectra in sunspots with a simple Zeeman
triplet model using a single field strength, which works well if
the field strength exceeds about 2 kG and the individual spectra
are not affected by strong Doppler and/or Zeeman variations. The
derived total field strengths may be compared with independent
spectrograph-based measurements from NSO, Hinode/SP, and Mt. Wilson
and with filter-based measurements from SoHO/MDI and SDO/HMI. NSO
plans to implement this reduction for all suitable archived SOLIS
spectra and to continue daily umbral field strength measurements
as cycle 24 proceeds. Preliminary comparisons show good agreements
in some cases and systematic differences in others.Abstract (2,250
Maximum Characters): Apparent cyclic and secular changes of sunspot
umbral intensities and magnetic field strengths have been reported for
many decades. Monthly measurements since 1998 show changes that have
been interpreted as a decline in sunspot vigor that, if continued, may
lead to very few visible sunspots in forthcoming cycles (Livingston,
Penn, and Svalgaard 2012, ApJ 757, L8). This dramatic notion is
controversial (e.g. Nagovitsyn, Pevtsov, and Livingston 2012, ApJ
758, L20), and additional observational evidence is needed based on
a minimum of interpretational steps and selection effects. The SOLIS
vector spectromagnetograph has recorded photospheric spectra around
630.2 nm over the full solar disk daily since late 2003 with spatial
and spectral pixel dimensions of about one arc second and 2.3 pm. We
fit the unpolarized intensity spectra in sunspots with a simple Zeeman
triplet model using a single field strength, which works well if the
field strength exceeds about 2 kG and the individual spectra are not
affected by strong Doppler and/or Zeeman variations. The derived total
field strengths may be compared with independent spectrograph-based
measurements from NSO, Hinode/SP, and Mt. Wilson and with filter-based
measurements from SoHO/MDI and SDO/HMI. NSO plans to implement this
reduction for all suitable archived SOLIS spectra and to continue daily
umbral field strength measurements as cycle 24 proceeds. Preliminary
comparisons show good agreements in some cases and systematic
differences in others.
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Title: On a Possible Explanation of the Long-term Decrease in Sunspot
Field Strength
Authors: Nagovitsyn, Yury A.; Pevtsov, Alexei A.; Livingston,
William C.
2012ApJ...758L..20N Altcode:
Recent studies revealed a controversy in long-term variations in sunspot
field strengths. On one hand, the sunspot field strengths computed
by averaging both large and small sunspots and pores show a gradual
decrease over the declining phase of solar Cycle 23 and the rising
phase of Cycle 24. On the other hand, the strongest sunspot field
strengths demonstrate only solar cycle variations with no long-term
decline. Here, we investigate the field strength and area properties of
sunspots in an attempt to reconcile the presence of both tendencies in
recent sunspot field strength measurements. First, we analyze the data
set from Penn & Livingston, and we show that in addition to the
previously reported long-term decline, the data show the solar cycle
variation when only sunspots with the strongest magnetic fields are
included. Next, we investigate the variations in the number of sunspots
of different sizes, and we find a negative correlation between the
numbers of small and large sunspots. Finally, we show that during the
period of 1998-2011, the number of large sunspots gradually decreased,
while the number of small sunspots steadily increased. We suggest that
this change in the fraction of small and large sunspots (perhaps,
due to changes in the solar dynamo) can explain the gradual decline
in average sunspot field strength as observed by Penn & Livingston.
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Title: Decreasing Sunspot Magnetic Fields Explain Unique 10.7 cm
Radio Flux
Authors: Livingston, W.; Penn, M. J.; Svalgaard, L.
2012ApJ...757L...8L Altcode:
Infrared spectral observations of sunspots from 1998 to 2011 have shown
that on average sunspots changed, the magnetic fields weakened, and the
temperatures rose. The data also show that sunspots or dark pores can
only form at the solar surface if the magnetic field strength exceeds
about 1500 G. Sunspots appear at the solar surface with a variety of
field strengths, and during the period from 1998 to 2002 a histogram of
the sunspot magnetic fields shows a normal distribution with a mean of
2436 ± 26 G and a width of 323 ± 20 G. During this observing period
the mean of the magnetic field distribution decreased by 46 ± 6 G
per year, and we assume that as the 1500 G threshold was approached,
magnetic fields appeared at the solar surface which could not form dark
sunspots or pores. With this assumption we propose a quantity called
the sunspot formation fraction and give an analytical form derived
from the magnetic field distribution. We show that this fraction can
quantitatively explain the changing relationship between sunspot number
and solar radio flux measured at 10.7 cm wavelengths.
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Title: Decreasing Sunspot Magnetic Fields Explain Unique 10.7cm
Radio Flux
Authors: Penn, Matthew J.; Livingston, W.; Svalgaard, L.
2012AAS...22011004P Altcode:
Infrared spectral observations of sunspots from 1998-2011 have shown
that on average sunspots changed; the magnetic fields weakened and
the temperatures rose. The data also show that sunspots or dark pores
can only form at the solar surface only if the magnetic field strength
exceeds 1500 Gauss. Sunspots appear at the solar surface with a variety
of field strengths, and during the period from 1998-2002 a histogram
of the sunspot magnetic fields shows a normal distribution with a mean
near 2400 Gauss and a width of about 340 Gauss. During this observing
period the mean of the magnetic field distribution decreased by about
64 Gauss per year, and we assume that as the 1500 Gauss threshold
was approached, magnetic fields appeared at the solar surface which
could not form dark sunspots or pores With this assumption we propose
a quantity called the sunspot formation fraction and give an analytical
form derived from the magnetic field distribution. We show this fraction
can quantitatively explain the changing elationship between sunspot
number and solar radio flux measured at 10.7cm wavelengths.
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Title: High-resolution solar spectral irradiance from extreme
ultraviolet to far infrared
Authors: Fontenla, J. M.; Harder, J.; Livingston, W.; Snow, M.;
Woods, T.
2011JGRD..11620108F Altcode:
This paper presents new extremely high-resolution solar spectral
irradiance (SSI) calculations covering wavelengths from 0.12 nm to
100 micron obtained by the Solar Irradiance Physical Modeling (SRPM)
system. Daily solar irradiance spectra were constructed for most of
Solar Cycle 23 based on a set of physical models of the solar features
and non-LTE calculations of their emitted spectra as function of viewing
angle, and solar images specifying the distribution of features on
the solar disk. Various observational tests are used to assess the
quality of the spectra provided here. The present work emphasizes
the effects on the SSI of the upper chromosphere and full-non-LTE
radiative transfer calculation of level populations and ionizations
that are essential for physically consistent results at UV wavelengths
and for deep lines in the visible and IR. This paper also considers the
photodissociation continuum opacity of molecular species, e.g., CH and
OH, and proposes the consideration of NH photodissociation which can
solve the puzzle of the missing near-UV opacity in the spectral range
of the near-UV. Finally, this paper is based on physical models of
the solar atmosphere and extends the previous lower-layer models into
the upper-transition-region and coronal layers that are the dominant
source of photons at wavelengths shorter than ∼50 nm (except for
the He II 30.4 nm line, mainly formed in the lower-transition-region).
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Title: Uniformity of the quiet solar disk: 3130 - 46700 Å
Authors: Livingston, W.; Galayda, E.; Milkey, R.
2011arXiv1110.1592L Altcode:
Taking advantage of the absence of solar activity in the recent 2008-9
epoch (no spots, few faculae), we have made equatorial and meridian disk
scans in continua from 3129 Å to 46700 Å. Averaging 20 scans at each
wavelength to suppress granulation, which takes a total of 35 minutes,
we achieve a system noise level of 0.01%. We believe this noise level
is a record low, not because of instrument improvements, but simply
because of observing procedures and the cooperation of the Sun and
sky. The observed solar fluctuations significantly exceed the noise
and range from 0.3% at 3130 Å, 0.05% at 34000 Å, to 0.06% at 46700
Å near disk center. These fluctuations (corresponding to about 3 K)
presumably arise from the incomplete averaging of granulation. Standard
solar models for limb darkening fit the data for true continuum
regions reasonably well. No significant differences are seen between
scan directions (EW, N-S). Perhaps our results can serve as a template
for exoplanet detection by the transit of quiet G2V-like stars.
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Title: Long-term evolution of sunspot magnetic fields
Authors: Penn, Matthew J.; Livingston, William
2011IAUS..273..126P Altcode: 2010arXiv1009.0784P
Independent of the normal solar cycle, a decrease in the sunspot
magnetic field strength has been observed using the Zeeman-split
1564.8nm Fe I spectral line at the NSO Kitt Peak McMath-Pierce
telescope. Corresponding changes in sunspot brightness and the strength
of molecular absorption lines were also seen. This trend was seen
to continue in observations of the first sunspots of the new solar
Cycle 24, and extrapolating a linear fit to this trend would lead to
only half the number of spots in Cycle 24 compared to Cycle 23, and
imply virtually no sunspots in Cycle 25. <P />We examined synoptic
observations from the NSO Kitt Peak Vacuum Telescope and initially
(with 4000 spots) found a change in sunspot brightness which roughly
agreed with the infrared observations. A more detailed examination
(with 13,000 spots) of both spot brightness and line-of-sight magnetic
flux reveals that the relationship of the sunspot magnetic fields with
spot brightness and size remain constant during the solar cycle. There
are only small temporal variations in the spot brightness, size, and
line-of-sight flux seen in this larger sample. Because of the apparent
disagreement between the two data sets, we discuss how the infrared
spectral line provides a uniquely direct measurement of the magnetic
fields in sunspots.
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Title: Solar Cycle Variation in Sun-as-a-star Ca II 854.2 nm Bisectors
Authors: Pietarila, A.; Livingston, W.
2011ApJ...736..114P Altcode: 2011arXiv1105.3437P
The bisector of the strong chromospheric Ca II 854.2 nm line has an
inverse-C shape, the cause of which is not yet fully understood. We
show that the amplitude of the bisector in Sun-as-a-star observations
exhibits a solar cycle variation with smaller amplitudes during highest
activity. The line core intensity is lower during solar minima while
the part of the bisector most sensitive to the line core shows no
systematic change with activity. Our results support the use of Ca
II 854.2 nm bisectors in studying the relationship between convection
and magnetic fields, not only in the Sun but in other stars as well.
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Title: An Optical and Near-infrared (2958-9250 Å) Solar Flux Atlas
Authors: Wallace, L.; Hinkle, K. H.; Livingston, W. C.; Davis, S. P.
2011ApJS..195....6W Altcode:
A line resolved (R = λ/Δλ ~ 350,000-700,000) solar flux atlas
covering the region ~2958-9250 Å is discussed. The atlas has been
prepared from ground-based spectra. The telluric spectrum was derived
from disk-center solar spectra taken at differing airmasses. This
telluric spectrum was removed from the flux spectrum. Identifications
are provided for solar lines. Both the data and plots with line
identifications are available digitally.
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Title: Weak Emission Lines in the Wings of Solar H and K
Authors: Livingston, W.; Wallace, L.; White, O. R.
2011SoPh..270..485L Altcode: 2011SoPh..tmp..116L
The rare-earth ions cerium II, lanthanum II, dysprosium II, and
additionally zirconium II and iron II, are seen as weak emission
features in the wings of the solar Ca II H and K lines. The strength of
these emission lines increases on the disk toward the limb. We provide
recent high-resolution observations at disk center and at the limb. The
identity of the weak lines is re-worked. We point out the unique role
of eclipse spectra in distinguishing between the photospheric and
chromospheric origins of emission lines. It is then demonstrated from
our full disk (Sun-as-a-Star) and center disk archives, 1974 - 2010,
that no activity cycle related signal is evident (save for the H and
K lines themselves).
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Title: A Decade of Diminishing Sunspot Vigor
Authors: Livingston, W. C.; Penn, M.; Svalgard, L.
2011SPD....42.1721L Altcode: 2011BAAS..43S.1721L
<SUP>1</SUP>A Decade of Diminishing Sunspot Vigor <P />William
Livingston<SUP>1</SUP> <P />Matt Penn<SUP>1</SUP> <P />Leif
Svalgard<SUP>2</SUP> <P />Sunspots are small dark areas on the solar
disk where internal magnetism, 1500 to 3500 Gauss, has been buoyed to
the surface. (Spot life times are the order of one day to a couple of
weeks or more. They are thought to be dark because convection inhibits
the outward transport of energy there). Their "vigor” can be described
by spot area, spot brightness intensity, and magnetic field. From 2001
to 2011 we have measured field strength and brightness at the darkest
position in umbrae of 1750 spots using the Zeeman splitting of the
Fe 1564.8 nm line. Only one observation per spot per day is carried
out during our monthly telescope time of 3-4 days average. Over this
interval the temporal mean magnetic field has declined about 500 Gauss
and mean spot intensity has risen about 20%. We do not understand the
physical mechanism behind these changes or the effect, if any, it will
have on the Earth environment. <P />1. <P />wcl@noao.edu</u>
mpenn@noao.edu <P />2. <P />leif@leif.org
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Title: Solar Cycle Variation of the Ca 854.2 nm Line Bisectors
Authors: Pietarila, Anna; Livingston, W.
2011SPD....42.1703P Altcode: 2011BAAS..43S.1703P
The bisector of the strong chromospheric Ca II 854.2 nm line has an
inverse-C shape the cause of which is not yet fully understood. We
show that the amplitude of the bisector in Sun-as-a-star observations
exhibits a solar cycle variation with smaller amplitudes during highest
activity. The line core intensity is lower during solar minima while
the part of the bisector most sensitive to the line core shows no
systematic change with activity. We also show preliminary results of
a connection between magnetic shadows and bisector amplitudes. Our
results support the use of Ca II 854.2 nm bisectors in studying the
relationship between convection and magnetic fields, not only in the
Sun but in other stars as well.
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Title: The minimal solar activity in 2008-2009 and its implications
for long-term climate modeling
Authors: Schrijver, C. J.; Livingston, W. C.; Woods, T. N.; Mewaldt,
R. A.
2011GeoRL..38.6701S Altcode: 2011GeoRL..3806701S
Variations in the total solar irradiance (TSI) associated with solar
activity have been argued to influence the Earth's climate system,
in particular when solar activity deviates from the average for a
substantial period. One such example is the 17th Century Maunder Minimum
during which sunspot numbers were extremely low, as Earth experienced
the Little Ice Age. Estimation of the TSI during that period has relied
on extrapolations of correlations with sunspot numbers or even more
indirectly with modulations of galactic cosmic rays. We argue that
there is a minimum state of solar magnetic activity associated with
a population of relatively small magnetic bipoles which persists
even when sunspots are absent, and that consequently estimates of
TSI for the Little Ice Age that are based on scalings with sunspot
numbers are generally too low. The minimal solar activity, which
measurements show to be frequently observable between active-region
decay products regardless of the phase of the sunspot cycle, was
approached globally after an unusually long lull in sunspot activity
in 2008-2009. Therefore, the best estimate of magnetic activity, and
presumably TSI, for the least-active Maunder Minimum phases appears to
be provided by direct measurement in 2008-2009. The implied marginally
significant decrease in TSI during the least active phases of the
Maunder Minimum by 140 to 360 ppm relative to 1996 suggests that
drivers other than TSI dominate Earth's long-term climate change.
---------------------------------------------------------
Title: Sun-as-a-Star, Chromospheric Lines, 1974-2009
Authors: Livingston, W.; White, O. R.; Wallace, L.; Harvey, J.
2010MmSAI..81..643L Altcode:
We update the McMath-Pierce spectral line scan archives for Ca II K,
He I 10830 Å, Ca II 8542 Å, and H I 6562 Å, both for full-disk
and center-disk measurements . The Ca K3 intensity feature displays
a peak-to-peak activity cycle modulation of ∼ 37% and He 10830
Å about 100%. SOLIS observations of the Ca K index suggest a cycle
23-24 minimum in late 2008 followed by a 0.7% rise by late 2009. Other
McMath-Pierce indices display no evidence yet of cycle 24. Center-disk
Ca K index measurements (optically averaged over the central 2-arcmin),
show no particular response to cycle activity, i.e. the quiet disk
is constant. A similar null response is found for the center-disk
Wilson-Bappu effect.
---------------------------------------------------------
Title: Are Sunspots Different During This Solar Minimum?
Authors: Livingston, W.; Penn, M.
2009EOSTr..90..257L Altcode:
For hundreds of years, humans have observed that the Sun has displayed
activity where the number of sunspots increases and then decreases
at approximately 11-year intervals. Sunspots are dark regions on the
solar disk with magnetic field strengths greater than 1500 gauss (see
Figure 1), and the 11-year sunspot cycle is actually a 22-year cycle in
the solar magnetic field, with sunspots showing the same hemispheric
magnetic polarity on alternate 11-year cycles. The last solar maximum
occurred in 2001, and the magnetically active sunspots at that time
produced powerful flares causing large geomagnetic disturbances and
disrupting some space-based technology. But something is unusual
about the current sunspot cycle. The current solar minimum has been
unusually long, and with more than 670 days without sunspots through
June 2009, the number of spotless days has not been equaled since 1933
(see http://users.telenet.be/j.janssens/Spotless//Spotless.html). The
solar wind is reported to be in a uniquely low energy state since
space measurements began nearly 40 years ago [Fisk and Zhao, 2009].
---------------------------------------------------------
Title: A Century of Solar Ca II Measurements and Their Implication
for Solar UV Driving of Climate
Authors: Foukal, Peter; Bertello, Luca; Livingston, William C.;
Pevtsov, Alexei A.; Singh, Jagdev; Tlatov, Andrey G.; Ulrich, Roger K.
2009SoPh..255..229F Altcode:
Spectroheliograms and disk-integrated flux monitoring in the strong
resonance line of Ca II (K line) provide the longest record of
chromospheric magnetic plages. We compare recent reductions of the Ca II
K spectroheliograms obtained since 1907 at the Kodaikanal, Mt. Wilson,
and US National Solar Observatories. Certain differences between the
individual plage indices appear to be caused mainly by differences
in the spectral passbands used. Our main finding is that the indices
show remarkably consistent behavior on the multidecadal time scales of
greatest interest to global warming studies. The reconstruction of solar
ultraviolet flux variation from these indices differs significantly
from the 20th-century global temperature record. This difference is
consistent with other findings that, although solar UV irradiance
variation may affect climate through influence on precipitation and
storm tracks, its significance in global temperature remains elusive.
---------------------------------------------------------
Title: Ca II H & K Spectra From The National Solar Observatory
Authors: Livingston, W. C.; Giampapa, M. S.; Harvey, J. W.; Keil,
S. L.; Toussaint, R. M.
2008AGUSMSP53B..04L Altcode:
When the Sun is observed as a star (i.e., spatially integrated full
disk) the cores of the chronospheric H and K resonance lines of
singly ionized calcium show the greatest cycle variability (up to
40% peak-to-peak) accessible from the ground. Synoptic archives are
available at monthly intervals from 1974 (Kitt Peak) and for K only
at almost a daily cadence from 1984 (Sacramento Peak). We discuss
these time series and compare them with, for example, sunspot numbers
and magnetic fields. Less frequent are center disk observations in
which the activity cycle is found to be absent, implying the quiet
basal atmosphere is constant and not, say, heated by cycle magnetic
activity. New, near daily, spatially integrated full disk solar data
from the SOLIS Integrated Sunlight Spectrometer (ISS)agree well with
the older work. We now propose to produce calibrated (Houtgast 1970;
Solar Phys 15, 273, high points: 387.5, 395.3, and 402.0 nm), low
dispersion full disk spectra that may be directly compared with that
from solar-type stars.
---------------------------------------------------------
Title: Precision (±0.005%) Quiet Sun Limb Darkening Scans Show E-W
Vs N-S Chords Same.
Authors: Livingston, W. C.; Milkey, R.; Sheeley, N., Jr.
2008AAS...21115906L Altcode:
Using the 80-cm McMath-Pierce image, we compare equatorial and meridian
limb darkening and find they are identical. Observations consist of
20 scans over 30 minutes at 15648 Å (H- opacity minimum) and 34168
Å continua. Noise is sky and disk structure limited. System noise is
negligible at ± 0.005%; disk structure noise is ± 0.03% at 15648 Å
0.02% at 34168 Å. Our next step will be to compare these limb darkening
results with those predicted by solar models. Ref: Livingston &
Sheeley, 2008, ApJ 672 no.1, in press.
---------------------------------------------------------
Title: Limits to the Radiative Asymmetry of the Quiet Solar Disk
Authors: Livingston, W.; Sheeley, N. R., Jr.
2008ApJ...672.1228L Altcode:
Precise data on the uniformity of photospheric radiation over the solar
disk seems not to exist. Such information is necessary to separate
the radiative behavior of the quiet basal atmosphere from the active
(magnetic) atmosphere. Is the latter the sole source of known irradiance
variation? How uniform can a solar-like stellar disk be? To obtain this
information we have made monochromatic scans along the central meridian
of the quiet Sun using single element detectors which do not require
flat fielding. The scans were in continua and in selected Fraunhofer
lines ranging from 3134 to 46880 Å the observational epoch was near
solar minimum: 2006 October to 2007 February. The meridian was chosen
to avoid rotational Doppler shifts. We extract the asymmetry between
the north and south hemispheres and present it as our main product. In
the near-infrared and visible continuum, averaging over granulation and
avoiding sunspots, we found that such asymmetry was as low as 0.05%
(at 34168 Å on 2007 February 8). In the violet and ultraviolet this
asymmetry typically increases to 1%. Asymmetry is larger in the cores
of the medium strong photospheric and chromospheric lines, which refer
to higher levels in the atmosphere, and may reach 15%. The contrast of
faculae increases in the blue (and with improved spatial resolution or
seeing), and is the probable source for the measured asymmetries. We
also find that line core scans are in general flatter than continuum
scans.
---------------------------------------------------------
Title: Thirty-five year trend of hydrogen chloride amount above Kitt
Peak, Arizona
Authors: Wallace, L.; Livingston, W. C.
2007GeoRL..3416805W Altcode:
We have analysed solar spectra obtained with the McMath-Pierce
telescope on Kitt Peak, Arizona, for column amount of HCl for the
period Sept. 1971 through Feb. 2007 using the absorption line at
3.4168 μm. In addition to the previously well-established increase
in amount from 1971 to ~1993 and a plateau between ~1993 and ~1997,
we now see a definite decrease from ~1997 to 2007.
---------------------------------------------------------
Title: Limits To The Radiative Asymmetry Of The Quiet Solar Disk
Authors: Livingston, W. C.; Sheeley, N. R.
2007AAS...210.2503L Altcode: 2007BAAS...39..131L
Precise data on the uniformity of photospheric radiation over the solar
disk seems not to exist. Such may be needed for the future detection
of planets crossing solar-like stellar disks, for example. To obtain
this information we have made monochromatic scans along the central
meridian of the quiet Sun using single element detectors which do not
require ’flat fielding’. The scans were in continua and selected
Fraunhofer lines ranging from 3129 to 46880 A; the observational epoch
was near solar minimum: Oct 2006 to Feb 2007. The meridian was chosen
to avoid rotational doppler shifts. We extract the asymmetry between
the N and S hemispheres and this is our main product. In the near IR
and visible continuum, averaging over granulation and discounting
sunspots, such asymmetry is as low as 0.01%; 0.005% at 34168 A on
8 Feb 2007. In the violet and UV this increases to 1%. In the cores
of medium strength photospheric lines and in chromospheric lines the
asymmetry is up to 15%. Faculae are the probable source of our measured
quiet disk asymmetries, and the continuum at 34168 A is favorable for
this reason. Line core scans are in general flatter than continuum
scans because they sample thinner, higher layers of the atmosphere,
where the temperature gradient is less.
---------------------------------------------------------
Title: Sun-as-a-Star Spectrum Variations 1974-2006
Authors: Livingston, W.; Wallace, L.; White, O. R.; Giampapa, M. S.
2007ApJ...657.1137L Altcode: 2006astro.ph.12554L
We have observed selected Fraunhofer lines, both integrated over
the full disk and for a small circular region near the center of the
solar disk, on 1215 days over the past 30 years. Our full disk results
for the chromosphere show that Ca II K 3933 Å nicely tracks the 11
yr magnetic cycle based on sunspot number, with a peak amplitude in
central intensity of ~37%. The wavelength of the midline core absorption
feature, called K3, referenced to nearby photospheric Fe, displays
an activity cycle variation with an amplitude of 3 mÅ (6 mÅ center
disk). Other chromospheric lines, such as He I 10830 Å, Ca II 8542 Å,
Hα, and the CN 3883 Å bandhead, track Ca II K intensity with lower
relative amplitudes. In the low photosphere, temperature-sensitive C I
5380 Å appears constant in intensity to 0.2%. In the high photosphere,
the cores of strong Fe I lines, Na D1 and D2, and the Mg I b lines,
present a puzzling signal, perhaps indicating a role for the 22 yr Hale
cycle. Solar minimum around 1985 was clearly seen, but the following
minimum in 1996 was missing. Our center disk results show that both
Ca II K and C I 5380 Å intensities are constant, indicating that the
basal quiet atmosphere is unaffected by cycle magnetism within our
observational error. A lower limit to the Ca II K central intensity
atmosphere is 0.040. This possibly represents conditions as they were
during the Maunder minimum. Converted to the Mount Wilson S-index
(H+K index), the Sun center disk is at the lower activity limit for
solar-type stars. An appendix provides instructions for URL access to
both the raw and reduced data.
---------------------------------------------------------
Title: Magnetic source of the solar cycle variation of the Mn I
539.4 nm line
Authors: Danilović, S.; Solanki, S. K.; Livingston, W.; Krivova,
N.; Vince, I.
2007msfa.conf..189D Altcode:
As a part of the long term program at KPNO, the Mn I 539.4 nm line has
been observed for nearly three solar cycles using the McMath telescope
and the 13.5 m spectrograph in double pass mode. These full-disk
spectrophotometric observations revealed an unusually large amplitude
change of its parameters over the solar cycle and its correlation with
Ca II K intensity. One of the proposed explanations for this phenomenon
is the optical pumping by the Mg II k line. With this work we would like
to show that this may not be the main mechanism behind the change. We
reconstructed the changes of the line parameters using a model that
takes into account only changes of the daily surface distributions of
magnetic field. This model has already been used to successfully model
total solar irradiance. We now apply it for modelling the Mn I line,
as well as its neighboring Fe I line using exactly the same value
of the free parameter as used for the reconstruction of total solar
irradiance. We reproduce well the Mn I and Fe I line changes over the
cycle purely with LTE modelling. This indicates that optical pumping
of the Mn I line by Mg II k is not the main cause of its solar cycle
change and sets an independent constraint on solar irradiance models.
---------------------------------------------------------
Title: An Atlas of the Spectrum of the Solar Photosphere from 13,500
to 33,980 cm<SUP>-1</SUP> (2942 to 7405 Å)
Authors: Wallace, L.; Hinkle, K.; Livingston, W.
2007assp.book.....W Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Sunspots with the Strongest Magnetic Fields
Authors: Livingston, W.; Harvey, J. W.; Malanushenko, O. V.;
Webster, L.
2006SoPh..239...41L Altcode: 2006SoPh..tmp...85L
The strongest observed solar magnetic fields are found in sunspot
umbrae and associated light bridges. We investigate systematic
measurements of approximately 32 000 sunspot groups observed from 1917
through 2004 using data from Mt. Wilson, Potsdam, Rome and Crimea
observatories. Isolated observations from other observatories are
also included. Corrections to Mt. Wilson measurements are required
and applied. We found 55 groups (0.2%) with at least one sunspot
with one magnetic field measurement of at least 4000 G including five
measurements of at least 5000 G and one spot with a record field of
6100 G. Although typical strong-field spots are large and show complex
structure in white light, others are simple in form. Sometimes the
strongest fields are in light bridges that separate opposite polarity
umbras. The distribution of strongest measured fields above 3 kG appears
to be continuous, following a steep power law with exponent about
−9.5. The observed upper limit of 5 - 6 kG is consistent with the
idea that an umbral field has a more or less coherent structure down
to some depth and then fragments. We find that odd-numbered sunspot
cycles usually contain about 30% more total sunspot groups but 60%
fewer >3 kG spots than preceding even-numbered cycles.
---------------------------------------------------------
Title: Obituary: A. Keith Pierce, 1918 - 2005
Authors: Livingston, William Charles
2006BAAS...38.1281L Altcode:
A. Keith Pierce was a solar astronomer who will be remembered for
bringing the physics lab to the telescope and for his design of the
world's largest solar telescope, the 1.5-meter McMath Telescope on
Kitt Peak in Arizona. Born in Lincoln, Nebraska, he died of cancer
in Tucson on 11 March 2005. He was eighty-six. <P />His father,
Tracy Pierce, had gone to graduate school in Berkeley, California,
with a major in mathematics and a minor in astronomy. Fellow students
of his class included Seth Nicholson and Donald Shane, people who were
later to influence young Keith's life. <P />Tracy Pierce received an
appointment as an instructor, later Professor, of mathematics at the
University of Nebraska in Lincoln. In his spare time dad Tracy became
something of a telescope nut, following "the bible" —Albert Ingall's
A.T.M (Amateur Telescope Making). His enthusiasm rubbed off on his
son. <P />Seth Nicholson, who became a famous Mt. Wilson Observatory
astronomer, and Donald Shane from Berkeley, both stayed at the Pierce
home while on their Sigma Xi lecture tours. After two years at Lincoln,
followed by two more at Berkeley, Keith had earned his bachelor's degree
in astronomy. <P />During World War II, Dr. Shane became personnel
director at the E.O. Lawrence Radiation Lab and arranged for Keith to
work there at the cyclotron. A crash program to produce U235 from U238
was under way. At a crucial point in 1942 the cyclotron turned out
the sought-after material. Much celebration ensued among the Rad Lab
leaders. During this gala, Keith was on the night-shift and pretty
much on his own. It was then that he turned a valve to the right,
when left was called for, and the entire system went down. Shortly
thereafter he was sent to Oak Ridge for the duration of the war. He
cannot have been thought of badly, however, because he was invited to
the Trinity test in New Mexico. (He didn't go because of the pending
birth of his first son, John.) <P />The year 1945 found Keith back in
Berkeley working on his Ph.D. under Shane. After finishing this degree,
Keith was brought by Leo Goldberg to the University of Michigan, Ann
Arbor, and then to Lake Angelus, where his association with Robert
McMath began. His prowess with instrumentation led to a mapping of
the infrared solar spectrum with unprecedented accuracy. <P />McMath,
a Detroit engineer, had this dream of building a large solar telescope
at a suitable elevated and dry location. Through friends in Washington
(viz. the Director of the Bureau of the Budget), he found funds to
construct this telescope under the guidance of Keith Pierce. Kitt
Peak National Observatory was an ancillary result. <P />The above
is a distillation of an interview with Keith regarding his career
on the occasion in 1992 of the re-dedication of the McMath-Pierce
Solar Facility. I would add that Keith carried out seminal work on
the solar spectrum. These include "The Chromospheric Spectrum Outside
Eclipse, ?? 3040-9266," with Jim Breckenridge, "The Kitt Peak Table of
Photographic Solar Spectrum Wavelengths," and with Charles Slaughter,
"Solar Limb Darkening, I and II." For sixteen years, Keith directed the
Solar Program of KPNO with a gentle hand. At home with his first wife,
Mildred, and later with his second, Trudy, he extended warm hospitality
to visitors from around the world. He leaves three children: John
(deceased), Barbara Isabel Orville, and Willard Ross.
---------------------------------------------------------
Title: Temporal Changes in Sunspot Umbral Magnetic Fields and
Temperatures
Authors: Penn, M. J.; Livingston, W.
2006ApJ...649L..45P Altcode:
We have observed high-resolution intensity spectra near the Fe I
1564.8 nm line at a single umbral point corresponding to the darkest
position in over 900 sunspots from 1998 through 2005. From these
data we determine that the maximum sunspot magnetic fields have been
decreasing at about 52 G yr<SUP>-1</SUP>. The same data set shows a
concurrent increase in the normalized umbral intensity from 0.60 to 0.75
(corresponding to a blackbody temperature rise from 5137 to 5719 K)
and a decrease of more than 50% in the molecular OH line strength. The
magnetic field and intensity changes observed over time in the sunspot
umbrae from different spots behave in the same way as the magnetic
field and intensity changes observed spatially across single sunspots.
---------------------------------------------------------
Title: Sunspot Magnetic Fields Measured up to 6000 Gauss
Authors: Livingston, W.; Harvey, J.; Malanushenko, O.; Webster, L.
2006IAUJD...3E..54L Altcode:
Photoelectric `magnetographs' underestimate field strength in sunspot
umbrae because of scattered light. Two techniques that do work are
photographic spectra or visual observations where the Zeeman sigma
components are matched by the observer with the Hale-Nicholson tipping
plate and the plate angle is converted to gauss. We study field measures
of 32000 spots, 1917 to 2004, from the archives of Mt. Wilson, Potsdam,
Rome, and the Crimea. We find 58 spot groups with fields of 4000
G or more. A careful look at the time history of equipment used at
Mt. Wilson reveals that the non-linearity of the glass plate at large
tilt angles was not taken properly into account, perhaps because of
their rarity. When we correct the Mt. Wilson values for strong fields
we find several cases of 5000 G and one of 6100 G. Often such strong
fields are associated with light bridges, but not always.
---------------------------------------------------------
Title: Modeling the cyclic modulation of photospheric lines
Authors: Penza, V.; Pietropaolo, E.; Livingston, W.
2006A&A...454..349P Altcode:
We have studied the behavior of three photospheric lines (Fe I 537.9,
C I 538.0 and Ti II 538.1 nm), which have been monitored on the Sun
for more than twenty years, either as full-disk or as center-disk
measurements (Gray & Livingston 1997; Livingston & Wallace
2003). The aim is to detect a possible photospheric variation with the
cycle. We try to reconstruct the cyclic variations of full-disk line
depths as due to active region (AR) modulation through a spectral
synthesis with FAL semi-empirical models (Fontenla et al. 1999)
weighted by AR coverage factors. The sensitivity of these lines to
thermodynamic variations and to AR presence is analyzed. We show that
the AR modulation alone cannot explain all the observational results,
either in amplitude or in phase. The "residual", i.e. the difference
between observed behavior of these three lines at full-disk and that
predicted by models for the AR modulation, results in a signal that is
correlated with the measured center-disk line variations, and should be
free from magnetic effects. Both the full-disk and the center-disk data
show several periodicities; furthermore there are two periodicities
shared by the three lines, one close to the 11 yr magnetic cycle and
the other of 2.8 yr.
---------------------------------------------------------
Title: Line depth variations along the solar cycle: a biennial
periodicity?
Authors: Penza, V.; Pietropaolo, E.; Livingston, W.
2006MSAIS...9..123P Altcode:
We study the behaviour of three photospheric lines (Fe I 537.9, C I
538.0 and Ti II 538.1 nm), monitored on the Sun since 1978. The aim is
to detect photospheric variations with the cycle. We reconstruct the
cyclic variations of full-disk line depths as due to the active regions
(ARs). We show that ARs alone cannot account all the observational
results. The differences between observed behaviour and the AR
contribution correlate with the measured center-disk line variations,
and a common periodicity of ∼ 2.7 yr is present.
---------------------------------------------------------
Title: Fundamentals of Solar Astronomy
Authors: Bhatnagar, Arvind; Livingston, William; Holman, Gordon D.
2006PhT....59j..66B Altcode:
No abstract at ADS
---------------------------------------------------------
Title: High Spectral Resolution Study of the He 10830 Spectral Region
Authors: Malanushenko, O.; Livingston, W.; Jones, H.; Malanushenko,
V. P.
2005ASPC..346..389M Altcode:
The He 1083 nm line, formed in the upper chromosphere, is used for
observations of coronal holes (CHs) near their origins at the solar
surface. The weak He profiles in CHs show some peculiarities such
as asymmetry, broadening, and different ratios between spectral
components. These effects are small and the influence of disturbing
noise and approximations in reductions may be crucial for their
definition. In the present work we used low noise and high spectral
resolution observations carried out at the Kitt Peak McMath-Pierce
telescope to establish the key characteristics of He profile. The
shape of He profile is affected by telluric water line and we suggest
a method for its correction. Also there are solar lines that lie
between the main and second He components and overlap with both. If
the He line is weak and blue shifted, as in a CH and in cell centers,
the blends distort the visual shape of the main component and obscure
the second component. As an example we analyze two integral spectra
of CH and quiet Sun and confirm the broadening and minor blue shift of
the He line in a CH. This result must be considered to be preliminary
and the work is in progress.
---------------------------------------------------------
Title: Quiet Sun unaffected by Activity Cycle
Authors: Livingston, W.; Gray, D.; Wallace, L.; White, O. R.
2005ASPC..346..353L Altcode:
The Sun's 11 year sunspot cycle, and all related phenomena, are driven
by magnetism in the form of hot flux tubes which thread through the
surface from below. Full disk chromospheric Ca K intensity observations
track the activity cycle. But center disk Ca K and photospheric
temperature sensitive lines are invariant to cycle magnetism. Recent
high resolution photographs of the photosphere show that the flux
tubes are confined between the granulation cells and do not interact
with them. The result is a constant basal atmosphere without cyclic
consequences for the Earth.
---------------------------------------------------------
Title: Obituary: A. Keith Pierce 1918 2005
Authors: Livingston, William; Harvey, John
2005SoPh..229..199L Altcode: 2005SoPh..229..199W
No abstract at ADS
---------------------------------------------------------
Title: The He I 1083 nm line in Coronal Holes, a study with high
spectral resolution.
Authors: Malanushenko, O.; Jones, H. P.; Livingston, W.; Malanushenko,
V. P.
2005AGUSMSP51B..08M Altcode:
The He 1083 nm line (He), formed in the upper chromosphere, is used
for observations of coronal holes (CH) near their origins at the solar
surface. Weak He 1083 nm profiles in CHs show some peculiarities
such as asymmetry, broadening, and a different ratio between the
spectral components. These effects are small so that the influence
of disturbing noise and approximations in reduction processes are
important for the results. In this research we have used low noise
and high spectral resolution observations carried out at the Kitt Peak
McMath-Pierce telescope to establish the key characteristics of the He
profile in CHs. For accurate reduction we corrected the He profile for
spectral blending from water vapor and weak solar lines. We confirm
our previous result, based on imaging-spectroscopy data from the Kitt
Peak Vacuum Telescope, regarding broadening of the He line in CHs and
explain previous instability of CH contrast in our procedure for CH
recognition as an influence of hidden photospheric lines.
---------------------------------------------------------
Title: Fundamentals of Solar Astronomy
Authors: Bhatnagar, Arvind; Livingston, William
2005fsa..book.....B Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Fundamentals Of Solar Astronomy
Authors: Bhatnagar, Arvind; Livingston, William
2005WSSAA...6.....B Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Study of photospheric line depth variations along the solar
cycle
Authors: Penza, V.; Pietropaolo, E.; Livingston, W.
2005MmSAI..76..856P Altcode:
We study the behaviour of three photospheric lines (Fe I 537.9,
C I 538.0 and Ti II 538.1 nm), monitored on the Sun since 1978,
either as full-disk or as center-disk measurements. The aim is to
detect photospheric variations with the cycle. We reconstruct the
cyclic variations of full-disk line depths as due to the active region
modulation, through a spectral synthesis with FAL semiempirical models
(Fontenla et al.). We show that ARs alone cannot account all the
observational results. The difference between observed behaviour of
these three lines at full-disk and the AR contributionm as predicted by
the models, correlates with the measured center-disk line variations,
and a common periodicity of ∼ 2.8 yr is present.
---------------------------------------------------------
Title: An atlas of sunspot umbral spectra in the visible from 15,000
to 25,500 cm-¹ (3920 to 6664 Å)
Authors: Wallace, Lloyd; Hinkle, Kenneth; Livingston, W. C.
2005asus.book.....W Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Imaging the Chromosphere using Photospheric Mn 539.4 nm
Authors: Malanushenko, Olena; Jones, H. P.; Livingston, W.
2004IAUS..223..645M Altcode: 2005IAUS..223..645M
Archival full disk observations of the central depth of Mn 539.467,
a photospheric line, have been found to correlate with chromospheric
Ca K intensity. In this paper we present spectroheliograms taken in
Mn I 539.467 and 542.32 nm lines and other nearby lines to see if the
other photospheric lines show chromospheric structures. We see both
Mn images and also Si I 542.118 mimic magnetograms the similar way,
while strong Fe and Ti lines only faintly reveal magnetic features,
and weak Fe lines of comparable strength to Mn show nothing.
---------------------------------------------------------
Title: Atmospheric Transmission Above Kitt Peak, 0.5 to 5.5 microns
Authors: Hinkle, K. H.; Wallace, L.; Livingston, W.
2003AAS...203.3803H Altcode: 2003BAAS...35R1260H
The transmission spectrum of the Earth's atmosphere over Kitt
Peak from 0.5 to 5.5 microns has been derived from solar spectra
taken with the N.S.O. McMath Fourier Transform Spectrometer. The
spectrum is presented as a poster, copies of which are available
from the author. The telluric spectrum is shown in absorption
against a normalized continuum. The data are on the NOAO web site at
ftp://ftp.noao.edu/catalogs/atmospheric_transmission/. The data are at
high resolution (about 1 km s<SUP>-1</SUP>). However, in the plotted
version the dispersion is very low so individual spectral lines are show
as sharp unresolved lines. The major molecular bands are identified on
the poster. The data are produced from ratios of solar spectra taken
at different airmasses. For those atmospheric lines that are opaque
there is no information in the line cores which results in gaps in
the data. The ratioing process cancels much of the solar spectrum but
residual features of strong lines can be detected. These result from
differing Doppler shifts between the solar observations.
---------------------------------------------------------
Title: High Resolution Infrared, Visible and Ultraviolet Spectral
Atlases of the Sun and Arcturus
Authors: Hinkle, K.; Wallace, L.; Livingston, W.; Ayres, T.; Harmer,
D.; Valenti, J.
2003csss...12..851H Altcode:
Various groups of the co-authors have produced series of solar and
stellar atlases. Some atlases are listed below and the most recent
products described.
---------------------------------------------------------
Title: Imaging Spectropolarimetry of Ti I 2231 nm in a Sunspot
Authors: Penn, M. J.; Cao, W. D.; Walton, S. R.; Chapman, G. A.;
Livingston, W.
2003SoPh..215...87P Altcode:
Spectro-polarimetric observations at 2231 nm were made of NOAA 10008
near the west solar limb on 29 June 2002 using the National Solar
Observatory McMath-Pierce Telescope at Kitt Peak and the California
State University Northridge - National Solar Observatory infrared
camera. Scans of spectra in both Stokes I and Stokes V were collected;
the intensity spectra were processed to remove strong telluric
absorption lines, and the Stokes V umbral spectra were corrected for
instrumental polarization. The sunspot temperature is computed using
the continuum contrast and umbral temperatures down to about 3700 K are
observed. A strong Ti i line at 2231.0 nm is used to probe the magnetic
and velocity fields in the spot umbra and penumbra. Measurements of the
Ti i equivalent width versus plasma temperature in the sunspot agree
with model predictions. Zeeman splitting measurements of the Stokes I
and Stokes V profiles show magnetic fields up to 3300 G in the umbra,
and a dependence of the magnetic field on the plasma temperature
similar to that which was seen using Fe i 1565 nm observations of the
same spot two days earlier. The umbral Doppler velocity measurements
are averaged in 16 azimuthal bins, and no radial flows are revealed to
a limit of ± 200 m s<SUP>−1</SUP>. A Stokes V magnetogram shows a
reversal of the line-of-sight magnetic component between the limb and
disk center sides of the penumbra. Because the Ti i line is weak in
the penumbra, individual spectra are averaged in azimuthal bins over
the entire penumbral radial extent. The averaged Stokes V spectra show
a magnetic reversal as a function of sunspot azimuthal angle. The mean
penumbral magnetic field as measured with the Stokes V Zeeman component
splitting is 1400 G. Several weak spectral lines are observed in the
sunspot and the variation of the equivalent width versus temperature
for four lines is examined. If these lines are from molecules, it is
possible that lines at 2230.67, 2230.77, and 2231.70 nm originate from
OH, while the line at 2232.21 nm may originate from CN.
---------------------------------------------------------
Title: Weak Infrared Molecular Lines Reveal Rapid Outflow in Cool
Magnetic Sunspot Penumbral Fibrils
Authors: Penn, M. J.; Cao, W. D.; Walton, S. R.; Chapman, G. A.;
Livingston, W.
2003ApJ...590L.119P Altcode:
New imaging spectropolarimetric observations of the Evershed flow
in sunspot penumbrae using weak infrared molecular absorption lines
are presented. A plane-polar coordinate system in the sunspot frame
is defined, allowing averaging of many raw spectra. Molecular lines
show Doppler shifts implying typical horizontal outflow speeds of 6
and up to 9 km s<SUP>-1</SUP>. The Ti I polarimetric spectra show the
same rapid outflow and suggest an average penumbral magnetic field
strength of 1400 G. While these observations show Doppler shifts of
the entire line profile, the velocities are in better agreement with
previous measurements from spectral line asymmetries.
---------------------------------------------------------
Title: Weak IR Lines Reveal Rapid Outflow in Cool Magnetic Penumbra
Authors: Penn, M. J.; Cao, W. D.; Walton, S. R.; Chapman, G. A.;
Livingston, W.
2003SPD....34.1106P Altcode: 2003BAAS...35..827P
New imaging spectropolarimetric observations of the Evershed flow in
sunspot penumbrae using weak infrared molecular absorption lines are
presented. A plane-polar coordinate system in the sunspot frame is
defined, allowing averaging of many raw spectra. Molecular lines show
Doppler shifts implying typical horizontal outflow speeds of 6 to 9
km/sec. The Ti I polarimetric spectra show the same rapid outflow
and suggest an average penumbral magnetic field strength of 1400
Gauss. While these observations show Doppler shifts of the entire
line profile the velocities are in better agreement with previous
measurements from spectral line asymmetries.
---------------------------------------------------------
Title: The Sun's immutable basal quiet atmosphere
Authors: Livingston, W.; Wallace, L.
2003SoPh..212..227L Altcode:
We employ limb darkening, spectral energy distribution (color),
and center-disk spectrum line strength to investigate photospheric
temporal variability. Current limb-darkening curves agree to 1%
with past observations taken at different epochs extending back to
1975. Concerning color, from the data of Labs and Neckel (Cox, 1999)
we deduce that the solar limb is 1000 Å more red than disk center. But
when integrated over the entire disk to represent the Sun-as-a-star,
the color shift is only 30 Å. Color is therefore not a very sensitive
indicator of full-disk photospheric change. We examine the center-disk
time series for C 5380 Å and Fe 5379 Å equivalent width and the Ca K
index. The ratio C 5380/Fe 5379 in equivalent width is 0.4221+0.00011
(± 0.00003) y<SUP>−1</SUP>, indicating secular change but with no
cycle modulation. Converted to temperature this variance amounts to ±
0.028 K. This is in contrast to the full-disk cycle modulation of these
lines reported by Gray and Livingston (1997b). Ca K index also exhibits
no cycle variation at disk center. Taking into account these findings,
plus the small fraction of the photosphere occupied by magnetic elements
as revealed in high-resolution G-band pictures, we suggest that cycle
magnetic fields thread through the basal atmosphere without physical
effect; that the basal quiet atmosphere is observationally immutable
to the magnetic cycle within the limits given above.
---------------------------------------------------------
Title: An atlas of the solar spectrum in the infrared from 1850 to
9000 cm-1 (1.1 to 5.4 micrometer)
Authors: Wallace, L.; Livingston, W.
2003assi.book.....W Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Spectroscopic Detection of the 3.934 Micron Line of Si IX in
the Solar Corona
Authors: Judge, P. G.; Tomczyk, S.; Livingston, W. C.; Keller, C. U.;
Penn, M. J.
2002ApJ...576L.157J Altcode:
We report the detection of the
2s<SUP>2</SUP>2p<SUP>2</SUP><SUP>3</SUP>P<SUB>1-->0</SUB> line of
Si IX using the McMath-Pierce telescope on Kitt Peak. Observations
were made of the solar disk and at various heights above the limb
between 2002 May 13 and 17, under nonideal sky conditions, using the
13.5 m vertical spectrograph and an InSb single-diode detector. We
report a new rest wavelength for the line and discuss its potential
use as a diagnostic of coronal magnetic fields using ground-based
telescopes. Our observations give λ<SUB>rest</SUB>=3.93434+/-0.00007
μm, consistent with earlier less accurate values, but it places the
blue wing of the line under a strong telluric N<SUB>2</SUB>O line. In
the active regions observed, the line's intensity is comparable to or
larger than predicted in earlier work for the quiet Sun.
---------------------------------------------------------
Title: Detection of the mercapto radical SH in the solar atmosphere
Authors: Berdyugina, S. V.; Livingston, W. C.
2002A&A...387L...6B Altcode:
We analyze new high-resolution UV observations of the solar photosphere
in the disk center and the limb and report the first detection of SH
lines in the solar atmosphere. We perform a synthesis of the solar
spectrum including many atomic and molecular lines and find a few
relatively unblended SH lines from which we determine the (0, 0) band
oscillator strength f<SUB>00</SUB>=2.2*E<SUP>-3</SUP>. We conclude
that these lines are excellent indicators of the sulfur abundance and
isotope ratio in G and K stars.
---------------------------------------------------------
Title: Solar Irradiance Observations during Solar Cycles 22 and 23
Authors: White, O. R.; de Toma, G.; Chapman, G. A.; Walton, S. R.;
Preminger, D. G.; Cookson, A. M.; Harvey, K. L.; Livingston, W. C.
2002AAS...200.5707W Altcode: 2002BAAS...34..737W
We present a study of Total Solar Irradiance (TSI) variations during
solar cycles 22 and 23 from 1986 to the present. We will review the
recent measurements of solar magnetism, solar activity, and radiative
variability from both ground-based and space observatories and compare
TSI observations with empirical models of solar irradiance variability
based on facular and sunspot observations. To estimate facular/plage and
sunspot contribution to TSI we use the photometric indices derived from
the SFO full-disk solar images from 1988 to the present in the CaIIK
line at 393.4nm and in the red continuum at 672.3 nm. In these indices,
each solar structure is included with its measured contrast and area. We
also use the MgII core-to-wing index from space observatories as an
alternative index for plages and network. Comparison of the rising
and maximum phases of the two solar cycles, shows that cycle 23 is
magnetically weaker with sunspot and facular area almost a factor of
two lower than in solar cycle 22. However, analysis of multi-wavelength
observations indicate that different wavelengths respond differently
to the decreased magnetic activity during solar cycle 23.
---------------------------------------------------------
Title: Sunspots Observed to Physically Weaken in 2000-2001
Authors: Livingston, W.
2002SoPh..207...41L Altcode:
The `strength' of a sunspot depends on its magnetic field and umbral
darkness, factors which go together. The strongest field in an umbra
is always found at the darkest position. We use this relationship,
B=f(1/T), to demonstrate that at the maximum of cycle 22 (1990-1991)
sunspots were statistically stronger than at the same phase of cycle
23 (2000-2001). Within our sample of 195 spots, cycle 23 exhibits an
excess of small bright spots, and possibly, a dearth of large dark
spots. This could alter the total solar irradiance (TSI)-sunspot
number relationship.
---------------------------------------------------------
Title: Sunspot umbral spectra in the regions 1925 to 2226 and 2392
to 3480 cm(-1) (2.87 to 4.18 and 4.48 to 5.35 [microns])
Authors: Wallace, L.; Hinkle, K.; Livingston, W. C.
2002sus..book.....W Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Cyclic variations in the solar lower atmosphere
Authors: Fang, C.; Zhang, Y. X.; Ding, M. D.; Livingston, W. C.
2002AdSpR..29.1947F Altcode:
The Ca II K line has been measured regularly nearly every month since
1974 at Kitt Peak. It is well known that the K <SUB>1</SUB> component
of the Ca II K line is formed in the temperature minimum region (TMR)
of the solar atmosphere. Our study of the data of CaII K profiles over
two solar cycles indicates that both in full disc integrated spectra and
in center disc spectra, the distance between the red K <SUB>1</SUB> and
the blue K <SUB>1</SUB> of the profiles and its average intensity show
periodic variations. But the variation for the full disc integrated
spectra fluctuates in the same way as the sunspot number does,
while that for the center disc spectra has a time delay with respect
to sunspot number. Non-LTE computations yield a cyclic temperature
variation of about 17 K of the TMR in the quiet-Sun atmosphere and a
cyclic variation of about 15-20 km in the height position of the TMR.
---------------------------------------------------------
Title: Sunspot umbral spectra in the region 4000 to 8640 cm(-1)
(1.16 to 2.50 [microns])
Authors: Wallace, L.; Hinkle, K.; Livingston, W. C.
2001sus..book.....W Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Variability of a composite chromospheric irradiance index
during the 11-year activity cycle and over longer time periods
Authors: Lean, J. L.; White, O. R.; Livingston, W. C.; Picone, J. M.
2001JGR...10610645L Altcode:
Chromospheric emission lines are the dominant energy input to
the Earth's upper atmosphere, where they create its embedded
ionosphere. Knowledge of the Sun's chromospheric radiation is
therefore essential for understanding variability in this region, which
contributes significantly to space weather. With the goal of obtaining
a suitable surrogate of extreme ultraviolet irradiance variability
for atmospheric studies, we construct a composite chromospheric index
by comparing and cross calibrating available ground- and space-based
indices. Since ground-based flux observations of the chromosphere
exist only since 1974, we construct 11-year activity cycles of the
index since 1950 by using a parameterization of the daily plage
index and the 100-day smoothed 10.7-cm flux, and prior to that by an
analogous parameterization of the daily and 100-day smoothed sunspot
group numbers. Comparisons of solar and stellar chromospheric indices
suggest that long-term changes in the Sun's chromospheric emission
since the Maunder minimum may exceed recent solar cycle amplitudes by
as much as a factor of 2. We simulate this by adding to the 11-year
activity cycles a speculated varying background component derived
from 15-year smoothed sunspot group numbers that increases from 1900
to 1950 and remains approximately level in the decades since then.
---------------------------------------------------------
Title: Solar Mn I 5432/5395 Å line formation explained
Authors: Doyle, J. G.; Jevremović, D.; Short, C. I.; Hauschildt,
P. H.; Livingston, W.; Vince, I.
2001A&A...369L..13D Altcode:
We present a solution for the long standing problem concerning the
“chromospheric” behaviour of the Mn i 5395/5432 Å lines in the
solar spectrum using multi-line/multi-species NLTE modelling. Using
comprehensive spectral line formation modelling, we show that the
Mn i lines are very sensitive to optical pumping in a transition
which overlaps with Mg ii k. It therefore follows that one has to be
careful with the choice of lines as temperature indicators and for
the determination of the Mn abundances although on the other hand,
due to the formation process of these lines they may be useful as a
solar and stellar activity diagnostic.
---------------------------------------------------------
Title: Quiet-Sun Variability In a Temperature Minimum Region
Authors: Zhang, Y. X.; Fang, C.; Ding, M. D.; Livingston, W. C.
2001ApJ...547L.179Z Altcode:
The results of monthly monitoring Ca II K line profiles at a quiet-Sun
region near solar disk center at Kitt Peak during about two solar cycles
since 1974 are presented to investigate the variations of K<SUB>1</SUB>
emission, which is strongly dependent on the temperature minimum region
(TMR). Cyclic variations are found in K<SUB>1</SUB> emission that are
similar to those in the sunspot numbers. However, there is an evident
time lag of about 1.2 yr between the K<SUB>1</SUB> emission and the
sunspot numbers. Non-LTE computations show that the corresponding
temperature variation and position fluctuation in the quiet-Sun
TMR region are estimated to be about 17 K and 1.7×10<SUP>-2</SUP>
g cm<SUP>-2</SUP>, respectively.
---------------------------------------------------------
Title: Limits on Line Bisector Variability for Stars with Extrasolar
Planets
Authors: Povich, M. S.; Giampapa, M. S.; Valenti, J. A.; Tilleman,
T.; Barden, S.; Deming, D.; Livingston, W. C.; Pilachowski, C.
2001AJ....121.1136P Altcode:
We present an analysis of high-resolution synoptic spectra of ten F-
and G-type stars, seven of which exhibit periodic radial velocity
variations due to the presence of one or more substellar companions. We
searched for subtle periodic variations in photospheric line asymmetry,
as characterized by line bisectors. In principle, periodic variations
in line asymmetry observed at lower spectral resolution could mimic the
radial velocity signature of a companion, but we find no significant
evidence of such behavior in our data. Observations were obtained
from 1998 March to 1999 February using the National Solar Observatory
(NSO) 1.52 m McMath-Pierce Solar Telescope Facility on Kitt Peak in
conjunction with the solar-stellar spectrograph, achieving a resolving
power of 1.2×10<SUP>5</SUP>. To characterize line asymmetry, we
first measured line bisectors for the unblended Fe I photospheric
line at 625.26 nm. To improve sensitivity to small fluctuations, we
then combined points in each bisector to form a velocity displacement
with respect to the line core. We searched for periodic variations in
this displacement, finding no substantial difference between stars with
substellar companions and those without reported companions. We find no
correlation between bisector velocity displacement and the known orbital
phase of substellar companions around our target stars. Simulations of
a periodic signal with noise levels that mimic our measurement errors
suggest that we can exclude bisector variations with amplitudes greater
than about 20 m s<SUP>-1</SUP>. These results support the conclusion
that extrasolar planets best explain the observed periodic variations
in radial velocity.
---------------------------------------------------------
Title: Umbral Spectra in the Ultraviolet via Molecular V-Stokes
Authors: Livingston, W.; Berdyugina, S. V.
2001ASPC..236..559L Altcode: 2001aspt.conf..559L
No abstract at ADS
---------------------------------------------------------
Title: Cyclic Variation in the Solar Lower Atmosphere
Authors: Fang, C.; Zahng, Y. X.; Ding, M. D.; Livingston, W. C.
2001IAUS..203..387F Altcode:
CaII K line has been measured regularly nearly every month since 1974
at Kitt Peak. It is known that the K<SUB>1</SUB> component of the CaII
K line is formed in the temperature minimum region (TMR) of the solar
atmosphere. Our study on the data of CaII K line profiles over nearly
two solar cycles indicates that both in full disc integrated spectra and
in disc-center spectra, the distance between red K<SUB>1</SUB> and blue
K<SUB>1</SUB> and its mean intensity show periodical variations, but
the former fluctuates in the same way as the sunspot number does, while
the later has a time delay with respect to the sunspot number. Non-LTE
computation indicates a cyclic temperature variation of about 15 K of
the TMR in the quiet-Sun atmosphere and a cyclic variation of about
15-20 km of the position of the TMR.
---------------------------------------------------------
Title: Color and Light in Nature, Second Edition
Authors: Lynch, David K.; Livingston, William
2001cln..book.....L Altcode:
This beautiful and informative guide provides clear explanations of
all naturally occurring optical phenomena seen with the naked eye,
including shadows, halos, water optics, eclipses and mirages. Separating
myth from reality, it outlines the basic principles involved, and
supports them with many figures and references, and a wealth of rare
and spectacular photographs, many in full color, illustrates the
phenomena throughout. In this new edition the authors have added over
50 new color images and provide new material on experiments readers can
conduct themselves, such as how to photograph geostationary satellites
with your own camera.
---------------------------------------------------------
Title: The Molecular Zeeman Effect and Solar Magnetic Fields
Authors: Berdyugina, S. V.; Frutiger, C.; Solanki, S. K.; Livingston,
W.
2001ASPC..236..551B Altcode: 2001aspt.conf..551B
No abstract at ADS
---------------------------------------------------------
Title: The Observation and Study of Two Prominence Events in the
Infrared
Authors: Cao, W. D.; Ye, B. X.; Livingston, W.
2001IAUS..203..257C Altcode:
This paper reports the infrared observation of two prominence events
on Jan. 8, 1999 and Feb. 9, 1999 at H Paschen β 12818Å, H Bracket
α 40512Å, and H Pfund β 46525Å using the McMath Telescope. We
scanned the spectrograph slit across the prominences parallel to
the solar limb to obtain three-dimensional data cubes (two spatial
dimensions and one spectral dimension). By fitting these observed
lines, we can directly determine some important physical parameters
such as Doppler width, the optical thickness at line center, and
the line displacement. Combined with simultaneous observation of
Balmer H<SUB>α</SUB>, H<SUB>β</SUB>, and K lines, the new results of
structure and dynamics of limb prominence are presented. These results
imply that these infrared lines can penetrate through the prominence
and become the potential probe and tool of them, while H<SUB>α</SUB>
and H<SUB>β</SUB> sense the prominence skin only.
---------------------------------------------------------
Title: Results from a revisit to the K<SUB>2V</SUB> bright points
Authors: Sivaraman, K. R.; Gupta, S. S.; Livingston, W. C.; Damé,
L.; Kalkofen, W.; Keller, C. U.; Smartt, R.; Hasan, S. S.
2000A&A...363..279S Altcode:
We have used pairs of temporally simultaneous CaII K-line
spectroheliograms and magnetic area scans to search for spatial
correlation between the CaII K<SUB>2V</SUB> bright points in the
interior of the network and corresponding magnetic elements. We find
that about 60% of the K<SUB>2V</SUB> bright points spatially coincide
with magnetic elements of flux density > 4 Mx cm<SUP>-2</SUP>. About
25% of the K<SUB>2V</SUB> bright points with equally enhanced emission
lie over bipole elements where the fields are > 4 Mx cm<SUP>-2</SUP>
for both polarity elements which merge and presumably cancel and
result in low fields. The rest, 15%, of the bright points coincide
with areas of fields < 4 Mx cm<SUP>-2</SUP> which is the noise
level set by us for the magnetic scans. When magnetic elements of
opposite polarity merge and form bipoles, the associated K<SUB>2V</SUB>
bright points show excess emission. Although such excess emission is a
magnetic-field-driven phenomenon, the measured value of the field at the
site of the bipole is typically low, and these cases would therefore be
excluded in the count of coincidences of excess emission with excess
magnetic fields. In our opinion, these cases of excess emission at
the sites of the bipoles, as well as at the sites of fields >
4 Mx cm<SUP>-2</SUP>, are both instances of magnetic-field-related
emissions. If the former are not taken into account as coincidences,
the correlation will drop down and this might be interpreted as not an
obvious correlation. Our present results, taking into account the low
fields of merging bipoles, establish the association of K<SUB>2V</SUB>
bright points with magnetic elements.
---------------------------------------------------------
Title: Solar Magnetographs
Authors: Livingston, W.
2000eaa..bookE1681L Altcode:
The Sun's disk is covered with magnetic fields, not only the strong
kilogauss concentrations of SUNSPOTS, but also as slightly weaker flux
in PLAGES, the network, and probably as truly weaker flux everywhere
(see also CHROMOSPHERE: NETWORK). These fields may be mapped using
the Zeeman effect: a spectral line formed in the presence of a field
splits into components, the separation of which is prop...
---------------------------------------------------------
Title: Solar Feeds
Authors: Livingston, W.
2000eaa..bookE1680L Altcode:
Observations of the Sun typically involve modest aperture and a
large and heavy spectrograph. In the field at ECLIPSES the telescope
itself may need to have a long focal length. These requirements
are conveniently met by having a tracking flat mirror which feeds a
stationary telescope and its instrumentation. Magnetograph observations,
which involve the polarization analysis of spectrum lines, pl...
---------------------------------------------------------
Title: Eclipse Science Results: Past and Present (Invited review)
Authors: Livingston, W.; Koutchmy, S.
2000ASPC..205....3L Altcode: 2000ltse.conf....3L
We have investigated X-ray ejecta above flare loops, which were observed
before soft X-ray peak time, using the Yohkoh soft X-ray observations
in 1996 when the background corona was very weak. We found 35 plasma
ejecta out of 84 flares and studied soft X-ray data to discover the
probability to observe the plasma ejecta. On the other hand, we searched
for prominence eruptions using Solar-Geophysical Data in the same flare
series and found 16 prominence eruptions out of 29 flares having soft
x-ray plasma ejecta. As a result, 76% of flares have plasma ejecta
observed in either Hα or soft X-ray wavelength. It follows from this
that there are many flare associated ejecta.
---------------------------------------------------------
Title: Last Total Eclipse of the Millennium in Turkey
Authors: Livingston, W.; Özgüç, A.
2000ASPC..205.....L Altcode: 2000ltse.conf.....L
On the occasion of the 11 August 1999 total eclipse of the Sun,
scientists from all over the world converged on Turkey. Their
expectations of clear skies for observations were fully realized. To
take edvantage of this assembly, astronomers of the Kandilli Observatory
organized a post-eclipse symposium which included invited talks (6)
and oral contributions (12) as well as poster presentations (15).
---------------------------------------------------------
Title: Cyclic variation in the temperature minimum region of solar
atmosphere.
Authors: Zhang, Yunxiang; Fang, Cheng; Livingston, W. C.; Ding, Mingde
2000AcASn..41...44Z Altcode:
Calcium K line as well as some other solar spectral lines have been
measured regularly nearly every month since 1974 at Kitt Peak. It is now
widely accepted that K<SUB>1</SUB> is formed in the temperature minimum
region (TMR) and that the distance of the component K<SUB>1</SUB> from
the line center and the intensity of K<SUB>1</SUB> is well related to
the position and temperature of TMR, respectively. The authors' study
on the data of K line profiles and on the sunspot numbers over decades
shows: in full disc integrated spectra the distance of K<SUB>1</SUB>
from the line center fluctuates in the same way as the sunspot number
does, indicating a solar cyclic variation.
---------------------------------------------------------
Title: Observations of the Total Solar Eclipse August 11, 1999
Authors: Özgüç, A.; Rusin, V.; Rybanský, M.; Livingston, W.
2000ASPC..205..184O Altcode: 2000ltse.conf..184O
Bougaziçi University, Kandilli Observatory and Earthquake Research
Institute and Astronomical Institute of the Slovak Academy of Sciences
organized collaborative expeditions for the August 11, 1999 total
solar eclipse in Turkey and in Hungary. In these expeditions some five
experiments were carried out associated with the white-light inner
and outer corona, coronal polarization and high resolution imaging
of helmety streamers. Here we present what we could do through out
the programs.
---------------------------------------------------------
Title: Sun
Authors: Livingston, William C.
2000asqu.book..339L Altcode:
No abstract at ADS
---------------------------------------------------------
Title: An atlas of sunspot umbral spectra in the visible, from 15,000
to 25,500 cm(-1) (3920 to 6664 [Angstrom])
Authors: Wallace, L.; Hinkle, K.; Livingston, W.
2000asus.book.....W Altcode:
No abstract at ADS
---------------------------------------------------------
Title: The Last Total Eclipse of the Millennium
Authors: Livingston, W.; Özgüc, A.
1999PASP..111.1597L Altcode:
Conference was held in Istanbul, Turkey, in 1999 August. Proceedings
will be edited by W. Livingston and A. Özgüc and published in the
ASP Conference Series.
---------------------------------------------------------
Title: Babcock's Solar Magnetograph
Authors: Livingston, William
1999ApJ...525C.537L Altcode: 1999ApJC..525..537L
No abstract at ADS
---------------------------------------------------------
Title: An atlas of the sunspot umbral spectrum in the red and infrared
from 8900 to 15,050 cm(-1) (6642 to 11,230 [angstroms]), revised
Authors: Wallace, L.; Livingston, W. C.; Bernath, P. F.; Ram, R. S.
1999asus.book.....W Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Expansion of solar magnetic flux tubes large and small
Authors: Solanki, S. K.; Finsterle, W.; Rüedi, I.; Livingston, W.
1999A&A...347L..27S Altcode:
In the solar photosphere the magnetic field of magnetic elements and
sunspots is known to expand with height. In the case of sunspots this
expansion is known to be very rapid, with the field forming an almost
horizontal canopy. In this contribution we present new results on
the superpenumbral canopy of sunspots based on fits to Stokes I and
V profiles of infrared spectral lines. The new models take pressure
balance across the boundary of the canopy field into account, which
leads to significantly lower canopy base heights than previously
determined from similar data. Due to the lower canopy base height,
the density above the canopy base is larger, so that estimates of
the mass transported by the Evershed effect in the canopy need to be
revised upwards: approximately 15-50% of the mass flowing through the
penumbra travels beyond the sunspot boundary above the canopy base. A
comparison with small flux tubes leads to the surprising result that
although the two types of features have magnetic fluxes that differ by
5-6 orders of magnitude, their relative rate of expansion with height
is very similar, suggesting that at least in this respect sunspots
can be described by the thin-tube approximation. The remaining small
differences between the relative expansion of the two types of flux
tubes is qualitatively compatible with the presence of magnetic flux
that returns into the solar interior at the spot boundary, as has been
proposed by Westendorp Plaza et al. (1997).
---------------------------------------------------------
Title: High Resolution Information on Granulation from Full Disk Fe
Line Asymmetry
Authors: Livingston, W.; Wallace, L.; Huang, Y.; Moise, E.
1999ASPC..183..494L Altcode: 1999hrsp.conf..494L
No abstract at ADS
---------------------------------------------------------
Title: Thermal Structure in Sunspots and Dynamic Solar Infrared
Granulation Imaged at 4. 8, 12. 4, and 18. 1 Microns
Authors: Gezari, D.; Livingston, W.; Varosi, F.
1999ASPC..183..559G Altcode: 1999hrsp.conf..559G
No abstract at ADS
---------------------------------------------------------
Title: On the expansion of large and small flux tubes with height
Authors: Solanki, S. K.; Rüedi, I.; Finsterle, W.; Livingston, W.
1999ASSL..243..397S Altcode: 1999sopo.conf..397S
No abstract at ADS
---------------------------------------------------------
Title: Infrared lines as probes of solar magnetic features. XIII. The
relative flux in weak and strong quiet-sun magnetic fields
Authors: Meunier, N.; Solanki, S. K.; Livingston, W. C.
1998A&A...331..771M Altcode:
An estimate of the fraction of magnetic flux in intrinsically weak-field
form, i.e. fields with less than 1 kG intrinsic strength, in the
quiet Sun is presented. We find that on average approximately 2/3 of
the flux is in weak-field form, although our data allow a range of
values between 25%\ and 85%. These estimates have been derived with
the help of radiative transfer model calculations from low-noise
scans through the quiet Sun at fixed wavelengths within a Zeeman
sensitive spectral line at 1.56 mu m. They represent the first rapidly
modulated polarimetric observations of solar 1.56 mu m radiation. These
scans show that the polarimetric signature near the core of the line
exhibits a very different spatial structure than in the outer line
wings. Since the outer part of the line profile is only sensitive to
intrinsically strong magnetic fields, while the central part reacts
also to intrinsically weak fields, this implies that intrinsically weak
fields are distributed differently on the surface than strong fields
are (weak-field features lie closer together). The spatial distribution
suggests that the strong fields we are observing are network elements,
whereas the weak fields are intranetwork features. Further results,
such as the average distance between weak and strong field features,
flux distribution, spatial power spectra and the Stokes asymmetry
of intrinsically weak fields are also presented. In particular, we
find that the flux per magnetic feature is distributed lognormally,
in agreement with a similar finding for sunspot umbral areas by Bogdan
et al. (1988).
---------------------------------------------------------
Title: Spectrum Line Strength Variability: Sun-As
Authors: Livingston, W. C.; Wallace, L.; White, O. R.
1998saco.conf..109L Altcode:
No abstract at ADS
---------------------------------------------------------
Title: An atlas of the spectrum of the solar photosphere from 13,500
to 28,000 cm-1 (3570 to 7405 A)
Authors: Wallace, L.; Hinkle, K.; Livingston, W.
1998assp.book.....W Altcode:
No abstract at ADS
---------------------------------------------------------
Title: At Tucson, looking at the solar system
Authors: Livingston, William C.
1998ASSL..222...66L Altcode: 1998ream.conf...66L
No abstract at ADS
---------------------------------------------------------
Title: Variability of the Solar Call K Line over the 22 Year Hale
Cycle
Authors: White, O. R.; Livingston, W. C.; Keil, S. L.; Henry,
Timothy W.
1998ASPC..140..293W Altcode: 1998ssp..conf..293W
No abstract at ADS
---------------------------------------------------------
Title: Solar Oscillations in CO at 4.6 Microns
Authors: Livingston, W.; Solanki, S.; Muglach, K.; Wallace, L.
1998ASPC..135..186L Altcode: 1998hcsp.conf..186L
The fundamental band lines of CO originate in the solar temperature
minimum and lower cool parts of the chromosphere. We have observed
velocity and intensity oscillations in the quiet sun disk center
and extreme limb, sunspots, and plage. We have also looked for CO
oscillations in the Sun-as-a-star (but detect nothing). We compare the
power spectra of these various features, noting well separated 3 min and
5 min peaks. We interpret our observations in terms of the models of
Carlsson and Stein (1995), and Solanki, et al., (1994). Active Region
Seismology: Results from TON Project Bala Balachandran (Dept. Physics,
National Tsing Hua University, Hsinchu, Taiwan 30043, R.O.C.) Taiwan
Oscillation Network (TON) is a ground based observation facility
for the study of solar oscillations. The data consists of full-disc
K-line images taken at every minute. Using the 512 images time series,
we have tried to infer the location of the magnetic field below the
photosphere using the property of the active regions to absorb the
p-mode power. Two consecutive days, one just when the magnetic flux
appears on the surface and the other the day before the emergence, were
analysed. For this, an annular region of 15 deg. around the region of
emerging flux was chosen for the analysis. The modes were decomposed
into incoming and outgoing waves and the absorption coefficient was
calculated as the fractional difference of the two types. We found
that the absorption is stronger after the emergence of the flux and
the flux was at a depth of about 4000 km below the surface just before
its appearance on the surface; that is about 15 hrs before. It was also
reported earlier by other groups that the quiet sun exhibits acoustic
emission. It is believed to be an observational effect and the cause is
yet to find out. We have carried out a systematic analysis of the quiet
sun emission using 512 images. The analysis is similar to the active
region study, but the region of interest is the solar disc centre. We
found that there exists negative absoption or emission for most modes
and the negative absorption increases with the angular distance from
the centre of the sun.
---------------------------------------------------------
Title: A twenty-five year record of stratospheric hydrogen chloride
Authors: Wallace, Lloyd; Livingston, William; Hall, Donald N. B.
1997GeoRL..24.2363W Altcode:
From 1971 through April 1997 we have tracked the variation of
stratospheric HCl using ground-based spectroscopic observations
of the sun. This HCl is a tracer of free chlorine, the agent which
catalytically destroys ozone. Our observations are dominated by a
general increase in HCl by a factor between three and four, although
since about 1990 the rate of increase may have slowed.
---------------------------------------------------------
Title: Mesosphere Sodium Column Density and the Sodium Laser Guide
Star Brightness
Authors: Ge, Jian; Angel, J. R. P.; Jacobsen, B. D.; Roberts, T.;
Martinez, T.; Livingston, W.; McLeod, B.; Lloyd-Hart, M.; McGuire,
P.; Noyes, R.
1997astro.ph..8275G Altcode:
The first time simultaneous measurements of sodium column density
and the absolute flux from a sodium laser guide star, created by
a monochromatic 3 W cw laser, tuned to the peak of the sodium D2
hyperfine structure, were conducted at the MMT and CFA 60 inch
telescope in 1997. The results show that linearly and circularly
polarized laser returns are proportional to the simultaneous sodium
column density. Moreover, circularly polarized laser provides about
30% increase in fluorescent return over linearly polarized laser. A
laser guide star with R = 10.3 mag. or absolute flux of 8.4x10^5
photons/s/m^2, could be formed from a 1 watt projected circularly
polarized sodium laser beam when sodium layer abundance N(Na) = 3.7x10^9
/cm^2. Together with the distributed column density measurements
(e.g. seasonal and diurnal variations), we can project laser power
requirements for any specified guide star brightness. The mesosphere
sodium column density variation was measured above Tucson sky throughout
the year, through sodium absorption line measurements in stellar and
solar spectra. Previous measurements, e.g. Papen et al, 1996, have
not been made at this latitude (32 degrees). Further, our absorption
method is more direct and may be more accurate than the lidar methods
normally used. The seasonal variation amplitude is smaller than that
at higher latitudes. While the annual mean sodium column density tends
to be lower than at higher latitudes. Diurnal sodium column density
tends to vary by as much as a factor of two within an hour.
---------------------------------------------------------
Title: Erratum: Monitoring the Solar Temperature: Spectroscopic
Temperature Variations of the Sun
Authors: Gray, David F.; Livingston, William C.
1997ApJ...484..511G Altcode:
In the paper “Monitoring the Solar Temperature: Spectroscopic
Temperature Variations of the Sun” by David F. Gray and William
C. Livingston (<A href="/abs/1997ApJ...474..802">ApJ, 474, 802
[1997]</A>), equation (4), giving the variation in observed
line depth, is incorrect. It should read δd<SUB>obs</SUB>=δs
((A<SUB>0</SUB>-1)d<SUB>true</SUB>)/((1-sA<SUB>0</SUB>)<SUP>2</SUP>)
. The remainder of § 5 following equation (4) stems from the incorrect
equation and should be disregarded. These changes do not affect the
results of the paper, except that a possible explanation for the nearly
synchronized variation of the central depths of all three spectral lines
no longer obtains. <P />The authors note that an error in setting the
continuum level is farthest from explaining the scaling behavior of the
line depths shown in Figures 4 and 5 of the original paper. Continuum
errors affect weaker lines proportionately more than stronger lines,
which is just the opposite of what is observed. An error in zero
level, which is close to the effect of scattered light, causes line
depths to scale proportional to their depth. This is closer to what
is observed, but does not go far enough in this direction, since the
percent variation in the weaker C I line (depth 0.13) is only about
half that of the Ti II (depth 0.48) and Fe I (depth 0.52) lines.
---------------------------------------------------------
Title: High resolution coronal imaging. 11 July, 1991 total eclipse
with University of Hawaii 2.24 meter telescope on Mauna Kea.
Authors: Labonte, B.; Livingston, W.; Zirker, J.
1997ASIC..494...35L Altcode: 1997topr.conf...35L
The authors observed the corona with the potential for unprecedented
spatial resolution afforded by a large stellar instrument at a prime
site. An ambitious experiment involving the recording of 5 narrow-band
1024×1024 CCD images failed because of a last minute software
change. Eclipses are unforgiving in this regard. However, a simple
video camera was also fed by a beam-splitter pickoff with excellent
results. This video tape, shown at the workshop, indicates how the
field of interest was selected, concentrating on a large prominence
at the NW limb. The role of seeing is evident; the smallest features
detected were 0.6 arcsec in size.
---------------------------------------------------------
Title: Did the 4B Flare of 9 March 1989 Dump Lithium into a SPOT
Umbra?
Authors: Livingston, W.; Poveda, A.; Wang, Y.
1997ASPC..118...86L Altcode: 1997fasp.conf...86L
Lithium is readily destroyed in the solar interior and its abundance on
the surface suggests an ongoing renewal process. Spallation in energetic
flares is one possibility, with its lithium by-products being deposited
in sunspot umbrae. Such enrichment could be identified by a transient
increase of Li line strength or as an enhancement of the Li(7}/Li({6))
ratio. (Li(6) has not yet been detected in the solar spectrum whereas
the ratio is ~ 12 in meteorites, for example). The resonance feature
of Li 670.78 nm is strong in large umbrae, central depth >0.5, but
the line is very temperature sensitive. We show how adjacent TiO lines
can be used to correct for temperature variations, enabling us to look
for any Li abundance change. Good observations were obtained following
the 4B flare of 9 Mar 89. Evidence is given for Li enhancement at
one umbral position. Careful line profile analysis, however, shows no
Li(6) . This problem is complicated by molecular blends and magnetic
splitting patterns. We discuss how better observations could be made
and the prospects for improving our knowledge of Li(7}/Li({6)) for
the Sun using sunspots.
---------------------------------------------------------
Title: Monitoring the Solar Temperature: Spectroscopic Temperature
Variations of the Sun
Authors: Gray, David F.; Livingston, William C.
1997ApJ...474..802G Altcode:
The C I λ5380 line in the solar flux spectrum was measured over
the 1978-1992 interval. Analysis of the data shows seasonal and
instrumental effects, but after allowance for these, the ratios of
spectral line depths, C I λ5380 to Fe I λ5379 and to Ti II λ5381,
are shown to be robust indicators of effective temperature. These
data show the solar temperature to have varied systematically during
the activity cycle and nearly in phase with other indicators of the
cycle. The amplitude of the variation is 1.5 K +/- 0.2 K, similar to
but slightly less than the range implied by the variations of the
sunspot-corrected irradiance. There is also evidence for a secular
trend amounting to ~+0.014 K per year.
---------------------------------------------------------
Title: Umbral Polarimetric Measurements Using the TI I Multiplet at
2.2 MU M %The temperature gradient of a sunspot umbra
Authors: Ruedi, I.; Solanki, S. K.; Livingston, W.
1997ASPC..118..237R Altcode: 1997fasp.conf..237R
We present the first measurements of sunspot magnetic fields using the
lines of the Ti I multiplet at 2.2 mu m. These lines are most sensitive
to the plasma in the umbra. The observed line profiles suggest that
the temperature gradient in mid-photospheric layers of a sunspot
umbra is steeper than that of the standard sunspot models of Maltby
et al. (1986).
---------------------------------------------------------
Title: Monitoring the Solar Temperature: Empirical Calibration of
the Temperature Sensitivity of C I λ5380
Authors: Gray, David F.; Livingston, William C.
1997ApJ...474..798G Altcode:
We observed a set of six dwarf stars spanning a range in temperatures
around the solar value, and from them we have determined empirically
the temperature sensitivity of C I λ5380.32, a line that has been
monitored in the solar flux spectrum for nearly two decades at Kitt
Peak. When the C I line is compared to the adjacent Fe I λ5379.58 line,
it should be possible to detect apparent temperature differences of
a fraction of 1 K.
---------------------------------------------------------
Title: The beat of the solar chromosphere's cold heart.
Authors: Solanki, S. K.; Livingston, W.; Muglach, K.; Wallace, L.
1996A&A...315..303S Altcode:
The cold heart of the solar chromosphere is best investigated using
fundamental band lines of carbon monoxide, CO, at 4.7μm. We have
obtained time series of CO spectra in the quiet sun and in active-region
plage at the solar limb and at disk centre. In addition, we have
recorded time series in sunspot umbrae located near disk centre. The
power spectra and RMS amplitudes of the quiet-sun oscillations at
disk centre and at the limb are not compatible with a generally
hot chromosphere which is periodically cooled, but support recent
suggestions that the low chromosphere is pervasively cool, interspersed
with hot, possibly shocked material. In the plage the CO oscillations
provide indirect evidence for the expansion of hot material (probably
inside magnetic elements) with height. In umbrae the CO lines exhibit
well-separated 3min and 5min peaks. We also present spectra of the phase
shift between velocity and intensity oscillations of CO lines. At disk
centre in the quiet sun the phase shift is on the whole similar to that
seen in atomic lines formed near the classical temperature minimum,
although with some properties peculiar to CO. In plages the quality
of the phase shift is marginal, but suggests either large radiative
damping or propagating waves in the 4 mHz frequency range. Finally,
in sunspots the phase shift resembles that of atomic chromospheric
lines in some umbrae.
---------------------------------------------------------
Title: Infrared Spectral Atlases of the Sun from NOAO
Authors: Wallace, L.; Livingston, W.; Hinkle, K.; Bernath, P.
1996ApJS..106..165W Altcode:
We have prepared a series of four solar spectral atlases. The atlases
illustrate the disk center photospheric spectrum from 0.7 to 22 μm
and the sunspot umbral spectrum from 1.2 to 21 μm. The spectra were
observed at high resolution (λ/Δλ∼300,000) with the Fourier
transform spectrometer (FTS) at the McMath-Pierce solar telescope
on Kitt Peak. When possible, solar observations at different air
masses and on different days have allowed the less opaque telluric
lines to be effectively removed from the program spectrum. The solar
lines have been identified by searching the literature on atomic and
molecular laboratory spectroscopy and when necessary by additional
laboratory spectroscopy. Many new identifications have been made,
including numerous SiO and hot water lines in the sunspot spectrum.
---------------------------------------------------------
Title: VizieR Online Data Catalog: Infrared Arcturus Atlas (Hinkle+
1995)
Authors: Hinkle, K.; Wallace, L.; Livingston, W.
1996yCat..61071042H Altcode:
The atlas is contained in 310 spectral files a list of line
identifications, plus a file containing a list of the files and
unobserved spectral regions. The spectral file names are in the form
'abnnnnn' where 'nnnnn' denotes the spectral region, e.g. file 'ab4300'
contains spectra for the 4300-4325 cm-1 range. The atomic and molecular
line identifications are in files 'appendix.a' and 'appendix.b', and
repeated with a uniform format in file 'lines'. The file 'appendix.c'
is a book-keeping device used to correlate the plot plages and
spectral files with frequency. See the author-supplied description in
'readme.dat' for more information. (311 data files).
---------------------------------------------------------
Title: Book Review: X-ray binaries / Cambridge U Press, 1995 &
1997
Authors: Lewin, W. H. G.; Livingston, William
1995JBAA..105R.284L Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Infrared Atlas of the Arcturus Spectrum, 0.9-5.3 microns
Authors: Hinkle, Kenneth; Wallace, Lloyd; Livingston, William
1995PASP..107.1042H Altcode:
A spectral atlas of the infrared spectrum of the bright K 2 giant
Arcturus has been completed using the 4 meter Mayall telescope
and FTS. The 0.9-5.3 micron spectrum of Arcturus was observed at
high signal-to-noise with a resolution of 100,000. Telluric lines
were removed by using telluric transmission spectra generated from
McMath-Pierce solar spectra or 4 meter lunar spectra. The spectrum of
Arcturus was observed on two different dates selected to give large
opposite heliocentric shifts. The spectra observed on the different
dates have been independently corrected for telluric absorption with
the result that the telluric spectrum has been effectively removed
from all but the most obscure wavelengths of the Arcturus spectrum. We
attempted to identify lines with central depths stronger than a few
percent. Identifications seem well in hand with the unidentified
lines apparantly atmoic in origin. The atlas is available either on
an AAS CD-ROM or as an ASP monograph. (c) Astronomical Society of the
Pacific Bergeron, et al., PHOTOMETRIC CALIBRATION OF HYDROGEN- AND
HELIUM-RICH WHITE DWARF MODELS Bolometric corrections and color indices
on various photometric systems are provided for an extensive grid
of hydrogen- and helium-rich white dwarf model atmospheres. Absolute
visual magnitudes, masses, and ages are also obtained for each model
from detailed evolutionary cooling sequences appropriate for these
stars. The results of our calculations are briefly compared with
published observational material. These calculations can easily be
extended to any given photometric system. (SECTION: Stars)
---------------------------------------------------------
Title: Interesting lines in the infrared solar spectrum. III. A
polarimetric survey between 1.05 and 2.50 μm.
Authors: Rueedi, I.; Solanki, S. K.; Livingston, W.; Harvey, J.
1995A&AS..113...91R Altcode:
We present a survey of Stokes I, V and Q in the near infrared
spectral range between 1.05 and 2.50μm, based on Fourier transform
spectrometer data obtained in a sunspot umbra and in an active region
plage. We discuss the diagnostic potential of a number of lines for
studying solar magnetic features. These include the Ti I multiplet near
22000A, the Fe I g=3 line at 15648.5A, He I 10830A, high excitation C I
lines, as well as CO and CN lines. As an example, we provide the first
estimate of the field strength gradient averaged over the height range
covered by the photosphere and chromosphere. We also identify lines
that show large Stokes V or Q amplitudes and analyze their profile
asymmetries. In our J-band plage spectrum the Stokes V and Q profiles
show an extremely large blue-red asymmetry, whose origin is not yet
clear. As an incidental result we obtain the first measured value of the
vertical gradient of the magnetic field strength in a plage. Averaged
over approximately 1500-2000km it corresponds to roughly 0.6G/km.
---------------------------------------------------------
Title: Infrared lines as probes of solar magnetic
features. XI. Structure of a sunspot umbra with a light bridge.
Authors: Rueedi, I.; Solanki, S. K.; Livingston, W.
1995A&A...302..543R Altcode:
We investigate the magnetic structure of an umbra and the light bridge
it contains using spectra at 1.56μm. The magnetic field strength in
the umbra reaches over 3500G on the first day of observation and 3200G
on the second and third days, while the field strength in the light
bridge is reduced by 1000-1400G relative to the nearby umbra. The
magnetic vector is also found to be much more horizontal in the light
bridge. There is evidence that the boundary between the strong and
weak magnetic field is less than 1" wide, implying the presence of
large currents there. At some locations a downflow of up to 1.5km/s is
seen in the light bridge relative to the umbral material. Finally, we
discuss the blending of the 1.5648μm line in sunspots and develop the
depth of the OH 15650.7A line as a diagnostic of umbral temperatures.
---------------------------------------------------------
Title: Water on the Sun
Authors: Wallace, Lloyd; Bernath, Peter; Livingston, William; Hinkle,
Kenneth; Busler, Jennifer; Guo, Bujin; Zhang, Keqing
1995Sci...268.1155W Altcode:
High-resolution infrared spectra of sunspot umbrae have been recorded
with the 1-meter Fourier transform spectrometer on Kitt Peak. The
spectra contain a very large number of water absorption features
originating on the sun. These lines have been assigned to the pure
rotation and the vibration-rotation transitions of hot water by
comparison with high-temperature laboratory emission spectra.
---------------------------------------------------------
Title: Color and Light in Nature
Authors: Livingston, William; Lynch, David K.
1995cln..book.....L Altcode:
No abstract at ADS
---------------------------------------------------------
Title: FTS Polarimetric Survey of the Infrared Solar Spectrum Between
1.0 and 2.5 MU M
Authors: Ruedi, I.; Solanki, S. K.; Livingston, W.; Harvey, J.
1995ASPC...81..107R Altcode: 1995lahr.conf..107R
No abstract at ADS
---------------------------------------------------------
Title: Oscillations in Active Plage Regions as Observed in 1.56
Micron Lines
Authors: Muglach, K.; Solanki, S. K.; Livingston, W. C.
1995itsa.conf..387M Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Kitt Peak Solar and Stellar Atlases
Authors: Hinkle, K. H.; Wallace, L.; Livingston, W.
1995ASPC...81...66H Altcode: 1995lahr.conf...66H
No abstract at ADS
---------------------------------------------------------
Title: Eclipse Measurements of the Distribution of CO Emission Above
the Solar Limb
Authors: Clark, T. A.; Lindsey, C.; Rabin, D. M.; Livingston, W. C.
1995itsa.conf..133C Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Chromospheric Magnetic Field Measurements in He I 10830Å
Authors: Rüedi, I.; Solanski, S. K.; Balthasar, H.; Livingston, W.;
Schmidt, W.
1995itsa.conf..431R Altcode:
No abstract at ADS
---------------------------------------------------------
Title: 4-Meter Upgrade of the McMath-Pierce Telescope and the
Detection of Space Debris
Authors: Livingston, W.; Lynch, D. K.
1995itsa.conf..175L Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Infrared atlas of the Arcturus spectrum, 0.9-5.3 microns
Authors: Hinkle, Kenneth; Wallace, Lloyd; Livingston, William Charles
1995iaas.book.....H Altcode: 1995ASPMP...1.....H; 1995QB883.H56......
This atlas provides spectra of the K giant Arcturus and a transmission
spectrum of the Earth's atmosphere observed at a resolution of ~100000
over the wavelength range 9130 to 53560 A. Line identifications are
shown for the Arcturus spectral lines. A table of the spectral lines
identified in Arcturus is included.
---------------------------------------------------------
Title: Solar eclipses.
Authors: Livingston, W.
1995AIPC..345...27L Altcode:
The occasion of a total eclipse impacts the human observer with a
bewildering rapid sequence of phenomena: mid-day cooling, failing light
without accustomed color change, shadow-bands transiting the ground,
cessation of bird sounds, possible frantic beating of jungle drums,
Baily's beads, appearance of flame-like prominences, and most fantastic
of all the solar corona. The author considers that although the corona
is known to be 2 - 20(10<SUP>6</SUP>)K, there is a lack of consensus
on the heating mechanism, except the energy must be non-thermal and
derived from surface and sub-surface convective motions. Theoreticians
invoke the Joule dissipation of magnetic fields by Alfvén waves,
electric currents in loop structures, or MHD turbulence. Although
eclipse experiments to discriminate between these ideas generally fail,
the sighting of 'plasmoids' was reported from the CFHT on Mauna Kea at
the 1991 eclipse. Future experiments include: IR mapping of the coronal
spectrum, spectroscopic velocity measurements, and the continued search
for waves, nanoflares, and plasmoids.
---------------------------------------------------------
Title: Infrared lines as probes of solar magnetic features. X. HeI
10830A as a diagnostic of chromospheric magnetic fields.
Authors: Rueedi, I.; Solanki, S. K.; Livingston, W. C.
1995A&A...293..252R Altcode:
The need for a simple but quantitative diagnostic of upper chromospheric
magnetic fields is keenly felt. We develop the HeI 10830A line as such a
diagnostic. An application to observations of an active region allows us
to compare the magnetic field in the upper chromosphere with the field
in the underlying photosphere. In general, the magnetic field in the
chromosphere is found to be significantly more homogeneous. We find that
dB/dz in the umbra of a large sunspot (0.4-0.6G/km) is similar to other
determinations of this quantity over an equivalent height range. Also,
dB/dz decreases outwards in the spot. Thus, in the outer penumbra it
has dropped to 0.1-0.3 G/km. A comparison of these values with the
results of dB/dz measurements in the photosphere suggests that dB/dz
decreases with height. We also find evidence for magnetic canopies near
sunspots and for the conservation of magnetic flux with height in solar
plages when averaged horizontally over a few arc s. Observations of
complex Stokes V profiles at the neutral line in a sunspot penumbra
(crossover effect) suggest that the upper chromospheric penumbral
magnetic field is not fluted to the same extent as the photospheric
field. The large line broadening of He I (up to 10km/s) is found to
be due to motions which are largely field aligned.
---------------------------------------------------------
Title: 1-5 micron Arcturus Atlas
Authors: Hinkle, K. H.; Wallace, L.; Livingston, W.
1994AAS...185.4514H Altcode: 1994BAAS...26.1381H
An atlas of the infrared spectrum of the bright K 2 giant Arcturus
recently has been completed using the 4 meter Mayall telescope
and FTS. The 0.9-5.4 microns spectrum of Arcturus was observed at
high signal-to-noise with a resolution of 100,000. Telluric lines
were removed by using telluric transmission spectra generated
from McMath-Pierce solar spectra and lunar spectra. The spectrum
of Arcturus was observed on two different dates selected to give
large opposite heliocentric shifts. The spectra observed on the
different dates have been corrected for telluric absorption and then
over-plotted, with the result that the telluric spectrum has been
effectively removed from all but the most obscured wavelengths of
the Arcturus spectrum. The over-plotted spectra also illustrate the
signal-to-noise and the believability of spectral features. An effort
has been undertaken to identify lines with central depths stronger than
a few percent. Identifications are marked on the atlas pages. While
the majority of the lines are identified, a few strong unidentified
lines are present. Identifications of the molecular features seem well
in hand and the unidentified lines appear to be atomic. Frequencies
for unidentified lines will be listed. Information concerning the
availability of the atlas will be given.
---------------------------------------------------------
Title: Eclipse Observations of the Extreme Solar Limb Profile of HI
Pfund beta Emission.
Authors: Clark, T. A.; Lindsey, C. A.; Rabin, D. M.; Livingston, W. C.
1994AAS...185.4412C Altcode: 1994BAAS...26.1378C
A region of the infrared solar spectrum (2147.7 - 2150.1 cm(-1)
) around the HI Pfund beta line (2148.79 cm(-1) ) was monitored
through 3 eclipse "contacts" with the Amber InSb array on the Main
spectrograph on the McMath-Pierce telescope during the 10 May 1994
partial solar eclipse over Kitt Peak National Observatory to produce
limb profiles of intensity and line width to an angular resolution
of 0.15 arc second. This line is broad (FWHM = 0.9 cm(-1) and shallow
(5.7%) in absorption at disk center but shows a narrow emission core
above the continuum envelope at 2 arc seconds inside the limb which
remains visible out to 4.5 arc seconds beyond the continuum limb. The
Pfund beta peak intensity appears to follow the continuum profile at
the limb but then intensifies again to reach a peak at about 1000 km
above the limb in a manner similar to that of the HeI D3 line. The line
width becomes narrower with height above the limb, reaching a FWHM of
0.22 cm(-1) at several arc seconds above the limb. These profiles will
be discussed in relation to those of other HI lines above the solar
limb. This work was supported by NSERC of Canada and by NSO, Tucson.
---------------------------------------------------------
Title: The solar Ca II K index and the Mg II core-to-wing ratio
Authors: Donnelly, R. F.; White, O. R.; Livingston, W. C.
1994SoPh..152...69D Altcode: 1994IAUCo.143...69D; 1994svs..coll...69D
The 1 å index of the solar Ca II K line is compared with the
core-to-wing ratio of satellite measurements of the Mg II h and k
lines. The correlation coefficient r = 0.976 for the Nimbus-7 Mg II
ratio during solar cycle 21 andr = 0.99 for the NOAA9 Mg II ratio in
cycle 22. Linear regression analysis for the full dynamic range of both
data sets is used to combine the Nimbus-7 and NOAA9 Mg II data. These
relations permit the ground-based Ca K index to estimate the solar
UV flux.
---------------------------------------------------------
Title: Infrared lines as probes of solar magnetic features. 7:
On the nature of the Evershed effect in sunspots
Authors: Solanki, S. K.; Montavon, C. A. P.; Livingston, W.
1994A&A...283..221S Altcode:
Stokes I and V profiles of 1.56 micron lines are observed in sunspots
and their surroundings near the solar limb. An analysis of these
observations confirms that the magnetic field of the sunspots continues
beyond their visible boundaries in the form of an extensive, low-lying
(supernumbral) canopy. We also find that the V profiles, which are
only formed above the canopy base, exhibit the Evershed effect with
line shifts of 0.5-2 km/s, while the non-magnetic material below the
canopy is at rest. The deduced geometry of the flow outside the sunspot
suggests a resolution of the long standing dispute about the existence
or not of an Evershed flow outside the visible sunspot. In addition,
the low density of the gas above the canopy base implies that the mass
flux in the magnetic canopy is much smaller (approximately equals 10%)
than the mass flux in the penumbra, where the 1.5 micron lines exhibit
wavelength shifts of approximately 4 km/s. The present observations
cast doubt on the standard interpretation of the photospheric Evershed
effect in terms of a steady flow, in particular if it is driven by
the siphon-flow mechanism.
---------------------------------------------------------
Title: 1.5 MU M Observations the Depth of Sunspot Penumbrae
Authors: Solanki, S. K.; Ruedi, I.; Livingston, W.; Schmidt, H. U.
1994IAUS..154..471S Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Observations of seeing at 0.5 and 12.4 μm
Authors: Livingston, W.; Kopp, G.; Gezari, D.; Varosi, F.
1994IAUS..158..299L Altcode:
No abstract at ADS
---------------------------------------------------------
Title: New Light on the Heart of Darkness of the Solar Chromosphere
Authors: Solanki, S. K.; Livingston, W.; Ayres, T.
1994Sci...263...64S Altcode:
Solar carbon monoxide spectra indicate the existence of a cool (less
than 4000 kelvin) component to the solar chromosphere coexisting with
the hot, bright gas at 6000 to 7000 kelvin. However, both the existence
and the location of the cool component have been controversial. New
high-resolution spectra show that carbon monoxide goes into emission
just beyond the limb, allowing it to be probed without photospheric
contamination. The cool component has temperatures as low as 3000 to
3500 kelvin and appears to cover 50 to 85 percent of the quiet solar
surface. There is a steep temperature rise to normal chromospheric
temperatures at a height of 900 to 1100 kilometers. Large horizontal
velocities are seen, suggesting that the cool component is maintained
by the supersonic adiabatic expansion of upwelling gas in overshooting
granules.
---------------------------------------------------------
Title: Preliminary properties of pores derived from 1.56 micron lines
Authors: Muglach, K.; Solanki, S. K.; Livingston, W. C.
1994ASIC..433..127M Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Variability of the Solar He 110830 Angstrom Triplet
Authors: Harvey, J. W.; Livingston, W. C.
1994IAUS..154...59H Altcode:
No abstract at ADS
---------------------------------------------------------
Title: The upper photosphere and lower chromosphere of small-scale
magnetic features
Authors: Solanki, S. K.; Bruls, J. H. M. J.; Steiner, O.; Ayres, T.;
Livingston, W.; Uitenbroek, H.
1994ASIC..433...91S Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Change in the radiative output of the Sun in 1992 and its
effect in the thermosphere
Authors: White, O. R.; Rottman, G. J.; Woods, T. N.; Knapp, B. G.;
Keil, S. L.; Livingston, W. C.; Tapping, K. F.; Donnelly, R. F.;
Puga, L. C.
1994JGR....99..369W Altcode:
Ground and space measurements of the solar spectral irradiance at radio,
visible, UV, and X ray wavelengths show a large decline in the first 6
months of 1992. This sustained drop in the solar output is important
in understanding the connection between the emergent magnetic flux
on the Sun and the radiative output as well as in understanding the
effects of such change in the upper atmosphere of the earth. We present
preliminary estimates of the observed changes as the means to spur
inquiry into this solar event in the declining phase of solar cycle
22. Typical decreases are 15% in Lyman alpha and 40% in 10.7-cm radio
flux. Mass spectrometer and incoherent scatter model calculations at
600 km in the thermosphere indicate a 30% decrease in the temperature
and a 3X decrease in the density of the thermosphere near the altitude
where both the Upper Atmosphere Research Satellite (UARS) and Hubble
Space Telescope (HST) are flying. Decrease of the orbital period of
the UARS shows the expected effect of decreasing density at flight
altitude. Work in progress indicates that the output change results
from the decline in solar magnetic flux to a lower level of activity
in the southern hemisphere of the Sun.
---------------------------------------------------------
Title: A 4-meter McMath Telescope for the Infrared
Authors: Livingston, W.
1994IAUS..154..589L Altcode:
No abstract at ADS
---------------------------------------------------------
Title: On the nature of the Evershed effect
Authors: Solanki, S. K.; Montavon, C. A. P.; Livingston, W.
1994smf..conf..173S Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Magnetic fields in the upper chromosphere: He I 10830 Å as
an almost ideal diagnostic
Authors: Rüedi, I.; Solanki, S. K.; Livingston, W. C.
1994smf..conf..363R Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Surrogates for total solar irradiance
Authors: Livingston, W.
1994seit.conf..145L Altcode:
No abstract at ADS
---------------------------------------------------------
Title: An atlas of the sunspot spectrum from 470 to 1233 cm-1 (8.1
to 21 micrometer) and the photospheric spectrum from 460 to 630 cm-1
(16 to 22 micrometer)
Authors: Wallace, L.; Livingston, W.; Bernath, P.
1994aass.book.....W Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Infrared lines as probes of solar magnetic features. VI. The
thermal-magnetic relation and Wilson depression of a simple sunspot
Authors: Solanki, S. K.; Walther, U.; Livingston, W.
1993A&A...277..639S Altcode:
We analyse the relationship between the temperature and the magnetic
vector, as derived from 1.56 μm spectra, in a simple sunspot. Due to
the high Zeeman sensitivity of the = 3, 1.56 μm line, we can study this
relationship throughout the sunspot. We confirm the field-strength, B,
vs. temperature, T, relationship found by Kopp & Rabin (1992). In
addition, we also find a linear relation between the magnetic
inclination angle, γ‧, and T. An analysis based on the assumption
of magnetohydrostatic force balance gives an estimate of the Wilson
depression, Z<SUB>W</SUB>, throughout the sunspot. Our analysis supports
a jump in Z<SUB>W</SUB> of 200-500 km at the umbral boundary and agrees
with a relatively constant Z<SUB>W</SUB> in the penumbra. In addition,
we constrain various gradients of magnetic parameters and judge the
strength of magnetic curvature forces. For example, we set tight limits
on the vertical gradient of γ‧, the magnetic inclination angle to
the vertical, in the penumbra. Finally, we discuss the consequences
for, e.g., the model proposed by Sanchez Almeida & Lites (1992)
to explain the broad-band circular polarization measured in sunspots.
---------------------------------------------------------
Title: Mirror seeing control in thick solid mirrors and the planned
upgrade of the McMath-Pierce Solar Telescope
Authors: Barr, Lawrence D.; Livingston, William C.
1993SPIE.1931...53B Altcode:
It is well known that telescope mirrors can produce seeing effects
when they are at a different temperature than the adjacent air. The
mirror acts as a reservoir for heat that can be convected to/from
the air. In this paper we will discuss some tactics for minimizing
mirror seeing in nighttime and daytime (solar) telescopes. Aluminum
mirrors with internal fluid cooling appear to be the optimum choice
for mirror substrates as a means for reducing mirror seeing. However,
the mirrors must be actively corrected for the distortions caused by
thermal gradients. The planned provisions are described.
---------------------------------------------------------
Title: An atlas of the photospheric spectrum from 8900 to 13600 cm(-1)
(7350 to 11230 [angstroms])
Authors: Wallace, L.; Hinkle, K.; Livingston, W. C.
1993aps..book.....W Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Thermal Images of Sunspots and the Quite Sun at 4.8, 12.4,
and 18 microns
Authors: Gezari, D.; Kopp, G.; Livingston, W.
1993AAS...181.8103G Altcode: 1993BAAS...25..733G
No abstract at ADS
---------------------------------------------------------
Title: Field Strength vs. Temperature Relation and the Structure
of Sunspots
Authors: Solanki, S. K.; Walther, U.; Livingston, W.
1993ASPC...46...48S Altcode: 1993IAUCo.141...48S; 1993mvfs.conf...48S
No abstract at ADS
---------------------------------------------------------
Title: Selected papers on instrumentation in astronomy.
Authors: Livingston, W.
1993SPIEM..87.....L Altcode:
This book is a compilation of outstanding papers selected from the
world literature on optical and optoelectronic science, engineering,
and technology.
---------------------------------------------------------
Title: Solar magnetograph employing integrated diode arrays (Applied
Optics 1976)
Authors: Livingston, W. C.; Harvey, J.; Slaughter, C.; Trumbo, D.
1993inas.book..493L Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Preface
Authors: Livingston, William
1993inas.bookD..11L Altcode:
No abstract at ADS
---------------------------------------------------------
Title: An atlas of the solar photospheric spectrum in the region
from 8900 to 13600 cm-¹ (7350 to 11230 Å) : with decomposition
into solar and atmospheric components and identifications of the
main solar features
Authors: Wallace, Lloyd; Livingston, W. C.; Hinkle, Kenneth
1993asps.book.....W Altcode:
No abstract at ADS
---------------------------------------------------------
Title: White-light movies of the solar photosphere from the SOUP
instrument on Spacelab 2 (Advances in Space Research 1986)
Authors: Title, A. M.; Tarbell, T. D.; Simon, G. W.; Acton, L.;
Duncan, D.; Ferguson, S.; Finch, M.; Frank, Z.; Kelly, G.; Lindgren,
R.; Morrill, M.; Pope, T.; Reeves, R.; Rehse, R.; Shine, R.; Topka,
K.; Harvey, J.; Leibacher, J.; Livingston, W.; November, L.
1993inas.book..100T Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Recent astronomical research utilizing a high gain image
intensifier tube (Advances in Electronics and Electron Physics 1966)
Authors: Livingston, W. C.; Lynds, C. R.; Doe, L. A.
1993inas.book..408L Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Evershed Effect in Sunspots and Their Canopies
Authors: Solanki, S. K.; Montavon, C.; Livingston, W.
1993ASPC...46...52S Altcode: 1993IAUCo.141...52S; 1993mvfs.conf...52S
No abstract at ADS
---------------------------------------------------------
Title: The Sun in a Non-Cycling State
Authors: White, O. R.; Skumanich, A.; Lean, J.; Livingston, W. C.;
Keil, S. L.
1992PASP..104.1139W Altcode:
Using the Baliunas and Jastrow (1990) study of cyclic variability in
solar-type stars, we transform existing solar data to the stellar HK
irradiance scale and examine the state of the solar chromosphere when a
solar-type star shows little cyclic variability and surface magnestis
m. To reduce the chromospheric emission to levels for G-type stars
showing no chromospheric activity cycles, no only must the sun be
free of plages and network; the brightness of the quiet chromosphere
in the K line must be reduced to levels seen only in 15% of the quiet
Sun area today. In contrast, the present day level of K emission from
the sun places it in the class of most active solar-type stars, far
removed from a non-cycling state. (SECTION: Stars)
---------------------------------------------------------
Title: Thermal Maps of Sunspots and the Quiet Sun
Authors: Livingston, W.; Kopp, G.; Gezari, D.
1992AAS...181.8103L Altcode: 1992BAAS...24.1252L
We present images of sunspots, surrounding plage, quiet Sun, and
the solar limb made at 4.8, 12.4, and 18 microns. These are basically
thermal maps, the infrared intensity being nearly linearly proportional
to temperature at these wavelengths. We believe these to be the most
detailed thermal images to date of the solar photosphere. Thermal
structure within sunspot penumbrae and the surrounding plage is evident
in several images, although umbrae appear homogeneous, at least down
to the approximately 2” diffraction limit of the telescope at 12
microns. We find the temperature of penumbrae to be roughly 5% less
than that of the quiet Sun, and umbrae to be about 25% less. Images
of the quiet Sun show spatial thermal fluctuations of about 2% in
patterns that change slowly with time. The measurements were made
with the NSO's windowless, filled-aperture 1.6 m McMath-Pierce Solar
Telescope, which fed the infrared image to a cryogenically-cooled
58x62 Si:Ge camera system built by D. Gezari.
---------------------------------------------------------
Title: Infrared lines as probes of solar magnetic features. V -
The magnetic structure of a simple sunspot and its canopy
Authors: Solanki, S. K.; Rueedi, I.; Livingston, W.
1992A&A...263..339S Altcode:
The Zeeman Lande g = 3 Fe I line at 15648 A is used here to determine
the strength and inclination of the magnetic field of a simple,
relatively symmetric sunspot. The largest field strength observed in
the sunspot is approximately 3100 G. The field strength at different
points along the outer penumbral edge varies beween 800 and 1000 G. The
angle of inclination at the outer penumbral boundary is close to 80
deg. A low-lying, almost horizontal superpenumbral magnetic canopy best
reproduces the observations. The magnetic field strength in the canopy
is consistent with a magnetic monopole. Evidence of small magnetic
elements underlying the superpenumbral canopy is presented.
---------------------------------------------------------
Title: Infrared lines as probes of solar magnetic features. II -
Diagnostic capabilities of Fe I 15648.5 A and 15652.9 A
Authors: Solanki, S. K.; Rueedi, I. K.; Livingston, W.
1992A&A...263..312S Altcode:
The properties of two Fe I lines at 15648.5 A and 15652.9 A in the
infrared H-band are investigated using numerical radiative transfer
calculations. It is shown that using this combination of a Lande g = 3
and a g(eff) = 1.53 line it is possible to measure the field strength in
solar magnetic features simply and with great accuracy. The g = 3 line
alone allows field strengths as low as 300-600 G to be measured. By
forming the line ratio between the V profiles of these lines it is,
in principle, possible to measure field strengths as low as 100 G,
thus achieving a sensitivity otherwise only possible with the emission
lines near 12 microns. Other diagnostic capabilities of these lines
are also analyzed.
---------------------------------------------------------
Title: Infrared lines as probes of solar magnetic features. III -
Strong and weak magnetic fields in plages
Authors: Rueedi, I.; Solanki, S. K.; Livingston, W.; Stenflo, J. O.
1992A&A...263..323R Altcode:
The diagnostics developed by Zayer et al. 1989 are applied to 27
Stokes V spectra of solar plates. The 1.5 micron lines at 15648 A and
15652 A are used to measure magnetic field strengths between 400 G
and 1700 G at z = 0 in active region plages with an accuracy of up
to 2-3 percent. The results confirm the accuracy of the line-ratio
technique of Stenflo (1973). It is estimated that the fraction of net
magnetic flux in strong-field form is close to 90 percent, supporting
the view that the small-scale magnetic fields are concentrated very
efficiently. The data clearly contradict the claims of Zirin and Popp
(1989) based on 12 micron lines that there is at most indirect evidence
for kG fields in solar plages. They also contradict the large fraction
of weak-field flux reported by Del Toro et al. (1990).
---------------------------------------------------------
Title: Solar Ca II K Measurements and Activity Cycles in Solar-Type
Stars
Authors: White, O. R.; Livingston, W. C.; Keil, S. L.
1992sers.conf..160W Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Observations of Solar Spectral Irradiance Variations at
Visible Wavelengths
Authors: Livingston, W.
1992sers.conf...11L Altcode:
No abstract at ADS
---------------------------------------------------------
Title: The effect of the Pinatubo cloud on hydrogen chloride and
hydrogen fluoride
Authors: Wallace, L.; Livingston, W.
1992GeoRL..19.1209W Altcode:
Ground-based spectroscopic observations from Kitt Peak in Arizona
showed no enhancement of stratospheric HCl or HF when the plume of
the Pinatubo volcano was overhead.
---------------------------------------------------------
Title: Proposed Upgrade of the McMath Solar/Stellar Telescope to a
4-m Aperture with a 6-m Feed
Authors: Barr, L. D.; Livingston, W. C.
1992ESOC...42..343B Altcode: 1992ptit.conf..343B
No abstract at ADS
---------------------------------------------------------
Title: Line Blanketing Variations in the Solar Irradiance Over the
Solar Cycle
Authors: Mitchell, W. E.; Livingston, W. C.
1992AAS...180.0704M Altcode: 1992BAAS...24..738M
No abstract at ADS
---------------------------------------------------------
Title: An atlas of a dark sunspot umbral spectrum from 1970 to 8640
cm(-1) (1.16 to 5.1 [microns])
Authors: Wallace, L.; Livingston, W. C.
1992adsu.book.....W Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Spatio-temporal fluctuations in HeI 10830 Å line parameters:
Evidence for spicule formation
Authors: Venkatakrishnan, P.; Jain, S. K.; Singh, Jagdev; Recely,
F.; Livingston, W. C.
1992SoPh..138..107V Altcode:
The equivalent width, line depth, line width, and Doppler shift
of the He I 10830 Å line were extracted from two time series of
spectra. Scatter plots of time-averaged line depth, line width, and
Doppler shifts, as well as the root mean square temporal fluctuation of
these quantities against the time-averaged equivalent width at a few
hundred spatial locations were obtained. The statistical behaviour of
these line parameters and their fluctuations was used to infer plausible
reasons for the fluctuations. Examination of these results showed
that the line parameter fluctuations could be caused by fluctuations
in the coronal UV radiation (which could drive the spicules) or by
the appearance of density inhomogeneities such as spicules within the
line forming domain. In either case, the data can be interpreted as
representing the initial phases of spicules.
---------------------------------------------------------
Title: What's Wrong with a Gibbous Moon?
Authors: Livingston, William
1992S&T....83..159L Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Proposed Upgrade of the McMath Solar/Stellar Telescope to a
4-Meter Aperture
Authors: Livingston, W.; Barr, L.
1992ASPC...26..604L Altcode: 1992csss....7..604L
No abstract at ADS
---------------------------------------------------------
Title: Proposed Upgrade of the McMath Solar/Stellar Telescope to a
4 m Aperture
Authors: Giampapa, M. S.; Livingston, W. C.; Rabin, D. R.
1992LNP...397..279G Altcode: 1992sils.conf..279G
No abstract at ADS
---------------------------------------------------------
Title: Book-Review - Solar Interior and Atmosphere
Authors: Cox, A. N.; Livingston, W. C.; Matthews, M. S.; Ghizaru, M.
1992RoAJ....2..210C Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Strong; Weak Solar Magnetic Fields
Authors: Solanki, S. K.; Ruedi, I.; Livingston, W. C.; Stenflo, J. O.
1992ASPC...26..262S Altcode: 1992csss....7..262S
No abstract at ADS
---------------------------------------------------------
Title: Proposed conversion of the McMath Telescope to 4.0-meter
aperture for solar observations in the IR
Authors: Livingston, William
1991SPIE.1494..498L Altcode:
Located on a 2076 m summit in Arizona, the present all-reflective McMath
optical system consists of a 2.0-m CERVIT flat mounted as a heliostat to
follow the Sun, a 1.6-m 86.4-m focal length quartz concave positioned
within an inclined underground tunnel, and a 1.5-m CERVIT flat that
directs the image to different fixed instrument stations. The building
is adequate to accommodate a 6.0-m tracking feed and a 4.0-m concave,
resulting in an f/22 beam which is hot but manageable. A 4.0-m aperture
is desirable for adequate flux and resolution at 12 micrometers where
a number of Zeeman sensitive atomic lines are found, lines which are
a diagnostic for solar magnetism. At 12 micrometers the diffraction
limit is 0.75 arc- sec, and this resolution might be realized a
significant fraction of time because of improved seeing at these IR
wavelengths. Direct vector measurements of solar magnetic fields would
become possible because effective Zeeman splitting is proportional
to wavelength, both the linear and circular Stokes amplitudes are
proportional to their vector field components, and instrumental
polarization becomes negligible at 12 micrometers . The telescope would
also be used at night by the solar/stellar community. The use of thin,
all-aluminum mirrors under active control is contemplated. Circulating
fluids would maintain the mirrors and image focal plane at a constant
temperature. Mechanically, the 6-m tracking feed presents the greatest
challenge. The preliminary concept calls for a 6-m cell supported
and driven by three push-pull rods whose exact length is monitored
by a laser 'meter stick.' These rods are held by a slowly rotating
azimuthal block. Wind protection for the 6-m assembly is by a fence
whose height depends on the object under observation.
---------------------------------------------------------
Title: Spectroscopic observations of atmospheric trace gases over
Kitt Peak. III - Long-term trends of hydrogen chloride and hydrogen
fluoride from 1978 to 1990
Authors: Wallace, L.; Livingston, W.
1991JGR....9615513W Altcode:
Solar spectra obtained with a 1-m Fourier-transform spectrometer
and 13.5-m spectrograph on Kitt Peak are analyzed for absorption
by hydrogen chloride and hydrogen fluoride. It is shown that
hydrogen-chloride and hydrogen-fluoride column amounts are increased
more or less linearly by factors of about two and three, respectively,
over a 12-year period of observations. These fractional increases are
found to be comparable to the published increases in the ground-level
concentrations of halocarbons. It is noted that a close correlation
between hydrogen-chloride and hydrogen-fluoride amounts points to a
single mechanism that is primarily responsible for the variability of
the gases. Excess amounts and large variability at times correlated
with volcanic ash clouds are found in few observations in the
hydrogen-chloride and hydrogen-fluoride time series.
---------------------------------------------------------
Title: Line-blanketing Variations in the Irradiance Spectrum of the
Sun from Maximum to Minimum of the Solar Cycle
Authors: Mitchell, W. E., Jr.; Livingston, W. C.
1991ApJ...372..336M Altcode:
Solar irradiance spectra obtained at or near the maximum and minimum
phases of the solar magnetic activity cycle are compared. The
characteristics of these spectra are related to the irradiance
measurements available from the Active Cavity Radiometer Irradiance
Monitor (ACRIM) of the SMM. An interpretation based on sunspots and
faculae being added to the atmosphere at solar maximum can account
for less than 4 percent of the ACRIM decrease to be arising in the
500-560 nm range. The UV, with its much greater line-blanketing,
is more important, in agreement with the finding of Lean (1989).
---------------------------------------------------------
Title: Sunspot Umbrae: Observed Correlation between Magnetic Field
and Temperature
Authors: Livingston, W.
1991BAAS...23.1030L Altcode:
No abstract at ADS
---------------------------------------------------------
Title: RISE Telescope Concept for Ca K Imaging
Authors: Livingston, W.
1991BAAS...23.1040L Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Radial filamentary structure in a sunspot umbra
Authors: Livingston, W.
1991Natur.350...45L Altcode:
THAT the dark umbrae of sunspots are not uniformly dark has long been
recognized<SUP>1</SUP>, but our knowledge of umbral structure is still
limited. Here I present two white-light photographs of the solar disk,
of different exposure, recently obtained during excep-tional seeing
conditions with the McMath Telescope on Kitt Peak (Fig. 1). The
shorter exposure reveals the solar granulation, and the longer
brings out details in the darker umbrae. When these two images are
suitably combined, the umbra of one small sunspot is resolved into
an approximately filamentary structure, connecting to the penumbra,
along with featureless voids. A 'light bridge9 partially spanning the
spot is found to have a broader underlying filamentary foundation
that completes the crossing. These photo-graphs suggest that the
contemporary view of umbral structure as consisting primarily of
granulation or 'umbral dots' is question-able. Given that a sunspot
is a place where kilogauss magnetic fields concentrate and diverge
outwards, filamentary brightness modulation can perhaps be attributed
to partly inclined field lines, and the voids may be places where the
field becomes perpendicular to the surface.
---------------------------------------------------------
Title: Sun-as-a-star spectrum variability.
Authors: Livingston, William; Donnelly, Richard F.; Grigor'ev, Viktor;
Demidov, M. L.; Lean, Judith; Steffen, Matthias; White, Oran R.;
Willson, Richard L.
1991sia..book.1109L Altcode:
The Sun is observed as a star in order to determine luminosity change,
detect minute variability in average granulation and facular signals,
and to use as a standard against which other stars may be compared. In
this regard, topics discussed include: total irradiance variability
as measured from space by the Activity Cavity Radiometer Irradiance
Monitor and Earth Radiation Budget radiometers; Fraunhofer line heights
of formation and examples of their variability in visible wavelengths;
ultraviolet and extreme ultraviolet irradiance variability as observed
from space; the magnetic origin of irradiance change; and the observed
mean magnetic field of the Sun.
---------------------------------------------------------
Title: Energy Input to the Earth
Authors: Livingston, W. C.
1991JCC....18..121L Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Sun-as-a-star: Its convective signature and the activity cycle
Authors: Livingston, W.
1991LNP...380..246L Altcode: 1991IAUCo.130..246L; 1991sacs.coll..246L
From May 1980 to April 1990 we have observed several times a year the
solar irradiance spectrum from 5000Å to 6300Å using the 1-m Fourier
Transform Spectrometer. During the ascending phase of the solar cycle,
spectrum line asymmetry diminishes about 15% as the total magnetic
field encreases. At some epoch near the time of total magnetic field
maximum, line asymmetry ceases to track surface magnetism and abruptly
assumes a value appropriate to solar minimum.
---------------------------------------------------------
Title: Sampling V-Stokes on the solar disk with Fe I 15648 Å and
H Paschen β.
Authors: Livingston, W.
1991sopo.work..356L Altcode:
From exploratory observations made with a scanning spectrometer
the author demonstrates that V-Stokes profiles exhibit a variety of
forms. He confirms earlier work that shows the Zeeman splitting of
Fe 15648 Å is complete in the magnetic fields of plage regions where
field strengths of between 1000 and 2000 G can be measured. In sunspot
umbrae, however, molecular blends limit the line's usefulness. Some
preliminary observations with chromospheric HPβ 12818 Å are given.
---------------------------------------------------------
Title: Solar interior and atmosphere
Authors: Cox, A. N.; Livingston, W. C.; Matthews, M. S.
1991sia..book.....C Altcode: 1991QB539.I5S65....
The present work discusses nuclear energy generation in the solar
interior, solar neutrino experiments, solar premain-sequence evolution,
the computation of standard solar models, radiative-zone mixing,
solar element separation by atomic diffusion, the observation
and theory of solar oscillations, the solar internal rotation
and magnetism implications of oscillations, solar gravity modes,
and solar oscillation-mode excitation. Also discussed are the solar
spectrum, the role of the solar photosphere and a radiative boundary,
high spatial-resolution techniques for solar study, high-resolution
observations of the solar granulation, large-scale velocity fields,
the solar activity cycle, the magnetic fields of active regions and
sunspots, the physics of flux tubes and filigrees, the heating of the
solar chromosphere, the fine structure of the solar transition region,
coronal activity, the coronal origins of the solar winds, and postmain
sequence solar evolution.
---------------------------------------------------------
Title: An atlas of the solar spectrum in the infrared from 1850 to
9000 cm-1 (1.1 to 5.4 micrometer)
Authors: Livingston, W.; Wallace, L.
1991aass.book.....L Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Spectroscopic observations of atmospheric trace gases over
Kitt Peak. II - Nitrous oxide and carbon monoxide from 1979 to 1985
Authors: Wallace, L.; Livingston, W.
1990JGR....9516383W Altcode:
Solar spectra obtained with the 1-m Fourier transform spectrometer
on Kitt Peak were analyzed for absorption by N2O and CO. During the
period 1979-1985, it is found that N2O shows no detectable seasonal
variation or trend and can place an upper limit on the growth rate of
1 ppb per year. This is consistent with results of ground level gas
sampling. For CO, a large seasonal variation is seen, but, because of
inadequate sampling, a trend cannot be detected. Combined with other
spectroscopic studies, the mean CO level suggests a Northern Hemisphere
tropospheric scale height for CO of about 3.5 km.
---------------------------------------------------------
Title: Secular change in equivalent width of C 5380, 1978 - 90.
Authors: Livingston, William C.
1990NASCP3086..336L Altcode: 1990cisv.nasa..336L
The equivalent width of the high excitation photospheric line of C 5380
Å has been measured 3-4 times monthly in the solar irradiance spectrum
since 1978. C 5380 behaves differently than other spectral lines in
that it is unmodulated by the activity cycle, yet has increased in
strength by 0.081±0.008 mÅ in 12 years. Nominal equivalent width
is 22.25 mÅ. Implied is a temperature increase of 4.6K which is an
order of magnitude greater than constraints allowed by ACRIM results.
---------------------------------------------------------
Title: Tracking atmospheric trace gases by spectroscopy from Kitt
Peak.
Authors: Wallace, L.; Livingston, W.
1990NASCP3086..365W Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Spectroscopic observations of atmospheric trace gases over
Kitt Peak. I - Carbon dioxide and methane from 1979 to 1985
Authors: Wallace, L.; Livingston, W.
1990JGR....95.9823W Altcode:
Atmospheric spectra obtained with the Fourier transform spectrometer
on Kitt Peak have been analyzed for absorption by CO2 and CH4. During
the period 1979-1985, the CO2 total column amount was increasing
at a rate of 0.4 percent/yr and CH4 was increasing at a rate of
1.1 percent/yr. This is in substantial agreement with air sampling
measurements from other sites. In addition, a weak seasonal variation
of about 2 percent is detected in CO2, but none is seen in CH4.
---------------------------------------------------------
Title: Estimation of the solar Lyman alpha flux from ground based
measurements of the Ca II K line
Authors: White, O. R.; Rottman, G. J.; Livingston, W. C.
1990GeoRL..17..575W Altcode:
Measurements of the solar Lyman alpha and CaII K from October 1981 to
April 1989 show a strong correlation (r=.95) that allows estimation of
the Lyman alpha flux at 1 AU from 1975 to December 1989. Our estimated
Lyman alpha strength of 3.9 × 10<SUP>11</SUP>±.15 × 10<SUP>11</SUP>
photons/s cm<SUP>2</SUP> on 7 December 1989 is at the same maximum
levels seen in Cycle 21. Relative to other UV surrogates (sunspot
number, 10.7 cm radio flux, and HeI 10830 line strength), Lyman alpha
estimates computed from the K line track the SME measurements well
from solar maximum, through solar minimum, and into Cycle 22.
---------------------------------------------------------
Title: Estimation of the solar Lyman alpha flux from ground based
measurements of the CA II K line
Authors: Rottman, G. J.; Livingston, W. C.; White, O. R.
1990GeoRL..17..575R Altcode:
Measurements of the solar Lyman alpha and Ca II K from October 1981
to April 1989 show a strong correlation (r = 0.95) that allows
estimation of the Lyman alpha flux at 1 AU from 1975 to December
1989. The estimated Lyman alpha strength of 3.9 x 10 to the 11th +
or - 0.15 x 10 to the 11th photons/s sq cm on December 7, 1989 is
at the same maximum levels seen in Cycle 21. Relative to other UV
surrogates (sunspot number, 10.7 cm radio flux, and He I 10830 line
strength), Lyman alpha estimates computed from the K line track the
SME measurements well from solar maximum, through solar minimum,
and into Cycle 22.
---------------------------------------------------------
Title: The Li<SUP>6</SUP>/Li<SUP>7</SUP> Ratio Derived from Sunspot
Umbrae
Authors: Livingston, W. C.
1990BAAS...22Q.810L Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Semiempirical Models at Different Heights of a Quiescent
Prominence
Authors: Fang, C.; Zhang, Q. H.; Yin, S. Y.; Livingston, W.
1990LNP...363..284F Altcode: 1990doqp.coll..284F; 1990IAUCo.117..284F
Semi-empirical models of a quiescent prominence observed on Dec. 12,
1972 with the McHath Telescope at Kitt Peak have been deduced for
different heights. The transfer, statistical equilibrium equations as
coupled with the hydrostatic equilibrium, and the partical conservtion
equations have been solved. The models reproduce well the simultaneously
observed H , H , Hr, CaII K,H and infrared triplet line profiles. The
study indicates that the pressure near the edge of prominences and
the microturbulence velocity in the prominences basically do not vary
with height, but the temperature decreases monotonously from the edge
toward the center. It is found that the temperature near the edge
of prominences increases only slightly with height, but the central
temperature decreases significantly. The results also indicate that
near the edge of prominences there is no radiative equilibrium and
the total radiative loss has a maxium which is mainly due to L. The
radiative loss due to CaII is negligible in comparison with that due
to hydrogen. The ionization problem of Calcium has also been discussed.
---------------------------------------------------------
Title: Stalking Geosats with a Camera
Authors: Livingston, W. C.; Talent, D.
1990S&T....80..319L Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Book Review: Astrophysics of the sun. / CUP, 1988
Authors: Livingston, W. C.
1989S&T....77..271L Altcode: 1989S&T....77..271Z
No abstract at ADS
---------------------------------------------------------
Title: SYSTEMATIC OBSERVATIONS OF THE SUN (In honour of Helen Dodson
Prince): Future work
Authors: Livingston, W.; Zwaan, K.; Hiei, E.; Paterno, L.
1989HiA.....8..677L Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Semi-empirical models at different heights of a quiescent
prominence.
Authors: Fang, Cheng; Zhang, Qizhou; Yin, Suying; Livingston, W.
1989HvaOB..13..363F Altcode:
Semi-empirical models of a quiescent prominence observed on Dec. 12,
1972 have been deduced for different heights. The transfer, statistical
equilibrium equations as coupled with the hydrostatic equilibrium,
and the partial conservation equations have been solved. The models
reproduce well the simultaneously observed Hα, Hβ, Hγ, Ca II K,
H and infrared triplet line profiles.
---------------------------------------------------------
Title: The Solar Observing Program of the HAO/Lowell/AFGL
Solar-Stellar Spectrophotometry Project (S<SUP>3</SUP>)
Authors: Mihalas, D.; Radick, R.; Lockwood, G. W.; Gilliland, R. L.;
Ramsey, L. W.; Fisher, R.; Livingston, W.; White, O. R.
1988BAAS...20Q1008M Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Height-varying semi-empirical models of a quiescent prominence
Authors: Fang, Cheng; Zhang, Qizhou; Yin, Suying; Livingston, W.
1988SSSMP..31..842F Altcode:
Semi-empirical models of a quiescent prominence on 12 December 1972
have been deduced for four different heights. The authors found that
the temperature near the prominence surface increases only slightly with
height, but that the central temperature decreases significantly, and so
its gradient from center to surface increases rapidly with height. The
study also indicates that near the surface of the prominence there is
no radiative equilibrium and the total radiative loss has a maximum.
---------------------------------------------------------
Title: Spectrum Line Intensity as a Surrogate for Solar Irradiance
Variations
Authors: Livingston, W. C.; Wallace, L.; White, O. R.
1988Sci...240.1765L Altcode:
Active Cavity Radiometer Irradiance Monitor (ACRIM) solar constant
measurements from 1980 to 1986 are compared with ground-based,
irradiance spectrophotometry of selected Fraunhofer lines. Both data
sets were identically sampled and smoothed with an 85-day running mean,
and the ACRIM total solar irradiance (S) values were corrected for
sunspot blocking (S<SUB>c</SUB>). The Strength of the mid-photospheric
manganese 539.4-nanometer line tracks almost perfectly with ACRIM
S<SUB>c</SUB>. Other spectral features formed high in the photosphere
and chromosphere also track well. These comparisons independently
confirm the variability in the ACRIM S<SUB>c</SUB> signal, indicate
that the source of irradiance is faculae, and indicate that ACRIM
S<SUB>c</SUB> follows the 11-year activity cycle.
---------------------------------------------------------
Title: The Sun as a Star: On Wavelength Stability
Authors: Wallace, L.; Huang, Y. R.; Livingston, W.
1988ApJ...327..399W Altcode:
Evidence for wavelength shifts as a function of the activity cycle in
the sun is searched for. An indirect method for solar line measurement,
involving the comparison of wavelengths at solar lines which have a
large convective blueshift relative to solar lines which are relatively
insensitive to blueshift, is shown to yield an upper limit of 5 m/s
over the 1976-1986 period. Line asymmetry measurements indicative of
surface convection demonstrate a trend of 7 m/s over the 1980-1986
period. The results suggest that intrinsic solar variability would not
be an obstacle to planetary detection using precision radial velocity
data for solar-type stars.
---------------------------------------------------------
Title: The Global Oscillation Network Group (GONG)
Authors: Harvey, J. W.; Hill, F.; Kennedy, J. R.; Leibacher, J. W.;
Livingston, W. C.
1988AdSpR...8k.117H Altcode: 1988AdSpR...8..117H
As a community facility, the National Solar Observatory is establishing
a six-site ground-based solar observing network around the world. This
Global Oscillation Network Group (GONG) aims at essentially continuous
imaged observations of global solar oscillations for a minimum of three
years. Resulting data will be used to study the solar interior using
helioseismology. The heart of the observing instrument is a thermally
compensated, wide-field Fourier Techometer operated automatically by a
computer control system. Data from the six GONG stations is expected to
total over one gigabyte per day. Pipeline processing of these data will
proceed contemporaneously, reducing the raw data to several standard
product data sets at sustained throughput rates in excess of 6 megaflops
and peak rates that may exceed 50 megaflops. In support of widespread
scientific participation, software analysis tools based on the Image
Reduction and Analysis Facility (IRAF) and data distribution will be
provided. Science teams have been formed and are actively supporting
the project. The field instrument will reach the prototype stage in
early 1989 and full operation of the network is expected in 1992. <P
/>Operated by the Association of Universities for Research in Astronomy,
Inc., under contract to the National Science Foundation.
---------------------------------------------------------
Title: Correlation Lifetimes of Quiet and Magnetic Granulation from
the SOUP Instrument on Spacelab 2
Authors: Title, A.; Tarbell, T.; Topka, K.; Acton, L.; Duncan, D.;
Ferguson, S.; Finch, M.; Frank, Z.; Kelly, G.; Lindgren, R.; Morrill,
M.; Pope, T.; Reeves, R.; Rehse, R.; Shine, R.; Simon, G.; Harvey,
J.; Leibacher, J.; Livingston, W.; November, L.; Zirker, J.
1988ApL&C..27..141T Altcode:
The time sequences of diffraction limited granulation images obtained by
the Solar Optical Universal Polarimeter on Spacelab 2 are presented. The
uncorrection autocorrelation limetime in magnetic regions is dominated
by the 5-min oscillation. The removal of this oscillation causes the
autocorrelation lifetime to increase by more than a factor of 2. The
results suggest that a significant fraction of granule lifetimes are
terminated by nearby explosions. Horizontal displacements and transverse
velocities in the intensity field are measured. Lower limits to the
lifetime in the quiet and magnetic sun are set at 440 s and 950 s,
respectively.
---------------------------------------------------------
Title: Variability of the spectroscopic temperature of the sun
Authors: Livingston, W.; Steffen, M.
1988AdSpR...8g.133L Altcode: 1988AdSpR...8..133L
The concept of temperature as it applies to the solar photosphere
is discussed. Spectroscopic diagnostics such as C I 5380Å and Fe I
5379Å are evaluated using model atmosphere calculations. New evidence
is presented for a secular change now being under way in the deep
photosphere temperature gradient.
---------------------------------------------------------
Title: Spectral analysis and the two-dimensional distribution of
physical parameters in a quiescent prominence
Authors: Zhang, Qizhou; Livingston, W. C.; Hu, Ju; Fang, Cheng
1988VA.....31...35Z Altcode:
The H-alpha and Ca II K line profiles at 120 points of a quiescent
prominence on April 1, 1971 are analyzed using the linearization method
of Zhang and Fang (1986). The contours of electron temperature and
microturbulent velocity are presented and the distribution of physical
parameters is discussed.
---------------------------------------------------------
Title: Sun as a Star - Rotation Rates from the CA K-Index
Authors: Singh, Jagdev; Livingston, W. C.
1987SoPh..109..387S Altcode:
Daily measurements for 18 months made at Tucson of the Ca K-index in
integrated sunlight have been used to derive solar rotation rates. Power
spectral analysis shows that one can obtain a well defined value
of solar rotation rate in a period of six months, provided the data
are fairly continuous. One might suppose it is possible to study the
variation of solar (or stellar) rotation rate with time, a variation
arising from a combination of differential rotation and shifts in
the active latitude. A comparison between our observed rates and the
prevailing dominant activity zones does not support this supposition,
at least for the interval studied. Rather, our rates seem to depend
on the circumstances of sampling and active region birth and decay.
---------------------------------------------------------
Title: Spectral Analysis and the Two-Dimensional Distribution of
Physical Parameters in a Quiescent Prominence
Authors: Zhang, Q. Z.; Livingston, W. C.; Hu, J.; Fang, C.
1987SoPh..114..245Z Altcode:
The profiles of Hα and Ca II K lines of a arch quiescent prominence on
April 1, 1971 have been analyzed and the two-dimensional distributions
of electron temperature T<SUB>e</SUB>, micro-turbulence velocity
v<SUB>t</SUB> and the column number density of hydrogen along the
line-of-sight N<SUB>H</SUB> have been obtained. T<SUB>e</SUB>,
υ<SUB>t</SUB>, and N<SUB>H</SUB> are found to be 7500 K, 6 km
s<SUP>−1</SUP> and 2.2 <SUP>×</SUP> 10<SUP>18</SUP> cm<SUP>−2</SUP>
on an average, respectively. The electron temperature at the central
part of the prominence and along the two arcades are greater than that
at the edges, while the distribution of the micro-turbulence velocity
in these regions is opposite. There is no systematic variation in
T<SUB>e</SUB> and v<SUB>t</SUB>, from the center to the periphery as
described by Hirayama (1971). The column number density in the central
region is lower than that at the two edges.
---------------------------------------------------------
Title: CN Bandhead and the Measurement of Magnetic Fields
Authors: Livingston, W.; Huang, Y. -R.; Holweger, H.
1987BAAS...19..940L Altcode:
No abstract at ADS
---------------------------------------------------------
Title: The amplification of solar-line asymmetries by rotation
Authors: Smith, Myron A.; Livingston, William; Huang, You-Ran
1987PASP...99..297S Altcode:
The effect of rotation on granulation-induced line asymmetries is
examined by computing composite, rotationally-broadened flux profiles
from a grid of observed solar center-to-limb intensity profiles. After
first demonstrating that the composite profiles are in reasonable
agreement with profiles observed from the full solar disk, it is shown
that rotation enhances these asymmetries. When the rotational velocity
exceeds the half width of the intensity profile, the effects magnify
rapidly. Using the bisector function as a measure of the asymmetries,
it is found that the deviations from symmetry increase roughly as the
rotational velocity squared. This study leads to the general conclusion
that any curvature in the bisector function of a line having a stellar
origin will be exaggerated by rotation.
---------------------------------------------------------
Title: Solar Luminosity Variation. V. The Photospheric Lines
1976--1985
Authors: Livingston, W.; Wallace, L.
1987ApJ...314..808L Altcode:
Kitt Peak full-disk spectrophotometric records for selected
spectrum lines observed during the period 1976-1985 are analyzed
using improved corrections for water vapor and an instrument slit
change. The equivalent width of the ground state line of Mn I 5394.7
A shows the greatest variability and correlates well with Ca K 3933 A
intensity. Temperature-sensitive C I 5380.3 A, after some apparently
nonthermal activity in 1976-1978, settles down to a near constant
level. The equivalent widths of other lines show little or no change
with time. Evidence is presented that the source of the variability
in Mn I 5394.7 A is not confined to solar plage regions alone. The
annual means in the central depth of C I 5380.3 A, interpreted as
indicative of fluctuations in T(eff), show a peak-to-peak variation
of 0.7 K over 1979-1985.
---------------------------------------------------------
Title: Variability of chromospheric and photospheric lines in solar
cycle 21
Authors: White, O. R.; Livingston, W. C.; Wallace, L.
1987JGR....92..823W Altcode:
A program to measure the variability of solar spectrum lines in
the visible wavelengths began in 1974 at Kitt Peak Observatory and
continues as we approach the minimum between solar cycles 21 and
22. Both photospheric and chromospheric lines are measured on a
monthly basis using an optical system that permits observation of
the irradiance from the full solar disk as well as a smaller region
near the center of the sun's disk. The full disk measurements of the
Ca II K line quantify the increase and subsequent decrease in line
flux with the change in solar activity. However, spectra of quiet
regions at disk center show little if any variation throughout the
cycle. Photospheric lines separate into two classes according to their
variability: low-excitation lines of neutral metals resemble the K
line in the shape of their solar cycle variability curve, but weaker
lines formed deeper in the photosphere show no variation from 1974 to
1986. All of these findings point to solar activity as the source of
the observed spectral variations, but the largest radiometric effects
occur in chromospheric lines, with little or no evidence of variability
in lines found deep in the photosphere.
---------------------------------------------------------
Title: Variability of chromospheric and photospheric lines in solar
cycle 21
Authors: Livingston, W. C.; Wallace, L.; White, O. R.
1987JGR....92..823L Altcode:
The variability of solar spectrum lines in the visible wavelengths
during solar cycle 21 is examined. Full disk measurements of the
photospheric and chromospheric lines are analyzed. The variation in
granular convection at the sun's surface is studied. It is observed for
the chromospheric lines that increases and decreases in line flux for
Ca II K correspond to the solar activity. The data for the photospheric
lines reveal that only low-excitation lines of neutral metals display
short-term variability.
---------------------------------------------------------
Title: Old and New Views of Solar Prominences
Authors: Livingston, W. C.; Engvold, O.; Jensen, E.
1987Ast....15...18L Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Astronomical detectors for .001 to 300000 Å, an overview.
Authors: Livingston, W. C.
1987JOpt...18..187L Altcode: 1987JOp....18..187L
No abstract at ADS
---------------------------------------------------------
Title: Astronomical Detectors for .001A to 300,000A an Overview
Authors: Livingston, W. C.
1987SPIE..702..221L Altcode:
A variety of imaging devices are necessary in astronomy, not only to
vocer the observable electromagnetic spectrum but also because of
constraints on time resolution and signal-to-noise. Representative
imagers are listed and a few specific applications discussed.
---------------------------------------------------------
Title: Line Asymmetry and the Activity Cycle
Authors: Livingston, W.
1987rfsm.conf...14L Altcode:
Moderate strength Fraunhofer lines in spatially averaged spectra
display a line asymmetry arising from the convective motions of surface
granulation. Several workers have shown that line asymmetry diminishes
in magnetic regions, implying an interaction between surface magnetism
and granular convection. The author reviews the evidence that the 11
year activity cycle modulates line asymmetry when the sun is viewed
as a star.
---------------------------------------------------------
Title: Convection Magnetic Fields and Line Asymmetry in the Sun
and Stars
Authors: Livingston, W.; Huang, Y. R.
1986tswo.work....1L Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Astronomical detectors for .001 to 300000 Å, an overview.
Authors: Livingston, W. C.
1986idq..conf..221L Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Time Standards and the Medieval Church
Authors: Livingston, W. C.
1986PinJ....2....2L Altcode:
No abstract at ADS
---------------------------------------------------------
Title: White-light movies of the solar photosphere from the soup
instrument on spacelab 2
Authors: Title, A. M.; Tarbell, T. D.; Simon, G. W.; Acton, L.;
Duncan, D.; Ferguson, S.; Finch, M.; Frank, Z.; Kelly, G.; Lindgren,
R.; Morrill, M.; Pope, T.; Reeves, R.; Rehse, R.; Shine, R.; Topka,
K.; Harvey, J.; Leibacher, J.; Livingston, W.; November, L.
1986AdSpR...6h.253T Altcode: 1986AdSpR...6..253T
We present initial results on solar granulation, pores and sunspots
from the white-light films obtained by the Solar Optical Universal
Polarimeter (SOUP) instrument on Spacelab 2. SOUP contains a
30-cm Cassegrain telescope, an active secondary mirror for image
stabilization, and a white-light optical system with 35-mm film
and video cameras. Outputs from the fine guidance servo provided
engineering data on the performance of the ESA Instrument Pointing
System (IPS). Several hours of movies were taken at various
disk and limb positions in quiet and active regions. The images
are diffraction-limited at 0.5 arc second resolution and are, of
course, free of atmospheric seeing and distortion. Properties of the
granulation in magnetic and non-magnetic regions are compared and are
found to differ significantly in size, rate of intensity variation,
and lifetime. In quiet sun on the order of fifty percent of the area
has at least one “exploding granule” occurring in it during a 25
minute period. Local correlation tracking has detected several types
of transverse flows, including systematic outflow from the penumbral
boundary of a spot, motion of penumbral filaments, and cellular flow
patterns of supergranular and mesogranular size. Feature tracking has
shown that in quiet sun the average granule fragment has a velocity
of about one kilometer per second.
---------------------------------------------------------
Title: Sun as a Star Spectrum Variability
Authors: Livingston, W.
1985tphr.conf..184L Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Activity Cycle Variations of Photospheric Lines in the Sun's
Irradiance Spectrum
Authors: Livingston, W.; Wallace, L.
1985BAAS...17..644L Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Variation of the Calcium K Line Profile Over Solaar Cycle 21.
Authors: White, O. R.; Livingston, W. C.
1985BAAS...17..640W Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Water Vapor and fe 5250.2
Authors: Livingston, W.; Wallace, L.
1985SoPh...95..251L Altcode:
The commonly used magnetograph line of Fe 5250.2 Å is found to be
weakly blended by telluric water vapor. This circumstance could bias
solar rotation measurements.
---------------------------------------------------------
Title: Report of IAU Commission 9: Instruments and techniques
(Instruments et techniques).
Authors: Livingston, W. C.
1985IAUTA..19...41L Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Can We See the Earth's Shadow?
Authors: Livingston, W. C.
1985ScAge...3...64L Altcode:
No abstract at ADS
---------------------------------------------------------
Title: The Spacelab 2 Experience: A Personal View from the Ground
Authors: Livingston, W. C.
1985ScAge...3...49L Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Sun-as-a-star spectrum variability.
Authors: Livingston, W.; Holweger, H.; Wallace, L.; White, O. R.
1985MPARp.212..184L Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Contributions by R.G. Giovanelli to the Study of Magnetic
Field Structures
Authors: Livingston, W.
1985AuJPh..38..775L Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Characteristics of Water Vapor Over Kitt-Peak as Determined
from FTS Data
Authors: Wallace, L.; Brault, J. W.; Brown, M.; Livingston, W.
1984PASP...96..836W Altcode:
Spectra of three water vapor lines obtained with the Fourier transform
spectrometer at the McMath telescope have been analyzed to obtain the
atmospheric water-vapor content. The results for 52 days between 1978
and 1983 show a maximum of between 20 and 25 mm precipitable water vapor
in July and August and minima between February and June and between
October and December. Outside of a secondary maximum due to two days
in January 1983 the results are in generally good agreement with those
obtained with a grating spectrograph. The pressure-broadened linewidths
have been used to make corrections not exceeding 11% to the results
obtained with the spectrograph.
---------------------------------------------------------
Title: Solar Eclipses. (Book Reviews: Total Eclipses of the Sun)
Authors: Livingston, W.
1984Sci...226...40Z Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Coelostat and heliostat: alignment and use for eclipse and
other field purposes
Authors: Pasachoff, Jay M.; Livingston, William C.
1984ApOpt..23.2803P Altcode:
No abstract at ADS
---------------------------------------------------------
Title: The sun as a star - Three-component analysis of chromospheric
variability in the calcium K line
Authors: Skumanich, A.; Lean, J. L.; Livingston, W. C.; White, O. R.
1984ApJ...282..776S Altcode:
A three-component model of the solar cycle variability of the Ca II
K emission is developed using extant contrast and fractional area
parameters for (1) cell, (2) network, and (3) plage components that
are resolution-consistent. A fit has been achieved for the quiet-sun
Ca II K emission (at solar minimum) as observed by White and Livingston
(1981) with cell and network features alone using extant limb-darkening
laws. The occurrence of plages during the growth of the solar cycle
was found to be insufficient to account for the cycle increase in
the K emission and required the introduction of additional network in
excess of the quiet-sun value. The implications of, and evidence for,
such an active network are discussed.
---------------------------------------------------------
Title: Modelling solar spectral irradiance variations at ultraviolet
wavelengths.
Authors: Lean, J. L.; Livingston, W. C.; White, O. R.; Skumanich, A.
1984NASCP2310..253L Altcode: 1984siva.work..253L
The authors examine solar ultraviolet irradiance variations with solar
activity by using a three component model of the Ca II K chromospheric
emission. This model, developed from ground based observations of the
location, area and relative intensity of Ca II K plage, in conjunction
with measurements throughout solar cycle 21 of the full disc Ca II
K emission, includes the contributions to the ultraviolet flux from
both plage and active network emission. Evolution and rotation of
the plage regions on the solar disc produce a 27-day modulation of
the UV flux. Over longer time scales, such as the eleven year solar
cycle, changes in the active network are an important source of UV
flux variability.
---------------------------------------------------------
Title: Solar Physics. (Book Reviews: Weather and Climate Responses
to Solar Variations)
Authors: Livingston, W. C.
1984Sci...223.1170M Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Characteristics of Water Vapor Over Kitt-Peak
Authors: Wallace, L.; Livingston, W.
1984PASP...96..182W Altcode:
Six years of spectroscopic measurements of the atmospheric line of
H<SUB>2</SUB>O at 1.0832 μm are reported. The equivalent width of this
line shows a stationary seasonal dependence corresponding to the range
4 to 27 mm precipitable water vapor in the monthly means. The extremes
are 1.3 and 32 mm p.w.v. or a factor of 25. Inferred spectroscopic water
vapor for Kitt Peak compares well with meteorological Rawinsonde data
from nearby Tucson. The water vapor over certain other sites of current
interest are then deduced from appropriate Rawinsonde records. A method
for unblending a solar line contaminated by weak H<SUB>2</SUB>O blends
is also given.
---------------------------------------------------------
Title: Secular Change of Full Disk Line Asymmetry
Authors: Livingston, W.
1984ssdp.conf..330L Altcode:
Bisectors of strong iron lines in the full disk Fraunhofer spectrum are
observed to diminish in curvature as the activity cycle proceeds from
minimum (1976) to maximum (1979 - 1982). The implication is reduced
granular convection on a global scale in response to an increase of
total magnetic flux.
---------------------------------------------------------
Title: A Reticon Array System for Solar Spectrometric Use
Authors: Livingston, W. C.; Bin-Xun, Y.; Chuan-Jin, W.; Doe, M.;
Mahaffey, C.; Seigel, M.
1984AcASn..25...98L Altcode:
A solar spectrometric system was designed and installed with a
Reticon diode array as its detector, the purpose being to determine
the long period variability of the K index of Ca II λ3933.6 Å, while
considering the sun disc as a whole. The authors briefly describe the
optical configuration, electronics of the instrument and associated
software. Also some observing results are given to show the performance
of the system.
---------------------------------------------------------
Title: Strobing Cumulus Growth by Means of Lightning
Authors: Livingston, W.
1984Wthr...39..240L Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Fraunhofer line variability, 1975-1983
Authors: Livingston, W.; Holweger, H.; White, O. R.
1984stp..conf..427L Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Line Asymmetry and Magnetic Fields
Authors: Livingston, W. C.
1984KodOB...4....7L Altcode:
The measurement of the asymmetries of Fraunhofer lines shows promise
as a diagnostic of convection at the surface layers of the sun and
stars. The author discusses the observational evidence that line
asymmetry, and by inference granular convection, is inhibited by
surface magnetism.
---------------------------------------------------------
Title: Volcanic Ash over Arizona in the Spring of 1982: Astronomical
Observations
Authors: Livingston, W.; Lockwood, G. W.
1983Sci...220..300L Altcode:
Astronomical observations in Arizona recorded the passage of one,
and possibly more, volcanic dust clouds between January and June
1982. On 15 May the increase in extinction in visible wavelengths at
Tucson was more than 40 percent or 0.4 in optical depth. At Flagstaff,
325 kilometers north, the increase in extinction on the same day was
25 percent. A detailed time history of atmospheric extinction plus
evidence for nongray absorption from the cloud is presented.
---------------------------------------------------------
Title: Sunspot cycle and associated variation of the solar spectral
irradiance
Authors: Holweger, H.; Livingston, W.; Steenbock, W.
1983Natur.302..125H Altcode:
Precise monitoring of the solar absorption-line spectrum in the
period 1976-80 has revealed systematic changes of the strength of
photospheric lines during the ascending part of the current solar
cycle<SUP>1</SUP>. The most likely cause is a slight cooling of the
lower photosphere and a concomitant heating of higher layers. The
total energy radiated into space thereby remains unchanged, in
accordance with high-precision radiometry<SUP>2</SUP> covering
the same period. Nevertheless, a flattening of the photospheric
temperature gradient will be accompanied by a redistribution of energy
in the solar spectrum. Its magnitude is predicted here using stellar
model-atmosphere techniques. This `change of colour' is characterized
by a 0.2% decrease of the irradiance in the blue, and an increase
of the same order in the red and near IR. In this way solar activity
may modulate terrestrial climate even in the absence of perceptible
changes of the solar constant.
---------------------------------------------------------
Title: Landscape as viewed in the 320-nm ultraviolet
Authors: Livingston, W.
1983JOSA...73.1653L Altcode: 1983OSAJ...73.1653L
No abstract at ADS
---------------------------------------------------------
Title: Test of vacuum vs helium in a solar telescope.
Authors: Engvold, O.; Dunn, R. B.; Livingston, W. C.; Smartt, R. N.
1983ApOpt..22...10E Altcode:
The consequences of filling a solar telescope with helium, a gas with an
exceptionally low index of refraction and a high thermal conductivity,
are reported. All the tests are conducted with the solar beam present to
provide normal heating. Internal seeing of the telescope is evaluated by
viewing the image of an He-Ne laser beam in autocollimation reflected
from the entrance window for different pressures of air or helium. The
total path of the laser beam through the tank (six times) becomes
about 100 m. Quantitative measurements of the wave front distortions
are derived by inserting a point-diffraction interferometer near the
focused image of the laser beam. Excursions of the fringe pattern yield
direct measures of the wave front errors in units of the 0.633-micron
laser wavelength. It is concluded that a helium-filled telescope is a
realistic alternative to a vacuum telescope for solar observations. The
barely detectable tank seeing with helium near atmospheric pressure
could possibly be rectified either by a high reflectivity coating of
the mirrors, which reduces the heat load, or by a forced circulation
of the helium in the tank.
---------------------------------------------------------
Title: Magnetic fields and convection - New observations
Authors: Livingston, W. C.
1983IAUS..102..149L Altcode:
Fourier Transform Spectrometer observations of Fraunhofer-line
displacement and asymmetry suggest that granular convection is
inhibited in regions of magnetic activity. The observations and a
method for removing the effects of solar rotation are discussed. In
integrated sunlight ('the sun as a star'), records of line asymmetries
indicate that a significant reduction in the amplitude of the sun's
convective signature took place between 1980 and 1982. To the extent
that full-disk line asymmetry arises strictly from convective motions,
the results constitute strong evidence that magnetic activity influences
(inhibits) convective motion on a global scale.
---------------------------------------------------------
Title: Chasing Rainbows
Authors: Livingston, W. C.
1983ScAge...1...28L Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Kurzzeitige Variationen im Spektrum des integrierten
Sonnenlichts
Authors: Holweger, H.; Livingston, W.
1983MitAG..60..225H Altcode:
No abstract at ADS
---------------------------------------------------------
Title: A three-component model of the variability of the solar
ultraviolet flux: 145-200 nM
Authors: Lean, J. L.; White, O. R.; Livingston, W. C.; Heath, D. F.;
Donnelly, R. F.; Skumanich, A.
1982JGR....8710307L Altcode:
A three-component model has been developed to examine the variation
with solar activity of the far ultraviolet irradiance between 145 and
200 nm. This model is based on spatially resolved observations of
the Call K chromosphere and includes the contributions to the full
disk flux from both plage and active network emission. The 27-day
modulation of the ultraviolet flux is explained by the evolution and
rotation of the plage regions on the solar disc. Over the longer time
scale of the eleven-year cycle it is essential that changes in the
active network arising from the decay of plage regions also be solar
flux is it possible to simultaneously reproduce the 27-day variability
observed by the solar backscatter ultraviolet experiment on the Nimbus 7
satellite and the changes from the minimum to the maximum of the solar
activity cycle observed by the rocket experiments of the Laboratory
for Atmospheric and Space Physics and by the extreme ultraviolet
spectrometer on the Atmospheric Explorer E satellite. It is shown that
the AE-E experiment measured a smaller solar cycle variability for the
ultraviolet irradiances than is predicted by the model calculations
because of the spatially restricted field of view of this instrument.
---------------------------------------------------------
Title: Low Noise Spectrometer for the Daily Measurement of Solar
Chromospheric Flux
Authors: Livingston, W. C.; Mahaffey, C.; Ye, B.
1982SPIE..331..249L Altcode:
A "sun as a star" spectrometer is described which measures the
variability of the core of Ca II 3933Å relative to the nearby continuum
at 3953Å. The system is capable of 0.001% photometry but differential
atmospheric extinction over the 20Å bandpass limits detectivity
to 0.02%.
---------------------------------------------------------
Title: Ca ii K<SUB>2V</SUB> spectral features and their relation
to small-scale photospheric magnetic fields
Authors: Sivaraman, K. R.; Livingston, W. C.
1982SoPh...80..227S Altcode:
Although the Ca II K<SUB>232</SUB> network is known to be cospatial with
magnetic elements there has been doubt as to the magnetic origin of
the fainter K<SUB>2V</SUB> points. We demonstrate that weak magnetic
elements also lie at the roots of the K<SUB>2V</SUB> points, and
because the latter are numerous they may contribute sensibly to the
integrated light profile of Ca II K.
---------------------------------------------------------
Title: Detection of solar flares when the sun is observed as a star.
Authors: Livingston, W. C.; Ye, B.
1982PASP...94..713L Altcode:
Solar flares are detectable in unfocused sunlight from minute,
transient, enhancements in the center of Fraunhofer Ca II K spectrum
line. A survey of flare-frequency in other solar-type stars could
establish the normalcy of the sun's present activity cycle.
---------------------------------------------------------
Title: Erratum - Solar Luminosity Variation - Part Four - the
Photospheric Lines 1976-1980
Authors: Livingston, W.; Holweger, H.
1982ApJ...258..904L Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Magnetic fields, convection and solar luminosity variability
Authors: Livingston, W. C.
1982Natur.297..208L Altcode:
Model calculations universally indicate that heat transport from
the solar interior is almost entirely by convection in the outer
envelope. Spiegel and Weiss<SUP>1</SUP> have recently discussed how
magnetic fields can intrude into this envelope to affect convection
and thus introduce transients into the Sun's luminosity. I demonstrate
here from Fourier transform spectrometer observations of Fraunhofer
line asymmetry that granular convection is retarded in the presence of
surface magnetism. I then present full disk observations which suggest
a lessening of convection over the past 5 yr. As this time interval
coincides with the rise from a minimum to a maximum of solar activity,
with the presumed injection of new magnetic flux from the interior,
the resolved disk and full disk observations are consistent. Finally I
note the continued temporal decrease in the spectroscopic temperature
of the low photosphere and consider how a change of convection and
the lowering temperature may be related.
---------------------------------------------------------
Title: New Twist for Sunspot
Authors: Livingston, W.
1982SciN..121..341L Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Photo-Electronic Image Devices
Authors: Livingston, W. C.
1982IAUTA..18...47L Altcode: 1982IAUT..18A...47L
No abstract at ADS
---------------------------------------------------------
Title: Solar luminosity variation. IV - The photospheric lines,
1976-1980
Authors: Livingston, W.; Holweger, H.
1982ApJ...252..375L Altcode:
Kitt Peak full disk spectrophotometric records covering the period
1976-1980 have been analyzed to study the behavior of seven spectrum
lines sensitive to photospheric parameters. A secular decrease of
equivalent widths ranging from 0 to 2.3% is observed. From the lack
of correlation with localized, short-lived features like sunspots and
plages, it is concluded that the line weakenings are due to global
variations of surface properties. Model atmosphere analysis suggests
that the observed response pattern reflects a slight flattening of
the lower photospheric temperature gradient, corresponding to a 15%
increase in mixing length, at constant, effective temperature. The
associated increase in the efficiency of convection can be reconciled
with a constant luminosity if the change is assumed to occur only in
the outer 100 km of the convection zone.
---------------------------------------------------------
Title: Preliminary Results from Eclipse Coronal Velocity Observation
Authors: Livingston, W.; Harvey, J.
1982tsef.conf...18L Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Preliminary results from eclipse coronal velocity observations.
Authors: Livingston, W.; Harvey, J.
1982PINSA..48...18L Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Observed variability in the Fraunhofer line spectrum of solar
flux, 1975 - 1980
Authors: Livingston, W.; Holweger, H.; White, O. R.
1981NASCP2191...95L Altcode: 1981vsc..conf...95L
Over the five years double-pass spectrometer observations of the
Sun-as-a-star revealed significant changes in line intensities. The
photospheric component weakened linearly with time 0 to 2.3%. From a
lack of correlation between these line weakenings and solar activity
indicators like sunspots and plage, a global variation of surface
properties is inferred. Model-atmosphere analysis suggests a slight
reduction in the lower-photospheric temperature gradient corresponding
to a 15% increase in the mixing length within the granulation
layer. Chromospheric lines such as Ca II H and K, Ca II 8543 and the CN
band head weaken synchronously with solar activity. Thus, the behavior
of photospheric and chromospheric lines is markedly different, with
the possibility of secular change for the former.
---------------------------------------------------------
Title: Solar luminosity variation. III - Calcium K variation from
solar minimum to maximum in cycle 21
Authors: White, O. R.; Livingston, W. C.
1981ApJ...249..798W Altcode:
Completion of measurements of the full disk Ca II H and K profiles
from minimum to maximum, in the current solar cycle 21, shows that
while the central intensity of the K line increases by 30% on the
average, a peak change of +40% was recorded near the maximum of solar
activity in late 1979. The 1 A K index shows a smaller, corresponding
increase of 18%, and it is suggested that these changes are due to the
occurrence of solar plages on the visible solar hemisphere. Spectral
features formed above the temperature minimum are closely related in
their variability, but not as well related to changes in the strength
of narrow photospheric lines and the K<SUB>1</SUB> wings. It is found
that Ca II variability correlates closely with the plage index, the
Zurich sunspot number, and the Ottawa 10 cm flux measurements.
---------------------------------------------------------
Title: Magnetic Fields Observed to Affect Granular Convection
Authors: Livingston, W.; Carbon, D.
1981BAAS...13..881L Altcode:
No abstract at ADS
---------------------------------------------------------
Title: a Proposed High Performance, Minimum Cost,
Telescope/magnetograph System
Authors: Livingston, W.
1981siwn.conf..305L Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Umbral Oscillations at the Photospheric Level
Authors: Livingston, W.; Mahaffey, C.
1981phss.conf..312L Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Langzeitverhalten solarer Spektrallinien
Authors: Livingston, W. C.; Holweger, H.
1981MitAG..52Q.108L Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Kitt Peak coronal velocity experiment.
Authors: Livingston, W.; Harvey, J.; Doe, L. A.; Gillespie, B.;
Ladd, G.
1981otse.conf...19L Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Solar Flux Spectrum Variability, 1975-1980, as Indicative of
a Change in the Photospheric Temperature Gradient
Authors: Holweger, H.; Livingston, W.
1980BAAS...12..897H Altcode:
No abstract at ADS
---------------------------------------------------------
Title: The Kitt-Peak Coronal Velocity Experiment
Authors: Livingston, W.; Harvey, J.; Doe, L. A.; Gillespie, B.;
Ladd, G.
1980BASI....8...43L Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Marcel Minnaert and optics in nature
Authors: Livingston, William C.
1980ApOpt..19..648L Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Observations with high temporal resolution of the solar Ca/+/
K line
Authors: Duvall, T.; Livingston, W.; Mahaffey, C.
1980LNP...125..237D Altcode: 1980nnsp.work..237D
High time resolution photometric scans of chromospheric Ca(+) K are
examined for evidence of propagating waves. The scans refer to a quiet
area (1 x 7 arcsec) near disk center. Diagnostics include line profile
movies, time sequence spectrograms and power spectra. Both upward and
downward (reflected) disturbances having lifetimes of approximately
1-2 min are seen.
---------------------------------------------------------
Title: Solar rotation, 1966 1978
Authors: Livingston, W.; Duvall, T. L., Jr.
1979SoPh...61..219L Altcode:
Photospheric and chromospheric spectroscopic Doppler rotation
rates for the full solar disk are analyzed for the period July,
1966 to July, 1978. An approximately linear secular increase of the
equatorial rate of 3.7% for these 12 years is found (in confirmation
of Howard, 1976). The high latitude rates above 65 ° appear to vary
with a peak-to-peak amplitude of 8%, or more, phased to the sunspot
cycle such that the most rapid rotation occurs at, or following,
solar maximum. The chromosphere, as indicated by Hα, has continued
to rotate on the average 3% faster than the photosphere agreeing with
past observations. Sources of error are discussed and evaluated.
---------------------------------------------------------
Title: Marcel Minnaert and Optics in Nature
Authors: Livingston, W. C.
1979ApOpt..19..648L Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Solar Input to the Terrestrial System
Authors: Livingston, W. C.
1979stiw.conf...45L Altcode: 1979stiw.symp...45L
The sun's input to the earth environment is apportioned as shown in
an illustrative table for total energy and distribution of energy as
to radiation and particles and fields. The paper reviews the physical
origin, spectral nature, energetics and known variability of all solar
emanations: photons, particles, and fields. Although not yet proven,
it seems probable that the solar constant will turn out to be time
invariant. In this case, irradiance is the prime candidate for the
sun-climate connection with the line-blanketing as the underlying
mechanism, transferring UV flux to the visible-IR. A secondary candidate
is the solar wind - both the particles and fields - mainly because of
its known efficiency in producing geomagnetic effects.
---------------------------------------------------------
Title: Long Time-Base Monitoring of the Solar Spectrum-An Instrumental
Challenge
Authors: Livingston, W. C.
1979SPIE..172..134L Altcode:
The Fraunhofer spectrum appears to show subtle variability at the
0.1% level, indicative of a nonconstant temperature and possibly
mechanical wave flux in the solar atmosphere. Spectrum line monitoring
would require control of spectrometer scattered light, zero point,
resolution and linearity to high accuracy (less than 0.5%). Since
systems components such as filters, detectors, gratings, etc. will break
or deteriorate, the general problems of maintaining a time-variant
instrument is discussed. Among these problems are filter fringes,
a disturbing channel modulation introduced by the colored glass
filter used for order separation, and interlopers such as 04 and
NO2. Attention is also given to defining the continuum, equivalent
width, l/f noise, the need for redundant detectors and preservation
of original raw data. It is concluded that an accuracy of 0.1% may
be possible but only by attention to many details and procedure. Two
methods for achieving long term accuracy are suggested: If a suitable
gas absorption cell could be found providing a constant reference,
spectrometer performance could be monitored, or, more promising,
the 1-m path difference Fourier transform spectrometer could be used.
---------------------------------------------------------
Title: Solar luminosity variation: II. Behavior of calcium H and K
at solar minimum and the onset of cycle 21.
Authors: White, O. R.; Livingston, W.
1978ApJ...226..679W Altcode:
A program for measuring the solar cycle variation of the profiles of Ca
ii H and K, using the McMath double-pass spectrometer, is described. The
observations are made both at disk center and in integrated light ("the
Sun as a star"). During the 2 year epoch covering minimum activity,
from 1974 October to 1976 October, the integrated light equivalent width
of K as bounded by a 1 A band centered on the line (the K-index) showed
no significant variation (cr = 0.22%). Internal error for a single day,
over a 7li5 period, is a = 0.066%. During 1977, apparently in response
to the onset of cycle 21 activity, the K-index increased by 2.7%, while
the central intensity of K3 rose by 5.7%. These changes are traceable
in detail to plages on the disk. Center disk observations of the quiet
regions containing network and supergranulation cells have shown no
change. Subject headings: Ca ii emission - Sun: activity - Sun: plages
---------------------------------------------------------
Title: The fine structure of prominences.
Authors: Engvold, O.; Malville, J. M.; Livingston, W.
1978SoPh...60...57E Altcode:
At least 1/3 of all quiescent prominences contain Doppler shifted
features associated with their edges or emission gaps between prominence
sub-structures. The individual spectral structures have lifetimes
of 5-15 min, dimensions perpendicular to the edge of 1-2 arc sec,
and may be lined along the visible edge of a prominence for distances
up to 30 arc sec. The velocities average 30-40 km s<SUP>-1</SUP>. The
emission line profiles are generally complex and may consist of several
components. Their Ca II K, He I D<SUB>3</SUB>, and Hα line intensity
ratios may be interpreted by a slightly higher temperature than average
for the prominence.
---------------------------------------------------------
Title: Motions in solar magnetic tubes. II: The oscillations.
Authors: Giovanelli, R. G.; Livingston, W. C.; Harvey, J. W.
1978SoPh...59...49G Altcode:
The method of Giovanelli and Brown (1977) has been used with a variety
of spectral lines to study oscillating longitudinal gas velocities
inside solar magnetic elements. Oscillations have been found inside all
elements observed, the amplitudes increasing with height from typically
±0.27 km s<SUP>−1</SUP> in Fe I 5166 Å (a line of low origin)
to ±0.75 km s<SUP>−1</SUP> in Hα. Simultaneous observations in
pairs of lines show that a given disturbance occurs later with height,
so that disturbances propagate outwards. The period is typically 5
min in all lines originating near or below Mg b<SUB>1</SUB>, but is
about 3 min in Hα.
---------------------------------------------------------
Title: Motions in solar magnetic tubes. III: Outward wave propagation
in sunspot umbras.
Authors: Giovanelli, R. G.; Harvey, J. W.; Livingston, W. C.
1978SoPh...58..347G Altcode:
The line-centre magnetogram technique has been used to study velocities
at spatial scales ≃5″ in several umbras without interference from
light scattered from the surrounding non-magnetic photosphere. In
addition, more traditional velocity observations of one sunspot were
also analysed. The velocities are highly variable within any spot and
from one spot to another. Rms velocities in Hα, b<SUB>1</SUB>, 5233
and 5166 Å were typically ±0.6, ±0.2<SUB>0</SUB>, ±0.1<SUB>0</SUB>,
and ±0.1<SUB>7</SUB> km s<SUP>−1</SUP> during present observations,
but factors of 2 smaller or larger are not uncommon. In 5166 and 5233
Å these velocities are about two-thirds of those in non-magnetic
photospheric regions.
---------------------------------------------------------
Title: Emanations from the Sun. (Book Reviews: The Solar Output and
Its Variation. Papers from a workshop, Boulder, Colo., Apr. 1976)
Authors: Livingston, W. C.
1978Sci...199.1429L Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Cooling of the Sun's photosphere coincident with increased
sunspot activity
Authors: Livingston, W. C.
1978Natur.272..340L Altcode:
IN summer 1975, I began to monitor the spectroscopic temperature
of integrated sunlight (`the Sun viewed as a star'). The first 1.5
yr of observations were taken at a time of minimum activity and the
full disk temperature was apparently constant at +/-1-2 K. However,
1977 produced a marked increase of activity with the onset of cycle
no. 21. In response to this activity the Sun seems to have cooled
by ~ 6 K. To the extent that the Sun is a black body, a 6 K change
in temperature corresponds to a ~0.5% reduction in luminosity. The
inverse relation between activity and temperature is a new discovery,
and may prove helpful in explaining certain aspects of the Sun-Earth
climate relationship.
---------------------------------------------------------
Title: Active edges of quiescent prominences.
Authors: Malville, J. M.; Engvold, O.; Livingston, W.
1977BAAS....9R.569M Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Active Edges of Quiescent Prominences.
Authors: Malville, J. M.; Engvold, O.; Livingston, W.
1977BAAS....9..569M Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Empirical sensitivity of the solar C I 5380 line to temperature
changes in static and oscillating systems.
Authors: Hill, H. A.; Livingston, W. C.; Caudell, T. P.
1977ApJ...214L.137H Altcode:
The temperature sensitivity of the equivalent width of the photospheric
line of C I at 5380.3 A in a steady-state system has been determined
from observations and found to be in fair agreement with theoretical
results. For an oscillating system, the ratio of the amplitude of the
modulated part of the central line depth to the velocity amplitude
was obtained from observations of the 5-minute oscillation. The
temperature sensitivity of central line depth in this oscillating
system was obtained from this ratio and from the relevant solutions
for acoustic-wave propagation in the photosphere. This sensitivity
was found to be essentially two order of magnitude below that for
the steady-state system, diminishing the utility of this spectral
line in a program looking for global oscillations. Implicit in this
work is the use of relatively large temperature amplitudes deep in
the photosphere. These amplitudes have been found theoretically to be
associated with the 5-minute oscillations as a direct manifestation
of the Kappamechanism operating in the hydrogen ionization zone.
---------------------------------------------------------
Title: Solar luminosity variation. I. C I 5380 as a temperature
indicator and a search for global oscillations.
Authors: Livingston, W.; Milkey, R.; Slaughter, C.
1977ApJ...211..281L Altcode:
The high-excitation, weak Fraunhofer line C 1 5380.3 A is shown to
originate within the same photospheric layers as the Sun's continuous
radiation. By monitoring the central depth of the C I line relative to
the local continuum, in unfocused sunlight, we may follow temperature,
and hence luminosity changes of the whole Sun as a function of time. The
technique is practically insensitive to telluric absorption effects and
instrumental spectral response. A power spectrum analysis of 100 hours
of observations reveals no dominant oscillation of period P rising above
the 3 a uncertainty limit of 0.4 K for m < p < 60 . For power at
2h40m the limit is 1.0 K; for 5h20m, 2.0 K. The day-to-day fluctuation
for a 3 month period is 0.85 K rms (which corresponds to 0.06% in the
solar constant, or 0.0006 mag in luminosity). Subject headings: Sun:
atmospheric motions - Sun: general
---------------------------------------------------------
Title: Diode Arrays - a Review
Authors: Livingston, W. C.
1977aaid.coll...22L Altcode: 1977IAUCo..40...22L
No abstract at ADS
---------------------------------------------------------
Title: Kitt Peak 60-cm vacuum telescope
Authors: Livingston, W. C.; Harvey, J.; Pierce, A. K.; Schrage, D.;
Gillespie, B.; Simmons, J.; Slaughter, C.
1976ApOpt..15...33L Altcode:
A major new solar-research telescope conceived and built during a
time of budget restraint is described. The observation of magnetic
and velocity (circulation) field structure on a synoptic basis and
with diffraction-limited resolution is the aim. New optical features
include the use of oversize mirrors and windows to avoid thermal
edge effects and the placement of the coelostat feed outside the
vacuum, mainly for economy. The site selected has prevailing winds
that clear thermals from these mirrors. Test data in the form of
the system MTF and optical transmission, together with examples of
full disk magnetograms and photoheliograms, show present performance
capability. Measured MTF indicates a response of 0.2 at 1 sec of arc
(whereas diffraction-limited response would be about 0.8). System
transmission, including the accompanying spectrograph, is only 2-3%
(wavelength 0.44-1.1 microns). Thus, both the optical quality and
efficiency are subject to improvement.
---------------------------------------------------------
Title: Instruments and techniques (Instruments et techniques).
Authors: Meinel, A. B.; Baranne, A.; Baum, W. A.; Dollfus, A.;
Duchesne, M.; Godoli, G.; Hunter, A.; de Jager, C.; Livingston, W. C.;
Mikhel'Son, N.; Sedmak, G.; Sinvhal, S. D.; Walker, M.
1976IAUTA..16a..19M Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Solar magnetograph employing integrated diode arrays.
Authors: Livingston, W. C.; Harvey, J.; Slaughter, C.; Trumbo, D.
1976ApOpt..15...40L Altcode:
A solar magnetograph employing as detectors a pair of self-scanning
512-element integrated diode arrays is described. Coupled to a 1.5-m
telescope, photospheric flux as small as 50,000 trillion maxwells is
detected. Measured photometric properties of the diode array are given
including MTF as a function of wavelength, dark current as a function
of temperature, completeness of readout, optical and electronic
fixed-pattern noise. An integrating preamplifier is presented that
achieves a measured noise, when connected to the array, equivalent to
950 electrons at the input for a bandwidth of 3,000 trillion Hz. These
data provide a basis for evaluating the detector performance at low
light levels beyond the needs of the magnetograph. Operated at near
liquid nitrogen temperature, the noise and cooling characteristics
indicate the detector has promise as a low light level sensor.
---------------------------------------------------------
Title: Visibility of the solar H and K lines in the glitter from snow
(A)
Authors: Livingston, William C.
1976JOSA...66.1088L Altcode: 1976OSAJ...66.1088L
No abstract at ADS
---------------------------------------------------------
Title: The Kitt Peak 60-cm Vacuum Telescope
Authors: Pierce, A. K.; Livingston, W. C.; Harvey, J. W.; Schrage,
D.; Gillespie, B.; Simmons, J.; Slaughter, C.
1976ApOpt..15...33P Altcode:
No abstract at ADS
---------------------------------------------------------
Title: C I 5380 as a Temperature Indicator and a Search for Global
Oscillations
Authors: Livingston, W. C.
1976IAUTB..16..245L Altcode: 1976IAUT...16B.245L
No abstract at ADS
---------------------------------------------------------
Title: The Photometry of Extended Objects: Diode Array Detectors
and Interactive Data Processing
Authors: Livingston, W. C.
1975ASSL...54...21L Altcode: 1975ipta.proc...21L
No abstract at ADS
---------------------------------------------------------
Title: New Observational Limits on the Sun as a Pulsating Star.
Authors: Livingston, W.
1975BAAS....7Q.407L Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Evidence for Downflow Following a Coronal Transient?
Authors: Hildner, E.; Livingston, W. C.
1975SoPh...42..391H Altcode:
On 11 September 1973 a peculiar prominence was observed. The prominence
displayed strong (∼ 50km s<SUP>−1</SUP>) systematic motions toward
and away from the observer. The unusual spectrographic appearance of
the prominence might have been due to downflowing material lifted into
the corona during an earlier coronal transient.
---------------------------------------------------------
Title: Saturn's Rings and Perfect Seeing
Authors: Livingston, W. C.
1975S&T....49..207L Altcode:
No abstract at ADS
---------------------------------------------------------
Title: A New Component of Solar Magnetism - The Inner Network Fields
Authors: Livingston, W. C.; Harvey, J.
1975BAAS....7..346L Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Coronal Rotational and Flow Motions Measured at the 1970 and
1973 Total Eclipses
Authors: Harvey, J.; Livingston, W.; Doe, L.
1974BAAS....6R.288H Altcode:
No abstract at ADS
---------------------------------------------------------
Title: A 512-Channel Solar Magnetograph
Authors: Trumbo, D.; Harvey, J.; Livingston, W.; Slaughter, C.
1974BAAS....6..296T Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Detection of Small Scale Structure in Metal Lines at the
Extreme Solar Limb
Authors: Livingston, W. C.; White, O. R.
1974SoPh...39..289L Altcode:
We describe a tangential limb spectrum at 5870 Å which geometrically
probes the high photosphere through the low chromosphere. Velocity
and brightness structures with sizes ranging from 500 to 1500
km are present in the stronger emission lines. Such structure is
consistent between the Fe I and Ba II lines, and emission knots in
these lines coincide with continuum bright streaks. But no correlation
is evident between structure in the He I D<SUB>3</SUB> line, emission
in the Na I D<SUB>2</SUB> line, and emission in the Fe I and Ba II
lines as a group. Two classes of near-horizontal velocity structure
are seen in the height range from 0 to 500 km above the limb: υ
≤ 1 km s<SUP>−1</SUP> for the weaker metals and υ ∼ 7-10 km
s<SUP>−1</SUP> for the Na I line. Differences in line opacity are
suggested as the cause of the low correlation between the fine structure
in the various lines.
---------------------------------------------------------
Title: Report on the Kitt Peak Vacuum Telescope
Authors: Livingston, W.; Harvey, J.; Pierce, K.; Schrage, D.;
Slaughter, C.
1974BAAS....6Q.291L Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Magnetic Pukas and the Lifetime of the Supergranulation
Authors: Livingston, W. C.; Orrall, F. Q.
1974SoPh...39..301L Altcode:
We direct attention to the existence of exceptionally long-lived
supergranular patterns (4-7 days) seen on synoptic magnetograms.
---------------------------------------------------------
Title: Polar Magnetic Fields and the New Solar Cycle
Authors: Gillespie, B.; Harvey, J.; Livingston, W.; Harvey, K.
1973ApJ...186L..85G Altcode:
Recent magnetograph observations show evidence of the onset of the
new solar cycle (number 21). A small active region with the new-cycle
polarity configuration appeared at S45 on 1973 August 22 and persisted
until 1973 August 26. In addition, ephemeral active regions have
shown a predominance of new-cycle polarity configurations at high
latitudes, especially in the southern hemisphere. The polar magnetic
fields reversed polarity during 1971-1972. This reversal is a prelude
to the start of the new cycle according to the models of Babcock and
Leighton. Subject headings: solar activity - magnetic fields, solar -
rotation, solar
---------------------------------------------------------
Title: Telluric lines in the vicinity of λ5250 and λ6562å
Authors: Livingston, W.; Ramsey, L.
1973SoPh...31..317L Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Magnetic Observations Related to the 3B Flare of 4 August
Authors: Livingston, W.
1973BAAS....5Q.276L Altcode:
No abstract at ADS
---------------------------------------------------------
Title: The San Manuel Effect -- A Progress Report
Authors: Livingston, W.; Ramsey, L.
1973BAAS....5R.276L Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Image-Tube Systems
Authors: Livingston, William C.
1973ARA&A..11...95L Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Observations of Sunspot Umbral Velocity Oscillations
Authors: Bhatnagar, Arvind; Livingston, W. C.; Harvey, J. W.
1972SoPh...27...80B Altcode:
Sunspot umbral molecular lines have been used to look for the
oscillatory velocities in the umbra. Power spectrum analysis showed
conspicuous power for periods in the range between 448 and 310 s. The
maximum peak-to-peak amplitude of the umbral oscillatory velocity
component is observed to be in the order of 0.5 km s<SUP>−1</SUP>.
---------------------------------------------------------
Title: Solar Rotation: The Photospheric Height Gradient
Authors: Livingston, W.; Milkey, R.
1972SoPh...25..267L Altcode:
For selected pairs of Fraunhofer lines the height of formation has been
calculated corresponding to that portion of the profile intercepted by
the magnetograph exit slits. A photospheric height discrimination of
150-300 km is realized. In 1971 simultaneous measurements of equatorial
angular velocity from spectroscopic displacements of these line pairs
indicate no height gradient in excess of 1%.
---------------------------------------------------------
Title: Solar Rotation: The Height Gradient
Authors: Livingston, W. C.
1972BAAS....4..387L Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Observations of Sunspot Umbral Velocity Oscillations
Authors: Bhatnagar, A.; Livingston, W. C.; Harvey, J. W.
1972BAAS....4R.378B Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Measuring Solar Photospheric Magnetic Fields
Authors: Livingston, W. C.
1972S&T....43..344L Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Solar Magnetograph Utilizing Fiber Optics
Authors: Doe, L. A.; Livingston, W. C.
1972inas.conf..149D Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Evidence for the Distribution of Angular Velocity Inside the
Sun and Stars - Comments
Authors: Livingston, W. C.
1972NASSP.308..304L Altcode: 1972sowi.conf..304L
No abstract at ADS
---------------------------------------------------------
Title: A Line-Profile Stokesmeter: Preliminary Results on Non-Sunspot
Fields
Authors: Harvey, J.; Livingston, W.; Slaughter, C.
1972lfpm.conf..227H Altcode:
No abstract at ADS
---------------------------------------------------------
Title: A 'Ducky' Prominence Spectrum
Authors: Livingston, W. C.
1972Mercu...1....4L Altcode:
No abstract at ADS
---------------------------------------------------------
Title: High Dispersion Spectroscopic Study of Quiescent Prominences
Authors: Engvold, O.; Livingston, W.
1971SoPh...20..375E Altcode:
The utility of very high dispersion spectra (5-11 mm/Å) for the
study of line profile and velocity structure in quiescent prominences
is demonstrated by observations, taken with the spectregraphic slit
positioned normal to the limb in Hα λ6563 Å, He D<SUB>3</SUB> λ5876
Å, and Ca<SUP>+</SUP>K λ3933 Å. The emission profiles of both Hα
and the K line often show a central reversal (absorption). Emission
structures in the K-line can be complex with details as narrow as 0.04
Å. Frequently this structure consists of two distinct components:
a central, strong, rather narrow line, and an often displaced, weak
feature of undefined profile appearing as `fuzz'. It is suggested that
this fuzz indicates an exchange of matter between the prominence and
the corona.
---------------------------------------------------------
Title: Solar Rotation: Direct Evidence from Prominences for a
Westward Wind
Authors: Livingston, W.
1971SoPh...19..379L Altcode:
Hα and K-line spectra of quiescent prominences, taken with the slit
placed normal to the limb, commonly reveal a gas streaming (5-50 km/s)
that is peculiar to the upper edge of these objects. On the average
this streaming is uni-directional and consistent with a hypothetical
east-west wind.
---------------------------------------------------------
Title: The Kitt Peak Magnetograph. Iv: 40-CHANNEL Probe and the
Detection of Weak Photospheric Fields
Authors: Livingston, W.; Harvey, J.
1971IAUS...43...51L Altcode:
No abstract at ADS
---------------------------------------------------------
Title: The Kitt Peak Magnetograph, Iii: Automation and the 40-CHANNEL
Probe
Authors: Livingston, W.; Harvey, J.; Slaughter, C.
1971PROE....8...52L Altcode: 1971auoa.conf...52L; 1971IAUCo..11...52L
No abstract at ADS
---------------------------------------------------------
Title: Observations of Magnetic Field Changes in Active Regions
Authors: Harvey, K. L.; Livingston, W. C.; Harvey, J. W.; Slaughter,
C. D.
1971IAUS...43..422H Altcode:
No abstract at ADS
---------------------------------------------------------
Title: The Kitt Peak magnetograph. I. Principles of the instrument.
Authors: Livingston, W.; Harvey, J.
1971CoKit.558.....L Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Comments on a Paper by Semel
Authors: Harvey, J.; Livingston, W.
1970A&A.....9..151H Altcode:
A fundamental difficulty is described which lilnits the applicability
of a magnetograph calibration technique proposed by Semel.
---------------------------------------------------------
Title: Photospheric Magnetic Fields on March 7, 1970
Authors: Livingston, W.; Harvey, J.; Slaughter, C.
1970Natur.226.1146L Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Spectroscopic Observations of Differential Rotation with
Height in the Solar Envelope
Authors: Livingston, W. C.
1970stro.coll..321L Altcode: 1970IAUCo...4..321L
No abstract at ADS
---------------------------------------------------------
Title: Double-K_{2} Emission Line Observed in Sunspots and in
Prominences
Authors: Engvold, O.; Livingston, W.
1969PASP...81..795E Altcode:
0. ENGVOLDt Institute for Theoretical Oslo, Norway AND W. LIVINGSTON
Kitt Peak National Observatory} Tucson, Arizona fteceived September
2, 1969
---------------------------------------------------------
Title: Magnetograph Measurements with Temperature-Sensitive Lines
Authors: Harvey, J.; Livingston, W.
1969SoPh...10..283H Altcode:
Certain discrepancies between theoretical and empirical calibrations
of magnetograph response are resolved by recognizing the existence
of line profile changes in magnetic regions. Many of the photospheric
lines commonly used for magnetic field measurements weaken greatly in
magnetic regions outside of sunspots. Unless due account is made of
the line profile change, the magnetograph measurements underestimate
magnetic flux and field strengths.
---------------------------------------------------------
Title: Observational Evidence for Quantization in Photospheric
Magnetic Flux
Authors: Livingston, W.; Harvey, J.
1969SoPh...10..294L Altcode:
Observations are presented which suggest that away from sunspots
photospheric magnetic flux is quantized. Assuming the elemental area
of a magnetic region to be 1 (arc-sec)<SUP>2</SUP> the elemental field
strength is 525 G.
---------------------------------------------------------
Title: On the Differential Rotation with Height in the Solar
Atmosphere
Authors: Livingston, W. C.
1969SoPh....9..448L Altcode:
Spectroscopic measurements of solar rotation having good height
discrimination show no change in angular velocity through the
photosphere layers but an increase of 8% for the Hα chromosphere
(epoch 1968.9). Spectroscopic results in general are compared with
measures made with tracers, i.e. sunspots, filaments, etc., and it is
seen that the spectroscopic method always shows increased differential
rotation with height, while tracers indicate none. A westward flowing
wind is proposed that increases in velocity with height, but produces
negligible movement to magnetic regions associated with tracers.
---------------------------------------------------------
Title: Determining the Rotation of the Sun
Authors: Livingston, W. C.
1969ASPL...10..265L Altcode: 1969ASPL..484.....L
No abstract at ADS
---------------------------------------------------------
Title: Progress Report on a 40-Channel Magnetograph
Authors: Aikens, R. S.; Doe, L. A.; Livingston, W. C.; Slaughter, C. D.
1969BAAS....1R.270A Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Magnetic Development of an Active Region
Authors: Angle, Karen L.; Livingston, W. C.
1969BAAS....1Q.271A Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Solar Rotation 1966-68
Authors: Livingston, W. C.
1969BAAS....1S.285L Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Solar rotation, 1966 68
Authors: Livingston, W. C.
1969SoPh....7..144L Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Aircraft and Cloud Formation
Authors: Livingston, W. C.
1969Wthr...24...56L Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Magnetograph Observations of the Quiet Sun. I. Spatial
Description of the Background Fields
Authors: Livingston, W. C.
1968ApJ...153..929L Altcode:
A photoelectric magnetograph is described which achieves an rms noise
equivalent sensitivity of 1 gauss (arc sec)-2 sec'. The dynamic
range is 0 5-4000 gauss Fine-scan maps of the center of the disk,
45000 x 52000 km, show Ca~ K-emission associated fields of `-~-`1O0
gauss and background fields of `-`lO gauss. Both the K-emission
fields and background fields resolve into elements of about the same
size, 1000-2000 km, when measured at the half-intensity point The
integrated flux contained in the back- ground fields was never zero
(1965-1967) but ranged from 0 25 to 0 5 of the flux in the K-emission
ele- ments. The background fields are suggested to he remnants of old
K-emission fields reduced in strength, but not size, by the action of
the supergranulation. Previously reported upper limits to a granular
mag- netic field probably represent measures of these relatively
large supergranule-related elements. Single line scans made with an
aperture of 360 X 360 km achieve an effective resolution of 500 km
when the seeing is good While velocity and brightness elements in the
quiet Sun exhibit a spatial fine structure down to this observational
resolution limit, no similar fine structure is found in magnetic fields
---------------------------------------------------------
Title: A Solar Granulation Spectrogram
Authors: Kirk, J. G.; Livingston, W.
1968SoPh....3..510K Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Some Observations bearing on the Problem of the Short-Period
Oscillations
Authors: Howard, Robert; Livingston, William C.
1968SoPh....3..434H Altcode:
Observations of solar velocity fields made simultaneously at Mount
Wilson and at Kitt Peak with the same size aperture (5 arc-sec)
and same position on the disk (± 1 arc-sec) are presented. The
object is to clarify whether the short-period oscillations (SPO's)
previously reported (Howard, 1967), could be caused by local seeing
conditions. The time of onset and general character of the SPO's are
found to be well correlated for the two sites, a condition that favors
a solar origin. However, because correlation in complete detail did
not prove possible, some doubt must remain regarding the source of
the SPO's.
---------------------------------------------------------
Title: Further Comments on the SPO Problem
Authors: Livingston, W. C.
1968SoPh....3..448L Altcode:
No abstract at ADS
---------------------------------------------------------
Title: High dispersion stellar spectroscopy and the role of the
image tube at the McMath solar telescope
Authors: Livingston, W.
1968BAICz..19..283L Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Wavelength Dependence of Solar Granulation- A Preliminary
Report.
Authors: Léna, P. J.; Livingston, W. C.; Slaughter, C. D.
1968AJS....73R..67L Altcode:
A photoelectric study of the continuum brightness fluctuations in the
solar granulation is being undertaken. The spectral range covers the
interval 0.4 to 5 microns, and 10 microns with reduced accuracy. Maps,
16X32 sec of arc, made with an exploring hole of 0.5 sec of arc,
require two minutes of time. Two such maps are made simultaneously for
the same area, one in the visible with a photomultiplier, one in the
infrared using a helium-cooled germanium bolometer. The process is
then repeated at other pairs of wavelengths. Isobrightness contour
maps are plotted by computer. The range of optical depths covered
goes from 75000=1.58 (N=1.7~) to r~~~~=1.20 (N=0.4~) or 75000=0.12
(N 10~). Thus, the vertical scale involved is of the order of 125
km. Three-dimensional time-varying pictures of granulation are then
provided. Fine structures, of the order of 1 sec of arc, have been
observed at both 1.7 and 5 microns, correlating with the structures
observed in the visible region. The rms value of the observed contrast
between bright and dark areas varies from 4% (at 1.7~) to 1.2%
(at 5~). The contrast observed is strongly affected by atmospheric
seeing. Theory predicts that improved atmospheric seeing should be
found at longer wavelengths, although the quantitative aspect of this
wavelength dependence is not yet very clear. Measurements have been
made in this study to evaluate the smearing of the solar limb by the
atmospheric turbulence as a function of wavelength. Narrower smearing
functions are found at longer wavelength, with a 1/NP dependence,
where -13~p~-21. Despite the fact that the granular contrast on the
sun decreases with increasing wavelengths, ground observations in the
infrared may provide a picture of the granulation which would be closer
to the actual contrast than is found from visible pictures.
---------------------------------------------------------
Title: High Dispersion Stellar Spectroscopy and the Role of the
Image Tube at the McMath Solar Telescope
Authors: Livingston, W. C.
1968IAUGA..19p.283L Altcode:
No abstract at ADS
---------------------------------------------------------
Title: On the Absence of Extremely Fine Structure in Quiet Sun
Magnetic Fields.
Authors: Livingston, W. C.
1968AJS....73Q..69L Altcode:
Magnetograph scans made with an exploring aperture of 360 X 360 km are
found to achieve an effective resolution of 500 km when the seeing is
good. Both K-network and the weaker background fields resolve into
elements of a constant size, about 1500 km, when measured at the
half-intensity point. While velocity and brightness elements exhibit
a spatial fine structure down to the 500 km observational limit,
no similar fine structure (+2 gauss) is found for the magnetic fields.
---------------------------------------------------------
Title: A Solar Image or Spectrum Scanning Technique
Authors: Livingston, W. C.
1968ApOpt...7..271L Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Temperature of the Solar Corona from Intensity Gradients
Measured during the May 30, 1965 Total Eclipse
Authors: Brandt, John C.; Livingston, W. C.; Trumbo, D. E.
1967PASP...79..140B Altcode:
No abstract at ADS
---------------------------------------------------------
Title: On correlations between brightness, velocity, and magnetic
fields in the solar photosphere
Authors: Livingston, W. C.
1967bsms.conf...61L Altcode: 1967msp.....3...61L
No abstract at ADS
---------------------------------------------------------
Title: Color through a Raindrop - the Mechanics of Rainbow Formation
Authors: Orville, R. E.; Livingston, W. C.
1967NatH...76...44O Altcode: 1967NatH...76.p.44O
No abstract at ADS
---------------------------------------------------------
Title: Surveyor 1 Observations of the Solar Corona
Authors: Norton, Robert H.; Gunn, James E.; Livingston, W. C.; Newkirk,
G. A.; Zirin, H.
1967JGR....72..815N Altcode:
The solar corona was observed by the Surveyor 1 television camera
on June 14, 1966. These observations and corroborative ground-based
measurements are presented.
---------------------------------------------------------
Title: Magnetic Fields on the Quiet Sun
Authors: Livingston, William C.
1966SciAm.215e..54L Altcode: 1966SciAm.215...54L
No abstract at ADS
---------------------------------------------------------
Title: Enhancement of Photocathode Sensitivity by Total Internal
Reflection as Applied to an Image Tube
Authors: Livingston, W. C.
1966ApOpt...5.1335L Altcode:
No abstract at ADS
---------------------------------------------------------
Title: An Image Tube Design for Spectroscopy
Authors: Livingston, W. C.
1966ApOpt...5.1336L Altcode:
No abstract at ADS
---------------------------------------------------------
Title: The Sodium D Lines in Comet Ikeya-Seki
Authors: Livingston, W.; Roddier, F.; Spinrad, H.; Slaughter, C.;
Chapman, D.
1966S&T....31...24L Altcode:
No abstract at ADS
---------------------------------------------------------
Title: New Spectroscope Observations of Quasi-Stellar Sources.
Authors: Lynds, C. R.; Stockton, A. N.; Livingston, W. C.
1965ApJ...142.1667L Altcode:
No abstract at ADS
---------------------------------------------------------
Title: 1/f Noise and the Astronomical Observation
Authors: Livingston, W.
1965PASP...77..133L Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Observations of Interstellar Lines with Very High Resolution.
Authors: Livingston, W. C.; Lynds, C. R.
1964ApJ...140..818L Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Application of the Image Orthicon to Spectroscopy
Authors: Livingston, W. C.
1964aste.book..330L Altcode: 1964S&SS....2..330L
No abstract at ADS
---------------------------------------------------------
Title: Recent Experiments with Image Tubes at Kitt Peak National
Observatory.
Authors: Livingston, William; Lynds, C. R.
1963AJ.....68Q.284L Altcode:
The image orthicon television-camera tube has been tested as
the light receiver for a fast nebular spectrograph on the 36-inch
telescope. Observations of astronomical objects, with exposure times
of up to 90 min, demonstrate the ability of the system to record faint
emission features which could not be reached by photographic methods
on this telescope. However, various effects that are peculiar to the
image orthicon such as beam bending and low latitude, seriously limit
the quantitative aspects of the spectra. More encouraging results
have been obtained with a high-gain imaging photomultiplier (English
Electric Valve P829) which permits the certain recording of individual
photoelectrons. A pulse counting field photometer utilizing this type
of tube is being developed. At the 60-inch solar telescope the imaging
photomultiplier has been used for highdispersion work on the planets
and bright stars.
---------------------------------------------------------
Title: Resolution of the Image-Orthicon Camera Tube under Non-Standard
Scan Conditions
Authors: Livingston, W. C.
1963SMPTE..72..771L Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Applications of the Image Orthicon to Spectroscopy
Authors: Livingston, W. C.
1962AstTe...2..330L Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Application of the Image Orthicon to Stellar Photometry
Authors: Livingston, W. C.
1961PASP...73..331L Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Applications of Image Orthicons in Solar and Stellar Astronomy
Authors: Livingston, William C.
1961NASSP...2..167L Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Application of the Image Orthicon to Astronomical Spectroscopy.
Authors: Livingston, William Charles
1959PhDT.........1L Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Changes in the Sun's Polar Magnetic Field
Authors: Babcock, H. D.; Livingston, W. C.
1958Sci...127.1058B Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Application of the Refrigerated Image Orthicon to
Spectrophotometry
Authors: Livingston, William
1957PASP...69..390L Altcode:
No abstract at ADS
