Binaries discovered by the SPY project

Napiwotzki, R.; Edelmann, H.; Heber, U.; Karl, C.; Drechsel, H.; Pauli, E.-M.; Christlieb, N.

doi:10.1051/0004-6361:20011223

Cited by 96 publications

(110 citation statements)

References 18 publications

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“…Nevertheless, the masses can be constrained by assuming tidal synchronisation (see also Napiwotzki et al 2001b). Combining the orbital parameters with an estimate of the sdB mass and with the determination of its v rot sin i and surface gravity, allows the mass of the invisible companion to be constrained.…”

Section: Discussionmentioning

confidence: 99%

Binaries discovered by the SPY project

Geier¹,

Heber²,

Kupfer³

et al. 2010

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Aims. The ESO SN Ia Progenitor Survey (SPY) aims at finding merging double degenerate binaries as candidates for supernova type Ia (SN Ia) explosions. A white dwarf merger has also been suggested to explain the formation of rare types of stars like R CrB, extreme helium or He sdO stars. Here we present the hot subdwarf B binary GD 687, which will merge in less than a Hubble time.Methods. The orbital parameters of the close binary have been determined from time resolved spectroscopy. Since GD 687 is a singlelined binary, the spectra contain only information about the subdwarf primary and its orbit. From high resolution spectra the projected rotational velocity was derived. Assuming orbital synchronisation, the inclination of the system and the mass of the unseen companion were constrained. Results. The derived inclination is i = 39.3 +6.2 −5.6• . The mass M 2 = 0.71 +0.22 −0.21 M indicates that the companion must be a white dwarf, most likely of C/O composition. This is only the fourth case that an sdB companion has been proven to be a white dwarf unambiguously. Its mass is somewhat larger than the average white dwarf mass, but may be as high as 0.93 M in which case the total mass of the system comes close to the Chandrasekhar limit. Conclusions. GD 687 will evolve into a double degenerate system and merge to form a rare supermassive white dwarf with a mass in excess of solar. A death in a sub-Chandrasekhar supernova is also conceivable.

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Section: Discussionmentioning

confidence: 99%

Binaries discovered by the SPY project

Geier¹,

Heber²,

Kupfer³

et al. 2010

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“…Some additional objects come from the Montreal-Cambridge survey (Demers et al 1990;Lamontagne et al 2000) and from the Edinburgh-Cape survey (Kilkenny et al 1991). A detailed discussion of the target selection is given in Napiwotzki et al (2001Napiwotzki et al ( , 2003. While some of the input catalogs, e.g.…”

Section: Introductionmentioning

confidence: 99%

High-resolution UVES/VLT spectra of white dwarfs observed for the ESO SN Ia Progenitor Survey

Koester¹,

Voß

Napiwotzki

et al. 2009

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Context. The ESO Supernova Ia Progenitor Survey (SPY) took high-resolution spectra of more than 1000 white dwarfs and pre-white dwarfs. About two thirds of the stars observed are hydrogen-dominated DA white dwarfs. Here we present a catalog and detailed spectroscopic analysis of the DA stars in the SPY. Aims. Atmospheric parameters effective temperature and surface gravity are determined for normal DAs. Double-degenerate binaries, DAs with magnetic fields or dM companions, are classified and discussed. Methods. The spectra are compared with theoretical model atmospheres using a χ 2 fitting technique. Results. Our final sample contains 615 DAs, which show only hydrogen features in their spectra, although some are double-degenerate binaries. 187 are new detections or classifications. We also find 10 magnetic DAs (4 new) and 46 DA+dM pairs (10 new).

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“…Heber et al (1999Heber et al ( , 2000 analysed high resolution spectra of four pulsating sdB stars taken with Keck/HIRES. Napiwotzki et al (2001) and Telting et al (2008) derived metal abundances of the sdB binary HE 1047−0436 and the hybrid sdB pulsator Balloon 090100001 from optical spectra, respectively. Finally, Edelmann et al (1999Edelmann et al ( , 2001, Przybilla et al (2006) as well as Pereira & Jeffery (2008) published some preliminary results of their analysis of high resolution spectra.…”

Section: Introductionmentioning

confidence: 99%

Hot subdwarf stars in close-up view

Geier

2013

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Context. Hot subdwarf B stars (sdBs) are considered to be core helium-burning stars with very thin hydrogen envelopes situated on or near the extreme horizontal branch. The formation of sdBs is still unclear as well as the chemical composition of their atmospheres. The observed helium depletion is attributed to atmospheric diffusion. Metal abundances have been determined for about a dozen sdBs only resulting in puzzling patterns with enrichment of heavy metals and depletion of lighter ones. Aims. We present a detailed metal abundance analysis of 106 sdBs. Methods. From high resolution spectra we measured elemental abundances of up to 24 different ions per star. A semi-automatic analysis pipeline was developed to calculate and fit LTE models to a standard set of spectral lines. Results. A general trend of enrichment was found with increasing temperature for most of the heavier elements. The lighter elements like carbon, oxygen, and nitrogen are depleted and less affected by temperature. Although there is considerable scatter from star to star, the general abundance patterns in most sdBs are similar. State-of-the-art diffusion models predict such patterns and are in qualitative agreement with our results. However, the highest enrichments measured cannot be explained with these models. Peculiar line shapes of the strongest metal lines in some stars indicate vertical stratification to be present in the atmospheres. Such effects are not accounted for in current diffusion models and may be responsible for some of the yet unexplained abundance anomalies.

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Binaries discovered by the SPY project

Cited by 96 publications

References 18 publications

Binaries discovered by the SPY project

Binaries discovered by the SPY project

High-resolution UVES/VLT spectra of white dwarfs observed for the ESO SN Ia Progenitor Survey

Hot subdwarf stars in close-up view

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