STELLAR WINDS DRIVEN BY RADIATION PRESSURE

1995 ◽  
Author(s):  
Zeljko Ivezic ◽  
Moshe Elitzur
Keyword(s):  
Radiation Pressure ◽  
Stellar Winds

Radiation Pressure and Accelerating Stellar Winds

1971 ◽  
Vol 169 ◽  
pp. 441 ◽  
Author(s):  
J. M. Marlborough
Keyword(s):  
Radiation Pressure ◽  
Stellar Winds

Stellar mass loss and atmospheric Instability

1988 ◽  
Vol 108 ◽  
pp. 102-113
Author(s):  
Cornelis de Jager ◽  
Hans Nieuwenhuijzen
Keyword(s):  
Mass Loss ◽  
Radiation Pressure ◽  
Stellar Mass ◽  
Stellar Winds ◽  
Evolved Stars ◽  
Upper Limit ◽  
Atmospheric Instability ◽  
Turbulent Pressure ◽  
Loss Component ◽  
Break Up

AbstractA review is given of rate of mass-loss values in the upper part of the Hertzsprung-Russell diagram. Near the luminosity limit of stellar existance = −10−4 M⊙ yr−1. Episodical mass loss in bright variable super- and hypergiants does not significantly increase this value. For Wolf-Rayet stars the rate of mass loss is larger by a factor 140 than for non-evolved stars with the same Teff and L; for C stars this factor is ten. This can be explained qualitatively. Rotation appears hardly to influence the rate of mass loss except for vrot-values close to the break-up velocity. This is in accordance with theory. We suggest the existence of a Red Supergiant Branch; along that branch mass loss is virtually independent of luminosity. Stellar winds along the upper limit of stellar existence are mainly due: to radiation pressure for hot supergiants (≳ 10 000 K); to turbulent pressure for cool supergiants (3000-10 000 K), and to dust-driven and pulsation-driven winds for cooler stars. The turbulent pressure may originate in largescale stochastic motions as observed in Alpha Cyg. Episodical mass loss, as observed in P Cyg, HR 8752 and other Very Luminous Variables may be due to occasional violent stochastic motions, resulting in a shock-driven episodical mass-loss component.

scholarly journals Atmospheric parameters and accelerations in the outer parts of luminous hot stars

1989 ◽  
Vol 113 ◽  
pp. 287-288
Author(s):  
Hans Nieuwenhuijzen ◽  
Cornells de Jager
Keyword(s):  
Radiation Pressure ◽  
Dynamic Pressure ◽  
Great Part ◽  
Hydrostatic Equilibrium ◽  
Stellar Winds ◽  
Gravitational Acceleration ◽  
Atmospheric Parameters ◽  
Hot Stars ◽  
Plane Parallel ◽  
Turbulent Pressure

In the atmospheres of the most extreme luminous stars, close to the Humphreys-Davidson limit, the inward gravitational acceleration is for a great part compensated by outward accelerations due to radiation pressure, turbulent pressure and dynamic pressure of the stellar winds. As a result the effective acceleration is very small, resulting in blown-up atmospheres that can no longer be considered plane-parallel or in hydrostatic equilibrium.

scholarly journals Stellar winds in A-type supergiants

1994 ◽  
Vol 162 ◽  
pp. 538-539
Author(s):  
E. Verdugo ◽  
A. Talavera
Keyword(s):  
Mass Loss ◽  
Radiation Pressure ◽  
Mechanical Energy ◽  
Stellar Winds ◽  
Early Type

A-type supergiants are just at the boundary between the early type supergiants, with strong stellar winds driven by radiation pressure and the cool supergiants in which the origin of mass loss is the dissipation of mechanical energy. The mechanisms involved in the mass loss processes in A supergiants as a whole, are still uncertain.

scholarly journals Stochastic Starformation and Bubbles in the Large Magellanic Cloud

1984 ◽  
Vol 108 ◽  
pp. 89-90
Author(s):  
J. V. Feitzinger
Keyword(s):  
Interstellar Medium ◽  
Radiation Pressure ◽  
Hii Regions ◽  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Shell Structures ◽  
Stellar Winds ◽  
Bubble Structure ◽  
Ring Nebulae

Nearly all places in the LMC where ring nebulae or shell structures in the neutral or ionized interstellar medium are observed, an OB association and/or WR-stars can be located (Braunsfurth, Feitzinger, 1983). Several mechanisms have been propsoed to generate shell or bubble structures: stellar winds, supernovae explosions, evolving HII regions, sequential starformation, collapsing hydrogen clouds interacting with stellar winds and radiation pressure. Ordered motions resulting in a shell or bubble structure are the result of almost any point like energy injection into the interstellar medium. Therefore all the mechanisms result in similar morphological structures, thus similar shapes can have heterogeneous origins.

scholarly journals The Effects of a Weak Magnetic Field in the Line Profiles of A-type Supergiant Winds

2002 ◽  
Vol 185 ◽  
pp. 574-575 ◽  
Author(s):  
E. Verdugo ◽  
A. de Castro Gómez ◽  
C. Ferro-Fontán ◽  
A. Talavera
Keyword(s):  
Magnetic Field ◽  
Radiation Pressure ◽  
Mhd Equations ◽  
Stellar Winds ◽  
Line Profiles ◽  
A Value ◽  
Field Lines ◽  
The Magnetic Field ◽  
Intense Radiation ◽  
Open Magnetic Field

Solutions for the stellar winds of hot luminous stars are obtained by solving the magnetohydrodynamic (MHD) equations, combined with the theory of radiation-driven winds. The formalism is basically the same as developed by Rotstein & Giménez de Castro (1996). We have considered the interaction of radiation pressure with an open magnetic field . The magnetic field lines are pushed by the intense radiation field and adopt a purely radial configuration:and the polar magnetic flux at the photosphere:Rotstein & Giménez de Castro (1996) assume all the lines contributing to the radiation pressure are optically thick (α = 1) in order to decouple the MHD equations. Here the model has been improved to adopt a value of α = 0.6 which is a better approach for A-supergiants.

scholarly journals The Theory of Radiation Driven Stellar Winds and the Wolf-Rayet Phenomenon

1982 ◽  
Vol 99 ◽  
pp. 185-196
Author(s):  
David C. Abbott
Keyword(s):  
Chemical Composition ◽  
Mass Loss ◽  
Radiation Pressure ◽  
Stellar Winds ◽  
List Type ◽  
Ob Stars ◽  
Wind Theory ◽  
Loss Rates

Peter Conti has a tradition of always talking about 0-type stars at Wolf-Rayet symposia, and Wolf-Rayet stars at 0 star symposia. Since there is no well-developed theory for the origin of the winds of WR stars, it is my pleasure to join Peter's tradition, and to talk mainly about the theory of radiation driven winds in OB stars. The advantage of OB stars is that there exists a fairly complete wind theory, which agrees well with the available observations. The question is, can the mass loss observed from Wolf-Rayet stars be explained by a version of this wind theory which is scaled to the conditions found in the envelopes of Wolf-Rayet stars? The topics I consider are: —The calculated radiation pressure in OB stars, and its dependence on temperature, density, and chemical composition.—A comparison between predicted and observed mass loss rates and terminal velocities for OB stars.—The applicability of the standard radiation driven wind models to Wolf-Rayet stars.—Speculations on how Wolf-Rayet stars achieve their enormous mass loss rates within the context of the radiation pressure mechanism.

scholarly journals Radiatively-Driven Stellar Winds

1986 ◽  
Vol 89 ◽  
pp. 75-87 ◽  
Author(s):  
L.B. Lucy
Keyword(s):  
Radiation Pressure ◽  
Stellar Winds ◽  
Radiation Hydrodynamics ◽  
Marked Contrast ◽  
Hot Stars ◽  
Supersonic Zones

In this review, attention will be focussed exclusively on the winds of hot stars, concentrating for the most part on spectral types 0 and B. For these stars, a clear consensus has emerged that it is the gradient of selective radiation pressure - i.e., line-driving - that explains the high terminal velocities, typically ~ 2000 km s−1, of their winds. Accordingly, few would now doubt that the supersonic zones of these winds present us with rather clean examples of line-driven flow, whose investigation therefore properly belongs under the heading “Radiation Hydrodynamics”. Moreover, in marked contrast with other astronomical environments where line-driven winds may exist, the stellar case is geometrically and parametrically well defined and is thus by far the best natural example from which to learn about such flows.

Introduction to Stellar Winds

1999 ◽  
Author(s):  
Henny J. G. L. M. Lamers ◽  
Joseph P. Cassinelli
Keyword(s):  
Stellar Winds
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