Author name code: cacciani
ADS astronomy entries on 2022-09-14
author:"Cacciani, Alessandro"
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Title: Magnetic Field Dependence of Polarized Scattering on Potassium
Authors: Thalmann, C.; Stenflo, J. O.; Feller, A.; Cacciani, A.
Bibcode: 2009ASPC..405..113T
Altcode:
The polarization that is generated by scattering of light on atoms
depends on the atomic quantum number structure. According to standard
scattering theory the sodium D_1 (5896 Å) and potassium D_1 (7699
Å) lines should be intrinsically unpolarizable. Since however the
existence of D_1 scattering polarization in the solar spectrum has been
well documented but resisted theoretical explanations, we have carried
out a laboratory experiment to find out if this is a problem of solar
physics or of quantum physics. We find that the polarization matrix
for scattering of the Stokes vector in the potassium D_1 line exhibits
a rich structure that changes dramatically when the field strength is
varied in the sub-gauss regime. In contrast, standard scattering theory
predicts zero polarization, even when optical pumping of the magnetic
sub-levels of the hyperfine structure multiplet is accounted for.
Title: Laboratory Experiment for Polarized Scattering at Potassium
Vapor
Authors: Thalmann, C.; Stenflo, J. O.; Feller, A.; Cacciani, A.
Bibcode: 2006ASPC..358..323T
Altcode:
The observed solar polarization peaks of the D1 lines
of sodium at 5896 Å and barium at 4934 Å still elude theoretical
explanation, in spite of considerable theoretical efforts over the past
decade. To clarify the underlying physics of D1 scattering we
have set up a laboratory experiment to explore the spectrally resolved
profiles of the Mueller matrix for D1 and D2
scattering at potassium vapor. Here we present initial results of
this experiment.
Title: Low-frequency magneto-acoustic waves in the solar chromosphere
Authors: Jefferies, S. M.; McIntosh, S. W.; Armstrong, J. D.; Bogdan,
T. J.; Cacciani, A.; Fleck, B.
Bibcode: 2006ESASP.624E..16J
Altcode: 2006soho...18E..16J
No abstract at ADS
Title: Magnetoacoustic Portals and the Basal Heating of the Solar
Chromosphere
Authors: Jefferies, Stuart M.; McIntosh, Scott W.; Armstrong, James
D.; Bogdan, Thomas J.; Cacciani, Alessandro; Fleck, Bernhard
Bibcode: 2006ApJ...648L.151J
Altcode:
We show that inclined magnetic field lines at the boundaries of
large-scale convective cells (supergranules) provide ``portals''
through which low-frequency (<5 mHz) magnetoacoustic waves can
propagate into the solar chromosphere. The energy flux carried by
these waves at a height of 400 km above the solar surface is found
to be a factor of 4 greater than that carried by the high-frequency
(>5 mHz) acoustic waves, which are believed to provide the dominant
source of wave heating of the chromosphere. This result opens up
the possibility that low-frequency magnetoacoustic waves provide a
significant source of energy for balancing the radiative losses of
the ambient solar chromosphere.
Title: Low-frequency magneto-acoustic waves in the solar chromosphere
Authors: Jefferies, S. M.; McIntosh, S. W.; Armstrong, J. D.; Cacciani,
A.; Bogdan, T. J.; Fleck, B.
Bibcode: 2006IAUJD...3E..62J
Altcode:
We demonstrate that low-frequency (< 5 mHz) propagating
magneto-acoustic waves provide a larger source of energy for balancing
the radiative losses of the solar chromosphere than their high-frequency
(> 5 mHz) counterparts. The low-frequency waves, which are normally
evanescent in the solar atmosphere, are able to propagate through
"acoustic portals" that exist in areas of strong, significantly
inclined (> 30° with respect to the vertical), magnetic field. Such
conditions are found both in active regions and at the boundaries of
supergranules. The latter implies that acoustic portals are omnipresent
over the solar surface and throughout the magnetic activity cycle,
an essential prerequisite for any baseline heating mechanism.
Title: The International Robotic Antarctic Infrared Telescope (IRAIT)
Authors: Tosti, Gino; Busso, Maurizio; Nucciarelli, Giuliano; Bagaglia,
Marco; Roncella, Fabio; Mancini, Alberto; Castellini, Sonia; Mariotti,
Mirco; Babucci, Ezio; Chiocci, Gianfranco; Straniero, Oscar; Dolci,
Mauro; Valentini, Gaetano; di Varano, Igor; Pelusi, Danilo; Di Rico,
Gianluca; Ragni, Maurizio; Abia, Carlos; Domínguez, Inma.; Corcione,
Leonardo; Porcu, Francesco; Conconi, Paolo; De Caprio, Vincenzo;
Riva, Alverto; Molinari, Emilio; Zerbi, Filippo M.; Bortoletto, Favio;
Bonoli, Carlotta; D'Alessandro, Maurizio; Colomé, Josep; Isern, Jordi;
Briguglio, Runa; Cacciani, Alessandro; Farnesini, Lucio; Checcucci,
Bruno; Strassmeier, Klaus G.
Bibcode: 2006SPIE.6267E..1HT
Altcode: 2006SPIE.6267E..47T
Thanks to exceptional coldness, low sky brightness and low content of
water vapour of the above atmosphere Dome C, one of the three highest
peaks of the large Antarctic plateau, is likely to be the best site
on Earth for thermal infrared observations (2.3-300 μm) as well as
for the far infrared range (30 μm-1mm). IRAIT (International Robotic
Antarctic Infrared Telescope) will be the first European Infrared
telescope operating at Dome C. It will be delivered to Antarctica at
the end of 2006, will reach Dome C at the end of 2007 and the first
winter-over operation will start in spring 2008. IRAIT will offer a
unique opportunity for astronomers to test and verify the astronomical
quality of the site and it will be a useful test-instrument for a new
generation of Antarctic telescopes and focal plane instrumentations. We
give here a general overview of the project and of the logistics and
transportation options adopted to facilitate the installation of IRAIT
at Dome C. We summarize the results of the electrical, electronics
and networking tests and of the sky polarization measurements carried
out at Dome C during the 2005-2006 summer-campaign. We also present
the 25 cm optical telescope (small-IRAIT project) that will installed
at Dome C during the Antarctic summer 2006-2007 and that will start
observations during the 2007 Antarctic winter when a member of the IRAIT
collaboration will join the Italian-French Dome C winter-over team.
Title: Low-frequency Magneto-acoustic Waves In The Solar Chromosphere
Authors: Fleck, Bernard; Jefferies, S. M.; McIntosh, S. W.; Armstrong,
J. D.; Cacciani, A.; Bogdan, T. J.
Bibcode: 2006SPD....37.0206F
Altcode: 2006BAAS...38..662F
We demonstrate that low-frequency (< 5 mHz) propagating
magneto-acoustic waves provide a larger source of energy for balancing
the radiative losses of the solar chromosphere than their high-frequency
(> 5 mHz) counterparts. The low-frequency waves, which are normally
evanescent in the solar atmosphere, are able to propagate through
"acoustic portals” that exist in areas of strong, significantly
inclined (> 30° with respect to the vertical), magnetic field. Such
conditions are found both in active regions and at the boundaries of
supergranules. The latter implies that acoustic portals are omnipresent
over the solar surface and throughout the magnetic activity cycle,
an essential prerequisite for any baseline heating mechanism.
Title: Precise measurement of the solar gravitational red shift
Authors: Cacciani, Alessandro; Briguglio, Runa; Massa, Fabrizio;
Rapex, Paolo
Bibcode: 2006CeMDA..95..425C
Altcode: 2006CeMDA.tmp....9C
We present the concept and the status of a multi-year project based on a
new method to measure the Gravitational Red Shift of the Solar Spectrum
with high precision. This project is aimed to conduct experimental
verifications of the effect that the Einstein theory of General
Relativity predicts for the frequencies of the Fraunhofer lines, that
is, the light spectrum emitted by the Sun in its strong gravitational
field. Previous determinations of such effect is limited to a precision
of 2%. In order to discriminate between classical and relativistic
explanations, we need to be sensitive to one part per million of the
predicted effect. We have developed a new powerful technique, the
Magneto-Optical Filter, that is able to provide far better precision
and, for the future, possible space instrumentations able to extend
our test to the second-order effect of the relativistic equivalence
principle, never done before. The present paper is intended to describe
the instrumentation, the procedure and the first encouraging results.
Title: A Proposal for Solar Gravitational Redshift Measurement
Authors: Cacciani, A.; Briguglio, R.; Massa, F.; Rapex, P.
Bibcode: 2006spse.conf..101C
Altcode:
No abstract at ADS
Title: Acoustic Mapping of the Magnetic Canopy in the Solar
Chromosphere
Authors: Jefferies, S. M.; Armstrong, J. D.; Cacciani, A.; Finsterle,
W.; McIntosh, S. W.
Bibcode: 2005AGUSMSH13C..11J
Altcode:
We show that high-frequency acoustic waves can be used to map the
location where the gas and magnetic pressures of the plasma in the
solar chromosphere are comparable. This transition region, which can be
considered as a "magnetic canopy" where MHD waves can transform from one
type into another, is believe to play a key role in the flow of mass
and energy through the chromosphere. Results will be presented from
the analysis of 18 (uninterrupted) hours of simultaneous, full-disk,
velocity observations using the Ni (676 nm), K (770 nm) and Na (589 nm)
Fraunhofer lines (with the SOHO/MDI and MOTH/South Pole instruments),
and 106 (uninterrupted) hours of K and Na data (from the MOTH/South
Pole instrument). The MOTH data were acquired every 10 seconds and the
MDI data every 60 seconds. This work was funded by awards OPP-0087541
and OPP-0338251 from the National Science Foundation.
Title: A new Instrument for High-cadence, Multi-height Observations
of the Velocity and Magnetic Fields of the Full Solar Disk
Authors: Jefferies, S. M.; Armstrong, J. D.; Cacciani, A.; Giebink,
C. A.; Rodgers, W.; Murphy, N.
Bibcode: 2005AGUSMSH13C..12J
Altcode:
We will describe a new instrument that is being built to measure the
velocity, intensity and line-of-sight magnetic fields of the full solar
disk, simultaneously at four heights in the solar atmosphere with a
resolution of 4 arc-seconds and a cadence of 10 seconds. The heart of
the instrument is the magneto-optical filter [1] that can be operated
using vapor cells containing K, Na, Ca and He. The instrument is also
designed to have a high-resolution imaging mode that will provide 1
arc-second resolution over a FOV of 450x450 square arc-seconds. The
instrument is scheduled for deployment to South Pole during the Austral
summer of 2005/2006. This work is funded by award OPP-0338251 from the
National Science Foundation. [1] Cacciani & Fofi, Solar Phys 59,
179 (1978)
Title: Travel Time and Phase Analysis of Waves in the Lower Solar
Chromosphere
Authors: Fleck, B.; Armstrong, J.; Cacciani, A.; de Pontieu, B.;
Finsterle, W.; Jefferies, S. M.; McIntosh, S. W.; Tarbell, T. D.
Bibcode: 2005AGUSMSH13C..04F
Altcode:
In an effort to better understand how the chromospheric plasma and
magnetic fields are guiding, converting and dissipating acoustic waves,
we analyze high-cadence time series taken in Na I D2 589.0 nm and K I
769.9 nm that were obtained with the Magneto Optical Filters at Two
Heights (MOTH) experiment at the South Pole in January 2003. These
data are complemented by a very high spatial resolution time series
taken in Na D with the Swedish Vacuum Solar Telescope in June 1992. The
travel time maps, power maps, and phase diagrams show some unexpected
behaviour, in particular in and around active regions.
Title: Instrument developments for asteroseismology at Dome-C
Authors: Briguglio, R.; Cacciani, A.; Antonello, E.
Bibcode: 2005EAS....14..313B
Altcode:
Helioseismology and Asteroseismology have already given important
contributions to stellar astrophysics, and they provide a powerful
diagnostic method to improve our knowledge about the interior and
evolution of star. Some experimental problems, however, such as the
atmospheric scintillation, affect the precision of the measurements
we can achieve. This kind of noise can ultimately be eliminated only
through space-based observation, at the expense of high organization
and financial costs. In the framework of a collaboration between the
Solar Physics Laboratory (G28) of University of Rome LaSapienza and
the Brera Astronomical Observatory of Milan-Merate, an experimental
set-up has been developed to increase the signal to noise ratio of
our photometric observations and reduce the scintillation noise. This
system appears to be a great help in observational asteroseismology
as it strongly rejects the scintillation noise while amplifies the
stellar signals. Dome-C would be the best ground based site for our
measurements because of its low scintillation noise level and high
atmospheric stability.
Title: Diagnostic of the Solar Atmosphere through Two Level Doppler
and Magnetic Measurements
Authors: Cacciani, A.; Rapex, P.; Massa, F.; Briguglio, R.; Jefferies,
S. M.; Finsterle, W.; Giebink, C.; Knox, A.
Bibcode: 2005EAS....14..269C
Altcode:
This contribution describes our solar project at the Antarctic sites
of Baia Terranova, South Pole and Dome-C. The project is based on a
multi-level helioseismology analysis, aimed to study, for the first
time, the local properties of the solar atmosphere. In addition,
we plan to detect the presence of Alfvèn waves in and around the
active regions, as an energy transfer vehicle from sunspots towards
the corona. The technology used is the well known compact, stable,
relatively unexpensive and still improving MOF (Magneto-Optical Filter).
Title: Acoustic Waves Reveal the Magnetic Topology of the Solar
Atmosphere
Authors: Finsterle, W.; Jefferies, S. M.; Cacciani, A.; Rapex, P.
Bibcode: 2004ESASP.559..223F
Altcode: 2004soho...14..223F
No abstract at ADS
Title: Helioseismic Mapping of the Magnetic Canopy in the Solar
Chromosphere
Authors: Finsterle, W.; Jefferies, S. M.; Cacciani, A.; Rapex, P.;
McIntosh, S. W.
Bibcode: 2004ApJ...613L.185F
Altcode:
We determine the three-dimensional topography of the magnetic canopy
in and around active regions by mapping the propagation behavior of
high-frequency acoustic waves in the solar chromosphere.
Title: Seismology of the solar atmosphere
Authors: Finsterle, Wolfgang; Jefferies, Stuart M.; Cacciani,
Alessandro; Rapex, Paolo; Giebink, Cynthia; Knox, Allister; DiMartino,
Vincenzo
Bibcode: 2004SoPh..220..317F
Altcode:
We describe a new instrument for seismically probing the properties
of the Sun's lower atmosphere, and present some first results from
an observational campaign carried out at the geographic South Pole
during the austral summer of 2002/2003. A preliminary analysis of the
data (simultaneous, high-cadence observations of the velocity signals
from the photosphere and low chromosphere) shows that the well-known
suppression of acoustic power in regions of strong magnetic field, and
enhancement of high-frequency power around active regions (acoustic
halos), are both consistent with a spreading out of the magnetic
field lines with increasing height in the atmosphere. The data have
also revealed some unexpected wave behavior. First, evanescent-like
waves are found at frequencies substantially above the acoustic
cut-off frequency in regions of intermediate magnetic field. Second,
upward- and downward-propagating waves are detected in areas of strong
magnetic field such as sunspots and plage: even at frequencies below
the acoustic cut-off frequency. Third, the wave behavior in regions
of strong magnetic field can change over periods of a few hours from
propagating to evanescent. While we have no concrete explanation for the
first two results, the latter result opens up the question of whether
sound waves are involved in short-term events such as flares or CME's.
Title: Full-disk magnetic oscillations in the solar photosphere
Authors: Moretti, P. F.; Cacciani, A.; Hanslmeier, A.; Messerotti,
M.; Otruba, W.; Warmuth, A.
Bibcode: 2003A&A...403..297M
Altcode:
Photospheric observations of the magnetic oscillations have been carried
out to research magneto-acoustic waves in spots. The coupling between
the magnetic field and the p-modes has been studied using reduced areas
on the solar disk, but a global scenario is still missing. Four hour
full-disk magnetograms (at 4 arcsec/pix spatial resolution) obtained in
the sodium D-lines were analysed pixel-by-pixel (locally) and using the
spherical harmonics decomposition (globally). Magnetic oscillations
were detected at different frequencies and identified on the solar
disk. The global properties of the magnetic oscillations, shown via
the l -nu diagrams, are for the first time presented and discussed.
Title: Eleven years of IRIS frequencies and splittings
Authors: Fossat, E.; Salabert, David; Cacciani, A.; Ehgamberdiev,
S.; Gelly, B.; Grec, G.; Hoeksema, J. T.; Kholikov, S.; Lazrek, M.;
Palle, P.; Schmider, F. X.; Tomczyk, S.
Bibcode: 2003ESASP.517..139F
Altcode: 2003soho...12..139F
Having acquired since July, 1989, a complete 11-year solar cycle of
full disk data, the IRIS++ network has now made available to anyone the
longest helioseismic data base to-date. A few results obtained from this
very long time series are briefly presented here, with some emphasis
on the low degree p-mode frequencies themselves, and their rotational
splittings that have been estimated with unprecedented accuracy.
Title: A new instrument for sounding the solar atmosphere
Authors: Cacciani, A.; Jefferies, S. M.; Finsterle, W.; Rapex, P.;
Knox, A.; Giebink, C.; di Martino, V.
Bibcode: 2003ESASP.517..243C
Altcode: 2003soho...12..243C
A new instrument based on Magneto-Optical Filters (MOFs) (Cacciani
et al., 1994) will be used to simultaneously map the line-of-sight
velocity at two heights in the solar atmosphere. Simultaneous Doppler
images of 5 arc-seconds resolution will be taken in the K I (7699 Å)
and Na I D2 (5890 Å) lines, which are separated by a few
hundred kilometers in the solar atmosphere (Grossman-Doerth, 1994). By
cross correlating the signals of the K and Na channels we will be able
to determine the travel time and thus the propagation speed of sound
waves in the solar atmosphere. The experiment will be run at the South
Pole during austral summer of 2002/2003.
Title: Seismology of the Solar Atmosphere
Authors: Finsterle, Wolfgang; Rapex, Paolo; Jefferies, Stuart M.;
Cacciani, Alessandro; Giebink, Cynthia; Knox, Allister
Bibcode: 2003IAUJD..12E..18F
Altcode:
We use full-disk Dopplergrams simultaneously acquired using the K1
(770 nm) and Na D2 (589 nm) Fraunhofer lines to examine the acoustic
properties of Sun's atmosphere. We present preliminary results of the
use of acoustic waves with frequencies beyond the cut-off frequency for
the solar atmosphere (~ 5mHz) to map the spatial and temporal changes
in the vertical wave travel time between the mid-chromosphere and
low-photosphere over a period of a single solar rotation. These types
of maps should provide a strong constraint for models of the solar
atmosphere . The data used for the analysis were obtained at South
Pole during January 2003 and represent four uninterrupted stretches
of between 46 and 106 hours.
Title: Data reduction and analysis of Solar Dopplergrams
Authors: Cacciani, A.; Rapex, P.; Subrizi, B.; Di Martino, V.
Bibcode: 2003MSAIS...1..103C
Altcode:
Helioseismology studies requires the acquisition and analysis of
sequence of line-of-sight velocity fields of the solar atmosphere. To
obtain such velocity maps of the full solar disk a doppler shift
analysis of the emitted photons is performed. Such velocity fields
are commonly indicated as dopplergram. It is necessary to correctly
correlate each pixel position corresponding to the same piece of the
solar atmosphere evolving in time. Such time series analysis require a
software procedure to aline acquired raw images that may be different
in size and position. In this presentation we show how we perform such
data reduction using ad hoc software, that in some cases require an
human interaction for validation to prevent the lost of single images
geometric characteristic. Almost all the images geometric characteristic
are automatically identified by our registration code. Due to the
optional human intervention we classify this software as a graphical
interface for solar data post processing.
Title: A two color pupil imaging method to detect stellar oscillations
Authors: Cacciani, A.; Dolci, M.; Jefferies, S. M.; Finsterle, W.;
Fossat, E.; Sigismondi, C.; Cesario, L.; Bertello, L.; Varadi, F.
Bibcode: 2003MSAIS...2..172C
Altcode:
Observations of stellar intensity oscillations from the ground are
strongly affected by intensity fluctuations caused by the atmosphere
(scintillation). However, by using a differential observational method
that images the pupil of the telescope in two colors at the same
time on a single CCD, we can partially compensate for this source of
atmospheric noise (which is color dependant) as well as other problems,
such as guiding and saturation. Moreover, by placing instruments at
different locations (eg. Dome C and South Pole) we can further reduce
the atmospheric noise contribution by using cross-spectral methods,
such as Random Lag Singular Cross-Spectrum Analysis (RLSCA). (We
also decrease the likelihood of gaps in the data string due to
bad weather). The RLSCA method is well suited for extracting common
oscillatory components from two or more observations, including their
relative phases. We have evaluated the performance of our method
using real data from SOHO. We find that our differential algorithm can
recover the absolute amplitudes of the solar intensity oscillations
with an efficiency of 70%. We are currently carrying out tests using a
number of telescopes, including Big Bear, Mt. Wilson, Teramo and Milano,
while waiting for the South Pole and Dome C sites to become available.
Title: Mapping the Sound Speed Structure of the Sun's Atmosphere
Authors: Cacciani, A.; Jefferies, S. M.; Finsterle, W.; Giebink, C.;
Knox, A.; Rapex, P.; Subrizi, B.; Cesario, L.
Bibcode: 2003MSAIS...2..190C
Altcode:
We describe an instrument for seismically probing the acoustic
properties of the Sun's lower atmosphere. The instrument, which
is based on magneto-optical filter technology, acquires full-disk
Dopplergrams simultaneously in the K D1 (770 nm) and Na D2 (589
nm) Fraunhofer lines. The Dopplergrams have a spatial resolution
of ~5 arc secs and are recorded at a cadence of one frame every 10
seconds, average from 16 frames per second. These data allow us to
use acoustic waves with frequencies beyond the cut-off frequency for
the solar atmosphere (~5mHz) to map the spatial and temporal changes
in the vertical wave travel time between the mid-chromosphere and the
low-photosphere. These types of maps will provide a strong constraint
for models of the solar atmosphere and possibly study early warnings
for explosive phenomena. We present some preliminary results from
observations made at the geographical South Pole during the 2002/2003
Austral summer. We also discuss our program for the next campaign
with instrumental improvements as far as a third level Dopplergram and
magnetographic capability. We also consider cloning the instrument for
Dome C in order to further minimize atmospheric noise and gaps in the
data string due to bad weather.
Title: An interpretation of the I-V phase background based on observed
plasma jets
Authors: Moretti, P. F.; Cacciani, A.; Hanslmeier, A.; Messerotti,
M.; Otruba, W.; Pddoto tzi, W.; Warmuth, A.
Bibcode: 2002A&A...395..293M
Altcode:
The presence of a solar background in the phase difference between the
intensity and velocity (I-V) p-mode oscillation signals recently has
been interpreted in terms of downflows due to convection (Skartlien
& Rast \cite{Skartlien00}) or due to chromospheric explosive
events (Moretti et al. \cite{Moretti01}a). In support of the latter,
we present I and V characteristics of impulsive brightenings observed
in the NaI D lines, show that these reproduce the frequency dependence
of the I-V modulation background, and show that explanations invoking
more frequently occurring phenomena such as seismic events are not
likely in low-l modulation data.
Title: IRIS++ database: Merging of IRIS + Mark-1 + LOWL
Authors: Salabert, D.; Fossat, E.; Gelly, B.; Tomczyk, S.; Pallé, P.;
Jiménez-Reyes, S. J.; Cacciani, A.; Corbard, T.; Ehgamberdiev, S.;
Grec, G.; Hoeksema, J. T.; Kholikov, S.; Lazrek, M.; Schmider, F. X.
Bibcode: 2002A&A...390..717S
Altcode:
The IRIS network has been operated continuously since July 1st
1989. To date, it has acquired more than a complete solar cycle
of full-disk helioseismic data which has been used to constrain
the structure and rotation of the deep solar interior. However,
the duty cycle of the network data has never reached initial
expectations. To improve this situation, several cooperations have
been developed with teams collecting observations with similar
instruments. This paper demonstrates that we are able to merge data
from these different instruments in a consistent manner resulting
in a very significant improvement in network duty cycle over more
than one solar cycle initiating what we call the IRIS++
network. The integrated radial velocities from the IRIS++
database (1989 to 1999) are available in electronic form at the
CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via
http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/390/717
Title: Simultaneous Hα and sodium observations at the Kanzelhöhe
Solar Observatory
Authors: Moretti, Pier F.; Andretta, V.; Cacciani, A.; Hanslmeier,
A.; Messerotti, M.; Otruba, W.; Warmuth, A.
Bibcode: 2002ESASP.477..147M
Altcode: 2002scsw.conf..147M
At the Kanzelhöhe Solar Observatory, Hα images are currently
obtained simultaneously with sets of intensity, velocity and
longitudinal magnetic images in the sodium D lines. Many flares
have been detected. The preliminary results of the analysis suggest
the events to occur at heights in the solar atmosphere below 1100
km, where the canopy magnetic lines stressed by the photospheric
motions can reconnect. The penetration of the downflowing plasma
jets is investigated in order to justify the solar background in the
photospheric intensity-velocity phase spectrum.
Title: Analysis of variability of p-mode parameters in 11 years of
IRIS data
Authors: Salabert, D.; Jiménez-Reyes, S. J.; Fossat, E.; Cacciani,
A.; Ehgamberdiev, S.; Gelly, B.; Grec, G.; Hoeksema, J. T.; Khalikov,
S.; Lazrek, M.; Pallé, P.; Schmider, F. X.; Tomczyk, S.
Bibcode: 2002ESASP.477..253S
Altcode: 2002scsw.conf..253S
11 years of IRIS (the low degree helioseismology network) have been
analysed for the study of p-modes parameters variability. The duty
cycle of the network data has been improved by the partial gap filling
method named "repetitive music". This paper discusses the variations
of all p-modes parameters along these 11 years.
Title: Extended UV corona imaging from the Solar Orbiter: the
Ultraviolet and Visible-light Coronagraph (UVC)
Authors: Fineschi, Silvano; Antonucci, Ester; Gardiol, Daniele; da
Deppo, Vania; Naletto, Giampiero; Romoli, Marco; Cacciani, Alessandro;
Malvezzi, Marco
Bibcode: 2001ESASP.493..217F
Altcode: 2001sefs.work..217F
No abstract at ADS
Title: Stokes profile measurements in each sodium D-line using single
and dual band magneto-optical filters on board Solar Orbiter
Authors: Cacciani, A.; Rapex, P.; Dolci, M.; Reale, F.; Landi, E.;
Stenflo, J.; Bianda, M.; Moses, D.
Bibcode: 2001ESASP.493..177C
Altcode: 2001sefs.work..177C
No abstract at ADS
Title: Coordinated space and ground-based observations of rapidly
evolving active regions
Authors: Zuccarello, F.; Cacciani, A.; Contarino, L.; Romano, P.
Bibcode: 2001ESASP.493..439Z
Altcode: 2001sefs.work..439Z
No abstract at ADS
Title: An estimation of global solar p-mode frequencies from IRIS
network data: 1989-1996
Authors: Serebryanskiy, A.; Ehgamberdiev, Sh.; Kholikov, Sh.; Fossat,
E.; Gelly, B.; Schmider, F. X.; Grec, G.; Cacciani, A.; Palle, P. L.;
Lazrek, M.; Hoeksema, J. T.
Bibcode: 2001NewA....6..189S
Altcode:
The IRIS network has accumulated full disk helioseismological data
since July 1989, i.e. a complete 11-year solar cycle. Since the
last paper publishing a frequency list [A&A 317 (1997) L71],
not only has the network acquired new data, but has also developed
new co-operative programs with compatible instruments [Abstr. SOHO
6/GONG 98 Workshop (1998) 51], so that merging IRIS files with these
co-operative program data sets has made possible the improvement
of the overall duty cycle. This paper presents new estimations of
low degree p-mode frequencies obtained from this IRIS++
data bank covering the period 1989-1996, as well as the variation of
their main parameters along the total range of magnetic activity, from
before the last maximum to the very minimum. A preliminary estimation
of the peak profile asymmetries is also included.
Title: Search for global oscillations on Jupiter with a double-cell
sodium magneto-optical filter
Authors: Cacciani, A.; Dolci, M.; Moretti, P. F.; D'Alessio, F.;
Giuliani, C.; Micolucci, E.; Di Cianno, A.
Bibcode: 2001A&A...372..317C
Altcode:
Doppler observations on Jupiter are presented and discussed. A two-cells
Magneto-Optical Filter (MOF), able to obtain two separate signals,
Red and Blue, on the opposite wings of the Sodium D-lines, along
with a continuum reference signal, has been used. This set of data
permits to discriminate between real oscillations and albedo ``modes"
by means of the two algorithms D=(B-R)/(B+R) and S=(B+R)/continuum. No
unambiguous oscillation modes were detected with amplitudes above
the 1-sigma level of ~ 1.2 m s-1 in the range between 0.5
and 0.7 mHz. However, using refined analysis for signal recovery in a
noisy background we notice an increase of power also in the region of
the solar 5 min oscillations. The albedo variations on the Jupiter's
surface and instrumental effects are addressed to be responsible for
the spurious signals.
Title: The source of the solar oscillations: Convective or magnetic?
Authors: Moretti, P. F.; Cacciani, A.; Hanslmeier, A.; Messerotti,
M.; Oliviero, M.; Otruba, W.; Severino, G.; Warmuth, A.
Bibcode: 2001A&A...372.1038M
Altcode:
The origin of solar oscillations has not yet been clearly
determined. The downflows due to convective rapid cooling at the surface
have been invoked as a possible source. In this paper we investigate
the properties of the source as inferred from the local analysis of
the intensity-velocity phase differences. The same spatial and temporal
characteristics of other observed events and their correlation with the
Hα bright points suggests downward plasma jets related to explosive
chromospheric evaporation to be another possible candidate.
Title: Observations of NOAA 8210 Using MOF and DHC of Kanzelhöhe
Solar Observatory
Authors: Warmuth, A.; Hanslmeier, A.; Messerotti, M.; Cacciani, A.;
Moretti, P. F.; Otruba, W.
Bibcode: 2001ASSL..259..259W
Altcode: 2001dysu.conf..259W
Two new instruments have recently been introduced at Kanzelhöhe
Solar Observatory: the Magneto-Optical Filter (MOF), a compact imaging
Doppler-magnetograph and the Digital Hα Camera (DHC). In 1998, these
instruments were first used in high-cadence mode to support a SOHO/UVCS
campaign. During this campaign, NOAA 8210 rotated onto the disk, evolved
rapidly and produced several major flares. Furthermore, we point out
the perspectives for our planned Flare Monitoring and Alerting System,
since the two new instruments are crucial components for this program.
Title: Coincidences between Magnetic Oscillations and Hα Bright
Points
Authors: Moretti, P. F.; Cacciani, A.; Messerotti, M.; Hanslmeier,
A.; Otruba, W.
Bibcode: 2001ASSL..259..243M
Altcode: 2001dysu.conf..243M
The origin of the solar oscillations and the interaction with the
magnetic field are usually considered as two distinct problems. Four
hours of 1 minute cadence full-disk dopplergrams, longitudinal
magnetograms and intensity images, taken in the sodium D lines at
Kanzelhöhe Solar Observatory, have been analyzed to investigate
possible spatial correlations between the magnetic oscillations and
the Hα bright points. The phase relation between the velocity and
intensity images is used to enhance the magnetic signatures in the
low spatial resolution images. The coincidences between the magnetic
oscillations locations and the Hα bright points suggest to investigate
the magnetic reconnections as a possible source of solar oscillations.
Title: Using Laser Beacons for Daytime Adaptive Optics
Authors: Beckers, Jacques M.; Cacciani, Alessandro
Bibcode: 2001ExA....11..133B
Altcode:
This article examines the use of Laser Beacons for daytime astronomical
observations. There are two potential applications: the diffraction
limited observation of (1) the structure in the solar corona at all
wavelengths, and (2) non-solar astronomical objects in the thermal
infrared part of the spectrum. We examine the brightness of the Laser
Beacon required as well as the limitations imposed by the daytime
sky brightness and sky/telescope thermal emission on the observable
magnitude limits. For both applications the use of Laser Beacon adaptive
optics in daytime results in important research opportunities.
Title: MOF data analysis of a 14 hour observing run in Antarctica
Authors: Cacciani, A.; di Martino, V.; Rapex, P.; Dolci, M.;
D'Alessio, F.
Bibcode: 2001MmSAI..72..516C
Altcode:
The Antarctic site, although not suitable for observations
lasting longer than a few months, is nevertheless very useful
for intercalibration and data merging purposes in networks for
Helioseismology. The data we present and analyze here constitute an
instrumental test. We present Power Spectra, I-V Phase Spectra, and
other results from 14 hours out of a 30 day run.
Title: MOF data analysis of a 14 hour observing run in Antarctica
Authors: Cacciani, A.; di Martino, V.; Rapex, P.; Dolci, M.;
D'Alessio, F.
Bibcode: 2001ESASP.464..343C
Altcode: 2001soho...10..343C
The Antarctic site, although not suitable for observations
lasting longer than a few months, is nevertheless very useful
for intercalibration and data merging purposes in networks for
Helioseismology. The data we present and analyze here constitute an
instrumental test. We present Power Spectra, I-V Phase Spectra, and
other results from 14 hours out of a 30 day run.
Title: Monitoring of the mesospheric sodium layer using a
magneto-optical filter
Authors: Patriarchi, Patrizio; Cacciani, Alessandro
Bibcode: 2000SPIE.4007..368P
Altcode:
Adaptive optics (AO) systems for atmospheric turbulence compensation
require a bright reference star for measuring and correcting wavefront
distortion. For these reasons a general use of AO requires a laser
guide star (LGS) to provide the wavefront information. An artificial
guide star can be created by focusing a laser beam tuned to the sodium
D2 line at 5890 Angstrom on the mesospheric sodium layer
at about 90 km altitude and observing the resonant scattering. The
D1 line of the sodium layer can be observed in absorption
on early type unreddened (or slightly reddened) stars using a high
resolution spectroscopic system. Recent studies have reported that the
column density of the layer is temporally variable with timescales from
a year down to tens of minutes. Therefore a monitoring of the column
density is necessary when observing with sodium LGS. It is demonstrated
that, with a sufficiently high spectral resolution, a relatively small
(50 cm) telescope observing a bright star can collect in minutes
the number of photons necessary to measure the equivalent width of
the sodium line with a good signal-to-noise ratio, provided that an
efficient spectroscopic device of suitable resolution is attached
to it. We propose here a system to monitor the column density of the
mesospheric sodium layer which is based on the sodium magneto-optical
filter developed by A. Cacciani and already widely used in solar
observations since the 70s. This filter is compact, stable in wavelength
and profile shape, with high efficiency (up to 40%) and narrow profile
width (20 mA). It is based on the magneto-optical activity of the sodium
gas embedded in a strong transverse magnetic field. The filter has a
central bandpass that can be fitted to the width of the D1
mesospheric line, plus two lateral symmetric bandpasses that observe
the adjacent stellar continuum. The D1 equivalent width can
be derived by observing the mesospheric sodium line in absorption on
the spectrum of a bright early type (O, B, A) star.
Title: NOAA AR 8210: Evolution and Flares from Multiband Diagnostics
Authors: Warmuth, Alexander; Hanslmeier, Arnold; Messerotti, Mauro;
Cacciani, Alessandro; Moretti, Pier Francesco; Otruba, Wolfgang
Bibcode: 2000SoPh..194..103W
Altcode:
NOAA 8210 has been a region showing a remarkable level of activity well
before solar maximum. Dominated by a large, rapidly rotating δ spot,
it produced several intense flares during its disk passage at the end
of April-beginning of May 1998. We examine the development of AR 8210 in
Hα and white light (WL) and study the evolution of its complex magnetic
topology. While the other principal flares are briefly reviewed,
the great X1.1/3B flare of 2 May, which was observed at Kanzelhöhe
Solar Observatory during a SOHO/UVCS ground support campaign, is
studied in detail. This event has been documented in full-disk Hα
and Na-D intensitygrams, Dopplergrams, and magnetograms, with a time
cadence of one minute each. The flare was associated with a CME and
produced significant geomagnetic effects. Furthermore, we point out
the perspectives for our planned Flare Monitoring and Alerting System,
since the two new instruments (Magneto-Optical Filter and Digital Hα
camera), which made their first operational run with the campaign,
are crucial components for this program.
Title: Local and Global Magnetic Oscillations in the Photosphere
Authors: Moretti, P. F.; Cacciani, A.; Hanslmeier, A.; Messerotti,
M.; Otruba, W.
Bibcode: 2000ESASP.463..381M
Altcode: 2000sctc.proc..381M
The solar influence on the terrestrial climate is typically associated
to changes during the solar cycle, that is at timescales of years and
more. In fact, the variability seems to be related to the magnetic
activity. Nevertheless, the dynamic of the magnetic field is still not
well understood. The characteristics of the processes acting at higher
temporal frequencies (such as flares etc.) are clearly a signature
of long term magnetic changes and their investigation supports the
understanding of the energy relaxing in the interplanetary space. Four
hour fulldisk magnetograms (with a 4 arcsec/pix resolution) obtained
in the Sodium D-lines have been analyzed pixel-by-pixel (locally) and
in the l-nu diagram (globally). The magnetic oscillations have been
detected at different frequencies and identified on the solar disk. Some
oscillations have been correlated to the H-alpha bright points as the
signature of the magnetic reconnection and subsequent plasma out-flow.
Title: The detectability of global oscillations on Jupiter and Saturn
with the Magneto-Optical Filter
Authors: Dolci, M.; Cacciani, A.
Bibcode: 1999DPS....31.5309D
Altcode:
The Magneto-Optical Filter (MOF) transmits the light in two very narrow
(40 m Angstroms) bandpasses (B and R) located on the opposite wings of a
spectral line. With a suitable elaboration of the transmitted channels
(cal R=(B-R)/(B+R) or cal S=(B+R)/continuum) it is possible to get
direct information about the velocity fields present on the surface
of the observed object. Jovian sesimological observations, carried
out in the past with this technique, found "global oscillations"
with amplitudes around 8 m s(-1) [3]; these "modes", however, could
also be due to albedo fluctuations on Jupiter's surface [2]. Recent
observations have detected no oscillations and given strong support
to the albedo hypothesis [1]. The various experimental results can be
reconciled if the sensitivities of cal R and cal S to the different
oscillation or albedo "modes" is carefully computed. These sensitivities
change with the mode degree (l,m) and with the observation date
tobs. When applied to the two above-mentioned experiments,
they agree very well with the observed results. The authors
thank the Ministero della Pubblica Istruzione and the Osservatorio
Astronomico "V.Cerulli" di Teramo for financial support. References
[1] Cacciani A., Moretti P. F., Dolci M., D'Alessio F., Giuliani C.,
Micolucci E., Di Cianno A., 1999: Search for global oscillations on
Jupiter with a double-cell Sodium Magneto-Optical Filter, submitted
to Astron. Astrophys. [2] Lederer S. M., Marley M. S., Mosser B.,
Maillard J. P., Chanover N. J., Beebe R. F., 1995: Albedo Features and
Jovian Seismology, Icarus, 114, 269 [3] Schmider F. X., Mosser B.,
Fossat E., 1991: Possible detection of Jovian global oscillations,
Astron. Astrophys., 248, 281
Title: Project for a world-wide network devoted to the seismology
of the giant planets.
Authors: Cacciani, A.; Moretti, P. F.; Dolci, M.; Giuliani, C.;
Patriarchi, P.
Bibcode: 1999BAAS...31.1157C
Altcode:
No abstract at ADS
Title: A new limit on the observed amplitude of Jovian global
oscillations
Authors: Moretti, P. F.; Cacciani, A.; Dolci, M.; Giuliani, C.
Bibcode: 1999DPS....31.5308M
Altcode:
Doppler observations of Jupiter carried out in 1996 are reported
[1]. A magneto-optical filter has been used providing the signals on
the opposite wings of the Sodium D-lines (B, R) and the continuum
reference signal. The two computed quantities cal R=(B-R)/(B+R)
and cal S=(B+R)/conti\-nuum have permitted to discriminate between
oscillation and albedo "modes" and to compare the results with
the previous ones obtained in 1991 [3] and 1993 [2]. A new upper
limit on the modes amplitude has been setted at ~ 2 m s(-1) . The
features of the intensity fluctuations in the power spectrum are due
probably to albedo variations on Jupiter's surface and to instrumental
effects. The authors thank the Ministero della Pubblica Istruzione
and the Osservatorio Astronomico "V.Cerulli" di Teramo for financial
support. References [1] Cacciani A., Moretti P. F., Dolci M., D'Alessio
F., Giuliani C., Micolucci E., Di Cianno A., 1999: Search for global
oscillations on Jupiter with a double-cell Sodium Magneto-Optical
Filter, submitted to Astron. Astrophys. [2] Mosser B., Mekarnia D.,
Maillard J. P., Gay J., Gautier D., Delache Ph., 1993: Seismological
observations with a Fourier transform spectrometer: detection of Jovian
oscillations, Astron. Astrophys., 267, 604 [3] Schmider F. X., Mosser
B., Fossat E., 1991: Possible detection of Jovian global oscillations,
Astron. Astrophys., 248, 281}
Title: Project for a world-wide network devoted to the seismology
of the giant planets
Authors: Cacciani, A.; Moretti, P. F.; Dolci, M.; Giuliani, C.;
Patriarchi, P.
Bibcode: 1999DPS....31.5310C
Altcode:
An increasing interest has been devoted in recent years to the
seismology of Jupiter and Saturn, as it is an intermediate case
between the Sun and the stars. Besides the theoretical modelling, few
observations have been carried out so far. An instrument, currently used
in Helioseismology, has been adapted to deal with the low photon flux
from the stars. It is based on the Magneto-Optical Filter (MOF), which
provides two narrow (40 m Angstroms) bandpasses centered on the Sodium
D-lines, 80 m Angstroms/ apart from the central wavelenght. A continuum
broad-band channel is simultaneously available. The MOF stability and
reference wavelenght permit to reach an high sensitivity in the power
spectrum of the oscillations, despite the very low spectral-limited
transmitted light. The most recent version of the instrument has
characteristics of portability (60x10x10 cm x 10 Kg, PMT not included),
fast mounting and low cost. Preliminary results obtained during the
impact of Comet SL-9 on Jupiter in 1994 and in 3 consecutive nights in
1996 are presented [1,2]. The importance of continuous observations
for an unambigous detection and identification of the oscillation
frequencies requires a network of at least 1m--class telescopes all
around the world. The authors thank the Ministero della Pubblica
Istruzione and the Osservatorio Astronomico "V.Cerulli" di Teramo for
financial support. References [1] Cacciani A., Moretti P. F., Dolci M.,
Brocato E., Smith E. J., 1995: Doppler Observations of the Impact of
Comet P/Shoemaker-Levy/9, Fragment A, Geophys. Res. Lett., 22, 2437
[2] Cacciani A., Moretti P. F., Dolci M., D'Alessio F., Giuliani C.,
Micolucci E., Di Cianno A., 1999: Search for global oscillations on
Jupiter with a double-cell Sodium Magneto-Optical Filter, submitted
to Astron. Astrophys.
Title: The detectability of global oscillations on Jupiter and Saturn
with the Magneto-Optical Filter.
Authors: Dolci, M.; Cacciani, A.
Bibcode: 1999BAAS...31.1157D
Altcode:
No abstract at ADS
Title: Laser guide star adaptive optics: measuring the sodium column
density using a magneto-optical filter
Authors: Patriarchi, P.; Cacciani, A.
Bibcode: 1999A&A...344L..45P
Altcode:
A general use of the adaptive optics requires an artificial guide
star created by focusing a laser beam tuned to the sodium D_2 line. We
propose here a system to monitor the column density of the mesospheric
sodium layer which is based on the sodium magneto-optical filter already
widely used in solar observations. The principal characteristics
of this system are high transmission and high spectral resolution
which allow to perform measurements in minutes on a relatively small
(e.g. 50 cm diameter) telescope, where the filter can easily mounted
due to its compactness.
Title: Full disk helioseismology: repetitive music and the question
of gap filling
Authors: Fossat, E.; Kholikov, Sh.; Gelly, B.; Schmider, F. X.;
Fierry-Fraillon, D.; Grec, G.; Palle, P.; Cacciani, A.; Ehgamberdiev,
S.; Hoeksema, J. T.; Lazrek, M.
Bibcode: 1999A&A...343..608F
Altcode:
Helioseismology requires continuous measurements of very long
duration, months to years. This paper addresses the specific and
limited case of full disk measurements of p-mode oscillations,
although it can be generalized, to some extent, to the case of imaged
helioseismology. First, a method of mode by mode (or rather pair of
modes by pair of modes) interpolation of the signal in gaps is tested,
and shown to be efficient for gaps as long as two days, but limited to
the frequency range where the signal to noise ratio is good. It is then
noted that the autocorrelation function of the full disk signal, after
dropping quickly to zero in 20 or 30 minutes, shows secondary quasi
periodic bumps, due to the quasi-periodicity of the peak distribution
in the Fourier spectrum. The first of these bumps, at 4 hours or so,
is higher than 70 percent and climbs to nearly 90 percent in limited
frequency ranges. This suggests that an easy gap filling method can
be developed, with a confidence of nearly 90 percent across all the
frequency range, as long as the gap does not exceed 8 hours, with
at least 4 hours of data at both ends. Even a short gap of one or
two periods is better filled by the data taken 4 hours earlier or
later than by local interpolation. This relaxes quite considerably
the requirement of continuity of the observations for the case the
full disk p-mode helioseismology. Applied to 7 years of IRIS data,
this method permits the detection of all low frequency p-modes already
seen by 2 years of the GOLF instrument data, and makes possible the
measurement of their frequencies with an accuracy consistent with the
partially filled 7 years of statistics.
Title: The Magneto-Optical Filter at Kanzelhöhe
Authors: Cacciani, A.; Moretti, P. F.; Messerotti, M.; Hanslmeier,
A.; Otruba, W.; Pettauer, T. V.
Bibcode: 1999ASSL..239..271C
Altcode: 1999msa..proc..271C
An observing station based on the Magneto-Optical Filter (MOF)
technology has been installed at Kanzelhöhe at the beginning of
1997. In this paper, the main characteristics of this instrument are
discussed and a one day solar velocity observing run is shown.
Title: The solar surveillance program at the Kanzelhoehe Solar
Observatory: new facilities for high speed digital imaging and
dynamic event tracking
Authors: Messerotti, M.; Otruba, W.; Warmuth, A.; Cacciani, A.;
Moretti, P. F.; Hanslmeier, A.; Steinegger, M.
Bibcode: 1999WPP...155..321M
Altcode:
The Kanzelhoehe Solar Observatory (Austria) has been devoted to
multiwavelength synoptic observations of the sun for a long time in the
frame of a long-term Solar Surveillance Program. Recently the observing
capabilities were boosted by two new instruments for full-disk imaging:
a digital H-alpha camera and a Magneto-Optical Filter (MOF) system. In
this frame, we sketch the feasibility of a fully digital flare survey
and a quasi-real time analysis system based on an artificial neural
network, which might be relevant to the prediction of solar events
affecting the solar-terrestrial environment.
Title: A new limit on the observed amplitude of Jovian global
oscillations.
Authors: Moretti, P. F.; Cacciani, A.; Dolci, M.; Giuliani, C.
Bibcode: 1999BAAS...31R1156M
Altcode:
No abstract at ADS
Title: A System for the Monitoring of the Mesospheric Sodium Layer
Using a Magneto-Optical Filter
Authors: Patriarchi, P.; Cacciani, A.
Bibcode: 1999ESOC...56..347P
Altcode: 1999aaop.conf..347P
No abstract at ADS
Title: Compact Doppler magnetograph
Authors: Ruzmaikin, Alexander; Moynihan, Philip I.; Vaughan, Arthur
H.; Cacciani, Alessandro
Bibcode: 1998SPIE.3442..115R
Altcode:
We designed a low-cost flight instrument that images the full solar
disk through two narrow band filters at the red nd blue 'wings' of
the solar potassium absorption line. The images are produced on a
1024 X 1024 charge-coupled device with a resolution of 2 arcsec per
pixel. Four filtergrams taken in a very short time at both wings in
the left and right states of circular polarization are used to yield
a Dopplergram and a magnetogram simultaneously. The noise-equivalent
velocity associated with each pixel is less than 3 m/s. The measured
signal is linearly proportional to the velocity in the range +/-
4000 m/s. The range of magnetic fields is from 3 to 3000 Gauss. The
optical system of the instrument is simple and easily aligned. With
a pixel size of 12 micrometers , the effective focal length is 126
cm. A Raleigh resolution limit of 4 arcsec is achieved with a 5-cm
entrance apertures, providing an f/25 focal ratio. The foreoptic is
a two-component telephoto lens serving to limit the overall optical
length to 89 cm or less. The mass of the instrument is 14 kg. the power
required is less than 30 Watts. The Compact Doppler Magnetograph can
be used in space mission with severe mass and power requirements. It
can also be effectively used for ground-based observations: large
telescope, dome or other observatory facilities are not required.
Title: RODOMA: The Rome network for Doppler and magnetic oscillations
Authors: Cacciani, A.; Hanslmeier, A.; Messerotti, M.; Moretti, P. F.;
Otruba, W.; Pettauer, Th.; Rodgers, W.
Bibcode: 1998ESASP.418..131C
Altcode: 1998soho....6..131C
The development of the RODOMA network is now at the point to start
taking regular observations from two sites: the Austria site in
Kanzelhoehe and the California site in Apple Valley. The final test
is connected with a UVCS(SOHO) campaign operating between april 20
and May 05 1998. The data consist of Doppler and simultaneous magnetic
and intensity fulldisk images taken at intervals of 30 or 60 seconds,
depending on the final desired precision. The contribution is aimed to
illustrate the state and the characteristics of the instrumentation and
to show samples of results. A third site will be Tashkent in Uzbekistan,
in the framework of the IRIS collaboration.
Title: Solar oscillations
Authors: Cacciani, A.
Bibcode: 1998MmSAI..69..547C
Altcode:
No abstract at ADS
Title: Magnetic Oscillations in an Active Region Around a Unipolar
Sunspot Close to the Limb
Authors: Cacciani, A.; Di Martino, V.; Jefferies, S.; Moretti, P. F.
Bibcode: 1998ESASP.418..617C
Altcode: 1998soho....6..617C
No abstract at ADS
Title: VAMOS: Velocity and Magnetic Observations of the Sun
Authors: Oliviero, M.; Dolci, M.; Severino, G.; Straus, Th.; Cacciani,
A.; Moretti, P. F.
Bibcode: 1998IAUS..185...53O
Altcode:
The VAMOS is an instrument, based on two sodium resonance cells,
that acquires full disc Doppler and magnetic images of the sun,
and is operative at the Osservatorio Astronomico di Capodimonte
in Napoli. The importance of a careful control of the two cells
temperatures is emphasized. The two approaches for calibrating velocity
data, based on the knowledge of both the solar rotation and the earth
- sun relative velocity, are applied. Doppler and magnetic data are
used to study some of the effects that solar active regions can have
on global oscillations.
Title: A Jupiter Seismology Project
Authors: Cacciani, A.; Dolci, M.; Giuliani, C.; Moretti, P. F.
Bibcode: 1998ESASP.418..381C
Altcode: 1998soho....6..381C
No abstract at ADS
Title: Case studies of magnetic topology evolution in active regions
Authors: Cacciani, A.; di Martino, V.; Hanslmeier, A.; Messerotti,
M.; Moretti, P. F.; Pettauer, Th.; Veronig, A.
Bibcode: 1998ASPC..155..229C
Altcode: 1998sasp.conf..229C
We give a preliminary report on the evolution of the magnetic field
topology extrapolated in the current-free approximation for two solar
active regions observed through an MOF imaging magnetograph.
Title: A MOF-based full vector imaging magnetograph
Authors: Cacciani, A.; Comari, M.; Furlani, S.; Hanslmeier, A.;
Messerotti, M.; Moretti, P. F.; Pettauer, Th.; Veronig, A.
Bibcode: 1998ASPC..155..265C
Altcode: 1998sasp.conf..265C
The scheme and the operating principles of a fast, compact,
magneto-optical filter-based, full-vector imaging magnetograph,
currently under development for solar observations, are briefly outlined
as well as planned improvements and possible applications.
Title: The Magneto-Optical Filter in Napoli: Perspectives and Test
Observations
Authors: Moretti, P. F.; Severino, G.; Cauzzi, G.; Reardon, K.;
Straus, T.; Cacciani, A.; Marmolino, C.; Oliviero, M.; Smaldone, L. A.
Bibcode: 1997ASSL..225..293M
Altcode: 1997scor.proc..293M
An observing station based on the Magneto-Optical-Filter (MOF)
technology is being installed at Osservatorio Astronomico di
Capodimonte, in Napoli. In this paper, the main characteristics and
goals of this new instrument are discussed, and several velocity and
magnetic observations from a test campaign are shown.
Title: Magnetic Contamination and Correction in Sodium Dopplergrams
Authors: Cacciani, A.; Moretti, P. F.
Bibcode: 1997SoPh..175....1C
Altcode:
Recently a new version of a sodium double-band magneto-optical filter
has been built in order to provide simultaneous Doppler and magnetograms
using the same optical path (Cacciani, Moretti, and Rodgers, 1997;
Cacciani et al., 1988, 1994). Two observing stations based on this
instrument are being installed as part of the French network IRIS. One
is already operational in Apple Valley, California, and the other one
will be delivered shortly to Tashkent, Uzbekistan. The performance of
the instrument is such as to detect the l = 0 mode of solar oscillations
from resolved images with a signal-to-noise ratio that has never been
achieved before (Cacciani and Moretti, 1994). The magnetic and velocity
signals are corrected for the changes that occur in the solar D-line
profile in active versus non-active regions. This kind of analysis
will be performed by our group in conjunction with parallel analysis
of GOLF and IRIS integrated data which use the same sodium lines.
Title: Measuring Doppler and Magnetic Fields Simultaneously
Authors: Cacciani, A.; Moretti, P. F.; Rodgers, W. E.
Bibcode: 1997SoPh..174..115C
Altcode:
A compact and inexpensive version of the magneto-optical filter,
developed in Rome during the 1970s, has attained the capability to
measure all the Stokes' parameters on the full solar disk. Without
the help of moving parts, each Stokes' image is taken simultaneously
with a companion Doppler image. The overall instrument is about 15
× 15 × 50 cm in size (telescope included). The working principle
of the instrument is described first, then samples of its present
applications are given. In this paper we address, for the first time,
questions relating to the MOF lifetime and their implications on
space applications.
Title: Solar P-mode frequencies from the IRIS network.
Authors: Gelly, B.; Fierry-Fraillon, D.; Fossat, E.; Palle, P.;
Cacciani, A.; Ehgamberdiev, S.; Grec, G.; Hoeksema, J. T.; Khalikov,
S.; Lazrek, M.; Loudagh, S.; Pantel, A.; Regulo, C.; Schmider, F. X.
Bibcode: 1997A&A...323..235G
Altcode:
The Iris network for helioseismology has operated since 1989. We present
tables of solar p-mode frequencies for observations taken during the
four summer seasons from 1989 to 1992. This analysis uses the technique
of maximum likelihood fitting and a χ_2_^2^ model for the probability
density function of the spectrum. The simultaneous fitting of odd and
even pairs of peaks strengthens the identification of the l=3 eigenmodes
and improves the error bars on the 0-2 group. The frequencies are in
good agreement with other observational results and with theoretical
values for the D_0_ and the {DELTA}ν parameters of the asymptotic
approximation. A decrease of 0.25+/-0.12μHz is seen between the 1989
and the 1992 data sets. The change is associated with the decrease of
solar activity and is comparable with results of previous studies.
Title: New IRIS constraints on the solar core rotation.
Authors: Gizon, L.; Fossat, E.; Lazrek, M.; Cacciani, A.; Ehgamberdiev,
S.; Gelly, B.; Grec, G.; Hoeksema, J. T.; Khalikov, S.; Palle, P. L.;
Pantel, A.; Regulo, C.; Schmider, F. -X.; Wilson, P. R.
Bibcode: 1997A&A...317L..71G
Altcode:
Four time series of IRIS data (4 to 6 months) have been used to obtain
improved measurements of the low degree (l=1,2,3) rotational splitting
frequencies. Assuming that the rotation law is known in the outer
layers of the Sun, we investigate the implications of IRIS splittings
for the central regions. Both a one-shell and a two-shell rotation
model have been considered in the solar core. A core rotating slightly
faster than the outer radiative envelope provides the best fit to the
data. Some evidence for the reliability of the observations is shown
by the visibility of differential rotation in the l=3 multiplets.
Title: Simultaneous Doppler and magnetic solar maps from a MOF
installed at the Osservatorio di Capodimonte
Authors: Cacciani, A.; Marmolino, C.; Moretti, P. F.; Oliviero, M.;
Severino, G.; Smaldone, L. A.
Bibcode: 1997MmSAI..68..467C
Altcode:
No abstract at ADS
Title: Osservazioni Doppler dell'impatto della cometa SL/9 su Giove,
frammento A.
Authors: Cacciani, A.; Moretti, P. F.; Dolci, M.; Brocato, E.
Bibcode: 1996GAst...22d..58C
Altcode:
Doppler observations of the impact of fragment A of comet SL-9 on
Jupiter.
Title: Osservazione degli impatti della cometa Shoemaker-Levy 9 su
Giove con il filtro magneto-ottico a vapori di sodio.
Authors: Catalano, S.; Cacciani, A.; Rodonò, M.; Ventura, R.
Bibcode: 1996GAst...22d..53C
Altcode:
Spectrophotometric observations of the impact of comet SL-9 on Jupiter
with a magneto-optical filter of sodium vapour.
Title: Magnetic contamination on integrated disk Doppler data (GOLF):
a procedure to correct it.
Authors: Cacciani, A.; Moretti, P. -F.
Bibcode: 1996BAAS...28.1193C
Altcode:
No abstract at ADS
Title: A Compact Instrument to Detect and Study Seismological Doppler
Signals from Jupiter. A Proposal for Flight Instruments on HST
Authors: Cacciani, A.; Moretti, P. F.
Bibcode: 1996swhs.conf..626C
Altcode:
No abstract at ADS
Title: Velocity Fields within the Solar Convection Zone: Evidence
from Oscillation Ring Diagram Analysis of Mount Wilson Dopplergrams
Authors: Patron, J.; Hill, F.; Rhodes, E. J., Jr.; Korzennik, S. G.;
Cacciani, A.
Bibcode: 1995ApJ...455..746P
Altcode:
A ring-diagram analysis of solar oscillations has been applied to
a 3 day time series of full-disk Doppler images obtained at Mount
Wilson. A model of the three-dimensional power spectrum assuming a
Lorentzian profile in frequency and the advection of the wave front by
horizontal flows has been fitted to the observed spectrum. The model
provides estimates of the two horizontal components of subsurface
flows averaged over depth. These estimates are then input to a
least-squares smoothness-constrained inversion procedure to infer
the depth dependence of the horizontal velocity. The method has been
applied at nine different heliographic positions. The results indicate
the presence of three east-west shear layers at all longitudes and
latitudes, associated in depth with the ionization zones of hydrogen
and helium in the outermost 20 Mm. The direction of the shear with
respect to the average surface rotation rate alternates with depth, with
organized north-south flows apparent between the east-west flows. Thus,
the resultant vector velocity field appears to execute a spiral as
a function of depth. Below ∼30 Mm, the organized character of the
flow disappears, and a chaotic spatial distribution dominates. There
is also an indication of a convergent flow at ∼10° north latitude,
suggesting the presence of a toroidal convective roll. The magnitudes
of the flows are on the order of 100-200 ms-1 in the outer
20 Mm, rising to several hundred ms-1 at 50 Mm.
Title: Doppler observations of the impact of comet P/Shoemaker-Levy/9,
fragment A
Authors: Cacciani, A.; Moretti, P. F.; Dolci, M.; Brocato, E.; Smith,
E. J.
Bibcode: 1995GeoRL..22.2437C
Altcode:
This paper discusses an attempt to detect the impact of fragment A of
the comet Shoemaker-Levy 9 on Jupiter using the Doppler effect. We give
a short description of the technique used to observe the impact, then
present the observations along with a tentative theoretical analysis
and interpretation. The instrumentation used is an advanced and more
sensitive version of the Magneto-Optical Filter (normally used in
Helioseismology to detect global oscillations of the Sun) and a 40
cm aperture telescope. The observed signal in July 16 (fragment A)
consists of a pair of transients that, if related to the comet impact,
could be interpreted as the signature of an expanding perturbation. We
present only the first step of the theoretical analysis simulating
a wave pulse expanding radially from the impact site. The result is
remarkable in that it reproduces the two peaks although with much lower
amplitudes than observed. Furthermore, the inferred particle speed is
in the range 5-20 km/s which is more consistent with the plume and
debris material expansion speeds derived from the HST observations
and/or with shock wave propagation away from the impact site.
Title: Test of the Magneto-Optical Filter during the Comet
Shoemaker-Levy 9 Impacts on Jupiter: a Doppler Signal Detected?
Authors: Cacciani, A.; Moretti, P. F.; Dolci, M.; Brocato, E.; Smith,
E. J.
Bibcode: 1995ESASP.376b.345C
Altcode: 1995soho....2..345C; 1995help.confP.345C
No abstract at ADS
Title: L=1 Rotational Splitting Detected from a 69 Day Run Using
the Magneto-Optical Filter Installed at Jpc
Authors: Cacciani, A.; Moretti, P. F.; Dolci, M.; Smith, E. J.
Bibcode: 1995ESASP.376b.311C
Altcode: 1995help.confP.311C; 1995soho....2..311C
No abstract at ADS
Title: An Instrument to Observe Low-Degree Solar Oscillations
Authors: Tomczyk, S.; Streander, K.; Card, G.; Elmore, D.; Hull, H.;
Cacciani, A.
Bibcode: 1995SoPh..159....1T
Altcode:
We have constructed an instrument optimized to observe solar
oscillations of low degree. The primary goal of this instrument,
which we call LOWL, is to measure the frequency splitting of the
low-degree modes in order to determine the rotation rate of the solar
core. The LOWL is a Doppler imager based on a magneto-optical filter. It
employs a two-beam technique to simultaneously observe solar images in
opposite wings of the absorption line of potassium at 769.9 nm. This
instrument is very stable against drifts in the wavelength zero-point,
is insensitive to noise sources due to intensity fluctuations and image
motion, and has a Doppler analyzer with no moving parts. The LOWL has
been deployed at HAO's observing station on Mauna Loa, Hawaii and will
operate for a period of at least two years.
Title: Evaluation of a Portable and Inexpensive MOF Unit for Doppler
Imaging
Authors: Cacciani, A.; Moretti, P. F.; Smith, E. J.
Bibcode: 1995ASPC...76..440C
Altcode: 1995gong.conf..440C
No abstract at ADS
Title: Doppler observations of the impact of comet SL9 fragment A.
Authors: Cacciani, A.; Moretti, P. F.; Dolci, M.; Brocato, E.; Smith,
E. J.
Bibcode: 1995ESOC...52..181C
Altcode: 1995esl9.conf..181C; 1995eslj.work..181C
The authors present Doppler observations on Jupiter during the impact
of the fragment A of the comet Shoemaker-Levy 9. The instrumentation
used is a suitable version of the Magneto-Optical Filter (normally used
in Helioseismology to detect global oscillations of the Sun) and a 40
cm aperture telescope. The observed signal consists of a double peak
transient that could be interpreted as the signature of an expanding
perturbation. The authors briefly describe the instrumentation,
present the observational data and discuss the probable association
of this signal with the Shoemaker-Levy impact.
Title: Ring Diagram Analysis of Mt. Wilson Data: Velocity Fields
within the Solar Convection Zone
Authors: Patron, J.; Hill, F.; Rhodes, E. J., Jr.; Korzennik, S. G.;
Cacciani, A.
Bibcode: 1995ASPC...76..208P
Altcode: 1995gong.conf..208P
No abstract at ADS
Title: Observations of the SL/9 impacts with a sodium magneto-optical
filter.
Authors: Catalano, S.; Rodonò, M.; Ventura, R.; Cacciani, A.
Bibcode: 1995ESOC...52..209C
Altcode: 1995eslj.work..209C; 1995esl9.conf..209C
The authors report on spectrophotometric observations of Jupiter
obtained during some of the SL/9 impacts by using a sodium
magneto-optical filter.
Title: Solar Cycle Dependence of p-Mode Frequencies at Intermediate
and High Degrees
Authors: Rhodes, E. J., Jr.; Johnson, N. M.; Rose, P. J.; Korzennik,
S. G.; Cacciani, A.
Bibcode: 1995ASPC...76..227R
Altcode: 1995gong.conf..227R
No abstract at ADS
Title: Observations of δ Scuti star pulsation modes with a sodium
magneto-optical filter.
Authors: Catalano, S.; Rodonò, M.; Ventura, R.; Cacciani, A.
Bibcode: 1995mscs.conf..195C
Altcode:
No abstract at ADS
Title: On the Determination of the Solar Internal Rotation
Authors: Korzennik, S. G.; Rhodes, E. J., Jr.; Johnson, N. M.; Rose,
P.; Cacciani, A.
Bibcode: 1995ASPC...76...12K
Altcode: 1995gong.conf...12K
No abstract at ADS
Title: Magneto-optical filter: concept and applications in astronomy
Authors: Cacciani, Alessandro; Moretti, Pier-Francesco
Bibcode: 1994SPIE.2198..219C
Altcode:
The MOF is a compact device (15 cm max dimension) displaying a very
narrow-band spectral transmission (20 to 70 m$angstrom, single
or multiple bands) with intrinsic absolute spectral reference
and stability, high peak transmission (close to 50%) and imaging
capability. It has been used so far mainly in solar astronomy to detect
solar magnetic and velocity fields. Doppler shifts as low as 1 cm/sec
equivalent velocity can be measured on the sun (whole disk) using 2
cm aperture telescope and 1 sec exposure time. Its working principle
is based on magneto-optical effects on metallic vapors in a magnetic
field. An overview of the theoretical model compared with experimental
spectroscopic measurements is discussed in the first part. Applications
in astronomy, namely helio and astero seismology and magnetographic
observations are shown in the second part of this paper.
Title: Ring Diagram Analysis of Mt. Wilson Data: Current Status
Authors: Hill, F.; Patron, J.; Rhodes, E. J., Jr.; Korzennik, S. G.;
Cacciani, A.
Bibcode: 1993BAAS...25R1193H
Altcode:
No abstract at ADS
Title: Confirmation of Solar Cycle--dependent Intermediate-Degree
p-Mode Frequency Shifts
Authors: Rhodes, Edward J., Jr.; Cacciani, Alessandro; Korzennik,
Sylvain G.; Ulrich, Roger K.
Bibcode: 1993ApJ...406..714R
Altcode:
Results of intercomparisons of seven different sets of frequencies of
intermediate-degree p-modes obtained at several different locations
between 1981 and 1989 are presented. It is shown that the frequency
shifts exhibited by all of these intermediate-degree p-modes are
consistent with the intermediate-degree frequency shifts presented by
Libbrecht and Woodward (1990) and also with the low-degree frequency
shifts presented by Elsworth et al. (1990). It is also shown that these
frequency shifts correlate with solar cycle-dependent changes in sunspot
number, area, and irradiance. Unbinned and binned differences between
1984 Mount Wilson Observatory and revised 1981 South Pole frequencies
are illustrated.
Title: The Stark Effect as a Calibration Tool in Helioseismology
Authors: Cacciani, A.; Moretti, P. F.; Papaldo, D.; Paverani, E.
Bibcode: 1993SoPh..144..205C
Altcode:
In this paper we address the problem of the calibration for the Doppler
signal obtained from resonant scattering spectrometers and magneto
optical filters that are being used to measure solar oscillations. After
discussing current methods of calibration, we suggest and study a new
method based on the Stark effect. Our analysis and preliminary test
confirm the capability and the advantages of the method.
Title: Ring Diagram Analysis of MT.WILSON Data
Authors: Patron, J.; Hill, F.; Rhodes, E. J., Jr.; Korzennik, S. G.;
Cacciani, A.; Brown, T. M.
Bibcode: 1993ASPC...42..437P
Altcode: 1993gong.conf..437P
No abstract at ADS
Title: Calibration methods in helio- and asteroseismology
Authors: Cacciani, A.; Moretti, P. F.; Papaldo, D.; Paverani, E.
Bibcode: 1993MmSAI..64..457C
Altcode:
No abstract at ADS
Title: Preliminary P-Mode Frequencies from a 93-DAY MT.WILSON 60-FOOT
Tower Observing Run
Authors: Rhodes, E. J., Jr.; Cacciani, A.; Korzennik, S. G.
Bibcode: 1993ASPC...42..193R
Altcode: 1993gong.conf..193R
No abstract at ADS
Title: Alfvén waves in the solar atmosphere
Authors: Smith, E. J.; Cacciani, A.; Moretti, P. F.; Papaldo, D.;
Paverani, E.
Bibcode: 1993MmSAI..64..451S
Altcode:
No abstract at ADS
Title: LOWL - an Instrument to Observe Low-Degree Solar Oscillations
Authors: Tomczyk, S.; Cacciani, A.; Veitzer, S. A.
Bibcode: 1993ASPC...42..469T
Altcode: 1993gong.conf..469T
No abstract at ADS
Title: Towards a Better Determination of Frequency Splittings at
Intermediate and High Degree Modes - Preliminary Results of Sectoral
Frequency Splittings from a 90-DAY Observing Run
Authors: Korzennik, S. G.; Cacciani, A.; Rhodes, E. J., Jr.
Bibcode: 1993ASPC...42..201K
Altcode: 1993gong.conf..201K
No abstract at ADS
Title: Observations of the Thermal Response of the Terrestrial
Atmosphere to the Solar Eclipse of 1991JUL11
Authors: Rhodes, E. J.; Cacciani, A.
Bibcode: 1993ASPC...42..297R
Altcode: 1993gong.conf..297R
No abstract at ADS
Title: Plans for MT.WILSON - Crimean Observatory High-Degree
Helioseismology Network
Authors: Rhodes, E. J., Jr.; Cacciani, A.; Dappen, W.; Didkovsky,
L. V.; Hill, F.; Korzennik, S. G.; Kosovichev, A. G.; Kotov, V. A.;
Scherrer, P. H.
Bibcode: 1993ASPC...42..477R
Altcode: 1993gong.conf..477R
No abstract at ADS
Title: Rotation Rate of the Supergranulation Pattern
Authors: Hathaway, D. H.; Rhodes, E. J., Jr.; Korzennik, S.;
Cacciani, A.
Bibcode: 1991BAAS...23.1051H
Altcode:
No abstract at ADS
Title: How Deeply Might Sunspots and Supergranules Be Anchored within
the Sun?
Authors: Rhodes, E. J., Jr.; Korzennik, S. G.; Hathaway, D. H.;
Cacciani, A.
Bibcode: 1991BAAS...23.1033R
Altcode:
No abstract at ADS
Title: The Supergranulation Spectrum
Authors: Hathaway, David H.; Rhodes, Edward J.; Cacciani, Alessandro;
Korzennik, Sylvain G.
Bibcode: 1991LNP...388..163H
Altcode: 1991ctsm.conf..163H
Full-disk Dopplergram observations obtained at the 60-foot
tower of the Mount Wilson Observatory with the Cacciani sodium
magneto-optical filter were analyzed to determine the spectrum of
the solar supergranulation. Individual Dopplergrams were averaged
together using a weighted average over 20-minute intervals to remove
the p-mode oscillations. The Doppler signals due to the motion of the
observer, the solar rotation, differential rotation, and limb shift
were then removed from the data to produce Dopplergrams dominated
by the supergranular flows. These data were mapped to heliographic
coordinates and projected onto the spherical harmonics. The resulting
spectrum exhibits a peak at spherical harmonic degree } 100, which
corresponds to typical cell diameters of about 40 Mm. Synthetic data
were constructed and passed through the same analysis procedures to
determine the actual spectrum required to reproduce the results. A
good fit was obtained with a kinetic energy spectrum which peaks at }
100 and decreases exponentially out to } 500 with an e-folding range
of } 90. A power law fit to the spectrum over this range in yields an
exponent of about -2.75. No corrections for seeing were included in
the analysis. Although the image was sampled at 8 arcsec resolution,
the effects of seeing may alter the actual slope of the spectrum and
make it somewhat flatter. The spectrum does not exhibit any evidence
for a distinct mesogranulation component out to } 500 (corresponding
to cell diameters of about 8 Mm).
Title: Solar Oscillation Ring Diagrams from Mt. Wilson Full-Disk
Magneto-Optical Dopplergrams
Authors: Hill, Frank; Rhodes, Edward J.; Korzennik, Sylvain G.;
Cacciani, Alessandro; Brown, Timothy M.
Bibcode: 1991LNP...388..271H
Altcode: 1991ctsm.conf..271H
Three-dimensional power spectra of solar oscillations have been
computed from moderate-resolution full disk Doppler images obtained
with the Magneto-Optical Filter at Mt. Wilson. Slices of the spectra
at constant frequency reveal the ring structures that are analogous
to the ridges in two-dimensional spectra. Ring diagrams obtained
at different heliographic positions show large differences in the
structure of the rings. These variations can be attributed to the
changing effective spatial resolution of the observations across the
disk. After correction for this effect, and .for terrestrial seeing,
the rings will be used to map the horizontal flows in the convection
zone as a function of position and depth.
Title: Observations of intermediate- and high-degree p-mode
oscillations during sunspot cycles 21 and 22
Authors: Rhodes, E. J.; Cacciani, A.; Korzennik, S. G.
Bibcode: 1991AdSpR..11d..17R
Altcode: 1991AdSpR..11...17R
Extensive time series of resolved solar images have been available
for helioseismological studies since the late 1970s. We will first
review the temporal coverage that has been built up over the past
11 years at several different observatories. Next, we will present
examples of the frequencies, power levels, modal energies, and widths
of solar intermediate-(5< l <120) and high-degree (120< l
<600) p-modes which were obtained at the Mount Wilson Observatory's
60-Foot Solar Tower Telescope during the rising phase of the current
sunspot cycle. We will demonstrate that the inclusion of frequency
splittings from the high-degree p-modes has allowed us to demonstrate
that the sun's internal equatorial angular velocity is not constant
with radius but rather varies systematically with radius throughout
the solar convection zone and below. Lastly, we will show that, by
intercomparing many of the available p-mode frequency datasets, we have
been able to confirm the recent suggestion by Libbrecht and Woodard
/1/ that the frequencies of the intermediate-degree p-modes do vary
systematically with varying levels of solar activity. In particular,
we will demonstrate that such frequency shifts have been occurring in
every year that observations have been obtained since 1980 and that
such variations are also consistent with similar variations that have
been recently noted in low-degree p-mode frequencies.
Title: Progress toward an advanced imaging vector magnetograph.
Authors: Cacciani, A.; Paverani, E.; Smith, E.; Zirin, H.
Bibcode: 1991sopo.work..133C
Altcode:
As part of the development phase of an imaging vector magnetograph
the authors have tested at Big Bear Solar Observatory a simple double
band imaging linear polarimeter based on a magneto-optical filter. An
isolated sunspot was observed and the orientation of the field lines of
the penumbra are displayed. They show an evident cyclonic aspect. If
it was caused by Faraday rotation it would be consistent with the
magnetic polarity of the spot.
Title: Measurements of Intermediate- and High-Degree (20<1<600)
p-Mode Solar Oscillation Power and Energy
Authors: Rhodes, Edward J.; Brown, Timothy M.; Cacciani, Alessandro;
Korzennik, Sylvain G.; Ulrich, Roger K.
Bibcode: 1991LNP...388..277R
Altcode: 1991ctsm.conf..277R
We present measurements of the total modal power and energy of
both intermediate- and high-degree (20< l <600) solar p-mode
oscillations which have been corrected to first order for the combined
effects of atmospheric seeing, image motion due to imperfect tracking,
and the point spread function of our optics. These power and energy
estimates have been obtained from an average of 20 separate zonal l -
n power spectra, which were obtained from observations obtained at the
60-Foot Solar Tower of the Mt. Wilson Observatory between July 1 and 20,
1988. The raw total power values were obtained from a least-squares
fitting of Lorentzian profiles to the p-mode ridges in the average
zonal power spectrum. As an initial method of correcting the observed
power levels, we adopted the procedure described by Kaufman (1988)
and deconvolved measurements of the observed limb profiles from one
of our images using two slightly different theoretical unblurred limb
profiles in order to obtain two estimates of the modulation transfer
function (mtf) of our experiment. The corrected power values which
resulted show systematic variations with both frequency and degree
which are similar to those obtained by Kaufman. For example, between
l = 100 and 600 our corrected power values drop by a factor of at
least 4.5, although the magnitude of our correction becomes less
certain as the degree is increased above 300. We also convert these
power values into estimates of the total energy of the modes to show
that the modal energies decrease by a factor of at least 15 over the
same range in l. Even given the uncertainty of our correction at the
higher degrees, the consistency of the l-dependent decrease in the
modal energies with similar results by Kaufman (1990) suggests that,
at least above l = 100, the modes are not in energy equipartition with
turbulent convective eddies.
Title: Further Evidence for Radial Variations in the Solar Equatorial
Angular Velocity Profile
Authors: Rhodes, Edward J.; Cacciani, Alessandro; Korzennik, Sylvain
G.; Ulrich, Roger K.
Bibcode: 1991LNP...388..285R
Altcode: 1991ctsm.conf..285R
One year ago we presented evidence that the rotationally-induced
frequency splittings of intermediate- and high-degree sectoral p-mode
oscillations vary systematically as a function of the degree, l,
of the modes (Rhodes, Cacciani, and Korzennik, 1989. Recently, we
confirmed the results presented there in three different ways. First,
we extended our earlier 5-day sequence of Dopplergrams to one of 20 days
which ran from July 1 through 20, 1988. We then repeated our earlier
cross-correlation analysis using the intrinsically higher frequency
resolution sectoral power spectra which resulted from the longer
data string. This analysis also showed the same l-dependence of the
frequency splittings which we had found in our earlier work. Second,
we computed a separate pair of 1024-minute long sectoral power
spectra for each of the 20 days and then averaged the 20 prograde
and 20 retrograde spectra into two average sectoral spectra. We
next computed the frequencies of the centers of both the prograde
and retrograde sectoral ridges at each even-l by fitting Lorentzian
profiles using a standard non-linear least-squares method and we then
simply subtracted the central frequencies of the corresponding prograde
and retrograde ridges at those same values of l. The splittings which
resulted from averaging these frequency differences over both l and
the radial overtone, n, showed the same l-dependence as did those
obtained from the cross-correlation analysis. Thirdly, we computed
Legendre coefficient expansions to the m - v frequency shifts of both
the high- and low-resolution tesseral power spectra. We then normalized
the sums of the odd Legendre expansion coefficients to obtain additional
estimates of the sectoral frequency splittings. Finally, we carried out
an inversion of the sectoral frequency splittings. This inversion shows
a rapid rise in the solar equatorial angular velocity from its surface
value to a value of 476 nHz at a depth of 0.07 to 0.08 solar radii below
the photosphere. The inverted profile also shows that the inner half
of the solar convection zone may be rotating at the magnetic feature
rate and that the equatorial angular velocity decreases inwardly of
the base of the convection zone to a depth of at least 0.50 solar radii.
Title: Further Evidence for Radial Variations in the Solar Equatorial
Angular Velocity Profile
Authors: Rhodes, E. J., Jr.; Cacciani, A.; Korzennik, S.; Ulrich, R. K.
Bibcode: 1990BAAS...22..896R
Altcode:
No abstract at ADS
Title: Depth and Latitude Dependence of the Solar Internal Angular
Velocity
Authors: Rhodes, Edward J., Jr.; Cacciani, Alessandro; Korzennik,
Sylvain; Tomczyk, Steven; Ulrich, Roger K.; Woodard, Martin F.
Bibcode: 1990ApJ...351..687R
Altcode:
One of the design goals for the dedicated helioseismology observing
state located at Mount Wilson Observatory was the measurement of the
internal solar rotation using solar p-mode oscillations. In this paper,
the first p-mode splittings obtained from Mount Wilson are reported
and compared with those from several previously published studies. It
is demonstrated that the present splittings agree quite well with
composite frequency splittings obtained from the comparisons. The
splittings suggest that the angular velocity in the solar equatorial
plane is a function of depth below the photosphere. The latitudinal
differential rotation pattern visible at the surface appears to persist
at least throughout the solar convection zone.
Title: Solar magnetic fields measurements with a magneto-optical
filter.
Authors: Cacciani, A.; Ricci, D.; Rosati, P.; Rhodes, E. J.; Smith,
E.; Tomczyk, S.; Ulrich, R. K.
Bibcode: 1990NCimC..13..125C
Altcode:
The presence of a magnetic field at different levels inside the Sun
has crucial implications for helioseismology. The solar oscillation
observing program carried out since 1983 at Mt. Wilson with Cacciani
magneto-optical filter (MOF) has recently been modified to acquire
full-disk magnetograms with 2 arcsec spatial resolution. The authors
present a method for the correct determination of magnetic maps
which are free of contamination by velocity signal. They show that no
cross-talk exists between the Doppler and Zeeman shifts of the Na D
lines, provided that instrumental polarization effects are taken into
account. They also used the observed line-of sight photospheric field
to map the vector field in the inner corona, above active regions,
in the "current free" approximation.
Title: Preparation of a second station for the measurement of solar
oscillations of low degree "l".
Authors: Cacciani, A.; Fabbri, F.; Ricci, D.; Rosati, P.; Marquedant,
R.; Smith, E.
Bibcode: 1990NCimC..13..163C
Altcode:
An observing station to detect low-degree global solar oscillations
is already operational at JPL. A second station for continuative
measurements of such oscillations has recently been installed and
successfully tested in Rome. The high transmission and stability of
the magneto-optical filter (MOF) coupled with the lock-in amplifier
technique allow analog and real time detection of oscillation modes
with a noise level of only a few cm/s. The authors show observing
runs and estimates of the signal-to-noise ratio in time and frequency
domains. Routine observations will establish whether the MOF sensitivity
and stability is suitable to detect stellar oscillations.
Title: Observations of Vector Magnetic Fields with a Magneto-Optic
Filter
Authors: Cacciani, Alessandro; Varsik, John; Zirin, Harold
Bibcode: 1990SoPh..125..173C
Altcode:
We describe the use of the magneto-optic filter (MOF) to observe solar
magnetic fields in the potassium line at 7699 Å. The filter has been
used in the Big Bear video-magnetograph since 23 October. It gives a
high sensitivity and dynamic range for longitudinal magnetic fields
and enables us to measure transverse magnetic fields using the sigma
component. Examples of the observations are presented.
Title: Contribution of High-Degree Frequency Splittings to the
Inversions of the Solar Rotation Rate
Authors: Korzennik, Sylvain G.; Cacciani, Alessandro; Rhodes, Edward
J.; Ulrich, Roger K.
Bibcode: 1990LNP...367..341K
Altcode: 1990psss.conf..341K
We present the contribution of high degree rotational splittings to
the inversion of the internal rotation rate around the equator. The
extention of the input data set to l of 500, allow us to improve the
resolution of the solution mainly in the outermost 15% of the solar
radius. The rotational profile obtained in the regions below the
surface leads to an attractive picture that could reconcile different
non-seismic estimates of the surface rotation rate.
Title: Evidence for Radial Variations in the Equatorial Profile of
the Solar Internal Angular Velocity
Authors: Rhodes, Edward J.; Cacciani, Alessandro; Korzennik, Sylvain G.
Bibcode: 1990LNP...367..163R
Altcode: 1990psss.conf..163R
We present evidence that the solar internal angular velocity, at least
as measured in the equatorial plane, shows systematic radial variations
in the outer half (by radius of the solar interior. Specifically,
we employ the rotationally-induced frequency splittings of both high-
and intermediate-degree sectoral p-mode oscillations to demonstrate
that the internal angular velocity rises inwardly from the observed
spectroscopic rotation rate of the photospheric gas to a higher value
that is at least equal to the observed rotation rate of sunspots, if
not higher, in the outer third of the convection zone before decreasing
inward of the convection zone to a value which is at least two percent
below the photospheric gas rotation rate. By making the assumption that
the observed splittings are sensitive to solar rotation at the midpoints
of the p-mode eigenfunctions we obtain an angular velocity profile which
rises from 452 nHz at the photosphere to 462 nHz at a depth of about
five percent of the solar radius below the photosphere. A comparison of
this inferred angular velocity profile with that obtained from a formal
inversion of these splittings (which is reported elsewhere in these
proceedings by Korzennik et al.) suggests that the angular velocity
might actually exceed the magnetic rotation rate over much of the
convection zone before decreasing inwardly toward the center of the sun.
Title: An experiment to measure the solar ℓ = 1 rotational
frequency splitting
Authors: Cacciani, A.; Paverani, E.; Ricci, D.; Rosati, P.; Marquedant,
R. M.; Smith, E. J.; Tomczyk, S.
Bibcode: 1990LNP...367..197C
Altcode: 1990psss.conf..197C
To date, only integrated light experiments have attained the high
signal-to-noise ratio and frequency resolution necessary to measure
the rotational frequency splitting of low degree solar p-modes. These
experiments, however, are limited by the finite mode linewidths coupled
with the inability of non-imaging experiments to unambiguously separate
prograde and retrograde modes. In particular, the separation of the
prograde and retrograde mode frequencies of the very important = 1
spherical harmonic, dictates that the experiment have the capability
to coarsely resolve the eastern from the western hemisphere of the
solar disk. Initial attempts to attain the desired image resolution
by masking the solar image at the focal plane of the telescope and
chopping the two hemispheres on the detector have been unsuccessful
due to the high velocity noise introduced by the solar rotation
through image motions and guiding instabilities. In this paper we
present the concept of what we call spectroscopic masking, which
provides the ability to filter oscillation modes spectroscopically,
and without the need to image the Sun. This results in an optical
configuration which is insensitive to image motions and guiding errors
while still providing adequate spatial resolution to separate prograde
and retrograde = 1 modes. A conceptual study will be presented along
with a test observing run showing the quality of the achievable data.
Title: Evidence for Degree-Dependent Variations in the Frequency
Splittings of Solar Sectoral p-Modes
Authors: Rhodes, E. J., Jr.; Cacciani, A.; Korzennik, S.
Bibcode: 1989BAAS...21..831R
Altcode:
No abstract at ADS
Title: Spectrum Lifetime, and Rotation Rate of Supergranules
Authors: Hathaway, D. H.; Rhodes, E. J., Jr.; Cacciani, A.;
Korzennik, S.
Bibcode: 1989BAAS...21..829H
Altcode:
No abstract at ADS
Title: Integrated solar disk oscillation measurements using the
magneto-optical filter. Tests with a two station network.
Authors: Cacciani, Alessandro; Rosati, P.; Ricci, D.; Marquedant,
R.; Smith, E.
Bibcode: 1988ESASP.286..181C
Altcode: 1988ssls.rept..181C
The magneto optical filter (MOF) has been extensively used to get high
and intermediate l-modes of solar oscillations. For very low l-modes
(0 - 4) the imaging capability of the MOF is still attractive since
it allows a pixel by pixel intensity normalization. However, a crude
attempt to get very low l power spectra from dopplergrams obtained
at Mt. Wilson gave noisy results. This means that a careful analysis
of all the factors potentially affecting high resolution dopplergrams
should be accomplished. In order to better investigate this problem,
we have considered a non-imaging channel using the lock-in amplifier
technique. Two systems are now operational, one at JPL and the other
at University of Rome. Observations are in progress. They will be
used to discuss the MOF stability, the noise level, and the possible
application in asteroseismology.
Title: Measurement of the rotational frequency splitting of the solar
five-minute oscillations from magneto-optical filter observations.
Authors: Tomczyk, Steven; Cacciani, Alessandro; Korzennik, Sylvain G.;
Rhodes, Edward J., Jr.; Ulrich, Roger K.
Bibcode: 1988ESASP.286..141T
Altcode: 1988ssls.rept..141T
Observations of the solar five-minute oscillations in the photospheric
velocity field were obtained during the summer of 1984 at the 60-foot
solar tower of the Mt. Wilson Observatory with a magneto-optical
filter. The magneto-optical filter employs magneto-optical effects in
an atomic vapor to isolate narrow bandpasses in alternate wings of
a spectral line. Time series of full disk velocity images having a
resolution of about 10 arcseconds and a noise level of 15 m/s/pixel
were obtained on 92 days between the months of May and September of
1984. A subset of two time series from this data of 16 and 19 days
duration having a total of 25744 doppler images were analyzed to provide
estimates of the rotational frequency splitting for spherical harmonic
degrees between 5 and 120. The results of this analysis indicate a
decrease in the rate of solar rotation with increasing depth inside
the sun. Also, a decrease in the rate of differential rotation with
increasing depth is observed.
Title: A prototype stellar photometer for magnetic field and Doppler
measurements.
Authors: Cacciani, Alessandro; Catalano, S.; Rodono, M.; Costa, G.
Bibcode: 1988ESASP.286..601C
Altcode: 1988ssls.rept..601C
A stellar photometer is in preparation as a joint project of the
University of Rome and the Astrophysical Observatory of Catania. It is
based on a suitable version of the Magneto-Optical Filter (MOF). The
aim is to detect magnetic and velocity signals on stars. The basic
idea is shown in the figure. The photometer is able to maximize the
collection of photons. As far as the magnetic field measurement is
concerned the authors consider only the transverse component of the
magnetic field that should provide detectable U and Q Stokes parameter
(linear polarization). Tests on the sun are part of this program.
Title: Inversion of the solar rotation rate versus depth and latitude.
Authors: Korzennik, Sylvain G.; Cacciani, Alessandro; Rhodes, Edward
J., Jr.; Tomczyk, Steven; Ulrich, Roger K.
Bibcode: 1988ESASP.286..117K
Altcode: 1988ssls.rept..117K
The authors have used three different inversion techniques to compute
the internal solar rotation rate from several sets of n-averaged
frequency splittings. They have used an iterative variation of the
spectral expansion method, the optimal averaging kernel method and
a piecewise constant constrained least square method to invert the
data. Each computation was carried out independently. While they
present similar trends, each of the solutions differs in detail. A
consistent feature in all the inversions is the disappearance of
differential rotation below the base of the convection zone. Also,
a strong differential signature in the deeper part of the convection
zone is present in most of the solutions. A slow decrease of the
rotation rate with depth for the equatorial and mid-latitude curves
is significant in the spectral expansion and the least square results
but only marginally apparent in the averaging kernel results.
Title: Acquisition and reduction procedures for MOF
Doppler-magnetograms.
Authors: Cacciani, Alessandro; Ricci, D.; Rosati, P.; Rhodes, Edward
J., Jr.; Smith, E.; Tomczyk, Steven; Ulrich, Roger K.
Bibcode: 1988ESASP.286..185C
Altcode: 1988ssls.rept..185C
The authors analyse defects occurred on the MOF first magnetograms,
particularly they discuss the problem of the apparent contamination
between velocity and magnetic fields. They find that a correct
acquisition and reduction procedure gives cleaner results. The authors
also suggest a new vector magnetograph and compute the vector field
at coronal levels using one MOF longitudinal magnetogram.
Title: Radial and latitudinal gradients in the solar internal
angular velocity.
Authors: Rhodes, Edward J., Jr.; Cacciani, Alessandro; Korzennik,
Sylvain G.; Tomczyk, Steven; Ulrich, Roger K.; Woodard, Martin F.
Bibcode: 1988ESASP.286...73R
Altcode: 1988ssls.rept...73R
The authors recently presented the results of an analysis of the
frequency splittings of intermediate-degree (3 < degree ≤ 170)
p-mode oscillations which were obtained from a 16-day subset of our 1984
Mt. Wilson 60-foot tower observations. These results showed evidence
for both radial and latitudinal gradients in the solar internal
angular velocity. In particular, the results indicated that, from
0.6 Rsun to 0.95 Rsun,
the solar internal angular velocity increases systematically from
440 to 463 nHz, corresponding to a positive radial gradient of ≍66
nHz/Rsun for that portion of the solar interior. A
previous analysis indicated that the latitudinal differential rotation
gradient which is seen at the solar surface persists throughout
the convection zone, although there was some indication that the
differential rotation might disappear entirely below the base of the
convection zone. Here the authors extend their previous analysis to
include comparisons with additional observational studies and they
also present comparisons between our earlier results and the results
of additional inversions of several of the observational datasets. All
of these comparisons reinforce the previous conclusions regarding
the existence of radial and latitudinal gradients in the internal
angular velocity.
Title: Initial high-degree p-mode frequency splittings from the 1988
Mt. Wilson 60-foot tower solar oscillation program.
Authors: Rhodes, Edward J., Jr.; Cacciani, Alessandro; Korzennik,
Sylvain G.
Bibcode: 1988ESASP.286...81R
Altcode: 1988ssls.rept...81R
The authors present here the initial frequency splitting results
of solar p-mode oscillations which they have obtained from their
1988 helioseismology at the Mt. Wilson Observatory. These frequency
splittings correspond to the rotational splittings of sectoral harmonics
which range in degree between 10 and 598. They were obtained from a
cross-correlation analysis of the prograde and retrograde portions
of a two-dimensional (l-ν) power spectrum. This power spectrum was
computed from an eight-hour sequence of full-disk Dopplergrams which
were obtained on July 2, 1988, at the 60-foot tower telescope with
a Na magneto-optical filter and a 1024×1024 pixel CCD camera. These
frequency splittings have an inherently larger scatter than did the
splittings obtained from earlier 16-day power spectra. Consequently,
the best one can say now is that these splittings are consistent with an
internal solar rotational velocity which is independent of radius along
the equatorial plane. The normalized frequency splittings averaged
449±3 nHz, a value which is very close to the observed equatorial
rotation rate of the photospheric gas of 451.7 nHz.
Title: Full-disk magnetograms obtained with a NA magneto-optical
filter at the Mount Wilson Observatory
Authors: Rhodes, Edward J., Jr.; Cacciani, Alessandro; Garneau, Glenn;
Misch, Tony; Progovac, Dusan; Shieber, Tom; Tomczyk, Steve; Ulrich,
Roger K.
Bibcode: 1988fnsm.work...33R
Altcode:
The first full-disk magnetograms to be obtained with the Na
magneto-optical filter (MOF) which is located at the 60 foot solar
tower of the Mount Wilson Observatory are presented. This MOF was
employed as a longitudinal magnetograph on June 18, 19, and July 1,
1987. On those three days the MOF was combined with a large format
(1024 x 1024 pixel) virtual phase change coupled device camera and
a high-speed data acquisition system. The combined system was used
to record both line-of-sight magnetograms and Dopplergrams which
covered the entire visible solar hemisphere. The pixel size of these
magnetograms and Dopplergrams was 2.3 arcseconds. On each of the three
days a time series of nine pairs of magnetograms and Dopplergrams
was obtained at the rate of one pair every two minutes. On the same
three day longitudinal magnetograms have one arcsecond pixels were
obtained with the vacuum telescope at Kitt Peak. The MOF and vacuum
tower magnetograms were compared at both the JPL Multi-Mission Image
Processing Laboratory and at USC and have found the two sets of images
to be well correlated both in spatial distribution and strength of the
measured magnetic field. The simultaneously-obtained MOF Dopplergrams to
remove the crosstalk which was present between the Doppler and Zeeman
shifts of the NaD lines from the magnetograms from all three days and
will also describe recent improvements to the system which allowed the
obtaining of full-disk magnetograms as rapidly as one every 25 seconds.
Title: Video Movies of 1987 Magneto-Optical Filter Observations
Recorded with the JPL 1024 x 1024 CCD Camera
Authors: Rhodes, E. J., Jr.; Cacciani, A.; Garneau, G.; Gorzennik,
S.; Smith, D.
Bibcode: 1988BAAS...20..678R
Altcode:
No abstract at ADS
Title: Full-Disk Magnetograms Obtained with a Na Magneto-Optical
Filter at the Mount Wilson Observatory
Authors: Rhodes, E. J.; Cacciani, A.; Garneau, G.; Misch, T.; Progovac,
D.; Shieber, T.; Tomczyk, S.; Ulrich, R. K.
Bibcode: 1988BAAS...20..744R
Altcode:
No abstract at ADS
Title: On the Constancy of Intermediate-Degree p-Mode Frequencies
during the Declining Phase of Solar Cycle 21
Authors: Rhodes, Edward J., Jr.; Woodard, Martin F.; Cacciani,
Alessandro; Tomczyk, Steven; Korzennik, Sylvain G.; Ulrich, Roger K.
Bibcode: 1988ApJ...326..479R
Altcode:
A comparison of two sets of frequencies of intermediate-degree (6 ≤ l
≤ 89) solar p-mode oscillations obtained in late 1981 and in mid-1984
shows agreement at the level of 0.02 μHz, or better than one part in
105. In particular, the frequencies of 573 modes obtained
at the South Pole during 1981 December 24 - 25, (reported by Duvall,
Harvey, and Pomerantz in 1987) were compared with the frequencies of
the same modes as observed at the Mount Wilson Observatory 60 foot
Solar Tower from 1984 July 29 through August 13. It is concluded that
the data are consistent with no change in intermediate-degree p-mode
frequencies between late 1981 and mid-1985.
Title: Full-Disk Solar Dopplergrams Observed with a 1024X1024 Pixel
CCD Camera
Authors: Rhodes, E. J., Jr.; Cacciani, A.; Tomczyk, S.
Bibcode: 1988IAUS..123..471R
Altcode:
The authors present here the first full-disk solar Dopplergram obtained
with the new 1024×1024-pixel CCD camera which has recently been
installed at the 60 foot Tower Telescope of the Mt. Wilson Observatory.
Title: Measurements of Solar Internal Rotation Obtained with the
Mt-Wilson 60-FOOT Solar Tower
Authors: Rhodes, E. J., Jr.; Cacciani, A.; Woodard, M.; Tomczyk, S.;
Korzennik, S.; Ulrich, R. K.
Bibcode: 1988IAUS..123...41R
Altcode:
The authors have obtained estimates of the solar internal rotational
velocity from measurements of the frequency splittings of p-mode
oscillations. Specifically, they have analyzed a 10-day time series
of full-disk Dopplergrams obtained during July and August 1984 at the
60-Foot Tower Telescope of the Mt. Wilson Observatory.
Title: Constancy of Intermediate-degree p-Mode Frequencies During
the Declining Phase of Solar Cycle 21
Authors: Rhodes, E. J., Jr.; Woodard, M. F.; Cacciani, A.; Tomczyk,
S.; Korzennik, S.; Ulrich, R. K.
Bibcode: 1987BAAS...19Q.933R
Altcode:
No abstract at ADS
Title: Angular Velocity of the Solar Interior Obtained by an
Asymptotic Inversion of P-Mode Frequency Shifts
Authors: Woodard, M. F.; Rhodes, E. J., Jr.; Tomczyk, S.; Korzennik,
S.; Cacciani, A.; Ulrich, R. K.
Bibcode: 1987BAAS...19..934W
Altcode:
No abstract at ADS
Title: A Magneto-Optical Filter for Solar Oscillation Measurements
Authors: Tomczyk, S.; Cacciani, A.; Rhodes, E. J., Jr.
Bibcode: 1987BAAS...19..701T
Altcode:
No abstract at ADS
Title: Estimates of the solar internal angular velocity obtained
with the Mt. Wilson 60-foot solar tower
Authors: Rhodes, Edward J., Jr.; Cacciani, Alessandro; Woodard,
Martin; Tomczyk, Steven; Korzennik, Sylvain; Ulrich, R. K.
Bibcode: 1987ASSL..137...75R
Altcode: 1987isav.symp...75R
Estimates are obtained of the solar internal angular velocity from
measurements of the frequency splittings of p-mode oscillations. A
16-day time series of full-disk Dopplergrams obtained during July and
August 1984 at the 60-foot tower telescope of the Mt. Wilson Observatory
is analyzed. Power spectra were computed for all of the zonal, tesseral,
and sectoral p-modes from l = 0 to 89 and for all of the sectoral
p-modes from l = 90 to 200. A mean power spectrum was calculated for
each degree up to 89. The frequency differences of all of the different
nonzonal modes were calculated for these mean power spectra.
Title: Full-disk solar dopplergrams observed with a one megapixel
CCD camera and sodium magnetooptical filter
Authors: Rhodes, Edward J., Jr.; Cacciani, Alessandro; Tomczyk, Steven
Bibcode: 1987ASSL..137...69R
Altcode: 1987isav.symp...69R
The paper presents here the first two full-disk solar Dopplergrams
obtained with the new 1024 x 1024-pixel CCD camera which has recently
been installed at the 60-Foot Tower Telescope of the Mt. Wilson
Observatory. These Dopplergrams have a spatial resolution of 2.2
arcseconds and were obtained in a total of one minute of time. The
Dopplergrams were obtained with a magnetooptical filter which was
designed to obtain images in the two Na D lines. The filter and the
camera were operated together as part of the development of a solar
oscillations imager experiment which is currently being designed at JPL
for the Joint NASA/ESA Solar and Heliospheric Observatory mission. Two
different images obtained by subtracting two pairs of the Dopplergrams
from the initial time series are also included.
Title: Evidence for Radial Gradients in the Solar Internal Rotational
Velocity
Authors: Rhodes, E. J., Jr.; Tomczyk, S.; Woodard, M. F.; Cacciani,
A.; Korzennik, S.; Ulrich, R. K.
Bibcode: 1986BAAS...18Q1010R
Altcode:
No abstract at ADS
Title: Applications of the magneto-optical filter to stellar pulsation
measurements
Authors: Rhodes, Edward J., Jr.; Cacciani, Alessandro; Tomczyk, Steven
Bibcode: 1986ASIC..169..359R
Altcode: 1986ssds.proc..359R
A proposed method of employing the Cacciani magneto-optical filter (MOF)
for stellar seismology studies is described. The method relies on the
fact that the separation of the filter bandpasses in the MOF can be
changed by varying the level of input power to the filter cells. With
the use of a simple servosystem the bandpass of a MOF can be tuned to
compensate for the changes in the radial velocity of a star introduced
by the orbital motion of the earth. Such a tuned filter can then be
used to record intensity fluctuations through the MOF bandpass over
an extended period of time for each given star. Also, the use of a two
cell version of the MOF makes it possible to alternately chop between
the bandpass located in the stellar line wing and a second bandpass
located in the stellar continuum. Rapid interchange between the two
channels makes it possible for atmospheric-introduced noise to be
removed from the time series.
Title: The 1984 solar oscillation program of the Mt. Wilson 60-foot
tower.
Authors: Rhodes, Edward J., Jr.; Cacciani, Alessandro; Tomczyk,
Steven; Ulrich, Roger K.
Bibcode: 1986ASIC..169..309R
Altcode: 1986ssds.proc..309R
The authors describe the instrumentation, data, and preliminary results
from the summer, 1984, solar oscillation observing program which
was carried out using the 60-foot tower telescope of the Mt. Wilson
Observatory.
Title: The effects of seeing on noise
Authors: Ulrich, R. K.; Rhodes, E. J., Jr.; Cacciani, A.; Tomczyk, S.
Bibcode: 1985sses.nasa..263U
Altcode:
The effect of the supergranulation velocity field combined with seeing
smearing of the solar image on the measurement of solar oscillations
is discussed. Depending on the nature of the observational velocity
determination scheme, the image motions can shift the background
velocity pattern and produce a source of noise that reduces the quality
of the observations. The magnitude of this effect is estimated and
observational results which are consistent with this estimate are
presented.
Title: The 1984 solar oscillation program of the Mount Wilson
60-foot tower
Authors: Rhodes, E. J., Jr.; Cacciani, A.; Tomczyk, S.; Ulrich, R. K.
Bibcode: 1985STIN...8612195R
Altcode:
The instrumentation, data, and preliminary results from the summer,
1984, solar oscillation observing program which was carried out
using the 60-foot tower telescope of the Mt. Wilson Observatory
are described. This program was carried out with a dedicated solar
oscillation observing system and obtained full-disk Dopplergrams every
40 seconds for up to 11 hours per day. Between June and September,
1984, observations were obtained with a Na magneto-optical filter on
90 different days. The data analysis has progressed to the point that
spherical harmonic filter functions were employed to generate a few
one-dimensional power spectra from a single day's observations.
Title: The magneto-optical filter, working principles and recent
progress.
Authors: Cacciani, A.; Rhodes, E. J., Jr.
Bibcode: 1984sses.nasa..115C
Altcode: 1984sss..conf..115C
The Magneto-Optical Filter is described which allows simultaneous
magnetic and velocity measurements (in both imaging and non-imaging
modes) without the need for a spectrograph. In this way the stability
and alignment problems of the spectrograph are completely overcome. Its
major advantages are: wavelength absolute reference and stability,
high signal to noise ratio and independence of the transmission
profile from the incidence angle of the solar beam. It is an imaging
instrument allowing high wave number analysis in the solar oscillation
spectrum and a continuous monitoring of the image position through the
chromospheric facular structures. The apparatus in use at Mt. Wilson
is assembled in a modular form. The most important part of it is a
glass cell containing the sodium vapor. The filter is easy to use but
the cell is not easy to construct in an optimal way. The technology is
in progress both to use Na and K together and to prevent the windows
from becoming coated during a long-term operation.
Title: Evaluation of a magneto-optical filter and a Fabry-Perot
interferometer for the measurement of solar velocity fields from
space.
Authors: Rhodes, E. J., Jr.; Cacciani, A.; Blamont, J.; Tomczyk, S.;
Ulrich, R. K.; Howard, R. F.
Bibcode: 1984sses.nasa..125R
Altcode: 1984sss..conf..125R
A program was developed to evaluate the performance of three
different devices as possible space-borne solar velocity field
imagers. Two of these three devices, a magneto-optical filter and
a molecular adherence Fabry-Perot interferometer were installed in
a newly-constructed observing system located at the 60-foot tower
telescope at the Mt. Wilson Observatory. Time series of solar
filtergrams and Dopplergrams lasting up to 10 hours per day were
obtained with the filter while shorter runs were obtained with the
Fabry-Perot. Two-dimensional k h-omega power spectra which
show clearly the well-known p-mode ridges were computed from the time
series obtained with the magneto-optical filter. These power spectra
were compared with similar power spectra obtained recently with the
13.7-m McMath spectrograph at Kitt Peak.
Title: Applications of the magneto-optical filter to stellar pulsation
measurements
Authors: Rhodes, E. J., Jr.; Cacciani, A.; Tomczyk, S.
Bibcode: 1984STIN...8612187R
Altcode:
A proposed method of employing the Cacciani magneto-optical filter (MOF)
for stellar seismology studies is described. The method relies on the
fact that the separation of the filter bandpasses in the MOF can be
changed by varying the level of input power to the filter cells. With
the use of a simple servosystem the bandpass of a MOF can be tuned to
compensate for the changes in the radial velocity of a star introduced
by the orbital motion of the Earth. Such a tuned filter can then be
used to record intensity fluctuations through the MOF bandpass over
an extended period of time for each given star. Also, the use of a two
cell version of the MOF makes it possible to alternately chop between
the bandpass located in the stellar line wing and a second bandpass
located in the stellar continuum. Rapid interchange between the two
channels makes it possible for atmospheric-introduced noise to be
removed from the time series.
Title: The effects of seeing on noise.
Authors: Ulrich, R. K.; Rhodes, E. J., Jr.; Cacciani, A.; Tomczyk, S.
Bibcode: 1984sses.nasa..263U
Altcode: 1984sss..conf..263U
The authors discuss the effect of the supergranulation velocity field
combined with seeing smearing of the solar image on the measurement
of solar oscillations. Depending on the nature of the observational
velocity determination scheme, the image motions can shift the
background velocity pattern and produce a source of noise that reduces
the quality of the observations. The authors give a rough estimate for
the magnitude of this effect and present observational results which
are consistent with this estimate.
Title: Observations of Solar Velocity Fields With Large-Format CCD
Cameras at the Mount Wilson Observatory
Authors: Rhodes, E. J., Jr.; Cacciani, A.; Tomczyk, S.; Ulrich, R. K.;
Dumont, P.; Howard, R. F.
Bibcode: 1984BAAS...16..979R
Altcode:
No abstract at ADS
Title: The Summer 1984 Solar Oscillation Program of the Mount Wilson
60-foot Solar Telescope
Authors: Tomczyk, S.; Rhodes, E. J., Jr.; Cacciani, A.; Ulrich, R. K.;
Howard, R. F.
Bibcode: 1984BAAS...16..978T
Altcode:
No abstract at ADS
Title: Magneto-Optical Filter Observations of Solar Oscillations at
the Mt. Wilson Observatory
Authors: Rhodes, E. J., Jr.; Cacciani, A.; Tomczyk, S.; Ulrich, R. K.;
Dumont, P.; Howard, R. F.
Bibcode: 1984BAAS...16..451R
Altcode:
No abstract at ADS
Title: A compact dopplergraph/magnetograph suitable for space-based
measurements of solar oscillations and magnetic fields
Authors: Rhodes, E. J., Jr.; Cacciani, A.; Tomczyk, S.; Ulrich, R. K.;
Blamont, J.; Howard, R. F.; Dumont, P.; Smith, E. J.
Bibcode: 1984AdSpR...4h.103R
Altcode: 1984AdSpR...4..103R
A compact Dopplergraph/magnetograph placed in a continuous solar-viewing
orbit will allow us to make major advancements in our understanding
of solar internal structure and dynamics. An international program
is currently being conducted at JPL and Mt. Wilson to develop such an
instrument. By combining a unique magneto-optical resonance filter with
CID and CCD cameras we have been able to obtain full- and partial-disk
Dopplergrams and magnetograms. Time series of the velocity images are
converted into k-ω power spectra which show clear- the solar nonradial
p-mode oscillations. Magnetograms suitable for studying the long-term
evolution of solar active regions have also been obtained with this
instrument. A flight instrument based on this concept is being studied
for possible inclusion in the SOHO mission.
Title: Searching for l = 1 modes of solar oscillations.
Authors: Cacciani, A.; Croce, V.; Fortini, T.; Torelli, M.
Bibcode: 1981SoPh...74..543C
Altcode:
An instrument to measure the non-full-disk low-order solar oscillations
that uses a magneto-optical filter in Na-D lines is described. It
has the advantage, over the resonant cells used by other observers,
that it gives an image of the Sun and a higher photonic flux.
Title: Magnetograph Based on Magneto-Optical Effects
Authors: Cacciani, A.
Bibcode: 1981SSRv...29..403C
Altcode:
Simple and low-cost instruments, reduced in dimensions and, possibly,
weight, are always welcome and very convenient, when they are intended
for space applications.
Title: Two-dimensional visualization of 5-minute solar oscillations
Authors: Cacciani, A.; Croce, V.; Fortini, T.; Torelli, M.
Bibcode: 1980MmSAI..51..621C
Altcode:
The use of a spectrophotometric apparatus to obtain instantaneous
two-dimensional images of the solar disk with which to monitor solar
oscillations of period approximately 5 minutes is discussed. The system
used consists of a selective filter mounted in a spectrograph, which is
capable of imaging a 400 x 400 arcsec area with a temporal resolution of
1.45 sec and a seeing-limited spatial resolution. The two-dimensional
system has the advantages of a lack of disalignment effects and ease
of solar tracking over the 5-min oscillation period with respect to
conventional one-dimensional spectrophotometric methods. The system
has been used to record oscillations in Na emission over the course
of three hours.
Title: Sodium Light Flare Observations - Mcmath 13043 - 1974JUL
Authors: Cacciani, A.; Fortini, T.; Torelli, M.
Bibcode: 1980SoPh...67..311C
Altcode:
We extract a temporal sequence of the 13∶55 UT 4 July, 1974 event
from monochromatic filtergrams in Na light obtained in Rome on the
McMath region No. 13043-July 1974. It is, to our knowledge, the first
temporal sequence of a flare seen through a narrow-band filter (80 mÅ)
in the Na-D lines. Due to the properties of Na filtergrams we could
also derive quite easily the exact relative position among sunspots,
magnetic fields and flare-knots. The last result is indeed a very useful
tool when studying an active region. For the McMath No. 13043 we were
able to infer some interesting remarks about the magnetic pattern at
the flaring site.
Title: Instantaneous probability density function and the
velocity-amplitudes in the five minutes oscillation in the sun
Authors: Cacciani, A.; Fofi, M.
Bibcode: 1980MmSAI..51..145C
Altcode:
No abstract at ADS
Title: The Magneto-Optical Filter. II. Velocity Field Measurements
Authors: Cacciani, A.; Fofi, M.
Bibcode: 1978SoPh...59..179C
Altcode:
In this paper we describe a filter which utilizes magneto-optical
effects for velocity fields measurements. The working principle
of the instrument is described and its transmission profiles are
given. Velocitygrams are shown of the five minutes oscillations (FMO)
and the results compared with the expected (theoretical) signal from
the instrument. We found a Vrms of 400 m s−1
for the FMO.
Title: Emissione dei flares in luce di sodio e posizione relativa
ai campi magnetici.
Authors: Cacciani, A.
Bibcode: 1977MmSAI..48..210C
Altcode:
No abstract at ADS
Title: Sodium-line emission in flares and source position relative
to magnetic fields
Authors: Cacciani, A.
Bibcode: 1977MmSAI..48..201C
Altcode:
The paper reviews the technology and results of the sodium D-line
observation of solar flares and the position of the source with
respect to magnetic field structure. A magnetooptical filter for
obtaining D-line spectrograms is described, which operates in three
modes. Consideration is then given to characteristic aspects of flare
observation, with emphasis placed on light curves and the sequence of
flare photography. Ways in which the obtained filtergrams can be used
to study the magnetic field structure in an active region are discussed.
Title: Errata: "The magneto-optical filter. I: Preliminary
observations in Na D lines" [Sol. Phys., Vol. 44, p. 509 - 518
(1975)].
Authors: Agnelli, G.; Cacciani, A.; Fofi, M.
Bibcode: 1976SoPh...46..272A
Altcode:
No abstract at ADS
Title: The Magneto-Optical Filter. I: Premilinary Observations in
Na D Lines
Authors: Agnelli, G.; Cacciani, A.; Fofi, M.
Bibcode: 1975SoPh...44..509A
Altcode:
Transmission curves and theoretical calculi of the magneto-optical
filter, designed and built by the authors, are shown together with
some observed transmission spectra. At present the filter has a total
halfwidth of ≈80må; and the maximum transmission is 25%. From the
analysis of the theoretical curves and from the observed spectra,
we deduced the possibility of making up a filter with a very narrow
passband (less than 30må) and a very high transmission (up to
nearly 100% apart from losses arising from the glass cell, lenses
and polarizers).
Title: La struttura delle stelle E dell'universo.
Authors: Cacciani, Alessandro
Bibcode: 1973sdse.book.....C
Altcode: 1973QB801.C15......
No abstract at ADS
Title: Solar phenomena.
Authors: Cimino, M.; Torelli, M.; Cacciani, A.; Croce, V.; Flamini,
R.; Bartolini, U.
Bibcode: 1972OARMB.169.....C
Altcode:
No abstract at ADS
Title: Solar phenomena.
Authors: Cimino, M.; Torelli, M.; Cacciani, A.; Croce, V.; Flamini,
R.; Bartolini, U.
Bibcode: 1972OARMB.167.....C
Altcode:
No abstract at ADS
Title: A Complete Stokes-Meter
Authors: Cacciani, A.; Fofi, M.
Bibcode: 1971SoPh...19..270C
Altcode:
A new polarimeter is described which allows the simultaneous
determination of the four Stokes parameters analysing the electric
signal both in frequency and phase. The signal consists of two
frequencies and 2. From the 2 component the amount and the azimuth
of linearly polarized light is obtained by using a two-phase lock-in
amplifier (or two separate amplifiers). From the component the circular
polarization is obtained. Instrumental and spurious effects, caused
by rotating elements, are avoided. Magnetographic applications in
solar physics and improvements as compared to previous magnetographs
are suggested.
Title: A Short Report on the Magnetic Beam Absorption Filter Research
at the Rome Astronomical Observatory
Authors: Cacciani, A.; Cimino, M.; Fofi, M.
Bibcode: 1971IAUS...43...94C
Altcode:
No abstract at ADS
Title: Solar phenomena.
Authors: Cimino, M.; Torelli, M.; Cacciani, A.; Croce, V.; Flamini,
R.; Bartolini, U.
Bibcode: 1971OARMB.156.....C
Altcode:
No abstract at ADS
Title: Solar phenomena.
Authors: Cimino, M.; Torelli, M.; Cacciani, A.; Croce, V.; Flamini,
R.; Bartolini, U.
Bibcode: 1971OARMB.163.....C
Altcode:
No abstract at ADS
Title: Some Developments of the Magnetic Beam Absorption Filter
Authors: Cimino, M.; Cacciani, A.; Fofi, M.
Bibcode: 1970SoPh...11..319C
Altcode:
In the present paper some experimental arrangements are shown which
utilize the magnetic filter described by Cimino et al. (1968). For a
single cell we have elaborated an elementary theory in the following
cases: (i) absorption by an atomic beam in a uniform magnetic field
(i.e. pure damping profile); (ii) atomic beam in a non-uniform magnetic
field; (iii) vapours in a uniform magnetic field (i.e. gaussian
distribution); (iv) vapours in a non-uniform magnetic field.
Title: Solar phenomena.
Authors: Cimino, M.; Torelli, M.; Bartolini, U.; Cacciani, A.; Croce,
V.; Flamini, R.
Bibcode: 1970OARMB.151.....C
Altcode:
No abstract at ADS
Title: Un tipo di polarimetro privo di elementi ruotanti.
Authors: Cacciani, A.
Bibcode: 1969RSAI...12...20C
Altcode:
No abstract at ADS
Title: Un tipo di polarimetro privo di elementi ruotanti
Authors: Cacciani, A.
Bibcode: 1969sai....12...20C
Altcode:
No abstract at ADS
Title: An Instrument to measure Solar Magnetic Fields by an
Atomic-Beam Method
Authors: Cimino, M.; Cacciani, A.; Sopranzi, N.
Bibcode: 1968SoPh....3..618C
Altcode:
Using the atomic-beam technique in absorption, a new kind of very
narrow-passband filter is obtained, which may also be used as a
high-resolution spectrograph and as a `Babcock window' for detecting
solar magnetic fields without a spectrograph.
Title: Strumentazione dell'Osservatorio di M. Mario in Roma per la
misura dei campi magnetici deboli del sole
Authors: Cacciani, A.
Bibcode: 1968sai....11..106C
Altcode:
No abstract at ADS