Asymmetrical Mass Loss from Rotating Red Giant Variables

Asida, S. M.; Tuchman, Y.

doi:10.1086/176576

Cited by 17 publications

(13 citation statements)

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“…Scenarios for such processes have been proposed by Soker (1994Soker ( , 1997 and -along with a detailed numerical modelling -by Mastrodemos & Morris (1998, 1999. The equatorial compression of the already ejected matter is possible also in winds from single, rotating stars, as shown by Bjorkman & Cassinelli (1993) and Asida & Tuchman (1995). The picture can be further enriched by introducing magnetic effects (García-Segura et al 1999).…”

Section: Discussionmentioning

confidence: 97%

On winds from giants in binary systems

Frankowski

Tylenda

2001

A&A

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Abstract. We explore the influence of a companion on the wind from a giant in a binary system. We have developed a simple method for estimating the enhancement and intrinsic non-sphericity of the outflow in this case. Assuming the Roche model (modified to account for the reduced effective gravity of the giant), local stellar parameters (T eff , g) are calculated. This, according to our approach, allows to derive the local mass loss rate. The influence of varying the model parameters on the results is studied. A relation between the ratio of the stellar radius to the Roche lobe radius and the overall wind enhancement is obtained both numerically and in an analytical approximation. A similar relation is derived for the equatorial-to-polar wind intensity contrast.

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Section: Discussionmentioning

confidence: 97%

On winds from giants in binary systems

Frankowski

Tylenda

2001

A&A

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“…There is good evidence from both theory and observation (e.g. Asida & Tuchman 1995;Tuthill et al 1999) that red giant winds should not be isotropic. Magnetic effects in the warmer stars, and pulsation and shocking effects in the cooler stars will mean that density enhancements are likely to exist in the wind as well, which may play an important part in shaping the observed line profile.…”

Section: Limitationsmentioning

confidence: 96%

Dust, pulsation, chromospheres and their rôle in driving mass loss from red giants in Galactic globular clusters

McDonald¹,

Loon²

2007

A&A

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Context. Mass loss from red giants in old globular clusters affects the horizontal branch (HB) morphology and post-HB stellar evolution including the production of ultraviolet-bright stars, dredge up of nucleosynthesis products and replenishment of the intracluster medium. Study of mass loss in globular clusters also allows one to investigate the metallicity dependence of the mass loss from cool, low-mass stars down to very low metallicities. Aims. We present an analysis of new VLT/UVES spectra of 47 red giants in the Galactic globular clusters 47 Tuc (NGC 104), NGC 362, ω Cen (NGC 5139), NGC 6388, M 54 (NGC 6715) and M 15 (NGC 7078). The spectra cover the wavelength region 6100−9900 Å at a resolving power of R = 110 000. Some of these stars are known to exhibit mid-infrared excess emission indicative of circumstellar dust. Our aim is to detect signatures of mass loss, identify the mechanism(s) responsible for such outflows, and measure the mass-loss rates. Methods. We determine for each star its effective temperature, luminosity, radius and escape velocity. We analyse the Hα and nearinfrared calcium triplet lines for evidence of outflows, pulsation and chromospheric activity, and present a simple model for estimating mass-loss rates from the Hα line profile. We compare our results with a variety of other, independent methods. Results. We argue that a chromosphere persists in Galactic globular cluster giants and controls the mass-loss rate to late-K/early-M spectral types, where pulsation becomes strong enough to drive shock waves at luminosities above the RGB tip. This transition may be metallicity-dependent. We find mass-loss rates of ∼10 −7 to 10 −5 M yr −1 , largely independent of metallicity.

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“…For spherical winds, we adopt the prescription in Hurley et al (2002), and , where β w = 1/8. In general, the equatorial disc has a lower outflow velocity than the spherical wind (Bjorkman & Cassinelli 1993; Asida & Tuchman 1995), and the typical wind velocity of a field giant is between ∼5 and 30 km s −1 . Owing to the existence of an extended zone above the AGB star (Soker 2008), the outflow velocity of the equatorial disc can be very low.…”

Section: Progenitor Modelmentioning

confidence: 99%

An alternative symbiotic channel to Type Ia supernovae

Lü

Zhu

Wang

et al. 2009

Monthly Notices of the Royal Astronomical Society

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By assuming an aspherical stellar wind with an equatorial disc from a red giant, we investigate the production of Type Ia supernovae (SNe Ia) via a symbiotic channel. We estimate that the Galactic birthrate of SNe Ia via the symbiotic channel is between 1.03 × 10−3 and 2.27 × 10−5 yr−1, while the delay time of SNe Ia has a wide range from ∼0.07 to 5 Gyr. The results are greatly affected by the outflow velocity and mass‐loss rate of the equatorial disc. Using our model, we discuss the progenitors of SN 2002ic and SN 2006X.

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Asymmetrical Mass Loss from Rotating Red Giant Variables

Cited by 17 publications

References 0 publications

On winds from giants in binary systems

On winds from giants in binary systems

Dust, pulsation, chromospheres and their rôle in driving mass loss from red giants in Galactic globular clusters

An alternative symbiotic channel to Type Ia supernovae

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