Evolution through mass exchange in close binary systems of total mass 2.5M ?

Refsdal, S.; Weigert, Alfred

doi:10.1007/bf00649604

Cited by 42 publications

(52 citation statements)

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“…(2) The lifetime of EL CVn-type stars, t. As discussion in section 3.2, t ∝ Menv/Ṁnuc, wherė Mnuc is very sensitive to the temperature in the burning shell T b . Since T b ∼ Mc/Rc (Refsdal & Weigert 1970) and Rc decreases with Z for a given Mc, the temperature T b , thenṀnuc, increase with decreasing Z. So, the value of t may not significantly deviate from that shown in this paper since Menv also increases with the decreasing Z as discussed above.…”

Section: Effects Of Metallicitysupporting

confidence: 54%

The Formation of EL CVn-type Binaries

Chen

Maxted

et al. 2017

Mon. Not. R. Astron. Soc.

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EL CVn-type binaries are eclipsing binaries that contain an A-or F-type dwarf star and a very low mass (∼ 0.2M ⊙ ) helium white dwarf precursor (proto-He WD). A number of such objects have been discovered in the WASP and Kepler photometric surveys. Here we have studied the formation of EL CVn-type binaries and give the properties and the space density of this population of stars in the Galaxy. We show that EL CVn binaries cannot be produced by common envelope evolution as previously believed because this process leads to merging of the components when giants have such low-mass cores. Stable mass transfer in low-mass binaries, from more than 65,000 runs of Population I binary evolution, may well reproduce the properties of EL CVn stars such as the evolutionary phase, mass ratios and the WD mass-period (M WD − P ) relation. The study shows that the most common donor mass range for producing the observed EL CVn-type stars is 1.15 − 1.20M ⊙ and that the lifetime of such objects increases dramatically with decreasing proto-He WD mass. This leads to an intrinsic peak mass around the minimum mass of proto-He WDs of ∼ 0.16M ⊙ . The most probable proto-He WD mass is 0.17 − 0.21M ⊙ after selection effects included. We estimated the number of EL CVn stars with P ≤ 2.2 d to be 2 − 5 × 10 6 in the Galaxy, indicating a local density of 4 − 10 × 10 −6 pc −3 . We conclude that many more EL CVntype binaries remain to be discovered and that these binaries will be predominantly low-mass systems in old stellar populations.

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Section: Effects Of Metallicitysupporting

confidence: 54%

The Formation of EL CVn-type Binaries

Chen

Maxted

et al. 2017

Mon. Not. R. Astron. Soc.

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“…As shown by Refsdal & Weigert (1970) and Tuchman et al (1983), the existence of an M c − L relation requires an inert transition region below the convective envelope where the luminosity remains constant and where the temperature, pressure, density, and radius present a steep dependence on the mass coordinate. In stars experiencing HBB, this transition region is absent because H burning extends into the convective envelope.…”

Section: The Interpulse Phasementioning

confidence: 97%

Evolution of massive AGB stars

Siess

2010

A&A

186

323

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Aims. We present the first simulations of the full evolution of super-AGB stars through the entire thermally pulsing AGB phase. We analyse their structural and evolutionary properties and determine the first SAGB yields.Methods. Stellar models of various initial masses and metallicities were computed using standard physical assumptions which prevents the third dredge-up from occurring. A postprocessing nucleosynthesis code was used to compute the SAGB yields, to quantify the effect of the third dredge-up (3DUP), and to assess the uncertainties associated with the treatment of convection.Results. Owing to their massive oxygen-neon core, SAGB stars suffer weak thermal pulses, have very short interpulse periods and develop very high temperatures at the base of their convective envelope (up to 140 × 10 8 K), leading to very efficient hot bottom burning. SAGB stars are consequently heavy manufacturers of 4 He, 13 C, and 14 N. They are also able to inject significant amounts of 7 Li, 17 O, 25 Mg, and 26,27 Al in the interstellar medium. The 3DUP mainly affects the CNO yields, especially in the lower metallicity models. Our post-processing simulations also indicate that changes in the temperature at the base of the convective envelope, which would result from a change in the efficiency of convective energy transport, have a dramatic impact on the yields and represent another major source of uncertainty.

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“…Refsdal & Weigert 1970;Ritter 1999) and at the end of the mass transfer phase it equals the maximum radius corresponding to the mass of its core, that is the white dwarf companion of the millisecond pulsar. Refsdal & Weigert (1971) gave a simple relationship between the maximum radius of the secondary and its core mass: R max /R = 10 4.1 (M/M ) 5.3 , valid for stars of solar chemical composition and neglecting the small difference between the mass of the secondary and that of its helium core (≤5%). Since the maximum radius is equal to the Roche lobe radius at the end of mass transfer, we can express the semi-major axis and the orbital period as a function of M .…”

Section: The Residual Eccentricitymentioning

confidence: 99%

The residual orbital eccentricity in close binaries

Lanza

Rodonò

2001

A&A

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Abstract. Density fluctuations in convective stars produce small variations of their outer gravitational field that give rise to a very small, though finite, orbital eccentricity in close binaries with convective components. We revisit the theory for such an effect, originally presented by Phinney (1992), and propose a new approach to compute the fluctuations of the outer gravitational field based on Chandrasekhar's virial theorem. It is applied to compute the eccentricities of binaries with a millisecond pulsar component in the framework of a simplified model of their evolution. The comparison with the observations allows us to test the models proposed for the formation of such systems, giving support to the evolutionary scenarios that connect them with low-mass X-ray binaries, and to provide a new test for turbulent convection models of giant stars.

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Evolution through mass exchange in close binary systems of total mass 2.5M ?

Cited by 42 publications

References 0 publications

The Formation of EL CVn-type Binaries

The Formation of EL CVn-type Binaries

Evolution of massive AGB stars

The residual orbital eccentricity in close binaries

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