A new HW Vir binary from the Palomar Transient Factory

Schindewolf, M.; Levitan, David; Heber, U.; Drechsel, H.; Schaffenroth, V.; Kuper, T.; Prince, Thomas A.

doi:10.1051/0004-6361/201425581

Cited by 11 publications

(5 citation statements)

References 36 publications

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“…More generally, both CRTS and PTF have been used to search for PCEBs not limited to WD+MS systems. These include eclipsing variables that can be in contact or semidetached (Drake et al 2014a) as well as PCEBs with sdB/sdO components rather than WDs (Schindewolf et al 2015).…”

Section: Introductionmentioning

confidence: 99%

Photometric variability of candidate white dwarf binary systems from Palomar Transient Factory archival data

Kao

Kaplan

Prince

et al. 2016

Mon. Not. R. Astron. Soc.

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We present a sample of 59 periodic variables from the Palomar Transient Factory, selected from published catalogues of white dwarf (WD) candidates. The variability can likely be attributed to ellipsoidal variation of the tidally distorted companion induced by the gravity of the primary (WD or hot subdwarf) or to the reflection of hot emission by a cooler companion. We searched 11 311 spectroscopically or photometrically selected WD candidates from three hot star/WD catalogues, using the Lomb-Scargle periodogram to single out promising sources. We present period estimates for the candidates, 45 of which were not previously identified as periodic variables, and find that most have a period shorter than a few days. Additionally, we discuss the eclipsing systems in our sample and present spectroscopic data on selected sources.

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Section: Introductionmentioning

confidence: 99%

Photometric variability of candidate white dwarf binary systems from Palomar Transient Factory archival data

Kao

Kaplan

Prince

et al. 2016

Mon. Not. R. Astron. Soc.

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“…All transient surveys are bound to find such objects at fainter magnitudes. For example the latest study(Schindewolf et al 2015) deals with an HWVir system discovered by the Palomar Transient Facility(Law et al 2009). Recently,Pietrukowicz et al (2013) andSoszyński et al (2015) announced the discovery of three dozen HWVir stars from the OGLE experiment.…”

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confidence: 99%

Hot Subluminous Stars

Heber¹

2016

PASP

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318

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Hot subluminous stars of spectral type B and O are core helium-burning stars at the blue end of the horizontal branch or have evolved even beyond that stage. Most hot subdwarf stars are chemically highly peculiar and provide a laboratory to study diffusion processes that cause these anomalies. The most obvious anomaly lies with helium, which may be a trace element in the atmosphere of some stars (sdB, sdO) while it may be the dominant species in others (He-sdB, He-sdO). Strikingly, the distribution in the Hertzsprung-Russell diagram of He-rich versus He-poor hot subdwarf stars of the globular clusters ω Cen and NGC2808 differ from that of their field counterparts. The metal-abundance patterns of hot subdwarfs are typically characterized by strong deficiencies of some lighter elements as well as large enrichments of heavy elements. A large fraction of sdB stars are found in close binaries with white dwarf or very low-mass main sequence companions, which must have gone through a common-envelope (CE) phase of evolution. Because the binaries are detached they provide a clean-cut laboratory to study this important but yet poorly understood phase of stellar evolution. Hot subdwarf binaries with sufficiently massive white dwarf companions are viable candidate progenitors of type Ia supernovae both in the double degenerate as well as in the single degenerate scenario as helium donors for double detonation supernovae. The hyper-velocity He-sdO star US708 may be the surviving donor of such a double detonation supernova. Substellar companions to sdB stars have also been found. For HWVir systems the companion mass distribution extends from the stellar into the brown dwarf regime. A giant planet to the acoustic-mode pulsator V391 Peg was the first discovery of a planet that survived the red giant evolution of its host star. Evidence for Earth-size planets to two pulsating sdB stars have been reported and circumbinary giant planets or brown dwarfs have been found around HWVir systems from eclipse timings. The high incidence of circumbinary substellar objects suggests that most of the planets are formed from the remaining CE material (second generation planets). Several types of pulsating star have been discovered among hot subdwarf stars, the most common are the gravity-mode sdB pulsators (V1093 Her) and their hotter siblings, the p-mode pulsating V361 Hya stars. Another class of multi-periodic pulsating hot subdwarfs has been found in the globular cluster ω Cen that is unmatched by any field star. Asteroseismology has advanced enormously thanks to the high-precision Kepler photometry and allowed stellar rotation rates to be determined, the interior structure of gravity-mode pulsators to be probed and stellar ages to be estimated. Rotation rates turned out to be unexpectedly slow calling for very efficient angular momentum loss on the red giant branch or during the helium core flash. The convective cores were found to be larger than predicted by standard stellar evolution models requiring very efficient angular momentum tr...

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“…This can be seen in Fig. A.1, where we show all known hot subdwarfs in close binary systems with known orbital and atmospheric parameters (Heber et al 2003;Silvotti et al 2012;Sener et al 2014;Kupfer et al 2015 and references therein;Kawka et al 2015;Schindewolf et al 2015;Latour et al 2014Latour et al , 2016Hillwig et al 2017, priv. comm.…”

Section: Helium Abundancementioning

confidence: 67%

Radial velocity variability and evolution of hot subdwarf stars

Geier,

Dorsch,

Pelisoli

et al. 2022

Preprint

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Hot subdwarf stars represent a late and peculiar stage in the evolution of low-mass stars, because they are likely formed by close binary interactions. Here we performed a radial velocity (RV) variability study of a sample of 646 hot subdwarfs with multi-epoch radial velocities from Sloan Digital Sky Survey (SDSS) and Large Sky Area Multi-Object Fibre Spectroscopic Telescope (LAMOST) spectra. Atmospheric parameters and RVs were taken from the literature. For stars with archival spectra but without literature values, we determined the parameters by fitting model atmospheres. In addition, we redetermined the atmospheric parameters and RVs for all the He-enriched sdO/Bs. This large sample allowed us to study RV-variability as a function of the location in the T eff − log gand T eff − log n(He)/n(H) diagrams in a statistically significant way. As diagnostics we used the fraction of RV-variable stars and the distribution of the maximum RV variations ∆RV max . Both indicators turned out to be quite inhomogeneous across the studied parameter ranges. A striking feature is the completely different behaviour of He-poor and He-rich hot subdwarfs. While the former have a high fraction of close binaries, almost no significant RV variations could be detected for the latter. This led us to the conclusion that there likely is no evolutionary connection between these subtypes. Intermediate He-rich-and extreme He-rich sdOB/Os on the other hand are likely related. We conclude further that the vast majority of this population is formed via one or several binary merger channels. Hot subdwarfs with temperatures cooler than ∼ 24 000 K tend to show less and smaller RV-variations. These objects might constitute a new subpopulation of binaries with longer periods and late-type or compact companions. The RV-variability properties of the extreme horizontal branch (EHB) and corresponding post-EHB populations of the He-poor hot subdwarfs match and confirm the predicted evolutionary connection between them. Stars found below the canonical EHB at somewhat higher surface gravities show large RV-variations and a high RV-variability fraction, which is consistent with most of them being low-mass EHB stars or progenitors of low-mass helium white dwarfs in close binaries.

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A new HW Vir binary from the Palomar Transient Factory

Cited by 11 publications

References 36 publications

Photometric variability of candidate white dwarf binary systems from Palomar Transient Factory archival data

Photometric variability of candidate white dwarf binary systems from Palomar Transient Factory archival data

Hot Subluminous Stars

Radial velocity variability and evolution of hot subdwarf stars

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