P Cygni stars and mass loss

Kuan, P.; Huhi, L. V.

doi:10.1086/153675

Cited by 33 publications

(15 citation statements)

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“…The problem of multiple-branched equal velocity surfaces is known from modeling of line profiles from decelerating atmospheres ( Kuan & Kuhi (1975), Surdej (1977). These authors adopted a decelerating velocity law, v(r) = V const (R ph /r) l , where l > 0 is a parameter of deceleration and R ph is the radius of the photosphere.…”

Section: Optical Depthmentioning

confidence: 99%

“…Another approximate approach was adopted by Kuan & Kuhi (1975) who ignored the radiative coupling between s and s ′ . In the literature this is known as the 'disconnected approximation' ( Marti & Noerdlinger (1977)).…”

Section: Radiation Field In a Linementioning

confidence: 99%

“…In the literature this is known as the 'disconnected approximation' ( Marti & Noerdlinger (1977)). Giving an extensive analysis of the problem of interconnection of different EFS branches for decelerating flow, these authors arrive to the conclusion that i) taking into account radiative coupling can be of importance for the calculation of the radiation force; ii) fortunately, the disconnected approximation of Kuan & Kuhi (1975) which completely neglects such coupling, works well and gives generally correct results for the source function and resultant profiles.…”

Section: Radiation Field In a Linementioning

confidence: 99%

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Gravitationally Distorted P-Cygni Profiles From Outflows Near Compact Objects

Dorodnitsyn

2008

Int. J. Mod. Phys. D

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We consider resonant absorption in a spectral line in the outflowing plasma within several tens of Schwarzschild radii from a compact object. We take into account both Doppler and gravitational shifting effects and re-formulate the theory of P-Cygni profiles in these new circumstances. It is found that a spectral line may have multiple absorption and emission components depending on how far the region of interaction is from the compact object and what is the distribution of velocity and opacity. Profiles of spectral lines produced near a neutron star or a black hole can be strongly distorted by Doppler blue-, or redshifting, and gravitational red-shifting. These profiles may have both red-and blue-shifted absorption troughs. The result should be contrasted with classical P-Cygni profiles which consist of red-shifted emission and blue-shifted absorption features.We suggest this property of line profiles to have complicated narrow absorption and emission components in the presence of strong gravity may help to study spectroscopically the innermost parts of an outflow.

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Section: Optical Depthmentioning

confidence: 99%

Section: Radiation Field In a Linementioning

confidence: 99%

Section: Radiation Field In a Linementioning

confidence: 99%

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Gravitationally Distorted P-Cygni Profiles From Outflows Near Compact Objects

Dorodnitsyn

2008

Int. J. Mod. Phys. D

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“…For application we use the prototype of LBVs, P Cyg, as the central star following Paper I. The envelope of this star may possess a deceleration region (Kuan & Kuhi 1975;Nugis et al 1979) and also exhibits shells or blobs (Vakili et al 1997). These outflows may not arise as thick-line-driven winds but from the absorption of a large number of the weak, optically thin spectral UV lines in the Balmer continuum (Lamers 1986).…”

Section: The Energetics Of Steady Shell Thermo-radiative Casementioning

confidence: 99%

“…By contrast, the strong winds observed in early main-sequence stars are traditionally modeled by the thick-line-driven wind theory (Castor et al 1975) which is based on the Sobolev approximation. However, the reduced acceleration near the stellar surface and the low terminal velocity of winds from supergiants cannot be accounted for thick-line driving (as for example has been extensively discussed by Lamers (1986) for P Cyg), as well as the possible deceleration regions in the stellar envelope (Kuan & Kuhi 1975). Assuming e-mail: akakour@cc.uoa.gr an optically thin stellar atmosphere, Kakouris & Moussas (1998), hereafter Paper I, proposed an alternative thermoradiative mechanism which can describe the deceleration region in the stellar envelope and steady shell formation under certain conditions.…”

Section: Introductionmentioning

confidence: 99%

On steady shell formation in stellar atmospheres

Kakouris

2001

A&A

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Abstract. The energy balance of the analytical solutions of for a steady state of an externally heated/cooled 2-D circumstellar envelope is investigated. It is found that the required heating/cooling rates are physically realistic and can be related to specific microscopic mechanisms. We find that in the subsonic region of the wind the fluid is mechanically heated. In the supersonic stellar envelope the fluid is cooled at a rate which is consistent with radiative cooling to space. The energy balance of steady shell or blob formation in the envelopes of luminous early or late type supergiants is also investigated (Kakouris & Moussas 1998). We find that radiative cooling occurs in the intermediate deceleration region of the three-zone envelope. Indicative of the local thermodynamic processes is the effective polytropic index α which takes values close to the star between 1 and 4, becoming 2 at larger distances. The heated subsonic region close to the stellar surface is isothermal and becomes adiabatic at the sonic transition. We find that the polytropic index α is less than unity in the vicinity of the dense blob, indicating that the region may be dominated by convection.

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Outflows and Accretion

2007

Astrophysical Hydrodynamics

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P Cygni stars and mass loss

Cited by 33 publications

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Gravitationally Distorted P-Cygni Profiles From Outflows Near Compact Objects

Gravitationally Distorted P-Cygni Profiles From Outflows Near Compact Objects

On steady shell formation in stellar atmospheres

Outflows and Accretion

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