On the formation of Super-AGB stars in intermediate mass close binary systems

Gil‐Pons, Pilar; Garcı́a–Berro, E.

doi:10.1051/0004-6361:20021416

Cited by 16 publications

(13 citation statements)

References 29 publications

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“…The basis of the (non explosive) evolution of SAGB stars was laid down in the 90's in a series of papers by García-Berro & Iben (1994), Ritossa et al (1996), García-Berro et al (1997), Iben et al (1997) and Ritossa et al (1999). Recently, new models have been computed for solar (Gil-Pons & García-Berro 2002;Siess 2006a;Doherty & Lattanzio 2006;Poelarends et al 2006) and primordial composition (Gil-Pons et al 2005 showing a renewal of interest for this specific stellar population.…”

Section: Introductionmentioning

confidence: 99%

Evolution of massive AGB stars

Siess¹

2007

A&A

260

315

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Context. Massive AGB (hereafter super-AGB or SAGB) stars ignite carbon off-center and have initial masses ranging between M up , the minimum initial mass for carbon ignition, and M mas the minimum mass for the formation of an iron core collapse supernova. In this mass interval, stars more massive than M n will undergo an electron capture supernova (EC-SN). Aims. We study the fate and selected evolutionary properties of SAGB stars up to the end of the carbon burning phase as a function of metallicity and core overshooting. Methods. The method is based on the analysis of a large set of stellar models covering the mass range 5−13 M and calculated for 7 different metallicities between Z = 10 −5 and twice solar. Core overshooting was considered in two subsets for Z = 10 −4 and 0.02. The models are available online at http://www-astro.ulb.ac.be/∼siess/database.html. The fate of SAGB stars is investigated through a parametric model which allows us to assess the role of mass loss and of the third dredge-up. Results. Our main results can be summarized as follows: a) prior to C-burning, the evolution of SAGB stars is very similar to that of intermediate-mass stars, being more luminous, b) SAGB stars suffer a large He enrichment at the end of the second dredge-up, c) the limiting masses M up , M n and M mas present a nonlinear behavior with Z, characterized by a minimum around Z = 10 −4 , d) the values of M up , M n and M mas are decreased by ∼2 M when core overshooting is considered, e) our models predict a minimum oxygenneon white dwarf mass of ∼1.05 M , f) the determination of M n is highly dependent on the mass loss and core growth rates, g) the evolutionary channel for EC-SN is limited to a very narrow mass range of < ∼ 1−1.5 M width and this mass window can be further decreased if some metallicity scaling factor is applied to the mass loss rate, h) the final fate of SAGB stars is connected to the second dredge-up and this property allowed us to refine the initial mass range for the formation of EC-SN. We find that if the ratio of the mass loss rate to the core growth rate averaged over the post carbon-burning evolution ζ = Ṁ loss /Ṁ core is greater than about 70−90, the evolutionary path to EC-SN is not accessible.

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Section: Introductionmentioning

confidence: 99%

Evolution of massive AGB stars

Siess¹

2007

A&A

260

315

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“…Recently, more models become available exploring the evolution at different metallicities (e.g. Gil‐Pons & García‐Berro 2002; Siess 2007) and investigating the effects of extra‐mixing and binarity (Gil‐Pons et al 2005, 2007; Poelarends et al 2008). As more and more SAGB studies populate the literature, all find qualitative similarities, despite large variations in the input physics.…”

Section: Introductionmentioning

confidence: 99%

Super asymptotic giant branch stars. I - Evolution code comparison

Doherty

Siess

Lattanzio

et al. 2010

Monthly Notices of the Royal Astronomical Society

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We present an extensive set of detailed stellar models in the mass range 7.7–10.5 M⊙ over the metallicity range Z= 10−5–0.02. These models were produced using the Monash University version of the Mount Stromlo Stellar Structure Program (monstar) and follow the evolution from the pre‐main sequence to the first thermal pulse of these super asymptotic giant branch stars. A quantitative comparison is made to the study of Siess. Prior to this study, only qualitative comparisons and code validations existed in this critical mass range, and the large variations in the literature were largely unexplained. The comparison presented here is particularly detailed due to the standardization of the input physics, where possible. The minimum initial mass of star which ignites carbon, Mup, was found to agree within 0.2 M⊙ between the codes over the entire metallicity range. We find exceptional agreement in the model results between these two codes for all stages of evolution up to and including carbon burning. For additional comparison, we also present results from the evolve code, a modified version of the iben code as described in Gil‐Pons, Gutiérrez & García‐Berro for some important variables during the carbon burning phase. Several numerical tests showed that the carbon burning phase is weakly dependent on the spatial resolution but that inadequate temporal resolution alters the behaviour of the convective zones. We also discovered that stars just below Mup may experience a carbon flash that is not followed by the development of the flame. Such aborted carbon burning models thus preserve a CO core surrounding by a 0.2–0.3 M⊙ shell of partially burnt carbon material. We present a simplified algorithm for calculating carbon burning that only relies on tracking two species, 12C and 16O, but which tests show works quite accurately for the a wide range of initial masses and compositions.

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“…In parallel, binary evolution provided additional paths to the formation of NeO white dwarf (e.g. Iben & Tutukov 1985;Dominguez et al 1993;Gil-Pons & Garcia-Berro 2002).…”

Section: Introductionmentioning

confidence: 99%

Evolution of massive AGB stars

Siess¹

2006

A&A

218

273

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We present new computations of the evolution of solar metallicity stars in the mass range 9−12 M . This first paper of a series focuses on the propagation of the carbon burning flame front and provides a detailed analysis of the structural evolution up to the formation of the neonoxygen core. Our calculations which do not include overshooting indicate that off-center carbon ignition is restricted to a small mass range between 9.0 and 11.3 M . The chemical imprints of the first and second dredge-ups on the surface composition are analyzed and compared to "standard" less massive stars. It results that, aside from being more luminous and slightly bluer in the HR diagram, massive AGB stars are almost indistinguishable from their lower mass counterparts, as far as the chemical composition is concerned. During the second dredge-up, we note however that the envelope penetrates deeper into the He burning shell than lower mass stars. Our simulations indicate that above ∼11.0 M , the depth of the second dredge up is considerably reduced, marking the transition between low and massive stars. We also investigate the effects of the nuclear uncertainties associated with 12 C + 12 C reactions and show that it has a little impact on the core composition. Finally we describe the nucleosynthesis and chemical structure of the newly formed neon-oxygen core.

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On the formation of Super-AGB stars in intermediate mass close binary systems

Cited by 16 publications

References 29 publications

Evolution of massive AGB stars

Evolution of massive AGB stars

Super asymptotic giant branch stars. I - Evolution code comparison

Evolution of massive AGB stars

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