Physical parameters of visual binaries with computed orbits

Kraicheva, Z.; Popova, E. I.; Тутуков, А. В.; Yungelson, L. R.

doi:10.1007/bf01084460

Cited by 13 publications

(10 citation statements)

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“…This would require a separation of a few times the radius of the presupernova star, if the stellar companion is also a massive star, implying a separation of D1012È1013 cm. The observed distribution of initial orbital separations of massive stars is (e.g., a init D1/a init Kraicheva et al 1979), so tens of percent of massive binaries are expected to be in this range of separations.…”

Section: Allowed Formation Historiesmentioning

confidence: 99%

Implications of the PSR 1257+12 Planetary System for Isolated Millisecond Pulsars

Miller

Hamilton

2001

ApJ

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The Ðrst extrasolar planets were discovered in 1992 around the millisecond pulsar PSR 1257]12. We show that recent developments in the study of accretion onto magnetized stars, plus the existence of the innermost, moon-sized planet in the PSR 1257]12 system, suggest that the pulsar was born with approximately its current rotation frequency and magnetic moment. If so, this has important implications for the formation and evolution of neutron star magnetic Ðelds as well as for the formation of planets around pulsars. In particular, it suggests that some and perhaps all isolated millisecond pulsars may have been born with high spin rates and low magnetic Ðelds instead of having been recycled by accretion.

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Section: Allowed Formation Historiesmentioning

confidence: 99%

Implications of the PSR 1257+12 Planetary System for Isolated Millisecond Pulsars

Miller

Hamilton

2001

ApJ

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“…However, if the internal energy of the envelope is efficiently used to unbind the envelope, we find α > 2. Using the initial mass function Kroupa et al 1993) and the distribution in orbital separation Γ(a) ∝ a −1 (Kraicheva et al 1978), we found that the number of systems that experienced a helium flash is comparable to the number of systems that ignited helium non-degenerately with α < 5. Thus, if the internal energy can unbind the envelope, we are less confident in excluding the non-degenerate scenario.…”

Section: The Orbital Separationmentioning

confidence: 99%

An evolutionary study of the pulsating subdwarf B eclipsing binary PG 1336-018 (NY Virginis)

Nelemans

Østensen

et al. 2007

A&A

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Context. The formation of subdwarf B (sdB) stars is not well understood within the current framework of stellar single and binary evolution. Aims. In this study, we focus on the formation and evolution of the pulsating sdB star in the very short-period eclipsing binary PG 1336−018. We aim at refining the formation scenario of this unique system, so that it can be confronted with observations. Methods. We probe the stellar structure of the progenitors of sdB stars in short-period binaries using detailed stellar evolution calculations. Applying this to PG 1336−018 we reconstruct the common-envelope phase during which the sdB star was formed. The results are interpreted in terms of the standard common-envelope formalism (the α-formalism) based on the energy equation, and an alternative description (the γ-formalism) using the angular momentum equation. Results. We find that if the common-envelope evolution is described by the α-formalism, the sdB progenitor most likely experienced a helium flash. We then expect the sdB mass to be between 0.39 and 0.48 M , and the sdB progenitor initial mass to be below ∼2 M . However, the results for the γ-formalism are less restrictive, and a broader sdB mass range (0.3-0.8 M ) is possible in this case. Future seismic mass determination will give strong constraints on the formation of PG 1336−018 and, in particular, on the CE phase.Key words. subdwarfs -stars: evolution -binaries: close -binaries: eclipsing -methods: numerical IntroductionSubdwarf B (sdB) stars are the dominant population of faint blue objects at high galactic latitudes (Green et al. 1986), and are found in both the disk and halo. They are also ubiquitous in giant elliptical galaxies, where they are believed to be the main source of the ultraviolet excess (Brown et al. 1997). In the Hertzsprung-Russell diagram they lie on the blue extension of the Horizontal Branch, and are therefore also known as Extreme Horizontal Branch (EHB) stars. It is generally thought that they are low mass (0.5 M ) core-helium burning stars with extremely thin hydrogen envelopes (<0.02 M ) (Heber 1986;Saffer et al. 1994). Their envelopes are too thin to sustain hydrogen burning, hence they will evolve directly to the white dwarf cooling track after core-helium exhaustion, without going through the Asymptotic Giant Branch and Planetary Nebulae phases.It is not clearly understood how the sdB progenitor manages to loose almost its entire hydrogen-envelope, but nevertheless starts core-helium fusion. Both single star evolution with enhanced mass loss on the Red Giant Branch (RGB) (D'Cruz et al. 1996), and binary evolution models (Mengel et al. 1976) have been proposed as formation channels. Extensive surveys show that a large fraction of sdB stars are in binaries (e.g. Allard et al. 1994;Morales-Rueda et al. 2006). This motivated Han et al. (2002Han et al. ( , 2003 to perform a detailed investigation of the main binary evolution channels that can produce an sdB star. They found that an sdB star can be formed after one or two commonenve...

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“…There is a sharp cutoff in the number of very wide binaries with physical separations greater than 0.1 pc, possibly dictated by dynamical evolution, as stated in classical (Tolbert 1964;Kraicheva et al 1985;Abt 1988;Weinberg & Wasserman 1988;Weis 1988;Close et al 1990;Latham et al 1991;Wasserman & Weinberg 1991 and references above) and modern works (Allen et al 2000;Palasi 2000;Chanamé & Gould 2004;Lépine & Bongiorno 2007;Makarov et al 2008). My aim is to characterise and look for very wide binaries and multiple systems with projected physical separations larger than s = 0.1 pc (2 × 10 4 AU).…”

Section: Introductionmentioning

confidence: 99%

Reaching the boundary between stellar kinematic groups and very wide binaries

Caballero¹

2009

A&A

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Aims. I look for and characterise very wide binaries and multiple systems with projected physical separations larger than s = 0.1 pc, which is generally believed to be a sharp upper limit to the distribution of wide binary semimajor axes. Methods. I investigated in detail 30 Washington double stars with angular separations of ρ > 1000 arcsec. I discarded 23 of them as probably unbound systems based on discordant astrometry, photometry, spectral types, and radial velocities. The remaining seven systems were subject to a comprehensive data compilation and derivation (multi-wavelength photometry, heliocentric distance, multiplicity, age, mass, metallicity, membership in a young kinematic group). Results. Of the seven very wide systems, six have projected physical separations greater than the hypothetical cutoff at s = 0.1 pc and four have separations s > 0.2 pc. Although there are two systems in young kinematic groups (namely HD 136654 and BD+32 2572 in the Hyades Supercluster, and AU Mic and AT Mic AB in the β Pictoris moving group), there is no clear prevalence of young systems (τ < 1 Ga) among these very wide binaries. Finally, I compare the binding energies of the seven systems with those of other weakly bound systems in the field.

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Physical parameters of visual binaries with computed orbits

Cited by 13 publications

References 13 publications

Implications of the PSR 1257+12 Planetary System for Isolated Millisecond Pulsars

Implications of the PSR 1257+12 Planetary System for Isolated Millisecond Pulsars

An evolutionary study of the pulsating subdwarf B eclipsing binary PG 1336-018 (NY Virginis)

Reaching the boundary between stellar kinematic groups and very wide binaries

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