scholarly journals The domain of radiatively driven mass loss in the H-R diagram

1979 ◽  
Vol 83 ◽  
pp. 235-240 ◽  
Author(s):  
David C. Abbott
Keyword(s):  
Steady State ◽  
Mass Loss ◽  
Radiation Pressure ◽  
Effective Temperature ◽  
Stellar Wind ◽  
Radiation Force ◽  
Theoretical Uncertainty ◽  
Line Radiation ◽  
Consistent Model ◽  
Self Consistent

Previous work by Castor, Abbott, and Klein (1975) presented a self-consistent model of a steady-state stellar wind. They also showed qualitatively that for O stars at least a static atmosphere could not exist. This paper extends that result by calculating in detail the minimum luminosity as a function of effective temperature required for the line radiation force to exceed gravity. Within the observational and theoretical uncertainty there is a one-to-one correspondence between a star's calculated ability to self-initiate a stellar wind by radiation pressure alone and the observed presence of outflowing material in the UV resonance lines.

scholarly journals The influence of stellar wind mass loss on the evolution of massive close binaries.

1979 ◽  
Vol 83 ◽  
pp. 409-414
Author(s):  
D. Vanbeveren ◽  
J.P. De Grève ◽  
C. de Loore ◽  
E.L. van Dessel
Keyword(s):  
Mass Loss ◽  
Stellar Wind ◽  
Binary Systems ◽  
Mass Loss Rate ◽  
Radiation Force ◽  
Roche Lobe ◽  
Close Binaries ◽  
Massive Binary Systems ◽  
Binary Evolution ◽  
X Ray Binaries

It is generally accepted that massive (and thus luminous) stars lose mass by stellar wind, driven by radiation force (Lucy and Solomon, 1970; Castor et al. 1975). For the components of massive binary systems, rotational and gravitational effects may act together with the radiation force so as to increase the mass loss rate. Our intention here is to discuss the influence of a stellar wind mass loss on the evolution of massive close binaries. During the Roche lobe overflow phase, mass and angular momentum can leave the system. Possible reasons for mass loss from the system are for example the expansion of the companion due to accretion of the material lost by the mass losing star (Kippenhahn and Meyer-Hofmeister, 1977) or the fact that due to the influence of the radiation force in luminous stars, mass will be lost over the whole surface of the star and not any longer through a possible Lagrangian point as in the case of classical Roche lobe overflow (Vanbeveren, 1978). We have therefore investigated the influence of both processes on binary evolution. Our results are applied to 5 massive X-ray binaries with a possible implication for the existence of massive Wolf Rayet stars with a very close invisible compact companion. A more extended version of this talk is published in Astronomy and Astrophysics (Vanbeveren et al. 1978; Vanbeveren and De Grève, 1978). Their results will be briefly reviewed.

scholarly journals Stellar-wind theory for O and B stars

1970 ◽  
Vol 36 ◽  
pp. 236-237
Author(s):  
Philip M. Solomon
Keyword(s):  
Mass Loss ◽  
Radiation Pressure ◽  
Stellar Wind ◽  
Conclusive Evidence ◽  
Driving Mechanism ◽  
Gravitational Acceleration ◽  
Hot Stars ◽  
B Stars ◽  
Wind Theory ◽  
Ultraviolet Observations

The rocket-ultraviolet observations of strong Doppler-shifted absorption lines of Siiv, Civ, Nv and other ions in the spectrum of O and B supergiants clearly indicate a high velocity outflow of matter from these stars. The presence of moderate ionisation stages in the stellar wind is conclusive evidence that the flow cannot be due to a high temperature corona as is the case for the solar wind. It is shown that the driving mechanism for the hot-star mass loss is radiation pressure exerted on the gas through absorption in resonance lines occurring at wavelengths near the maximum of the star's continuum flux. In the upper layers of these stars the outward force per gram of matter due to the radiation pressure can greatly exceed the gravitational acceleration making a static atmosphere impossible.The problem of a steady-state moving reversing layer is formulated and the solution leads to predictions of mass-loss rates as a function of effective temperature and gravity for all hot stars. These results are in substantial agreement with the observations.

Spectroscopic Investigations of Herbig-Ae-Be-Stars

1982 ◽  
Vol 98 ◽  
pp. 501-507
Author(s):  
Ulrich Finkenzeller
Keyword(s):  
Mass Loss ◽  
Radiation Pressure ◽  
Stellar Wind ◽  
Main Sequence ◽  
Physical Structure ◽  
Pressure Effects ◽  
Theoretical Knowledge ◽  
Be Stars ◽  
Be Star ◽  
Moderate Mass

“Herbig-Ae-Be-Stars” are assumed to be pre-main sequence objects of moderate mass with line emitting envelopes of an unknown nature. From our present theoretical knowledge it is not clear whether the physical structure of these envelopes is dominated by mass accretion or mass loss induced by a stellar wind or radiation pressure effects. Radial velocities and remarks on peculiarities are given for the star HD 200 775, which seems to represent a typical Herbig-Ae-Be-star fairly well. A catalogue of about 60 supposed Herbig-Ae-Be-stars is presented and comments, in particular on the brighter members, are invited.

A Hydrodynamic Modelling of Atmospheric Escape and Absorption Line of WASP-12b

2018 ◽  
Vol 14 (S345) ◽  
pp. 301-303
Author(s):  
N. K. Dwivedi ◽  
M. L. Khodachenko ◽  
I. F. Shaikhislamov ◽  
A. G. Berezutsky ◽  
I. B. Miroshnichenko ◽  
...  
Keyword(s):  
Mass Loss ◽  
Stellar Wind ◽  
Energy Input ◽  
Gravitational Interaction ◽  
Radiation Energy ◽  
Tidal Force ◽  
Atmospheric Escape ◽  
Planetary Mass ◽  
Stellar Radiation ◽  
Self Consistent

AbstractSelf-Consistent 2D modelling of stellar wind interaction with the upper atmosphere of WASP-12b has been performed. The two case-scenarios of the planetary material escape and interaction with the stellar wind, namely the ‘blown by the wind’ (without the inclusion of tidal force) and ‘captured by the star’ (with the tidal force) have been modelled under different stellar XUV radiations and stellar wind parameters. In the first scenario, a shock is formed around the planet, and the planetary mass loss is controlled completely by the stellar radiation energy input. In the second scenario, the mass loss is mainly due to the gravitational interaction effects. The dynamics of MGII and related absorption were modelled with three sets of different stellar wind parameters and XUV flux values.

Mass flow and evolution of UW Canis Majoris

1979 ◽  
Vol 83 ◽  
pp. 281-286
Author(s):  
Yoji Kondo ◽  
George E. McCluskey ◽  
Jürgen Rahe
Keyword(s):  
Mass Loss ◽  
Mass Flow ◽  
Radiation Pressure ◽  
Stellar Wind ◽  
Loss Rate ◽  
Mass Loss Rate ◽  
Primary Component ◽  
Uv Spectrum ◽  
Solar Mass ◽  
Eclipsing Binary

The far-UV spectrum of the eclipsing binary UW CMa (O7f + O-B) had earlier been utilized to derive a mass-loss rate of about 10−6 to 10−5 solar mass per year. The mass flow seems to be basically in the form of a stellar wind emanating from the O7f primary component, with radiation pressure as the controlling factor. The main characteristics that make UW CMa a possible progenitor of a Wolf-Rayet system are discussed.

scholarly journals Spectroscopic Investigations of Herbig-Ae-Be-Stars

1982 ◽  
Vol 98 ◽  
pp. 501-507
Author(s):  
Ulrich Finkenzeller
Keyword(s):  
Mass Loss ◽  
Radiation Pressure ◽  
Stellar Wind ◽  
Main Sequence ◽  
Physical Structure ◽  
Pressure Effects ◽  
Theoretical Knowledge ◽  
Be Stars ◽  
Be Star ◽  
Moderate Mass

“Herbig-Ae-Be-Stars” are assumed to be pre-main sequence objects of moderate mass with line emitting envelopes of an unknown nature. From our present theoretical knowledge it is not clear whether the physical structure of these envelopes is dominated by mass accretion or mass loss induced by a stellar wind or radiation pressure effects. Radial velocities and remarks on peculiarities are given for the star HD 200 775, which seems to represent a typical Herbig-Ae-Be-star fairly well. A catalogue of about 60 supposed Herbig-Ae-Be-stars is presented and comments, in particular on the brighter members, are invited.

scholarly journals On the variations of [OIII] lines intensities in the spectrum of PN IC 4997

1997 ◽  
Vol 180 ◽  
pp. 289-289
Author(s):  
A. G. Yeghikyan
Keyword(s):  
Mass Loss ◽  
Electron Temperature ◽  
Effective Temperature ◽  
Stellar Wind ◽  
Planetary Nebula ◽  
Loss Rate ◽  
Mass Loss Rate ◽  
Radiation Fields ◽  
Ionization Structure ◽  
Ionization Model

The causes of asynchronous variations of the intensities of OIII ions forbidden lines in the spectrum of compact planetary nebula IC 4997 are considered on the basis of the observational data of. It is shown that the rise of the intensity of line 4363 å and decrease of the intensities of N1 and N2 lines may be best explained by increase of mass-loss-rate from nucleous from 5 × 10–8 up to 2 × 10–7 M/yr within a few years (at constant nucleous effective temperature), with appropriate change of ionization structure of nebula. The arguments of existence of variable hot stellar wind are discussed. The theoretical intensities of lines are calculated by the ionization model of planetary nebulae [4], gyven the radiation fields of the nucleous and hot stellar wind with electron temperature Te= 500000 K.

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