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Author name code: souffrin
ADS astronomy entries on 2022-09-14
author:Souffrin, Pierre
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Title: On the theory of shock-heated atmospheres. III - Discussion
of the formalism and application to stellar coronae
Authors: Souffrin, P.
1982A&A...109..205S Altcode:
Thermally sustained coronas and stellar winds are investigated using
a two-zone corona model describing a lower zone at constant pressure
in which the mechanical dissipation and wind effects are neglected,
and an upper zone characterized by an extended isothermal region. The
interface between the two zones is treated as a dissipative layer of
neglectable vertical extent, so that jumps of the physical quantities
are consistently fixed by the conservation equations. The physical
meaning of transition zone and coronal temperature is discussed, and
the lower zone, shock formalism, and dissipation layer are analyzed,
as are the upper bounds for the coronal temperature, base pressure, and
mechanical flux. A detailed study of the model's special loss function
is presented, including the minimum shock strength, conduction dominated
case, pressure-mechanical flux relation, and base-temperature relation.
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Title: On the theory of thermally sustained stellar winds
Authors: Souffrin, P.
1982A&A...106...14S Altcode:
A reconsideration of the influence of boundary layer structure on
a stellar wind is presented, in which Couturier et al's (1979)
discussion of the role of the conductive flux boundary layer is
extended to include the role of the temperature boundary layer. It is
shown that the constraint between the wind parameters is insensitive
to the temperature at the lower level, so that the structure of the
wind, including the transition zone, is dependent on the mechanical
flux entering the transition zone only. Although the structure of the
wind is determined by the heating mechanism, the conclusion given is
independent of mechanism.
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Title: Stellar mass flux and coronal heating by shock waves
Authors: Couturier, P.; Mangeney, A.; Souffrin, P.
1980IAUS...91..127C Altcode:
A self-consistent oversimplified model is proposed which maintains
the global balance of energy sources and sinks from the chromospheric
level to the interplanetary medium. The heating mechanism chosen is
the shock wave dissipation. The model includes self-consistently the
different couplings between convective energy flux, conductive flux,
radiation losses in optically thin atmospheres, shock wave pressure, and
dissipation terms. The input parameters are the base pressure, the base
temperature, and the mechanical flux introduced at the chromospheric
level in the form of shock waves. For one set of input parameters,
some characteristic quantities are presented for four levels: the
chromospheric level, the temperature maximum, the critical point,
and the earth orbit.
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Title: On the two-parameter models for stellar coronae.
Authors: Mangeney, A.; Souffrin, P.
1979A&A....78...36M Altcode:
The two-parameter model developed by Hearn (1975) is reconsidered. A
constraint required within the framework of such models is found
which is not consistent, in general, with the minimum-flux condition
conjectured by Hearn and which provides an alternative reduction of
the models to one parameter. The corresponding relations are given
explicitly for the special case of heating by weak shock waves when
heat conduction back to the chromosphere dominates the energy losses
by the corona.
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Title: On the theory of shock-heated atmospheres. II. The influence
of the chromospheric boundary layer structure on the solar wind.
Authors: Couturier, P.; Mangeney, A.; Souffrin, P.
1979A&A....74....9C Altcode:
Summary. We show that the complex boundary-layer structure of the
solar upper chromosphere discussed in a previous paper implies a new
constraint between the parameters of the coronal plasma flow. In the
simple model of a one fluid symmetric solar wind with the mechanical
heating due to acoustic wave dissipation, it results that the mechanical
energy generated in the waves determines both the mass flux in the
solar wind and the gas pressure in the inner transition zone. Key words:
heating mechanisms - stellar winds
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Title: The sun, a variable star.
Authors: Fossat, E.; Souffrin, P.
1978Rech....9..526F Altcode:
The paper describes supergranules in the solar surface and a local
oscillation with a 5-minute frequency in the solar atmosphere. The
supergranules can be approximately 30 times the size of the granules
and are more stable than the granules, the supergranules persisting
more than 10 hours, that is, more than 100 times the lifetime of a
granule. While the existence of two systems - granules and supergranules
- can not yet be explained by convection theory, the horizontal
movements in the supergranules do explain the reticular structure
of the solar magnetic field, as the movement from the center to the
edge of the supergranule drags the magnetic field to the border. The
local oscillations extend a distance of a few thousand meters and
persist approximately 20 minutes. The implications of supergranules
and local oscillation for an understanding of the external layers of
stars are discussed.
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Title: On the theory of shock-heated atmospheres. I. A methodological
discussion with special reference to the solar case.
Authors: Gonczi, G.; Mangeney, A.; Souffrin, P.
1977A&A....54..689G Altcode:
The paper reconsiders the physics and the mathematical formulation
of the theory of shock-heated atmospheres. A complex boundary-layer
structure is found which accounts for the gross features of the vertical
stratification of the solar chromosphere. The existence of two different
regimes for shock propagation is discussed, and the formalism is
extended to include both regimes and the transition from one to the
other. The validity of the description of the dynamics is shown to
be restricted to small shock strength. Although high velocities are
shown to be necessary in the low chromosphere, they are confined in a
dynamical boundary layer, so that the formalism described is relevant
for the study of the outer layers of the sun.
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Title: Sur la dynamique de l'atmosphère solaire.
Authors: Souffrin, P.
1977rese.proc...95S Altcode:
No abstract at ADS
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Title: On the mechanical heating of the external layers of the sun -
A methodological discussion
Authors: Souffrin, P.
1976MmSAI..47..365S Altcode:
Theoretical treatments of the mechanical heating of the external
layers of stars are reviewed; the problem is posed as one of
stationary nonhomogeneous turbulence (that is, the Rayleigh-Benard
problem) with the essential difficulty lying in the solution of a
hierarchy of equations of motion, mass and energy through a chosen
closure hypothesis. In particular, the closure relation proposed by
Schwarzschild (1948), which makes reference to acoustic waves, and the
closure hypothesis of Schatzman (1949), a more general treatment based
on linear acoustics, are analyzed. It is suggested that a description
of the propagation of an isolated unsustained shock in a homogeneous
compressible fluid at rest, developed by Brinkley and Kirkwood (1947),
may be quite effectively applied to the problem of the heating of the
solar atmosphere.
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Title: Introduction à la 'instabilities Hydrodynamiques a L'origine
des Mouvements dans les Atmospheres Stellaires'
Authors: Souffrin, P.
1976pmas.conf...17S Altcode:
No abstract at ADS
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Title: Ray Trapping in Stellar Envelopes, Pulsational Instabilities
and Heating of External Layers
Authors: Souffrin, P.
1974IAUS...56..293S Altcode:
No abstract at ADS
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Title: Sur la Dynamique de l'Atmosphère Solaire
Authors: Souffrin, P.
1973JPhys..34....2S Altcode:
No abstract at ADS
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Title: Note on the Growth Rate of Convective Modes in a Self
Gravitating Gas Sphere
Authors: Grisvard, P.; Souffrin, P.; Zerner, M.
1972A&A....17..309G Altcode:
It is shown that within Cowling's approximation the growth rate of the
eigen modes in a convectively unstable self gravitating gas sphere
is a bounded monotonically increasing function of the degree of the
harmonic. Key words: convection - stellar structure.
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Title: Radiative Relaxation of Sound Waves in an Optically Thin
Isothermal Atmosphere
Authors: Souffrin, P.
1972A&A....17..458S Altcode:
The radiative damping of oscillatory modes in an optically thin
isothermal atmosphere is investigated within the approximation of
Newton's law of cooling (Sections I-Il). Special attention is paid to
vertical modes sustained by harmonic boundary conditions (III) and to
the discussion of the validity of the adiabatic and isothermal limiting
cases. The influence of relaxation on the response of an infinite
model to an applied body-force is studied in the one-dimensional
case (W). Application to the solar conditions indicates that the
dissipation in the chromosphere has little effect on the dynamics of the
chromospheric oscillation (V). Key words: stellar atmospheres - the sun
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Title: Convection
Authors: Souffrin, P.
1971tdas.conf..238S Altcode: 1971SAAS....1..238S
Introduction Basic Equations Thermal Instabilities of a Homogeneous
Compressible Fluid Pressure-modes and entropy-mode Stability of the
compressible homogeneous fluid when heat exchange - is taken into
account Dynamics of a Stratified Compressible Atmosphere The local
dispersion relation The condition for dynamic instability The stable
case. Pressure and gravity modes The unstable case. Pressure modes and
convective modes The "parcel method". Phenomenological discussion of
dynamical - stability Thermal, Pulsational and Convective Instabilities,
and the "Parcel - Approximation" of the Equations of Hydrodynamics
The "parcel" model and the equations of hydrogynamics Convection and
thermal instability Convection and dynamical instability A general
phenomenological discussion of the relation between - convection
and pulsational instability Mixing - Length Theory Convection and
the structure of a star The mixing-length formalism A discussion
of the mixing-length theory A Study of the Non-Radial Motions of a
Self-Gravitating Gas Sphere - within Cowling's Approximation Initial
values problem and boundary conditions Sufficient condition for
stability The growth rates of unstable modes The oscillation properties
of the unstable modes
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Title: Convection.
Authors: Souffrin, P.
1971tsa..conf..238S Altcode:
No abstract at ADS
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Title: Theorie des atmospheres stellaires
Authors: Mihalas, D.; Pagel, B.; Souffrin, P.
1971tdas.conf.....M Altcode: 1971QB809.M52......; 1971tsat.book.....M; 1971SAAS....1.....M
No abstract at ADS
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Title: Hydrodynamics of an Atmosphere Excited by an Underlying
Turbulent Convective Zone. II. Response of an Atmosphere to an
Applied Random Body-Force
Authors: Souffrin, P.
1970A&A.....7..227S Altcode:
The response of atmospheres to stationary random applied forces
homogeneous over horizontal planes is formulated in a very general way
(Part I and II). We discuss the occurrence of divergences at cut-off
frequencies on the special case of an isothermal atmosphere. The
analysis applies without modifications to a large class of models
characterized by a propagation operator whose Green's function is
singular when the group velocity vanishes. We ultimately relate these
divergences to the lack of reflections in the medel and we show that
the common energy argument is inadequate (Part II and III). Our view
is supported by a detailed analysis of the response of two models:
the semi-infinite isothermal atmosphere bounded by a rigid bottom (Part
IV), and an infinite model with reflections at one level (Part V). The
response is discussed in terms of the spatial extention and coherence
of the momentum sources. It is shown that the response to a white-noise
force can be enhanced at frequencies different from the local cut-off
frequency of the region where the force acts. A prelinary discussion
of the implications of this result to the situation prevailing in the
solar upper layers strongly suggest the relevance of this study to
the interpretation of the photospheric oscillation. (Part VI)
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Title: Book Review: The Solar Granulation. R. J. BRAY and
R. E. LOUGHHEAD: Chapman and Hall, London; Barnes and Noble, New York,
1967. xiv + 150. 60s
Authors: Souffrin, P.
1968P&SS...16..144S Altcode:
No abstract at ADS
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Title: An overstability of gravity waves
Authors: Souffrin, P.; Spiegel, E. A.
1967AnAp...30..985S Altcode:
No abstract at ADS
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Title: Waves in the Solar Atmosphere
Authors: Schatzman, E.; Souffrin, P.
1967ARA&A...5...67S Altcode:
No abstract at ADS
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Title: Hydrodynamique d'une atmosphère perturbée par une zone
convective turbulente sous-jacente
Authors: Souffrin, P.
1966AnAp...29...55S Altcode:
No abstract at ADS
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Title: Réponse d'une Atmosphère Excitée par une Source Acoustique
Etendue Stationnaire. Application à l'Atmosphère Solaire
Authors: Souffrin, P.
1965CRASB.260.2135S Altcode:
No abstract at ADS
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Title: Réponse d'une Atmosphère Excitée par une Source Acoustique
Etendue Stationnaire
Authors: Souffrin, P.
1964CRASB.259.2355S Altcode:
No abstract at ADS
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Title: Remarques sur les mouvements transitoires des systèmes
instables. Application à un modèle de granulation solaire
Authors: Souffrin, P.
1963AnAp...26..170S Altcode:
No abstract at ADS
