Very massive stars: Evolution with mass loss

Klapp, Jaime

doi:10.1007/bf00650350

Cited by 10 publications

(9 citation statements)

References 33 publications

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“…Past calculations of the wind contributions from VMOs can be found in the works by El Eid et al (1982), Klapp (1983Klapp ( , 1984, and more recently Portinari et al (1998). These latter estimates are based on the results of semi-analytic stellar models developed by Bond et al (1984).…”

Section: The Stellar Yieldsmentioning

confidence: 99%

“…There are few studies in the literature that present evolutionary models of very massive zero-metallicity stars with mass loss during the pre-supernova phases. In the very massive domain (500−1000 M ) Klapp (1983Klapp ( , 1984 carried out evolutionary calculations by adopting a simple empirical law for mass-loss (Barlow & Cohen 1977) -based on Galactic observations -that linearly scales with the stellar luminosity. On the basis of semi-analytical models of very massive objects (with masses 10 2 −10 5 M ), Bond et al (1984) argued that the same kind of dynamical instability arising in the H-burning shell of Population I models -which should cause the ejection of the entire envelope -might also affect Population III VMOs, depending on the actual abundance of the CNO catalysts in the H-shell.…”

Section: Introductionmentioning

confidence: 99%

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Zero-metallicity stars

Marigo

Chiosi

Kudritzki

2003

A&A

109

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Abstract.We present evolutionary models of zero-metallicity very massive objects, with initial masses in the range 120 M -1000 M , covering their quiescent evolution up to central carbon ignition. In the attempt of exploring the possible occurrence of mass loss by stellar winds, calculations are carried out with recently-developed formalisms for the mass-loss rates driven by radiation pressure (Kudritzki 2002) and stellar rotation . The study completes the previous analysis by Marigo et al. (2001) on the constant-mass evolution of primordial stars. Our results indicate that radiation pressure (assuming a minimum metallicity Z = 10 −4 × Z ) is not an efficient driving force of mass loss, except for very massive stars with M > ∼ 750 M . On the other hand, stellar rotation might play a crucial role in triggering powerful stellar winds, once the ΩΓ-limit is approached. However, this critical condition of intense mass loss can be maintained just for short, as the loss of angular momentum due to mass ejection quickly leads to the spinning down of the star. As by-product to the present work, the wind chemical yields from massive zero-metallicity stars are presented. The helium and metal enrichments, and the resulting ∆Y/∆Z ratio are briefly discussed.

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Section: The Stellar Yieldsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Zero-metallicity stars

Marigo

Chiosi

Kudritzki

2003

A&A

109

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“…Other groups have computed the yields for zero-metallicity VMOs (e.g. Ober, El Eid & Fricke 1983;Klapp 1984), and Marigo et al's yields are not in a smooth continuation with the yields of low-mass zero-metal stars given by Limongi & Chieffi (2002). The discontinuity may not be a big issue if the mass loss in VMOs may happen in an extreme fashion (Smith 2006).…”

Section: Discussionmentioning

confidence: 99%

First stars as a possible origin for the helium-rich population in ? Cen

Choi¹,

Yi²

2006

Monthly Notices RAS Letters

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The most massive Galactic globular cluster ω Cen appears to have two, or perhaps more, distinct main sequences. Its bluest main sequence is at the centre of debate because it has been suggested to have an extremely high helium abundance of Y ∼ 0.4. The same helium abundance is claimed to explain the presence of extreme horizontal branch stars of ω Cen as well. This demands a relative helium-to-metal enrichment of Y / Z ∼ 70; that is, more than one order of magnitude larger than the generally accepted value. Candidate solutions, namely asymptotic giant branch stars, massive stars and supernovae, have been suggested; but in this study, we show that none of them is a viable channel, in terms of reproducing the high value of Y / Z for the constrained age difference between the red and blue populations. Essentially no populations with an ordinary initial mass function, including those candidates, can produce such a high Y / Z because they all produce metals as well as helium. As an alternative, we investigate the possibility of the stochastic 'first star' contamination to the gas from which the younger generation of ω Cen formed. This requires the assumption that the Population III star formation episode overlaps with that of Population II. While the required condition appears extreme, very massive objects in the first star generation provide a solution that is at least as plausible as any other suggestions made before.

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“…This opened the field for many studies that were mainly concerned with later evolutionary stages (Cary 1974;Castellani et al 1983;El Eid et al 1983;Ober et al 1983;Klapp 1983Klapp , 1984. Motivated by the still ongoing debate about the initial mass function of Pop-III stars, Marigo et al (2001) present the most comprehensive study of zero-metal evolutionary models (0.7-100 M ) starting from the ZAMS until the AGB in the case of low-and intermediate-mass stars, or to the onset of carbon burning in massive stars.…”

Section: Introductionmentioning

confidence: 99%

Massive zero-metal stars: Energy production and mixing

Straka

Tscharnuter

2001

A&A

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Abstract. Time-dependent nuclear network calculations at constant temperature show that for zero-metal stars &20 M (i) β-decay reactions and (ii) the14 O reaction must be included. It is also shown that the nuclear timescale in these zero-metal stars is shorter than the mixing timescale and therefore the assumption of instantaneous mixing across convective regions is not fulfilled. We conclude that proper modeling of these processes may alter the evolution of massive zero-metal stars.

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Very massive stars: Evolution with mass loss

Cited by 10 publications

References 33 publications

Zero-metallicity stars

Zero-metallicity stars

First stars as a possible origin for the helium-rich population in ? Cen

Massive zero-metal stars: Energy production and mixing

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