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Author name code: delache
ADS astronomy entries on 2022-09-14
author:Delache, Philippe
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Title: Estimating Long-Term Solar Irradiance Variability: A New
Approach
Authors: Vigouroux, Anne; Pap, Judit M.; Delache, Philippe
1997SoPh..176....1V Altcode:
The detection of solar irradiance variations (both bolometric and at
various wavelengths) by satellite-based experiments during the last
one-and-a-half decades stimulated modeling efforts to help identify
their causes and to provide estimates of irradiance data for those time
intervals when no satellite observations exist. In this paper we present
estimates of the long-term irradiance changes developed with Fourier
and wavelet transforms. The month-to-month irradiance variations,
after removing the solar cycle related long-term changes, are studied
with the cross-correlation technique. Results of the analysis reveal
a significant phase shift at 3 months between the full-disk magnetic
field strength and total solar and UV irradiance, with irradiance
leading the magnetic field variability. In addition to this time
delay between the changes in solar irradiance and the magnetic field,
a 10-month phase shift has been found between the UV flux at 280 nm and
total solar irradiance corrected for sunspot darkening. The existence
of these phase shifts suggests the possibility of a coupling between the
physical processes taking place below, in, and above the photosphere.
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Title: Study of the Distribution of Daily Fluctuations in Observed
Solar Irradiances and Other Full-Disk Indices of Solar Activity
Authors: Pap, Judith M.; Vigouroux, Anne; Delache, Philippe
1996SoPh..167..125P Altcode:
Analyses based on irradiance observations from space within the last
one and a half decades have discovered variations in the entire
solar spectrum and at UV wavelengths on time scales of minutes to
decades. In this paper we analyze the distribution of the measuring
uncertainties and daily fluctuations in total solar irradiance measured
by the Nimbus-7/ERB and SMM/ACRIM I radiometers as a function of solar
cycle. Changes in solar total irradiance and its surrogates shorter
than the solar rotation have also been considered as `noise' and have
been removed from the data. Our results show that the noise (both
instrumental and solar noise) changes as a function of the solar cycle,
being higher during high solar activity conditions. The analysis of the
scatter plot diagrams between the data and their standard deviation,
the so-called `dispersion diagrams', provides a useful tool to estimate
and predict the time of solar maximum and minimum activity conditions.
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Title: VIRGO: Experiment for Helioseismology and Solar Irradiance
Monitoring
Authors: Fröhlich, Claus; Romero, José; Roth, Hansjörg; Wehrli,
Christoph; Andersen, Bo N.; Appourchaux, Thierry; Domingo, Vicente;
Telljohann, Udo; Berthomieu, Gabrielle; Delache, Philippe; Provost,
Janine; Toutain, Thierry; Crommelynck, Dominique A.; Chevalier,
André; Fichot, Alain; Däppen, Werner; Gough, Douglas; Hoeksema,
Todd; Jiménez, Antonio; Gómez, Maria F.; Herreros, José M.; Cortés,
Teodoro Roca; Jones, Andrew R.; Pap, Judit M.; Willson, Richard C.
1995SoPh..162..101F Altcode:
The scientific objective of the VIRGO experiment (Variability of solar
IRradiance and Gravity Oscillations) is to determine the characteristics
of pressure and internal gravity oscillations by observing irradiance
and radiance variations, to measure the solar total and spectral
irradiance and to quantify their variability over periods of days to
the duration of the mission. With these data helioseismological methods
can be used to probe the solar interior. Certain characteristics of
convection and its interaction with magnetic fields, related to, for
example, activity, will be studied from the results of the irradiance
monitoring and from the comparison of amplitudes and phases of the
oscillations as manifest in brightness from VIRGO, in velocity from
GOLF, and in both velocity and continuum intensity from SOI/MDI. The
VIRGO experiment contains two different active-cavity radiometers for
monitoring the solar `constant', two three-channel sunphotometers (SPM)
for the measurement of the spectral irradiance at 402, 500 and 862 nm,
and a low-resolution imager (LOI) with 12 pixels, for the measurement
of the radiance distribution over the solar disk at 500 um. In this
paper the scientific objectives of VIRGO are presented, the instruments
and the data acquisition and control system are described in detail,
and their measured performance is given.
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Title: Global Oscillations at Low Frequency from the SOHO Mission
(GOLF)
Authors: Gabriel, A. H.; Grec, G.; Charra, J.; Robillot, J. -M.; Roca
Cortés, T.; Turck-Chièze, S.; Bocchia, R.; Boumier, P.; Cantin, M.;
Cespédes, E.; Cougrand, B.; Crétolle, J.; Damé, L.; Decaudin, M.;
Delache, P.; Denis, N.; Duc, R.; Dzitko, H.; Fossat, E.; Fourmond,
J. -J.; García, R. A.; Gough, D.; Grivel, C.; Herreros, J. M.;
Lagardère, H.; Moalic, J. -P.; Pallé, P. L.; Pétrou, N.; Sanchez,
M.; Ulrich, R.; van der Raay, H. B.
1995SoPh..162...61G Altcode:
The GOLF experiment on the SOHO mission aims to study the internal
structure of the sun by measuring the spectrum of global oscillations in
the frequency range 10<SUP>−7</SUP> to 10<SUP>−2</SUP> Hz. Bothp
andg mode oscillations will be investigated, with the emphasis on
the low order long period waves which penetrate the solar core. The
instrument employs an extension to space of the proven ground-based
technique for measuring the mean line-of-sight velocity of the viewed
solar surface. By avoiding the atmospheric disturbances experienced
from the ground, and choosing a non-eclipsing orbit, GOLF aims to
improve the instrumental sensitivity limit by an order of magnitude
to 1 mm s<SUP>−1</SUP> over 20 days for frequencies higher than
2.10<SUP>−4</SUP> Hz. A sodium vapour resonance cell is used in
a longitudinal magnetic field to sample the two wings of the solar
absorption line. The addition of a small modulating field component
enables the slope of the wings to be measured. This provides not only
an internal calibration of the instrument sensitivity, but also offers a
further possibility to recognise, and correct for, the solar background
signal produced by the effects of solar magnetically active regions. The
use of an additional rotating polariser enables measurement of the
mean solar line-of-sight magnetic field, as a secondary objective.
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Title: Remarques sur la définition et la mise en œvre d'un plan
d'action pour l'astronomie.
Authors: Delache, P.
1995JAF....47...15D Altcode:
No abstract at ADS
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Title: A New TEchnology Network for Asteroseismology - A.N.T.E.N.A.
Authors: Roca Cortes, T.; Belmonte, J. A.; Delache, P.; Michel, E.;
Frandsen, S.; Schmider, F. X.; Auvergne, M.; Fossat, E.; Vidal, I.;
Kjeldsen, H.; Douglas, N.; Lelievre, G.; Chevreton, M.; Vauclair,
G.; Audard, N.; Baglin, A.; Berthomieu, G.; Christensen-Dalsgaard,
J.; Dolez, N.; Goupil, M. J.; Perez Hernandez, F.; Pfeiffer, B.;
Provost, J.; Viskum, M.
1995ASPC...76..630R Altcode: 1995gong.conf..630R
No abstract at ADS
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Title: VIRGO - the Solar Monitor Experiment on SOHO
Authors: Appourchaux, T.; Domingo, V.; Frohlich, C.; Romero, J.;
Wehrli, C.; Andersen, B. N.; Berthomieu, G.; Delache, P.; Crommelynck,
D.; Jimenez, A.; Roca Cortes, T.; Jones, A. R.
1995ASPC...76..408A Altcode: 1995gong.conf..408A
No abstract at ADS
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Title: Are There "Natural" Wavelets in Solar Five-Minute Oscillations?
Authors: Delache, P.; IRIS Collaboration
1995ASPC...76..508D Altcode: 1995gong.conf..508D
No abstract at ADS
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Title: Periodicities in solar radius measurements
Authors: Gavryusev, V.; Gavryuseva, E.; Delache, P.; Laclare, F.
1994A&A...286..305G Altcode:
The frequency spectrum of solar radius measurements from the CERGA
astrolabe has been analyzed by the statistical method already developed
for the case of poor "signal/noise" ratio. We evaluate and discuss
correlation of radius data with several combinations of harmonics
obtained from neutrino analysis.
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Title: Panel discussion on Solar diameter variations
Authors: Delache, P.; Kroll, R. J.
1994seit.conf..193D Altcode:
No abstract at ADS
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Title: Seismological observations with a Fourier transform
spectrometer - Detection of Jovian oscillations
Authors: Mosser, B.; Mekarnia, D.; Maillard, J. P.; Gay, J.; Gautier,
D.; Delache, P.
1993A&A...267..604M Altcode:
This paper describes a new method to search for giant-planet
oscillations based on the detection of small Doppler shifts of
tropospheric absorption lines. By using the multiplex properties of a
Fourier Transform Spectrometer (FTS) the Doppler information in the
whole bandpass of a planetary spectrum dominated by strong but non
saturated atmospheric absorptions can be retrieved from the resulting
amplitude modulation of the output signal recorded continuously at
a fixed path difference. Hence, the Fourier transform of this signal
will yield the frequency spectrum of the planetary oscillations. After
presenting the principle of this interferometric method, the paper
describes its application to Jupiter by observing the planet with the
CFHT-FTS in the region of the 3 nu3 band of CH4 at 1.1 micron. The
analysis of the recorded signal led to the positive detection of
low-degree pressure oscillations through the identification of the l =
1 and l = 2 p-modes and a measure of their equidistance. The deduced
value of the characteristic frequency of Jovian oscillations does not
agree with theoretical determinations and calls for revision of the
standard model of Jupiter's interior.
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Title: Signal and noise in long duration solar radius observations
Authors: Delache, P.; Laclare, F.; Gavryusev, V.; Gavryuseva, E.
1993MmSAI..64..237D Altcode:
No abstract at ADS
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Title: Time Variations of Solar Acoustical Mode Frequencies Radius
and Neutrino Counting Rate
Authors: Gavryuseva, E.; Gavryusev, V.; Regulo, C.; Roca-Cortes, T.;
Delache, P. H.; Laclare, F.
1993ASPC...42..285G Altcode: 1993gong.conf..285G
No abstract at ADS
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Title: Book-Review - Modeling the Stellar Environment how and why
Authors: Delache, P.; Laloe, S.; Magnan, C.; Tran Thanh Van, J.;
Dyson, J.
1990Ap&SS.172..326D Altcode:
No abstract at ADS
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Title: Book-Review - Modeling the Stellar Environment - how and why
Authors: Delache, P.
1990Sci...247..584D Altcode:
No abstract at ADS
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Title: Modeling the Stellar Environment: How and Why? IAP4, 1989
Authors: Delache, Philippe; Laloe, Suzanne; Magnan, Christian; Tran
Thanh Van, J.
1989mse..proc.....D Altcode:
Topics presented include selected examples of relevant observations,
relevant theories, and astrophysical models in principle and in
practice. Also considered are parameters for disks around young stellar
objects from polarization observations, the birth of a slowly evolving
flare, line formation depths and modified Pecker weighting functions,
observations of the circumstellar environment of two red supergiants,
and large-scale CS structures in star-forming regions.
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Title: Effects of convective velocities on solar pressure mode
frequencies.
Authors: Delache, Philippe; Fossat, Eric
1988ESASP.286..671D Altcode: 1988ssls.rept..671D
There are persistent discrepancies between observations and
theoretical calculations of solar p-mode frequencies, ν<SUB>obs</SUB>,
ν<SUB>calc</SUB>, in spite of improvements in the theory (e.g. equation
of state). In this short communication, the authors propose to
approximate roughly the difference (observation-calculation)
versus frequency as: δν = ν<SUB>obs</SUB>-ν<SUB>calc</SUB>
≍ -Kν<SUP>2</SUP>, where the constant K is of the order of 1
second, and independent of degree l. It has been already suggested by
T. Brown that "Solar p-mode eigenfrequencies are decreased by turbulent
convection". The authors want to revisit this suggestion and reformulate
it in the following manner: is this physical effect responsible for
some of the difference ν<SUB>0</SUB>-ν<SUB>calc</SUB>? After a brief
discussion of the mechanism, the authors present an order of magnitude
evaluation which shows that, indeed, it is worthwhile to pursue the
idea further: this will be done in improving the description of the
coupling between convection and oscillations.
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Title: VIRGO: The solar monitor experiment on SOHO.
Authors: Froehlich, C.; Andersen, Bo Nyborg; Berthomieu, G.;
Crommelynck, D.; Delache, Philippe; Domingo, V.; Jimenez, A.; Jones,
A. R.; Roca Cortés, Teodoro; Wehrli, Ch.
1988ESASP.286..371F Altcode: 1988ssls.rept..371F
The VIRGO Experiment (Variability of solar Irradiance and Gravity
Oscillations) contains two types of active cavity radiometers for
monitoring of the solar "constant", two three channel sunphotometers
(SPM) for the measurement of spectral irradiance at 335, 500 and 865 nm
and a low resolution imager (LOI) with 12 pixels. The main scientific
objective is probing the solar interior by helioseismology with p-
and g-mode solar oscillations determined from spectral irradiance
(SPM) and radiance (LOI) variations on time scales of minutes to
the mission time. Moreover, the measurements of the variability of
the solar "constant" and spectral irradiance over periods of days to
the mission time will yield information about the convection zone, as
will the comparison of the amplitudes and phases of the oscillations
as manifested in irradiance and radiance (from VIRGO) and velocity
(from GOLF and SOI).
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Title: Oscillations of Jupiter as a tool for probing its internal
structure.
Authors: Mosser, B.; Gautier, D.; Delache, Philippe
1988ESASP.286..593M Altcode: 1988ssls.rept..593M
The internal structure of Jupiter is still uncertain. According to
current models the planet exhibits two discontinuities of sound speed
in the interior. The first one located in the external part of the
hydrogen-helium atmosphere corresponds to the transition of molecular
to metallic hydrogen, while the second one to the transition between
the H-He envelope and the high density core. The authors use the
method of ray tracing of acoustic modes to predict the behaviour of
expected pressure modes of Jupiter. Due to the inner discontinuity the
regular spating between frequencies of adjacent models is broken in a
characteristic manner which provides a clear signature. Observations
of low degree p-modes, achievable from the ground, would accurately
provide the value of the radius of the planetary core. Observations of
high degree modes would provide a signature of the external transition.
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Title: Modelling the solar oscillation time series by a randomly
excited oscillator.
Authors: Lazrek, Mohamed; Delache, Philippe; Fossat, Eric
1988ESASP.286..673L Altcode: 1988ssls.rept..673L
If the individual solar oscillations were pure standing waves of
constant amplitude inside a stationary Sun, there would be in principle
no intrinsic limits to the accuracy with which their frequencies could
be measured. Unfortunately, it is not so. In their analysis of 10
months of irradiance data from the SMM/ACRIM experiment, Woodard and
Hudson have proposed to describe the individual modes as independent
and chaotically excited oscillators, the linewidths being of the
order of 1.2 μHz in the central frequency range, around 3 mHz. This
paper deals with artificial full disk data. The goal is to determine
the parameters of a randomly excited oscillator by comparison with
the best data available. Such artificial signal is then used to test
the methods of analysis used for the precise determination of mode
frequencies, amplitudes and linewidths. The authors present tests of
the reliability of centroid measurements made by barycenter, Lorentzian
fit, Gaussian fit, with and without background noise. Several methods
are also tested for linewidth measurements.
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Title: Measuring the Jovian oscillations as a tool for investigating
the internal structure of the planet.
Authors: Mosser, B.; Delache, P.; Gautier, D.
1988CRASB.307.1641M Altcode: 1988CRASM.307.1641M
The oscillations of Jupiter, if detectable, would constrain theories of
its interior. This work predicts the pattern of expected pressure modes,
using the ray tracing method. Observations of low degree p-modes,
obtainable from the ground, would accurately provide the value of
the radius of the planetary core; observations of high degree modes,
conducted from space, would provide a signature of the external
transition.
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Title: Measuring the Size of the Core of Jupiter from Low p-Mode
Oscillations of the Planet
Authors: Mosser, B.; Gautier, D.; Delache, P.
1988BAAS...20R.870M Altcode:
No abstract at ADS
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Title: Long Periods in Diameter Irradiance and Activity of the Sun
Authors: Delache, P.; Laclare, F.; Sadsaoud, H.
1988IAUS..123..223D Altcode:
Long periods have been detected in solar diameter measurements obtained
during the past 10 years. The same periodicities are also present in
other global Sun parameters such as the 10 cm radio flux, the total
irradiance, and possibly the neutrino flux. Special attention is paid
to periods corresponding to the solar cycle ("C"), 1000 days ("P")
and 320 days ("W"). Studying the respective phases of the signals gives
some insight into the possible physical origins of these variations.
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Title: Variability of the solar diameter
Authors: Delache, Philippe
1988AdSpR...8g.119D Altcode: 1988AdSpR...8..119D
Although the solar diameter has been monitored for around three
centuries, very little is known on its secular variations. The subject
is still controversial, dealing with historical archives or with
more recent observations as well. <P />Most of the available data
come from visual determinations. The precision of the measurements
depends on the method, on the instrument, on the site, and on the
observer's skill. Systematic errors arise also from the instrument,
from the data reduction, and from the observer's eye. Fortunately,
modern instruments no longer rely upon human vision, but they have
not yet been routinely operated for very long. We shall try to compare
the relative precisions of the various techniques. <P />Variations of
amplitude in the semi-diameter of order 0.1” have been reported. We
assess here their degree of statistical significance by intercomparison
of diameter time series between themselves, and also with some other
relevant available data sets. We conclude that even if the variations
in the apparent values are well established, it is still impossible to
relate them to variations of the real solar diameter with confidence. <P
/>Laboratoire associé au C.N.R.S. 128
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Title: Change of solar oscillation eigenfrequencies with the solar
cycle.
Authors: Delache, Philippe
1986ASIC..169..305D Altcode: 1986ssds.proc..305D
Observations of the solar diameter with a Danjon-type visual astrolabe
have been recorded at the C.E.R.G.A. Observatory since 1975. A harmonic
analysis of these measurements shows the existence of very long solar
periods. In order to assess the significance of peaks in the power
spectrum four different methods are presented.
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Title: Long period oscillations in solar diameter measurements
Authors: Delache, P.; Laclare, F.; Sadsaoud, H.
1985Natur.317..416D Altcode:
Observations of the Sun with a Danjon-type visual astrolabe have
been recorded since 1975 at the CERGA Observatory. The primary goal
of these observations is to determine the orbital elements of the
Earth around the Sun. However, they also provide very good quality,
homogeneous values of the solar diameter. The working principle of the
astrolabe, which relies on the method of equal elevations<SUP>1</SUP>,
has been described elsewhere<SUP>2</SUP>. The diameter value is
obtained from the difference between the zenith distances of the
solar centres corresponding to the instances of successive limbs
crossing the same almucantar. The solar diameters are obtained
up to 16 times per day. The heliographic latitude of the observed
points varies throughout the day and changes with the seasons. In the
present study, we have discarded the data taken at zenith distances
>60° because of their lower quality on average. We consider then
all the retained measurements on equal footing. The existence of a
long period, ~1,000 days, in the variation of the solar diameter has
already been reported<SUP>3</SUP>. The low-frequency domain of the
power spectrum deserved a more detailed analysis which the more recent
data permit. Here, we present this analysis, which reveals several
previously undetected periodicities.
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Title: X-ray and optical variability at the hour timescale for 1E
0630+178 (GEMINGA) and its proposed optical couterpart
Authors: Vigroux, L.; Paul, J. A.; Delache, P.; Bignami, G. F.;
Caraveo, P. A.; Salotti, L.
1985SSRv...40...91V Altcode:
Einstein and EXOSAT data on the soft X-ray source IE 0630+178,
the proposed counterpart of the γ-ray source GEMINGA, are analyzed
for variability on the time scale of one to three hours. The EXOSAT
September 1983 data, with an uninterrupted strech of over 10 hours offer
the most interesting case. In parallel, a similar analysis is presented
for the first time, for the optical data of the m<SUB>V</SUB>∼21
proposed counterpart. About 30 CCD exposures, of 15 min. each, taken
over two consecutive nights at the 3.6 m CFH telescope, yield evidence
of variability, when compared to the data of similar nearby objects
in the field.
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Title: Solar gravity modes from ACRIM/SMM irradiance data.
Authors: Frohlich, C.; Delache, P.
1984sses.nasa..183F Altcode: 1984sss..conf..183F
The record of 280 days of continuous data of the ACRIM radiometer
on board the Solar Maximum Mission satellite is analysed in the
frequency range from 10 to 80 μHz. Gravity modes of degree one and
two with orders from about 10 to several hundreds can be localized. A
statistical method to determine the fundamental period T<SUB>0</SUB>
and the rate of rotation ν<SUB>R</SUB> as seen by rotational splitting
is described and the results for 33.5 < T<SUB>0</SUB> < 45.5
minutes and 0.4 < ν<SUB>R</SUB> < 2.0 μHz presented. They
indicate a rather high T<SUB>0</SUB> and it cannot be excluded that
it is above the upper limit analysed.
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Title: Solar gravity modes - Detection and identification
Authors: Delache, P.
1984MmSAI..55...75D Altcode:
Analytical methods for the detection and identification of very low
frequency gravity modes in the solar oscillation are presented. The
relative ease of detection of 5-min p-modes is contrasted with
the difficulties posed by noisy spectra, visibility problems,
complex mode signature, side lobes, and rotational splitting from
g-modes. Theoretical criteria are developed and shown to permit the
simultaneous detection and identification of g-modes from data of
the quality presently available, and improved results are predicted
if longer-time-series observations can be obtained. Graphs, digrams,
and tables are provided.
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Title: Solar G modes
Authors: Isaak, G. R.; van der Raay, H. B.; Palle, P. L.; Roca Cortes,
T.; Delache, P.
1984MmSAI..55...91I Altcode:
A statistical analysis of the frequency spectrum of 85 days of
data obtained from integral solar velocity signals, has shown that
significant signals exist in the frequency range 25 - 150 μHz. The
signal structure is shown to have characteristics of constant period
spacings indicative of the existence of g modes in the solar oscillation
spectrum. Utilising the asymptotic Tassoul relation a total of 58 lines
are identified covering the l<SUB>1</SUB>, l<SUB>2</SUB>, l<SUB>3</SUB>
and l<SUB>4</SUB> modes.
---------------------------------------------------------
Title: Solar gravity modes from ACRIM/SMM irradiance data
Authors: Froehlich, C.; Delache, P.
1984MmSAI..55...99F Altcode:
The record of 280 days of continuous data of the ACRIM radiometer
on board the Solar Maximum Mission satellite is analyzed in the
frequency range 2-80 microhertz. Gravity modes of degree one and two
with orders from about 10 to several hundred can be localized. Due
to the complexity of the spectrum of the enormous number of lines
in a given frequency interval, the individual identification is very
difficult. A statistical method to determine the fundamental period
and the rate of rotation as seen by rotational splitting is described,
and the results compared with other determinations.
---------------------------------------------------------
Title: Report of ESA's topical team on solar and heliospheric physics.
Authors: Christensen-Dalsgaard, J.; Delache, P.; Hoyng, P.; Priest,
E. R.; Schwenn, R.; Stenflo, J. O.
1984ESASP1070...26C Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Recent Progress in the Detection and Identification of Solar
Gravity Modes
Authors: Delache, P.
1984apoa.conf..176D Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Detection of solar gravity mode oscillations
Authors: Delache, P.; Scherrer, P. H.
1983Natur.306..651D Altcode:
An analysis of solar velocity data obtained at the Stanford Solar
Observatory shows the existence of solar global oscillations in the
range 45-105 µHz (160-370 min). These oscillations are interpreted
as internal gravity modes of degree l = 1 and l = 2. A good estimate
of the order of the modes has also been made.
---------------------------------------------------------
Title: Detection of solar gravity mode oscillations
Authors: Delache, P.; Scherrer, P. H.
1983dsgm.book.....D Altcode:
An analysis of solar velocity data obtained at the Stanford Solar
Observatory shows the existence of solar global oscillations in the
range 45 to 105 microHz (160 to 370 minutes). These oscillations are
interpreted as internal gravity modes of degree l = 1 and l = 2. A
good estimate of the order of the modes has also been made.
---------------------------------------------------------
Title: Observation of solar oscillations for periods close to 160 mn.
Authors: Delache, P.
1981CRASB.293..949D Altcode: 1981CRASM.293..949D
An attempt is made to prove that recently observed solar power spectrum
oscillations with a period near 160 min are actually an artifact
caused by 5 min pulsations interacting with the calibration signals
used by other observers. The power spectrum calculated by means of a
Fourier transformation of readings from observed 5 min observations is
defined, noting that since the readings are only made during the day,
diurnal variations result. The distribution of the observed 160 min
spectrum is shown to match the Fourier transformed 5 min spectrum,
which corresponds to the 160 min spectrum at low frequencies. Only
the amplitudes observed are explainable by use of a 5 min, rather
than a 160 min, period of oscillation, and further study to explain
the discrepancy is recommended.
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Title: Quiet Sun
Authors: Delache, P.
1981SSRv...29..367D Altcode:
We underline the diagnostic strength of recent observations of the
oscillating quiet Sun. While high quality (k, ω) power spectra permit
a better knowledge of the convection zone, long and continuous survey
of oscillations of the integrated Sun provides an efficient sounding
of the inner solar body.
---------------------------------------------------------
Title: Observations of solar oscillations with periods near 160 min
Authors: Delache, P.
1981CR2...293..949D Altcode:
No abstract at ADS
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Title: Rapport d'activité de l'A.D.I.O.N. par le Secrétaire
Général et rapport financier. Report 1975 and 1976.
Authors: Delache, P.; Schatzman, E.; Frisch, H.
1978BONic..13...33D Altcode:
No abstract at ADS
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Title: Rapport d'activité de l'A.D.I.O.N. par le Secrétaire
Général et rapport financier. Report 1974.
Authors: Delache, P.; Berruyer, N.
1975BONic..12...29D Altcode:
No abstract at ADS
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Title: Rapport d'activité de l'Observatoire de Nice pour 1974,
présenté par son directeur.
Authors: Delache, P.
1975BONic..12...49D Altcode:
No abstract at ADS
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Title: A New Formulation of an Approximate Transfer Equation
Authors: Delache, Philippe
1974ApJ...192..475D Altcode:
Athay's derivation of a transfer equation from a statistical approach
is criticized, and a new alternative is presented in which the same
equation is established on different grounds. The independent variable
which was taken as the reciprocal escape probability is redefined
in a slightly different way. The quality of this new formulation is
better than the previous one, and can be extended to time-dependent
problems where it also shows exceptionally good agreement with the
exact solutions. The present work is presented only in the frame of
a two-level atom, in an atmosphere of constant T, for the sake of
simplicity. However, it is more general, and some possible tests
of its validity for complex cases are described. Subject heading:
radiative transfer
---------------------------------------------------------
Title: Non-Static Structure of the Chromosphere-Corona Transition
Region
Authors: Delache, P.
1974IAUS...56...91D Altcode:
No abstract at ADS
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Title: The next decade in stellar atmospheres theory.
Authors: Delache, P.
1974HiA.....3..109D Altcode:
No abstract at ADS
---------------------------------------------------------
Title: "theoritical Understanding of Chromospheric INHOMOGENEITIES,"
Authors: Delache, Philippe
1973NASSP.317..207D Altcode: 1973stch.coll..207D; 1973IAUCo..19..207D
No abstract at ADS
---------------------------------------------------------
Title: Rapport d'activité de l'Observatoire de Nice pour 1971.
Authors: Delache, P.
1972BINic...9...45D Altcode:
No abstract at ADS
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Title: Rapport d'activité de l'Observatoire de Nice pour 1970.
Authors: Delache, P.
1971BINic...8...43D Altcode:
No abstract at ADS
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Title: Une interprétation possible de l'émission OH galactique
Authors: Delache, P.
1970pfa..conf...21D Altcode: 1969pfa..conf...21D
No abstract at ADS
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Title: Energy Deposition and Momentum Transfer in the Transition
Region
Authors: Delache, P.
1969cctr.conf..183D Altcode:
No abstract at ADS
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Title: Some problems of radiative transfer in an atmosphere having
a stellar wind
Authors: Delache, Philippe
1968JQSRT...8..317D Altcode:
During the expansion of a stellar corona (stellar wind), highly charged
ions may move faster than protons under the action of thermal diffusion
in the temperature gradient region, as well as slower under the action
of gravitational separation in the isothermal region. We discuss here
the different consequences of these diffusion phenomenas. Noting that
the reactions of ionization and recombination have characteristic times
which are not small compared to the time for a significant change in the
temperature experienced by a single ion, one sees that it is necessary
to treat the equations of diffusion together with the equations of
ionization. The results are the following:local over abundance of the
heavy elements in the corona;stationary state out of local equilibrium,
the “apparent temperature” that would be deduced from the ratio
of the number density of two successive ions being lower than the
electron temperature. Therefore, the interpretation of the eclipse
and UV observations of the lower solar corona has to be reconsidered
owing to the non-LTE state of a given atom, and to the variation of its
abundance with height. The purpose of this paper is to describe some
physical phenomena that take place in the transition region between
the chromosphere and the corona in the presence of a stellar wind, and
the bearing of these on the problem of interpreting coronal emissions.
