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Author name code: caccin
ADS astronomy entries on 2022-09-14
author:"Caccin, Bruno"
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Title: High-Precision Measurements of the Solar Diameter and
Oblateness by the Solar Disk Sextant (SDS) Experiment
Authors: Egidi, A.; Caccin, B.; Sofia, S.; Heaps, W.; Hoegy, W.;
Twigg, L.
2006SoPh..235..407E Altcode:
We reduce and analyze, in a uniform way, all of the data obtained by
the Solar Disk Sextant (SDS) experiment, concerning high-precision
measurements of the solar radius and oblateness, in the bandwidth 590
{-} 670 nm, made onboard stratospheric balloons during a series of
flights carried out in 1992, 1994, 1995, and 1996. The measured radius
value appears anti-correlated with the level of solar activity, ranging
from about 959.5 to 959.7 arcsec. Its variation from year to year is
outside the error range, which is mostly due to a systematic diurnal
behavior, particularly evident in the 1996 flight. The oblateness
shows an analogous temporal behavior, ranging from about (4.3 to 10.3)
× 10<SUP>−6</SUP>.
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Title: The sensitivity of the C I 538.0 nm Fe I 537.9 nm and Ti II
538.1 nm lines to solar active regions
Authors: Penza, V.; Caccin, B.; Del Moro, D.
2004A&A...427..345P Altcode:
Using spectroscopy to probe stellar global parameters, such as effective
temperature, is much exploited in the literature. In the solar case
it can be used as an indicator of magnetic cycle variations. In
this work we study the sensitivity to bright active regions of three
photospheric lines (Fe I 537.9 nm, C I 538.0 nm and Ti II 538.1 nm),
which have been monitored on the sun for more than twenty years. In our
analysis we compare our experimental results, from observations with
the THEMIS telescope, with theoretical results, obtained by spectral
synthesis with FAL semi empirical models (Fontenla et al. \cite{FAL99},
ApJ, 518, 480). We demonstrate the inappropriateness of using these
lines (full disk integrated) as indicators of quiet sun irradiance
modifications without considering their intrinsic variations due to
active regions. Instead, their different sensitivity to the presence of
active regions can be exploited in order to discriminate the background
quiet sun variations from the magnetic region contributions.
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Title: Comparison of model calculations and photometric observations
of bright “magnetic” regions
Authors: Penza, V.; Caccin, B.; Ermolli, I.; Centrone, M.
2004A&A...413.1115P Altcode:
Since 1981, several attempts to build series of semiempirical models
designed to represent, in addition to the quiet Sun, the various
types of magnetic regions across the solar disk (network, faculae and
sunspots), have followed one another. Here we test the capability
of those calculated by Fontenla et al. (\cite{FAL99}) to reproduce
different experimental data, comparing the computed spectra with the
observations made by the PSPT of the Rome Observatory. In particular,
we study the average center-limb variation of the network and facular
contrast. In this way, we are able to single out the models best
reproducing the different photospheric structures operationally
identified by the PSPT observations and data analysis. We show also
that it would be possible, with slight modifications of the models,
to further improve the agreement with the experimental data.
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Title: The sensitivity of three lines to AR
Authors: Penza, V.; del Moro, D.; Caccin, B.
2004IAUS..223..137P Altcode: 2005IAUS..223..137P
We study the sensitivity to AR of three photospheric lines, comparing
experimental results, from THEMIS observations, with spectral synthesis,
demonstrating the inappropriateness of using these lines as indicators
of quiet sun modifications, because their variations in the active
regions. We try to reconstruct the cyclic lines behavior.
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Title: New data analysis technique developed for the determination
of the solar limb position in measurements of the solar diameter
and oblateness, and application to observations obtained with the
balloon-borne Solar Disk Sextant (SDS) experiment.
Authors: Djafer, D.; Sofia, S.; Irbah, A.; Thuillier, G.; Egidi, A.;
Caccin, B.
2004cosp...35..643D Altcode: 2004cosp.meet..643D
Solar diameter measurements performed from ground by several
instruments during these last decades show variations which are not
in agreement. In relation with solar activity, these measurements do
not reveal consistent results. These results can be either attributed
to Earth atmosphere effects or to instrumental ones especially in
presence of noise. Noise affects directly the determination of the
solar diameter defined as the zero crossing of the second derivative
of the solar limb. Furthermore, presence of noise in data causes
additional problems requiring appropriate data filtering without
changing the solar limb slope. Several methods have been developed and
used for a correct inflexion point position determination, among them,
is the Fast Fourier Transform Definition (FFTD). We first present a
complete description of the FFTD tool and in particular a new method
to choose the filtering parameter (a) to be determined for applying
FFDT. An alternative method by filtering using the wavelet analysis
is also shown. The Solar Disk Sextant (SDS) is an instrument which
has been flown on stratospheric balloons from 1992 to 1998 at 37
km altitude preventing all atmospheric effects. SDS uses a prism as
angular reference. We present and discuss results obtained from SDS
data analysis and compare them using others methods of inflexion point
position detection. Finally, we discuss all other SDS experimental
parameters able to cause solar diameter measurement variations.We show
the relationship between the diameter variation and solar variability.
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Title: Semiempirical modeling of bright magnetic structures observed
with Rome PSPT
Authors: Caccin, B.; Penza, V.; Ermolli, I.; Centrone, M.
2003ESASP.535..295C Altcode: 2003iscs.symp..295C
Since the beginning of 1980s, semiempirical atmospheric models designed
to represent the various features across the solar disk (quiet sun,
network, plage and sunspot) have followed one other. We tested the
capability of those proposed by Fontenla et al. (1999) to reproduce
experimental data that are different from those in which the models
were verified. In particular we studied the center to limb variation
of the facular and network contrast and compared the results of the
computed models with those obtained analyzing the observations carried
out with the PSPT at the Rome Observatory. In this way, we single out
the models better reproducing the two solar features operationally
identified by the PSPT data analysis.
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Title: Modeling solar irradiance variations through PSPT images and
semiempirical models
Authors: Penza, V.; Caccin, B.; Ermolli, I.; Centrone, M.; Gomez, M. T.
2003ESASP.535..299P Altcode: 2003iscs.symp..299P
We try to reconstruct the variations of the disk integrated spectrum,
both in the spectral ranges of VIRGO (blue at 403 nm, green at 501
nm and red at 863 nm) and in the bolometric flux, using semiempirical
models (FAL models, Fontenla et al. 1999), built to reproduce different
features in the solar atmosphere. Each computed spectrum is weighted
with the disk coverage factor of the corresponding feature provided by
the PSPT observations carried out at the Rome Observatory. We present
the results obtained reconstructing the variations measured by VIRGO
bolometers during periods of about one solar rotation and of the entire
ascending phase of Solar Cycle 23.
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Title: Modeling solar irradiance variations through full-disk images
and semi-empirical atmospheric models
Authors: Ermolli, I.; Caccin, B.; Centrone, M.; Penza, V.
2003MmSAI..74..603E Altcode:
We summarize the results of both accurate measurement and models
calculations carried out with the aim of understanding the physical
origins of the solar irradiance variability arising from variations of
surface structures through the solar activity cycle. In particular, we
used the new high-quality measurements of the photospheric contrast of
facular regions and the network, together to the accurate description
of the temporal variation of their disk coverage since the last
solar minimum obtained analyzing the archive of daily observations
carried out with the PSPT at the Rome Observatory. We used these image
analysis results together to the output of semi-empirical models of
solar features to compute variations of the solar irradiance during
periods spanning from few weeks up to the full ascending phase of
the current solar cycle. We present the comparison of the computed
variations with those measured by Virgo radiometers on board of SOHO.
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Title: Spectral Line Ratios as Temperature Indicators in Solar-Like
Stars
Authors: Caccin, B.; Penza, V.
2003IAUS..210P.E47C Altcode:
No abstract at ADS
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Title: Search for T<SUB>eff</SUB> variations along the Solar Cycle
Authors: Caccin, B.; Penza, V.
2003MmSAI..74..663C Altcode:
The measurements of the total solar irradiance (TSI) show the existence
of variations on characteristic times going from few minutes to whole
solar cycle, as a result of different physical mechanisms acting
on different temporal scales. Along the cycle delta (TSI) is the
order of 0.15%, in phase with the magnetic activity (cf. Fröhlich,
\cite{frohlich}), attributed mainly to the overcompensation of the
facular brightness vs the spot darkness and to a network variation. The
problem of determining also a possible contribution due to a global
variation of the photospheric background remains open. \ Here we
study the variations of the line-depth ratios measured by Gray and
Livingston (\cite{grayliv97a}, \cite{grayliv97b}) to determine delta
T<SUB>eff</SUB> along the cycle and show that they cannot be attributed
to a modulation of the photospheric background alone, but that active
region effects are, probably, dominant.
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Title: Spectral line ratios as T<SUB>eff</SUB> indicators in
solar-like stars
Authors: Caccin, B.; Penza, V.; Gomez, M. T.
2002A&A...386..286C Altcode:
The ratios of spectral line depths are often used as indicators of
the stellar effective temperature T_eff. In particular, Gray &
Livingston (\cite{grayliv97a}) calibrated the temperature sensitivity
of the ratios between the central depths of the line C I 538.032
nm and either the Fe I 537.958 or the Ti II 538.103, making use of
observed spectra of several solar-like stars. The ultimate reason
for choosing these lines was the subsequent application of their
calibration to a long series of solar data, collected at Kitt Peak
(in disk-integrated light) from 1978 to 1992, in order to get the
T_eff variation of the Sun during its 11-yr magnetic cycle (Gray &
Livingston \cite{grayliv97b}). We propose a theoretical calibration
that includes a careful treatment of convective transport and fits the
stellar data very well , showing, at the same time, that the empirical
calibration of Gray and Livingston incorporates in the T_eff sensitivity
an undesired dependence of line ratios on the surface gravities of the
individual stars they used. A possible dependence of the calibration
upon stellar rotation is also explored.
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Title: Line-depth and T<SUB>eff</SUB> variations with the solar cycle
Authors: Caccin, B.; Penza, V.
2002ESASP.477..205C Altcode: 2002scsw.conf..205C
We show that the sensitivity of line-depth ratios, used as indicators
of T<SUB>eff</SUB> variations (δT<SUB>eff</SUB> = C<SUB>0</SUB>δr/r),
are sensibly dependent on surface gravity. We propose a theoretical
calibration, including a careful treatment of the convective transport
and its dependence on surface gravity (Canuto & Mazzitelli, 1991;
Ludwig et al. 1999), which fits very well the stellar observations
by Gray & Livingston (1997) of the same lines monitored at Kitt
Peak since 1976 (C I 538.032 nm, Fe I 537.958 nm and Ti II 538.103
nm). The immediate consequence is the impossibility of applying
the empirical calibration used by Gray & Livingston (1997)
to interpret the line variations with the solar cycle, because it
was derived from stars of different surface gravity, while in the
solar case the value of g remains practically constant. Using our
theoretical values of C<SUB>0</SUB>, we obtain a T<SUB>eff</SUB>
variation too large, which would produce almost twice the measured
variation of irradiance. However, as already showed by Caccin &
Penza (2000), a simultaneous variation of the granulation size of the
order of that observed (Muller & Roudier, 1984) might compensate
for this excess. Therefore the observed variations of line-depth ratios
with the solar cycle might be consistent with a dominant contribution of
bright & dark magnetic regions to the total irradiance variations.
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Title: 2-D multiline spectroscopy of the solar photosphere
Authors: Berrilli, F.; Consolini, G.; Pietropaolo, E.; Caccin, B.;
Penza, V.; Lepreti, F.
2002A&A...381..253B Altcode:
The structure and dynamics of the photosphere are investigated, with
time series of broadband and monochromatic images of quiet granulation,
at the solar disk center. Images were acquired with the IPM observing
mode at the THEMIS telescope. Velocity and line center intensity fields,
derived from the observation of three different photospheric lines,
are used to study velocity and intensity patterns at different heights
in the photosphere. Automatic segmentation procedures are applied
to velocity and intensity frames to extract solar features, and to
investigate the dependence of their properties at different scales and
heights. We find a dependence of the statistical properties of upflow
and downflow regions on the atmospheric height. Larger granules, passing
through a great part of the photosphere, are used to investigate the
damping of convective motions in stably stratified layers. The results
suggest the occurrence of an intense braking in the deep photosphere
(first ~ 120 km). Furthermore, we investigate the temporal and spatial
evolution of velocity fields, deriving typical time scales of dynamical
processes relative to different solar features. In particular, for two
selected isolated exploders, we reveal a velocity deceleration in the
central region since the early phase of their fragmentation. Based on
observations made with THEMIS-CNRS/INSU-CNR operated on the island of
Tenerife by THEMIS S.L. in the Spanish Observatorio del Teide of the
Instituto de Astrofisica de Canarias.
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Title: Analysis of high resolution and full disk solar images
Authors: Berrilli, F.; Caccin, B.; Cantarano, S.; Egidi, A.; Penza,
V.; Criscuoli, S.; del Moro, D.; Pietropaolo, E.; Consolini, G.;
Ermolli, I.; Lepreti, F.; Mainella, G.; Severino, G.; Zuccarello, F.
2001ESASP.493..173B Altcode: 2001sefs.work..173B
No abstract at ADS
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Title: Statistical description of the intensity fluctuations in the
solar photosphere
Authors: Caccin, B.; Penza, V.
2001MmSAI..72..541C Altcode:
The solar photosphere is characterized by several phenomena
(granulation, oscillations, etc.) causing spatial and temporal
variations of the emergent intensity. Here we examine the relations
between some statistical descriptors of the observable intensity
fluctuations (δI) and those of the corresponding hydrodynamic
fluctuations (δT, δP, δv) in the case of a simplified analytical
model of a convective cell, representative of an average granule.
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Title: The extreme limb of the Sun
Authors: Ambrosino, D.; Caccin, B.
2001MmSAI..72..528A Altcode:
We compute, with different atmospheric models, the centre-limb
variation of the observable intensity near the extreme edge of the
solar disk, estimating the effects on the astrometric limb position
due to spherically symmetric perturbations of the thermodynamic state
of the gas.
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Title: Foreword (2nd National Meeting on the Italian Solar Research)
Authors: Francia, Patrizia; Pietropaolo, Ermanno; Caccin, Bruno
2001MmSAI..72..477F Altcode:
No abstract at ADS
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Title: 2nd National Meeting on the Italian Solar Research
Authors: Francia, P.; Pietropaolo, E.; Caccin, B.
2001MmSAI..72.....F Altcode:
Contents: Solar interior and global structure. Solar photosphere and
chromosphere. Solar corona. Solar wind, interplanetary medium and
Sun-Earth relationsons.
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Title: Line-Depth and T<SUB>eff</SUB> Variations with the Solar
Cycle due to Possible Size-Changes of Photospheric Granulation
Authors: Caccin, B.; Penza, V.
2000ESASP.463..293C Altcode: 2000sctc.proc..293C
No abstract at ADS
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Title: Commission 38: Exchange of Astronomers: (Echange Des
Astronomes)
Authors: Roberts, M. S.; West, R. M.; Chitre, D.; Ducati, J.;
Jorgensen, H.; Krishna, G.; Morimoto, M.; Tolbert, C.; Ye, S.;
Boyarchuk, A.; Caccin, B.; Cannon, R.; Capaccioli, M.; Florsch, A.;
Haupt, H.; Kozai, Y.; Leung, K.; MacRae, D.; Nha, S.; Ninkovic, S.;
Okoye, S.; Othman, M.; Routly, P.; Sahade, J.; Smith, G.; Straizys,
V.; Swarup, G.; van den Heuvel, E.; Wang, S.; Zhao, J.
2000IAUTA..24..421R Altcode:
No abstract at ADS
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Title: Performances of THEMIS IPM and First Analyses of 1999
Observations
Authors: Caccin, B.; Giammanco, C.; Pietropaolo, E.; Berrilli, F.;
Ceppatelli, G.; Egidi, A.
1999ESASP.448..235C Altcode: 1999ESPM....9..235C; 1999mfsp.conf..235C
No abstract at ADS
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Title: Calibration of the THEMIS-IPM High Speed Acquisition System
Authors: Berrilli, F.; Cantarano, S.; Egidi, A.; Caccin, B.
1999ESASP.448.1301B Altcode: 1999mfsp.conf.1301B; 1999ESPM....9.1301B
No abstract at ADS
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Title: Scaling behavior of the vertical velocity field in the solar
photosphere
Authors: Consolini, G.; Carbone, V.; Berrilli, F.; Bruno, R.;
Bavassano, B.; Briand, C.; Caccin, B.; Ceppatelli, G.; Egidi, A.;
Ermolli, I.; Florio, A.; Mainella, G.; Pietropaolo, E.
1999A&A...344L..33C Altcode:
We analyze, for the first time, the scaling behavior of the photospheric
vertical velocity field. Our analysis is based on data collected by the
Italian Panoramic Monocromator (IPM) mounted at the THEMIS telescope
at the Spanish “Observatorio del Teide” (Tenerife) of the Instituto
de Astrofisica de Canarias. We investigate the occurrence of scaling in
the cancellations between downflow and upflow of the vertical velocity
field, showing that the field possesses well pronunced sign-singularity
in the range of scales from more than 10 Mm down to the granulation
scale. Based on THEMIS/CNRS--INSU/CNR telescope observations
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Title: Dependence of the photospheric vertical flow characteristics
on the granule dimension
Authors: Berrilli, F.; Florio, A.; Consolini, G.; Bavassano, B.;
Briand, C.; Bruno, R.; Caccin, B.; Carbone, V.; Ceppatelli, G.; Egidi,
A.; Ermolli, I.; Mainella, G.; Pietropaolo, E.
1999A&A...344L..29B Altcode:
The first high spectral resolution and white-light images obtained at
the THEMIS telescope with the Italian Panoramic Monochromator (IPM), are
analyzed to study intensity and velocity fluctuations in the photosphere
of the sun. Monochromatic images, in two spectral ranges around 538.03
nm (C I line) and 557.61 nm (Fe I line), are used to characterize the
vertical structure of the photosphere. Granulation cells and granules
are obtained by segmentation of white-light images using suitable
finding algorithms. We observe the height dependence of velocity
vs. intensity fluctuations, and we found a dependence of velocity and
intensity on granule dimension. Our results show that granules increase
their intensity with dimension in the lower solar photosphere. In the
higher photosphere, on the contrary, the intensity decreases with the
dimension. Based on THEMIS/CNRS-INSU/CNR telescope observations
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Title: Italian panoramic monochromator for the THEMIS telescope:
the first results and instrument evaluation
Authors: Cavallini, Fabio; Berrilli, Francesco; Caccin, Bruno;
Cantarano, Sergio; Ceppatelli, Guido; Egidi, Alberto; Righini, Alberto
1998SPIE.3355..940C Altcode:
We briefly describe the design and the characteristics of the Italian
Panoramic Monochromator installed at the focal plane of the THEMIS
telescope built in Izana by a joint venture of the French and Italian
National Research Councils. The Panoramic Monochromator substantially
is a narrow band filter (approximately equals 22 mAngstrom bandwidth)
tunable on the visible spectrum for quasi simultaneous bidimensional
spectrometry of the solar atmosphere. The narrow bandwidth is
obtained by using a non standard birefringent filter and a Fabry Perot
interferometer mounted in series. This assembly has the advantage of
the spectral purity of one channel of the Fabry Perot interferometer
and a very large free spectral range. Moreover the spectral stability
depends on the interferometer, the environment of which may be carefully
controlled. The design of this instrument is not really new, but,
only now it has been possible to build it thanks to the development
of servo controlled Fabry Perot interferometers, which are stable in
time and may easily be tuned. The system seems to perform well. It is
stable in wavelength and the spectral pass band and stray light are
within the expected values, as it may be deduced by very preliminary
tests performed at the THEMIS Telescope and in Arcetri (Firenze) at the
'G. B. Donati' solar tower.
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Title: The Prototype RISE-PSPT Instrument Operating in Rome
Authors: Ermolli, I.; Fofi, M.; Bernacchia, C.; Berrilli, F.; Caccin,
B.; Egidi, A.; Florio, A.
1998SoPh..177....1E Altcode:
The breadboard prototype of the PSPT (Precision Solar Photometric
Telescope), built by NSO at Sacramento Peak, has been operating in Rome
since February 1996 to test observing procedures and future network
operations. In this paper we briefly describe the kind of preliminary
data we are deriving from the first observations concerning the contrast
histogram and the fractal analysis of the `network cells.'
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Title: On the temperature determination in theoretical modelling of
stellar atmospheres
Authors: Giammanco, C.; Crivellari, L.; Caccin, B.
1998MmSAI..69..663G Altcode:
No abstract at ADS
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Title: The Prototype RISE-PSPT Instrument Operating in Rome
Authors: Ermolli, I.; Fofi, M.; Bernacchia, C.; Berrilli, F.; Caccin,
B.; Egidi, A.; Florio, A.
1998sers.conf....1E Altcode:
No abstract at ADS
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Title: THEMIS-IPM: performance analysis of the system and future
developments
Authors: Mainella, G.; Bavassano, B.; Berrilli, F.; Briand, C.; Bruno,
R.; Caccin, B.; Cantarano, S.; Ceppatelli, G.; Egidi, A.
1998MmSAI..69..659M Altcode:
No abstract at ADS
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Title: Variation of the effective temperature with the solar cycle
Authors: Caccin, B.; Staro, F.; Gomez, M. T.
1998MmSAI..69..595C Altcode:
No abstract at ADS
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Title: Variations of the Chromospheric Network with the Solar Cycle
Authors: Caccin, B.; Ermolli, I.; Fofi, M.; Sambuco, A. M.
1998SoPh..177..295C Altcode:
We have digitized a small sample of Caii K spectroheliograms from
the photographic archive of Arcetri Observatory for the period
1950-1970. For each digitized plate, active regions have been
automatically identified and masked by applying an algorithm based on
the geometrical connection between active pixels. Contrast histograms
have been derived for the full disk and for `quiet' regions. Both of
them show a neat Gaussian profile on the dark side and a significant
tail on the bright side, due to the brightness enhancements associated
with magnetic fields. A solar cycle dependence of the histogram
asymmetry is clearly evident in `quiet' region data, thus confirming
that the network component might provide a significant contribution
to long-term variations of the total irradiance.
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Title: THEMIS-IPM: characterization of the photospheric velocity field
Authors: Consolini, G.; Bruno, R.; Bavassano, B.; Mainella, G.;
Carbone, V.; Berrilli, F.; Caccin, B.; Pietropaolo, E.; Ermolli, I.;
Florio, A.
1998MmSAI..69..651C Altcode:
No abstract at ADS
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Title: Properties of solar granulation cells in quiet regions as
derived from a time series of white light images
Authors: Cauzzi, G.; Consolini, G.; Berrilli, F.; Smaldone, L. A.;
Straus, T.; Bavassano, B.; Bruno, R.; Caccin, B.; Carbone, V.; Egidi,
A.; Ermolli, I.; Florio, A.; Pietropaolo, E.
1998MmSAI..69..647C Altcode:
No abstract at ADS
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Title: Recent results of the Italian solar
research. Proceedings. Meeting, Roma (Italy), 18 - 20 Mar 1998.
Authors: Ermolli, I.; Berrilli, F.; Caccin, B.
1998MmSAI..69..513E Altcode:
Provided with new data from space missions, following topics were
dealt with: solar interior and global structure, solar photosphere
and chromosphere, solar corona, solar wind and interplanetary medium.
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Title: Preliminary results on solar photospheric MHD turbulence
studied via signed measures. (Based on THEMIS/IPM observations.)
Authors: Consolini, G.; Bruno, R.; Bavassano, B.; Carbone, V.;
Mainella, G.; Berrilli, F.; Caccin, B.; Pietropaolo, E.; Ermolli,
I.; Florio, A.
1998joso.proc..115C Altcode:
In the present paper the autors report about the occurrence of
sign-singularity in the solar photospheric MHD turbulence, using
Dopplergrams provided during the past August 1997 by the Italian
Panoramic Monochromator (IPM) at the THEMIS telescope (Tenerife).
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Title: Variations of the Chromospheric Network with the Solar Cycle
Authors: Caccin, B.; Ermolli, I.; Fofi, M.; Sambuco, A. M.
1998sers.conf..295C Altcode:
No abstract at ADS
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Title: Foreword
Authors: Ermolli, I.; Berrilli, F.; Caccin, B.
1998MmSAI..69..519E Altcode:
No abstract at ADS
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Title: Image acquisition system for the Italian Panoramic
Monochromator of the THEMIS telescope.
Authors: Berrilli, F.; Caccin, B.; Cantarano, S.; Egidi, A.
1997NCimC..20..967B Altcode:
Describes the image acquisition system of the Italian Panoramic
Monochromator which will be in operation at the focus F<SUB>2</SUB>
of the THEMIS solar telescope to acquire images of the Sun in the
visible spectrum (between 420 and 700 nm) with a spectral resolving
power of about 300000. The system consists of two CCD cameras (using
either 512×512 or 1024×1024 square-pixel sensors) controlled and
readout by dedicated electronics and a personal computer. The data
transmission between the sensors and the computer is performed by
means of an optical link.
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Title: Variations of the network contribution to the solar irradiance
Authors: Caccin, B.; Ermolli, I.; Fofi, M.; Sambuco, A. M.
1997MmSAI..68..459C Altcode:
No abstract at ADS
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Title: The IPM-Italian Panoramic Monochromator operating at the
THEMIS telescope.
Authors: Cavallini, F.; Ceppatelli, G.; Righini, A.; Berrilli, F.;
Caccin, B.; Cantarano, S.; Egidi, A.
1997cpyt.conf..119C Altcode:
From April 20, 1997 the Italian Panoramic Monochromator (henceforth IPM)
will be the first operating mode of the THEMIS telescope. It basically
consists of a Fabry-Perot interferometer mounted in tandem with an
universal birefringent filter. The image acquisition system consists
of two CCD cameras controlled and read-out by dedicated electronics and
personal computers. One of these cameras acquires a simultaneous white
light image for the application of off-line destretching procedures
in order to reduce seeing effects. An optical link connects the CCD
camera and the PCs while the handshaking and the data transfer between
the PCs and the work station controlling the IPM is performed via LAN
and IEE488 bus.
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Title: Modelling umbrae
Authors: Severino, G.; Gomez, M. -T.; Caccin, B.
1994ASIC..433..169S Altcode:
No abstract at ADS
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Title: The formation of the alkali resonance lines in cool
atmospheres. I. NaI and KI in a sunspot umbra
Authors: Caccin, B.; Gomez, M. T.; Severino, G.
1993A&A...276..219C Altcode:
We have studied the formation of the Na I and K I resonance lines
in a sunspot umbra looking at their diagnostic value. <P />We have
computed different cross-sections and rates for the excitation
of the alkali atoms by collisions with neutral hydrogen atoms in
addition to electrons, and we have evaluated their effects on the
emergent line profiles. <P />The main results of the line synthesis,
which allowed for different temperature structures, line blend, the
Zeeman broadening produced by a constant vertical magnetic field, and
a possible overcorrection for stray light of the observed spectrum,
are that: <P />i) the comparison between the observed and the computed
inner wings of the sodium profiles suggests that the umbral upper
photosphere is cooler than in a standard model; <P />ii) there is
no satisfactory fit of the reversed and asymmetric line cores of the
sodium and potassium resonance lines in the umbral spectrum.
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Title: Atmospheric structure of sunspots
Authors: Gomez, M. T.; Caccin, B.; Severino, G.
1993MmSAI..64..519G Altcode:
No abstract at ADS
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Title: The importance of collisional excitations by HI in cool
atmospheres
Authors: Severino, G.; Caccin, B.; Gomez, M. T.
1993MmSAI..64..565S Altcode:
No abstract at ADS
---------------------------------------------------------
Title: The solar CCD imaging system at Tor Vergata University
Authors: Berrilli, F.; Caccin, B.; Cantrano, S.; Egidi, A.; Ermolli, I.
1993MmSAI..64..549B Altcode:
No abstract at ADS
---------------------------------------------------------
Title: First measurements of solar oscillations with the THEMIS
panoramic monochromator
Authors: Berrilli, F.; Caccin, B.; Cantrano, S.; Cavallini, F.;
Ceppatelli, G.; Egidi, A.; Francia, P.; Pietropaolo, E.; Righini, A.
1993MmSAI..64..781B Altcode:
No abstract at ADS
---------------------------------------------------------
Title: The Importance of Collisional Excitations by HI in Cool
Atmospheres
Authors: Deverino, G.; Caccin, B.; Gomez, M. T.
1993MmSAI..64..565D Altcode:
No abstract at ADS
---------------------------------------------------------
Title: New Observations of 5 Minute Oscillations in the Opposite
Flanks of Solar Fraunhofer Lines. I. The Effect of Varying the
Spectral and Temporal Resolution
Authors: Bertello, L.; Caccin, B.; Francia, P.; Pietropaolo, E.
1992ApJ...401..768B Altcode:
Results of an investigation of the rms wavelength fluctuations in
the 5-min range, at fixed intensity levels, in the opposite flanks
of 15 Fe I and two Fe II lines, selected from the range 6200-6400 A
are presented. Critical values for these quantities are evaluated. The
number of used lines makes it possible to analyze the height dependence
of the oscillations within the photosphere, and a clear correlation
between the formation height of the emergent intensity and the ratio
of the oscillation power in the two flanks of the lines is found. The
existence of a unique relationship, independent of the characteristics
of the single lines, confirms the diagnostic value of this ratio
to investigate the variations of the wave properties throughout the
solar atmosphere. The effect is argued to be due to radiative damping,
which produces a height-dependent phase shift between velocity and
thermodynamic perturbations within the line-forming region.
---------------------------------------------------------
Title: High-resolution spectroscopic imaging of the Sun with a
Universal Birefringent filter and a Fabry-Perot interferometer.
Authors: Cavallini, F.; Ceppatelli, G.; Righini, A.; Berrilli, F.;
Caccin, B.; Cantarano, S.; Egidi, A.; Francia, P.; Pietropaolo, E.
1992NCimC..15..509C Altcode:
The authors describe an optical device consisting of a Universal
Birefringent Filter and a Fabry-Perot interferometer used in tandem
to obtain monochromatic images of the Sun in the visible spectrum
(between 4200 and 7000 Å). They give an account of the preliminary
results obtained by measuring the global velocity field on the solar
photosphere. These results show that the instrument is well suited
for global oscillation measurements.
---------------------------------------------------------
Title: Formation of the KI 7699A Line in Sunspots
Authors: Caccin, B.; Carlsson, M.; Gomez, M. T.; Severino, G.
1991ASIC..341..415C Altcode: 1991sabc.conf..415C
No abstract at ADS
---------------------------------------------------------
Title: Anisotropies in solar oscillations
Authors: Caccin, B.; Fofi, M.; Torelli, M.; Smaldone, L. A.
1990A&A...232..516C Altcode:
Spherical harmonic filtering 20 less than or equal to l = m less than
or equal to 100 has been applied to analyze a time series of Doppler
observations in Na light in order to find eventual anisotropies
between sectorial modes propagating along east-west and north-south
directions. The results obtained show that the strongest power is
connected with the north-south direction and that the power ratio
NS/EW grows linearly with l.
---------------------------------------------------------
Title: Non-adiabatic modelling of '5-min' oscillations - Effects on
photospheric line profiles
Authors: Bertello, L.; Caccin, B.
1990A&A...231..509B Altcode:
A realistic form of the temperature, pressure, and velocity
perturbations representing the '5-min' oscillations with a
monochromatic bidimensional wave in the solar photosphere is derived
and used to compute the oscillations of typical Fe I and Fe II line
profiles. Results demonstrate the role of radiative damping in producing
different amplitudes of the oscillation in the opposite flanks of
the lines, by causing a depth-dependent phase difference between the
thermodynamical and the velocity perturbations. A comparison of results
obtained with wave models with observations showed that an agreement
can be obtained along the whole profile of the Fe I and Fe II lines,
provided that 0th order temperature gradients are taken into acccount.
---------------------------------------------------------
Title: On the diagnostic of 5<SUP>m</SUP> oscillations through
photospheric line profiles.
Authors: Bertello, L.; Caccin, B.
1988ESASP.286...17B Altcode: 1988ssls.rept...17B
Recent measurements show that the 5<SUP>m</SUP> oscillations have
different amplitudes in the opposite flanks of several photospheric
lines. This effect can be suitably described by giving the (blue
wing)/(red wing) ratio of the r.m.s. wavelength shift at any given
level of residual intensity. The authors suggest that the main
cause is radiative damping, which produces a depth dependent phase
difference between the velocity and the thermodynamical (temperature
and pressure) perturbations within the line forming region. Synthetic
profiles of the Fe I λ6301.5 Å line, obtained by numerical solution
of the time independent radiative transfer equation in the oscillating
atmosphere (quasi static radiation field approximation), show that
agreement between observed and computed profiles can be achieved. The
consequences of this effect (which is also dependent on the magnetic
flux concentration) on the diagnostic properties of line profiles are
briefly discussed.
---------------------------------------------------------
Title: Summary of Panel Discussion
Authors: Mazzitelli, I.; Coradini, A.; Forni, O.; Caccin, B.; Messina,
A.; Benacchio, L.
1988sca..conf...85M Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Observational Maps of the Moments of Strong Line Profiles on
the Solar Disk
Authors: Caccin, B.; Donati-Falchi, A.; Falciani, R.; Smaldone, L. A.;
Tozzi, G. P.
1987SoPh..112..383C Altcode:
Using the method of solar bidimensional spectroscopy based on
the Universal Birefringent Filter (UBF), we have determined the
bidimensional maps of moments of some chromospheric lines. The
observational material, referring to a quiet region on the disk center,
have been acquired with the UBF of the NSO at Sacramento Peak on
Aug. 27,1985. In this note we present the work in progress and the
new observational aspects arising from this diagnostic method.
---------------------------------------------------------
Title: The importance of colour-colour loops in the determination
of the physical parameters of pulsating variables.
Authors: Onnembo, A.; Buonaura, B.; Caccin, B.; Russo, G.; Sollazzo, C.
1985A&A...152..349O Altcode:
Attention is drawn to the importance of studying the surface
brightness of pulsating stars as a function of two colors, in order to
disentangle the contributions of temperature and gravity variations
to the observed curve from that due to the simultaneous variation of
the emitting surface of the star. The area of the observed color-color
loops obtained with different colors is compared with the area delta B
of the surface-brightness color loop, inferred from calibrations. The
existence of the color-color loops and the dependence of the loop area
on the pulsation period, very similar to that of delta B, is easily
explained, under the assumption of quasi-static approximation, by the
existence of a loop in the plane of effective temperature and effective
gravity, the area of which varies with the period. The consistency
and adequacy of the whole picture on which the CORS method (used to
determine the radius of classical Cepheids) is based are strongly
supported by the experimental evidence.
---------------------------------------------------------
Title: Terrestrial O2 lines used as wavelength references Experimental
profiles and asymmetries vs. model computations
Authors: Caccin, B.; Cavallini, F.; Ceppatelli, G.; Righini, A.;
Sambuco, A. M.
1985A&A...149..357C Altcode:
In order to evaluate wind and pressure effects on telluric lines,
the profiles and the bisectors of four rotational lines of the
gamma band is compared with the results of detailed theoretical
calculations. The analysis is carried out using standard models of
the terrestrial atmosphere and the molecular data available in the
literature. In particular, a height-dependent pressure shift of the
line profile has been included in the calculations, leading to a
satisfactory agreement with the observations. The computer code for
line transfer in the earth's atmosphere correctly reproduces also the
profiles and the bisectors of the same lines obtained at the height of
the Jungfraujoch, as can be deduced from the Liege Atlas (Delbouille et
al., 1973). Finally, the line shifts observed by Balthasar et al. (1982)
are compared with line shifts computed with the present code, including
wind shifts and pressure shifts. It is found that the amount by which
the varying asymmetry of the lines may affect wavelength determinations
depends upon the definition of the line wavelength itself.
---------------------------------------------------------
Title: A Generalization of the CORS Method to Determine Cepheid Radii
Authors: Caccin, B.; Buonaura, B.; Onnembo, A.; Russo, G.; Sambuco,
A. M.; Sollazzo, C.
1985cto..conf...43C Altcode: 1985IAUCo..82...43C
The CORS method for the empirical determination of the radii of
pulsating variables (Caccin et al., 1981; Sollazzo et al., 1981) is
discussed in the framework of the quasistatic approximation to the
variations of the atmospheric parameters (Unno, 1965) and reformulated
in a way that does not make direct use of theoretical calibrations of
the photometric system in terms of model atmospheres.
---------------------------------------------------------
Title: Radii and masses of cepheids and RR Lyrae variables.
Authors: Buonaura, B.; Caccin, B.; Onnembo, A.; Russo, G.; Sollazzo, C.
1985MmSAI..56..153B Altcode:
A reliable determination of absolute luminosities of RR Lyrae
variables would provide a crucial test of stellar evolution and
a mean to determine the distance and age of globular clusters. The
authors have developed a modification of the classical Baade-Wesselink
method, aimed at exploiting the possibilities offered by multicolor
photometric systems, by taking into proper account metallicity and
gravity effects. Here the authors present the fundamental aspects of the
method, emphasizing the importance of a self-consistent bidimensional
approach to multicolor photometry, and give preliminary results of
a first application to five field variables (SW And, RR Lyr, X Ari,
SU Dra, VY Ser).
---------------------------------------------------------
Title: Bidimensional spectroscopy of the solar chromosphere during
the maximum year
Authors: Caccin, B.; Falchi, A.; Falciani, R.; Roberti, G.; Smaldone,
L. A.
1984AdSpR...4g.215C Altcode: 1984AdSpR...4..215C
Our program was based on simultaneous observations of the same solar
region with the Universal Birefringent Filter (UBF) at the Vacuum
Tower Telescope (VTT) and with the Big Dome BD Universal Spectrograph
(USG). For the UBF images analysis we refer to the 13 June 1980 RG
2502/2511 (N12-E11) observations. Selected pictures present the line
profiles for Hα, H<SUB>β</SUB>, Mg-b<SUB>1</SUB> and Na-D<SUB>2</SUB>
at some interesting “pixels” of the analyzed AR. We present the
detailed photometric morphology of the observed active area and the
longitudinal velocity field pattern. A comparison with the corresponding
UVSP data is given.
---------------------------------------------------------
Title: Report on the 1984 activity of the section « Sun and Solar
System » of the GNA-CNR
Authors: Caccin, B.
1984MmSAI..55..521C Altcode:
The activities related with solar physics, planetology, fundamental
and spherical astronomy are reported.
---------------------------------------------------------
Title: Bidimensional Analysis of Solar Active Regions and Flares -
Part One - Imaging Spectroscopy with Universal Birefringent Filters
Authors: Caccin, B.; Falciani, R.; Roberti, G.; Sambuco, A. M.;
Smaldone, L. A.
1983SoPh...89..323C Altcode:
We describe a method of solar bidimensional spectroscopy exploiting
the performances of a Universal Birefringent Filter (UBF) like that
of the Sacramento Peak Observatory, which enable an estimate of the
profile of some chromospheric lines with moderate spectral resolution
(). The numerical inversion technique of Backus and Gilbert has been
used to retrieve the estimated line profiles; the capabilities of
the proposed method is fully analyzed with some numerical tests and
examples. Correction procedures for errors in the positions of the UBF
passband, random fluctuations of the exposure times and non-uniform
brightness distribution on the filtergrams are also presented. The
whole method has been tested on the recovery of quiet atmosphere line
profiles and the results derived for the Na D<SUB>2</SUB> line show
that the proposed method is completely suitable for many investigations
in solar physics.
---------------------------------------------------------
Title: Velocity fields and spectral line asymmetries - A linearized
analytical approach to the theory of the line bisector in a
Milne-Eddington atmosphere
Authors: Buonaura, B.; Caccin, B.
1982A&A...111..113B Altcode:
A method using the bisector of a spectral line profile for the
analysis of macroscopic velocity fields in the solar atmosphere,
based on the linear approximation derived by Canfield (1976) for the
case of velocities substantially smaller than the thermal velocity,
is applied to get a fully analytical solution for the case of an
exponentially stratified Milne-Eddington atmosphere. Ultimate limits
to the information on the depth dependence of the velocity field that
might be retrieved in this way from data obtained with infinite spatial
and temporal resolution are derived from the intrinsic smoothing due
to radiative transfer.
---------------------------------------------------------
Title: UV, optical and IR observations of cepheid R Mus.
Authors: Eichendorf, W.; Heck, A.; Caccin, B.; Russo, G.; Sollazzo, C.
1982A&A...109..274E Altcode:
Ultraviolet IUE spectra, optical 12 A/mm red and blue spectra, optical
BV photometry and infrared JHKL photometry of the 7.5-d classical
Cepheid R Muscae equals HD 110 311 are presented and discussed together
with some earlier photometric and radial velocity data. Using the CORS
method, a newly derived radius is given, as well as new values for
effective temperature and log g. The UV spectra confirmed the predicted
trend to increasing amplitudes with decreasing wavelength and indicate
that R Mus has a shallow chromosphere, while no transition region
lines could be detected. From all the data from 1200 A to 5 microns
it is concluded that R Mus does not have a companion detectable with
the sensitivity given, contrary to earlier results.
---------------------------------------------------------
Title: Digital processing of high resolution solar filtergrams.
Authors: Caccin, B.; Russo, P.; Smaldone, L. A.
1982MmSAI..53..287C Altcode:
The authors describe the techniques for digital processing of
high resolution solar filtergrams developed at the Naples ASTRONET
station. Preliminary results obtained with Hα filtergrams provided
by the Ottawa River Solar Observatory are presented.
---------------------------------------------------------
Title: Magnetic Fine-Structures and Granular Velocities
Authors: Caccin, B.; Falciani, R.; Gomez, M. T.; Marmolino, C.;
Roberti, G.; Severino, G.; Smaldone, L. A.
1981SSRv...29..373C Altcode:
In the last years we have gained some experience in the diagnostics
of small-scale structures, both on the interpretative and on the
observational point of view. We report here the conclusions and the
suggestions for future developments attained in two main fields of
interest.
---------------------------------------------------------
Title: Minicomputer version of the NLTE line transfer program of Auer,
Heasley, and Milkey.
Authors: Caccin, B.; Gomez, M. T.; Roberti, G.
1981JQSRT..26...15C Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Cepheid radii and masses by means of VBLUW photometry.
Authors: Sollazzo, C.; Russo, G.; Onnembo, A.; Caccin, B.
1981A&A....99...66S Altcode:
Caccin et al. (1981) have illustrated a new method for the determination
of the radii of pulsating variables. The current investigation
utilizes the new method for a more precise determination of the radii
of classical cepheids. The radius of a radially pulsating star can
be obtained by solving a certain implicit equation. The equation is
solved for thirty cepheids considered by Pel (1976) in connection
with his VBLUW observations. Attention is given to aspects of radius
determinations, and masses and luminosities. It is believed that a
full agreement of luminosities based on data obtained with the aid
of the new method and theoretical luminosities has to be reached by
means of a fully hydrodynamical treatment of the cepheid atmosphere,
instead of introducing inhomogeneous models.
---------------------------------------------------------
Title: An improvement of the Baade-Wesselink method to determine
the mean radius of pulsating variables
Authors: Caccin, B.; Onnembo, A.; Russo, G.; Sollazzo, C.
1980MmSAI..51..607C Altcode:
No abstract at ADS
---------------------------------------------------------
Title: The formation of NA I spectral lines in the solar atmosphere
Authors: Caccin, B.; Gomez, M. T.; Roberti, G.
1980A&A....92...63C Altcode:
The kinetic equilibrium of Na I in the solar atmosphere is studied for
different atomic models (up to 9 bound levels). The line transfer
problem is solved, in its differential form, for the complete
redistribution of line photons. The intensity profiles of the visible
lines are calculated at different positions on the solar disk and
compared with the observed values. It is found that a satisfactory
agreement with the observations can be reached, for the whole
spectrum, with the HSRA and a suitable choice of the microturbulence
and macroturbulence when the currently accepted values of the atomic
parameters are used. The best choice of the microturbulence seems
to be intermediate between those proposed by Gehren and Lites. The
corresponding macroturbulence distributions, depending on angle and
depth, increase outward and reach, around the temperature minimum,
values larger than those commonly quoted in the literature.
---------------------------------------------------------
Title: An interactive procedure to determine the mean radius of
Cepheids
Authors: Caccin, B.; Onnembo, A.; Russo, G.; Sollazzo, C.
1980MmSAI..51..505C Altcode:
No abstract at ADS
---------------------------------------------------------
Title: On the retrieval of velocity gradients from photospheric line
asymmetries - A linearized approach
Authors: Caccin, B.; Marmolino, C.
1980A&A....83...73C Altcode:
The first-order effects of a velocity field on the asymmetry of
Fraunhofer lines are analyzed and a method for recovering the velocity
gradient from the observed asymmetries is described. The method -
which does not require the concept of formation depth - is applied
to the inversion of synthetic data; the results obtained show that it
has the properties of stability and sensitivity necessary for working
in practice within a fairly large range of photospheric velocities
(up to the order of the Doppler width of the lines).
---------------------------------------------------------
Title: Bidimensional spectroscopy of chromospheric active regions
with the Universal Birefrangent Filter
Authors: Caccin, B.; Falciani, R.; Roberti, G.
1980fsoo.conf..121C Altcode:
No abstract at ADS
---------------------------------------------------------
Title: A method for a rough reconstruction of line profiles from a
series of narrow-band filtergrams
Authors: Caccin, B.; Roberti, G.
1979MmSAI..50..393C Altcode:
Azzarelli et al. (1979) have shown that high-resolution two-dimensional
spectroscopy of active regions on the sun is feasible, using a
photoelectrically guided computer controlled telescope provided with
a high-performance tunable birefringent filter. In fact, with such
an instrument it is possible to obtain a set of N filtergrams of the
same active region by shifting the center of the passband along the
profile of a strong absorption line. If the shape of the passband does
not change, the true line profile can be recovered by conventional
spectroscopic techniques. In the case where the shape of the passband
does change, the true line profile can be still recovered, but the
problem must be formulated in a more general way. In the present paper,
such a mathematical formulation is presented.
---------------------------------------------------------
Title: Project for bidimensional spectroscopy of solar chromospheric
active regions with the universal birefringent filter
Authors: Azzarelli, L.; Caroti, F.; Chimenti, M.; Caccin, B.; Falciani,
R.; Roberti, G.
1979MmSAI..50..443A Altcode:
In the present work, the universal birefringent filter of the Sacramento
Peak Observatory, which can operate effectively over a wide range
of wavelengths and whose bandwidth is comparable to that of the
instrumental profile of a low-resolution spectrograph, was used to
obtain a sequence of monochromatic images of a solar active region at
selected points along the profile of a strong Fraunhofer line, i.e.,
at different wavelengths from the line center. A series of observations
is proposed to cover exhaustively a wide range of depths in the solar
atmosphere.
---------------------------------------------------------
Title: On the continuum diagnostics of photospheric faculae.
Authors: Caccin, B.; Severino, G.
1979ApJ...232..297C Altcode:
Maps reproducing the intensity contrast in the continuum (wavelength of
5000 A) are obtained for a facular point at different positions on the
solar disk, and the contribution function of the emergent intensity is
analyzed for several representative lines of sight. A two-component
axially symmetric model is used whose thermodynamic structure is
derived from that of a magnetostatic flux tube representative of a
small filigree element. The wall of the flux tube appears to have
a dominant role, with respect to the interior, in determining the
observable contrast: Hence the reliability of the semiempirical models
obtained by inversion of continuum data is seriously questioned. The
center-to-limb variation of the average contrast does not vary with
the shape of the flux tube (a cylinder and a funnel are considered),
the only difference being that the map at mu equals 1.0 for the
funnel shows a thin very bright ring. The two-component approximation,
neglecting the precise structure of the wall, causes an overestimate
of the contrast; a discussion of this effect is given.
---------------------------------------------------------
Title: Bidimensional spectroscopy of chromospheric active regions
with the universal birefringent filter.
Authors: Caccin, B.; Falciani, R.; Roberti, G.
1979MmArc.106..121C Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Determinazione dei gradienti di velocità nella fotosfera
solare dalle asimmetrie delle righe di Fraunhofer: un approccio
lineare.
Authors: Caccin, B.; Marmolino, C.
1979RSAI...22..146C Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Variation of the profiles of medium-strong photospheric lines
with heliographic latitude.
Authors: Caccin, B.; Falciani, R.; Donati Falchi, A.
1978SoPh...57...13C Altcode:
The asymmetric profiles of 11 metallic lines are studied, at μ =
0.3, as functions of ϑ. Their variations cannot be interpreted as
due to temperature effects, but might imply a dependence on ϑ of the
photospheric velocity field.
---------------------------------------------------------
Title: The Formation of NA i Spectral Lines in the Solar Atmosphere
Authors: Caccin, B.; Gomez, M. T.; Roberti, G.
1978hrs..conf..494C Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Bidimensional spectroscopy of chromospheric active regions
with the Universal Birefrangent Filter
Authors: Caccin, B.; Falciani, R.; Roberti, G.
1978fsoo.conf..121C Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Tecniche osservative e discussione - Critica dell'emissione
ottica - II
Authors: Caccin, B.
1977MmSAI..48..199C Altcode:
No abstract at ADS
---------------------------------------------------------
Title: The sun, a tool for stellar physics. Proceedings of the 6th
Course of the Advanced School of Astronomy held at the "E. Majorana"
Centre for Scientific Culture, Erice, Italy, August 8 - 21, 1976.
Authors: Zichichi, A.; Renzini, A.; Rigutti, M.; Caccin, B.
1977MmSAI..48..335Z Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Response functions and contribution functions of photospheric
lines.
Authors: Caccin, B.; Gomez, M. T.; Marmolino, C.; Severino, G.
1977A&A....54..227C Altcode:
An attempt is made to obtain the response function (RF) of a
photospheric Fraunhofer line by solving the equation of radiative
transfer in LTE using an appropriate perturbation method. A first-order
expression for the RF is derived with which effects of arbitrary
perturbations in thermodynamic quantities or velocity-field parameters
on emergent line intensity can be evaluated. Perturbations considered
to be amenable to such treatment include line-opacity Doppler shifts
due to velocity fields, microturbulence variations, and temperature
variations at constant electron density. Some examples of RFs for
photospheric lines are presented, and an attempt is made to define
the contribution function (CF) of a line depression in full analogy
with that of the emergent intensity. It is noted that a CF should not
be employed in place of the appropriate RF to predict the sensitivity
of a Fraunhofer line to a perturbation at a given depth.
---------------------------------------------------------
Title: Temperature variations in the solar photosphere. III. Kitt
Peak measurements of the variations of photospheric line profiles
with the heliographic latitude.
Authors: Caccin, B.; Falciani, R.; Donati-Falchi, A.
1976SoPh...46...29C Altcode:
We reproduced the observed center-to-limb variations of 11 weak line
profiles with the HSRA and the microturbulence distribution given by
Lites (1973), introducing an anisotropic macroturbulence (vertical
component of 1.5 km/sec and horizontal one of 2.3 km/sec).
---------------------------------------------------------
Title: The visible spectrum of quiescent prominences
Authors: Caccin, B.; Correra, L.
1975MmSAI..46..293C Altcode:
The paper reviews various attempts to derive plasma parameters, such
as kinetic temperature, turbulent motions, electron density, effective
thickness, and electron temperature, of quiescent prominences from
data on their visible spectrum, and examines the central question
of the co-existence of very different excitation components in the
spectra. Theoretical explanations of this phenomenon include the
existence of a thin hot skin coating the prominence region as a
result of thermal conductivity effects, or different penetration of
UV radiation.
---------------------------------------------------------
Title: L'utilizzazione degli audiovisivi.
Authors: Caccin, B.
1975GAst....1..383C Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Temperature Effects on Measurements of Photospheric Magnetic
Fields
Authors: Caccin, B.; Falciani, R.; Donati-Falchi, A.
1974SoPh...35...31C Altcode:
The effects of line profile variations, due to the temperature
enhancements connected with photospheric magnetographic measurements
are evaluated in a quantitative way: taking into account these results,
the differences found by many authors between the values of the field
obtained with different Fraunhofer lines can be reduced within 10-30%.
---------------------------------------------------------
Title: Some Remarks on Line Weakenings in Photospheric Faculae
Authors: Caccin, B.; Falciani, R.; Donati-Falchi, A.
1974SoPh...35...41C Altcode:
A revision of Schmahl's facular model is used for comparisons with the
HSRA as average photosphere. On its basis many of the available data,
in the visible spectrum, can be explained quantitatively.
---------------------------------------------------------
Title: Temperature Variations in the Solar Photosphere. II:
Temperature Sensitivity of Some Fraunhofer Lines
Authors: Caccin, B.; Donati-Falchi, A.; Falciani, R.
1973SoPh...33...49C Altcode:
We made detailed LTE calculations of the sensitivities of some
Fraunhofer lines to local variations of the effective temperature of
the Sun, taking also into account the effects of local variations of
the microturbulence. The temperature sensitivities we got show a clear
dependence upon the mean optical depth at which lines originate and
upon the binding energy of the lower level involved in the transition.
---------------------------------------------------------
Title: Spectropolarimetric Analysis of the Solar Corona during the
12 November 1966 Total Eclipse
Authors: Caccin, B.; Moschi, G.; Rigutti, M.; Falciani, R.
1971SoPh...17...89C Altcode:
Spectropolarimetric observations of the solar corona during the 12
November, 1966 total eclipse are analyzed. The trend of the intensity,
the polarization degree p, and the polarization angle α of the coronal
continuum are given as functions of ρ and compared with those of
other authors.
---------------------------------------------------------
Title: Temperature Difference Between the Equator and the Poles of
the Sun
Authors: Caccin, B.; Falciani, R.; Moschi, G.; Rigutti, M.
1970SoPh...13...33C Altcode:
A possible variation of the photospheric temperature from the
equator to the poles is investigated through the observation of the
variation of the equivalent width of selected spectral lines sensitive
to temperature variations. The present observations, made during
the summer of 1964, show that the temperature variations, if any,
must roughly be smaller than 1% of the limit temperature. A possible
dependence of the temperature variations on the phase of the solar cycle
has also been examined and it seems that no definite statement may be
done at present. There are, however, some reasonable suspects that no
temperature difference between poles and equator may exist at any time.
---------------------------------------------------------
Title: Isophotes and equalpolarization curves of the solar corona
during the March 7, 1970 total eclipse
Authors: Caccin, B.; Donati Falchi, A.; Moschi, G.
1970MmSAI..41..355C Altcode:
No abstract at ADS
