Mass loss from dynamically unstable stellar envelopes

Tuchman, Y.; Sack, N.; Barkat, Z.

doi:10.1086/155767

Cited by 53 publications

(29 citation statements)

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“…Glatzel & Kiriakidis (1998) have recently contended that the nonadiabatic radial oscillation eigenfrequency should be used to test for dynamical instability. However, as shown by the one-zone model (Stothers & Chin 1997) as well as by numerical calculations of distributed stellar models (Tuchman, Sack, & Barkat 1978 ;Stothers 1999), the nonadiabatic contribution shows up only as pulsational instability, in the form of periodic oscillations superimposed on the quasi-adiabatic, dynamical expansion of the outer envelope. Dynamical instability itself is an adiabatic phenomenon, not related to the pulsational instability.…”

Section: Criterion For Dynamical Instabilitymentioning

confidence: 95%

Rotational Effects on the Dynamical Instability of Luminous Blue Variables

Stothers

1999

ApJ

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Rotation inÑuences the dynamical stability of a star in both direct and indirect ways. Directly, it supplies rotational kinetic energy to the star and changes the starÏs hydrostatic structure. Indirectly, it inÑuences the possible course of stellar evolution. Calculations show that, for a luminous blue variable (LBV), rotation is not expected to greatly a †ect the onset of dynamical instability in any direct way, but could be important through its indirect evolutionary e †ect on the starÏs luminosity-to-mass ratio. If the classical LBVÏs are evolving in an advanced stage of central helium burning, when their envelopes are most prone to dynamical instability, the luminosity-to-mass ratio would probably be increased by rotation. It is shown that a brightening of the star lessens its dynamical stability and so leads to a somewhat hotter e †ective temperature during the phase of dynamical instability. How rotation modiÐes the Eddington luminosity limit is also discussed.

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Section: Criterion For Dynamical Instabilitymentioning

confidence: 95%

Rotational Effects on the Dynamical Instability of Luminous Blue Variables

Stothers

1999

ApJ

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“…The specific instability which causes AGB envelope ejection is still debated, but numerous previous studies exist (see, e.g., Paczyński & Ziółkowski 1968;Kutter & Sparks 1974;Tuchman et al 1978Tuchman et al , 1979Fox & Wood 1982;Wagenhuber & Weiss 1994;Han et al 1994;Soker 2008).…”

Section: Introductionmentioning

confidence: 99%

On the role of recombination in common-envelope ejections

Іванова

Justham

Podsiadlowski

2015

Monthly Notices of the Royal Astronomical Society

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The energy budget in common-envelope events (CEEs) is not well understood, with substantial uncertainty even over to what extent the recombination energy stored in ionised hydrogen and helium might be used to help envelope ejection. We investigate the reaction of a red-giant envelope to heating which mimics limiting cases of energy input provided by the orbital decay of a binary during a CEE, specifically during the post-plunge-in phase during which the spiral-in has been argued to occur on a time-scale longer than dynamical. We show that the outcome of such a CEE depends less on the total amount of energy by which the envelope is heated than on how rapidly the energy was transferred to the envelope and on where the envelope was heated. The envelope always becomes dynamically unstable before receiving net heat energy equal to the envelope's initial binding energy. We find two types of outcome, both of which likely lead to at least partial envelope ejection: "runaway" solutions in which the expansion of the radius becomes undeniably dynamical, and superficially "self-regulated" solutions, in which the expansion of the stellar radius stops but a significant fraction of the envelope becomes formally dynamically unstable. Almost the entire reservoir of initial helium recombination energy is used for envelope expansion. Hydrogen recombination is less energetically useful, but is nonetheless important for the development of the dynamical instabilities. However, this result requires the companion to have already plunged deep into the envelope; therefore this release of recombination energy does not help to explain wide post-common-envelope orbits.

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“…It is clear that this is only a rough estimate; nevertheless a comparison with models of convective envelopes calculated for the same conditions with the mixing length theory using the method described by Tuchman et al (1978) give an agreement better than a factor of 3.…”

Section: The Convective Timescalementioning

confidence: 88%

Carbon‐poor Stellar Cores as Supernova Progenitors

Waldman

Barkat

2007

ApJ

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Exploring stellar models which ignite carbon off-center (in the mass range of about 1.05Y1.25 M , depending on the carbon mass fraction), we find that they may present an interesting Type 1 supernova (SN I ) progenitor scenario, since whereas in the standard scenario runaway always takes place at the same density of about 2 ; 10 9 g cm À3 , in our case, due to the small amount of carbon ignited, we get a whole range of densities from 1 ; 10 9 up to 6 ; 10 9 g cm À3. These results could contribute to resolving the emerging recognition that at least some diversity among SNe I exists, since runaway at various central densities is expected to yield various outcomes in terms of the velocities and composition of the ejecta, which should be modeled and compared to observations.

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Mass loss from dynamically unstable stellar envelopes

Cited by 53 publications

References 0 publications

Rotational Effects on the Dynamical Instability of Luminous Blue Variables

Rotational Effects on the Dynamical Instability of Luminous Blue Variables

On the role of recombination in common-envelope ejections

Carbon‐poor Stellar Cores as Supernova Progenitors

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