Author name code: delache ADS astronomy entries on 2022-09-14 author:Delache, Philippe ------------------------------------------------------------------------ Title: Estimating Long-Term Solar Irradiance Variability: A New Approach Authors: Vigouroux, Anne; Pap, Judit M.; Delache, Philippe Bibcode: 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. 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 Bibcode: 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. 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. Bibcode: 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. 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. Bibcode: 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 10−7 to 10−2 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−1 over 20 days for frequencies higher than 2.10−4 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. Title: Remarques sur la définition et la mise en œvre d'un plan d'action pour l'astronomie. Authors: Delache, P. Bibcode: 1995JAF....47...15D Altcode: No abstract at ADS 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. Bibcode: 1995ASPC...76..630R Altcode: 1995gong.conf..630R No abstract at ADS 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. Bibcode: 1995ASPC...76..408A Altcode: 1995gong.conf..408A No abstract at ADS Title: Are There "Natural" Wavelets in Solar Five-Minute Oscillations? Authors: Delache, P.; IRIS Collaboration Bibcode: 1995ASPC...76..508D Altcode: 1995gong.conf..508D No abstract at ADS Title: Periodicities in solar radius measurements Authors: Gavryusev, V.; Gavryuseva, E.; Delache, P.; Laclare, F. Bibcode: 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. Title: Panel discussion on Solar diameter variations Authors: Delache, P.; Kroll, R. J. Bibcode: 1994seit.conf..193D Altcode: No abstract at ADS 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. Bibcode: 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. Title: Signal and noise in long duration solar radius observations Authors: Delache, P.; Laclare, F.; Gavryusev, V.; Gavryuseva, E. Bibcode: 1993MmSAI..64..237D Altcode: No abstract at ADS 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. Bibcode: 1993ASPC...42..285G Altcode: 1993gong.conf..285G No abstract at ADS Title: Book-Review - Modeling the Stellar Environment how and why Authors: Delache, P.; Laloe, S.; Magnan, C.; Tran Thanh Van, J.; Dyson, J. Bibcode: 1990Ap&SS.172..326D Altcode: No abstract at ADS Title: Book-Review - Modeling the Stellar Environment - how and why Authors: Delache, P. Bibcode: 1990Sci...247..584D Altcode: No abstract at ADS Title: Modeling the Stellar Environment: How and Why? IAP4, 1989 Authors: Delache, Philippe; Laloe, Suzanne; Magnan, Christian; Tran Thanh Van, J. Bibcode: 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. Title: Effects of convective velocities on solar pressure mode frequencies. Authors: Delache, Philippe; Fossat, Eric Bibcode: 1988ESASP.286..671D Altcode: 1988ssls.rept..671D There are persistent discrepancies between observations and theoretical calculations of solar p-mode frequencies, νobs, νcalc, 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 = νobs-νcalc ≍ -Kν2, 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 ν0-νcalc? 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. 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. Bibcode: 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). Title: Oscillations of Jupiter as a tool for probing its internal structure. Authors: Mosser, B.; Gautier, D.; Delache, Philippe Bibcode: 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. Title: Modelling the solar oscillation time series by a randomly excited oscillator. Authors: Lazrek, Mohamed; Delache, Philippe; Fossat, Eric Bibcode: 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. Title: Measuring the Jovian oscillations as a tool for investigating the internal structure of the planet. Authors: Mosser, B.; Delache, P.; Gautier, D. Bibcode: 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. Title: Measuring the Size of the Core of Jupiter from Low p-Mode Oscillations of the Planet Authors: Mosser, B.; Gautier, D.; Delache, P. Bibcode: 1988BAAS...20R.870M Altcode: No abstract at ADS Title: Long Periods in Diameter Irradiance and Activity of the Sun Authors: Delache, P.; Laclare, F.; Sadsaoud, H. Bibcode: 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. Title: Variability of the solar diameter Authors: Delache, Philippe Bibcode: 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.

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.

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.

Laboratoire associé au C.N.R.S. 128 Title: Change of solar oscillation eigenfrequencies with the solar cycle. Authors: Delache, Philippe Bibcode: 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. Title: Long period oscillations in solar diameter measurements Authors: Delache, P.; Laclare, F.; Sadsaoud, H. Bibcode: 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 elevations1, has been described elsewhere2. 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 reported3. 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. 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. Bibcode: 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 mV∼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. Title: Solar gravity modes from ACRIM/SMM irradiance data. Authors: Frohlich, C.; Delache, P. Bibcode: 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 T0 and the rate of rotation νR as seen by rotational splitting is described and the results for 33.5 < T0 < 45.5 minutes and 0.4 < νR < 2.0 μHz presented. They indicate a rather high T0 and it cannot be excluded that it is above the upper limit analysed. Title: Solar gravity modes - Detection and identification Authors: Delache, P. Bibcode: 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. Title: Solar G modes Authors: Isaak, G. R.; van der Raay, H. B.; Palle, P. L.; Roca Cortes, T.; Delache, P. Bibcode: 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 l1, l2, l3 and l4 modes. Title: Solar gravity modes from ACRIM/SMM irradiance data Authors: Froehlich, C.; Delache, P. Bibcode: 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. Bibcode: 1984ESASP1070...26C Altcode: No abstract at ADS Title: Recent Progress in the Detection and Identification of Solar Gravity Modes Authors: Delache, P. Bibcode: 1984apoa.conf..176D Altcode: No abstract at ADS Title: Detection of solar gravity mode oscillations Authors: Delache, P.; Scherrer, P. H. Bibcode: 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. Bibcode: 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. Bibcode: 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. Title: Quiet Sun Authors: Delache, P. Bibcode: 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. Bibcode: 1981CR2...293..949D Altcode: No abstract at ADS 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. Bibcode: 1978BONic..13...33D Altcode: No abstract at ADS 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. Bibcode: 1975BONic..12...29D Altcode: No abstract at ADS Title: Rapport d'activité de l'Observatoire de Nice pour 1974, présenté par son directeur. Authors: Delache, P. Bibcode: 1975BONic..12...49D Altcode: No abstract at ADS Title: A New Formulation of an Approximate Transfer Equation Authors: Delache, Philippe Bibcode: 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. Bibcode: 1974IAUS...56...91D Altcode: No abstract at ADS Title: The next decade in stellar atmospheres theory. Authors: Delache, P. Bibcode: 1974HiA.....3..109D Altcode: No abstract at ADS Title: "theoritical Understanding of Chromospheric INHOMOGENEITIES," Authors: Delache, Philippe Bibcode: 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. Bibcode: 1972BINic...9...45D Altcode: No abstract at ADS Title: Rapport d'activité de l'Observatoire de Nice pour 1970. Authors: Delache, P. Bibcode: 1971BINic...8...43D Altcode: No abstract at ADS Title: Une interprétation possible de l'émission OH galactique Authors: Delache, P. Bibcode: 1970pfa..conf...21D Altcode: 1969pfa..conf...21D No abstract at ADS Title: Energy Deposition and Momentum Transfer in the Transition Region Authors: Delache, P. Bibcode: 1969cctr.conf..183D Altcode: No abstract at ADS Title: Some problems of radiative transfer in an atmosphere having a stellar wind Authors: Delache, Philippe Bibcode: 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.