scholarly journals Gaia Data Release 2 catalogue of extremely low-mass white dwarf candidates

2019 ◽  
Vol 488 (2) ◽  
pp. 2892-2903 ◽  
Author(s):  
Ingrid Pelisoli ◽  
Joris Vos
Keyword(s):  
White Dwarf ◽  
Theoretical Models ◽  
Dwarf Stars ◽  
Single Star ◽  
Common Envelope ◽  
White Dwarf Stars ◽  
Final Sample ◽  
Data Release ◽  
Low Mass ◽  
Binary Evolution

ABSTRACT Extremely low-mass white dwarf stars (ELMs) are M < 0.3 M⊙ helium-core white dwarfs born either as a result of a common-envelope phase or after a stable Roche lobe overflow episode in a multiple system. The Universe is not old enough for ELMs to have formed through single-star evolution channels. As remnants of binary evolution, ELMs can shed light onto the poorly understood phase of common-envelope evolution and provide constraints to the physics of mass accretion. Most known ELMs will merge in less than a Hubble time, providing an important contribution to the signal to be detected by upcoming space-based gravitational wave detectors. There are currently less than 150 known ELMs; most were selected by colour, focusing on hot objects, in a magnitude-limited survey of the Northern hemisphere only. Recent theoretical models have predicted a much larger space density for ELMs than estimated observationally based on this limited sample. In order to perform meaningful comparisons with theoretical models and test their predictions, a larger well-defined sample is required. In this work, we present a catalogue of ELM candidates selected from the second data release of Gaia (DR2). We have used predictions from theoretical models and analysed the properties of the known sample to map the space spanned by ELMs in the Gaia Hertzsprung–Russell diagram. Defining a set of colour cuts and quality flags, we have obtained a final sample of 5762 ELM candidates down to Teff ≈ 5000 K.

scholarly journals White Dwarf Stars

2017 ◽  
Vol 45 ◽  
pp. 1760023
Author(s):  
S. O. Kepler ◽  
Alejandra Daniela Romero ◽  
Ingrid Pelisoli ◽  
Gustavo Ourique
Keyword(s):  
White Dwarf ◽  
Final Stage ◽  
White Dwarfs ◽  
Sloan Digital Sky Survey ◽  
Dwarf Stars ◽  
Multiple Systems ◽  
White Dwarf Stars ◽  
Sky Survey ◽  
Data Release ◽  
Low Mass

White dwarf stars are the final stage of most stars, born single or in multiple systems. We discuss the identification, magnetic fields, and mass distribution for white dwarfs detected from spectra obtained by the Sloan Digital Sky Survey up to Data Release 13 in 2016, which lead to the increase in the number of spectroscopically identified white dwarf stars from 5[Formula: see text]000 to 39[Formula: see text]000. This number includes only white dwarf stars with [Formula: see text], i.e., excluding the Extremely Low Mass white dwarfs, which are necessarily the byproduct of stellar interaction.

scholarly journals Evolutionary and pulsational properties of low-mass white dwarf stars with oxygen cores resulting from close binary evolution

2004 ◽  
Vol 347 (1) ◽  
pp. 125-136 ◽  
Author(s):  
L. G. Althaus ◽  
A. H. Córsico ◽  
A. Gautschy ◽  
Z. Han ◽  
A. M. Serenelli ◽  
...  
Keyword(s):  
White Dwarf ◽  
Close Binary ◽  
Dwarf Stars ◽  
White Dwarf Stars ◽  
Low Mass ◽  
Binary Evolution

scholarly journals Comparing the asteroseismic properties of pulsating pre-extremely low mass white dwarf and δ Scuti stars

2018 ◽  
Vol 616 ◽  
pp. A80 ◽  
Author(s):  
Julieta P. Sánchez Arias ◽  
Alejandra D. Romero ◽  
Alejandro H. Córsico ◽  
Ingrid Pelisoli ◽  
Victoria Antoci ◽  
...  
Keyword(s):  
White Dwarf ◽  
Variable Stars ◽  
Period Change ◽  
Period Range ◽  
Ionization Zone ◽  
Dwarf Stars ◽  
White Dwarf Stars ◽  
Low Mass ◽  
The Mean ◽  
Scuti Stars

Context. Pulsating extremely low-mass pre-white dwarf stars (pre-ELMV), with masses between ~0.15 M⊙ and ~0.30 M⊙, constitute a new class of variable stars showing g- and possibly p-mode pulsations with periods between 320 and 6000 s (frequencies between 14.4 and 270 c/d), driven by the κ mechanism operating in the second He ionization zone. On the other hand, main sequence δ Scuti stars, with masses between 1.2 and 2.5 M⊙, pulsate in low-order g and p modes with periods in the range [700–28 800] s (frequencies in the range [3–123] c/d), driven by the κ mechanism operating in the He II ionization zone and the turbulent pressure acting in the HI ionization layer. Interestingly enough, the instability strips of pre-ELM white dwarf and δ Scuti stars nearly overlap in the Teff vs. log g diagram, leading to a degeneracy when spectroscopy is the only tool to classify the stars and pulsation periods only are considered. Aims. Pre-ELM white dwarf and δ Scuti stars are in very different stages of evolution and therefore their internal structure is very distinct. This is mirrored in their pulsational behavior, thus employing asteroseismology should allow us to distinguish between these groups of stars despite their similar atmospheric parameters. Methods. We have employed adiabatic and non-adiabatic pulsation spectra for models of pre-ELM white dwarfs and δ Scuti stars, and compare their pulsation periods, period spacings, and rates of period change. Results. Unsurprisingly, we found substantial differences in the period spacing of δ Scuti and pre-ELM white dwarf models. Even when the same period range is observed in both classes of pulsating stars, the modes have distinctive signature in the period spacing and period difference values. For instance, the mean period difference of p-modes of consecutive radial orders for δ Scuti model are at least four times longer than the mean period spacing for the pre-ELM white dwarf model in the period range [2000–4600] s (frequency range [18.78–43.6] c/d). In addition, the rate of period change is two orders of magnitudes larger for the pre-ELM white dwarfs compared to δ Scuti stars. In addition, we also report the discovery of a new variable star, SDSSJ075738.94+144827.50, located in the region of the Teff versus log g diagram where these two kind of stars coexist. Conclusions.The characteristic spacing between modes of consecutive radial orders (p as well as g modes) and the large differences found in the rates of period change for δ Scuti and pre-ELM white dwarf stars suggest that asteroseismology can be employed to discriminate between these two groups of variable stars. Furthermore, we found that SDSSJ075738.94+144827.50 exhibits a period difference between p modes characteristic of a δ Sct star, assuming consecutive radial order for the observed periods.

scholarly journals Asteroseismological Probing of the Thermal Evolution of White Dwarf Stars

1992 ◽  
Vol 9 ◽  
pp. 643-645
Author(s):  
G. Fontaine ◽  
F. Wesemael
Keyword(s):  
White Dwarf ◽  
White Dwarfs ◽  
Main Sequence ◽  
Thermal Evolution ◽  
Sequence Evolution ◽  
Helium Burning ◽  
Dwarf Stars ◽  
White Dwarf Stars ◽  
The Galaxy ◽  
Low Mass

AbstractIt is generally believed that the immediate progenitors of most white dwarfs are nuclei of planetary nebulae, themselves the products of intermediate- and low-mass main sequence evolution. Stars that begin their lifes with masses less than about 7-8 M⊙ (i.e., the vast majority of them) are expected to become white dwarfs. Among those which have already had the time to become white dwarfs since the formation of the Galaxy, a majority have burnt hydrogen and helium in their interiors. Consequently, most of the mass of a typical white dwarf is contained in a core made of the products of helium burning, mostly carbon and oxygen. The exact proportions of C and 0 are unknown because of uncertainties in the nuclear rates of helium burning.

scholarly journals Towards Ensemble Asteroseismology of the Pulsating DB White Dwarf Stars

2002 ◽  
Vol 185 ◽  
pp. 608-609
Author(s):  
G. Handler ◽  
M.A. Wood ◽  
A. Nitta ◽  
Keyword(s):  
White Dwarf ◽  
White Dwarfs ◽  
The Other ◽  
Archival Data ◽  
Dwarf Stars ◽  
Helium Atmosphere ◽  
Individual Stars ◽  
White Dwarf Stars ◽  
Binary Evolution ◽  
Insight Into

The origin of the helium-atmosphere DB white dwarfs is still a matter of debate. In particular, the question is unresolved whether binary evolution produces a significant number of DBs. The pulsating DB white dwarfs (DBV stars) offer a complementary insight into this problem through asteroseismology; DBs descending from binaries will have different interior structures than DBs originating from single stars (Nitta & Winget, 1998).GD 358 is by far the best-observed pulsating DBV star, and the only one for which asteroseismology has been performed to date. This star’s structure has been shown to be inconsistent with an origin from binary evolution (Nitta & Winget, 1998), but most of the other DBVs are relatively poorly studied.We therefore analysed archival data on all DBVs and obtained new measurements of stars with very little data available (Table 1), firstly to identify suitable targets for asteroseismological investigations and secondly to examine the pulsation spectra of the DBVs as a group, following the works of Clemens (1994) and Kleinman (1995) on the pulsating DA white dwarfs. Our study also produced new seismological results on individual stars and promising targets for future Whole Earth Telescope (WET, Nather et al., 1990) runs.

scholarly journals Cool Companions to White Dwarf Stars from the Two Micron All Sky Survey All Sky Data Release

2007 ◽  
Vol 134 (1) ◽  
pp. 26-42 ◽  
Author(s):  
D. W. Hoard ◽  
S. Wachter ◽  
Laura K. Sturch ◽  
Allison M. Widhalm ◽  
Kevin P. Weiler ◽  
...  
Keyword(s):  
White Dwarf ◽  
Dwarf Stars ◽  
White Dwarf Stars ◽  
Sky Survey ◽  
Data Release

scholarly journals The seismic properties of low-mass He-core white dwarf stars

2012 ◽  
Vol 547 ◽  
pp. A96 ◽  
Author(s):  
A. H. Córsico ◽  
A. D. Romero ◽  
L. G. Althaus ◽  
J. J. Hermes
Keyword(s):  
White Dwarf ◽  
Dwarf Stars ◽  
Seismic Properties ◽  
White Dwarf Stars ◽  
Low Mass

scholarly journals White dwarf and subdwarf stars in the Sloan Digital Sky Survey Data Release 14

2019 ◽  
Vol 486 (2) ◽  
pp. 2169-2183 ◽  
Author(s):  
S O Kepler ◽  
Ingrid Pelisoli ◽  
Detlev Koester ◽  
Nicole Reindl ◽  
Stephan Geier ◽  
...  
Keyword(s):  
Survey Data ◽  
White Dwarf ◽  
White Dwarfs ◽  
Main Sequence ◽  
Sloan Digital Sky Survey ◽  
Dwarf Stars ◽  
White Dwarf Stars ◽  
Sky Survey ◽  
Data Release ◽  
Hot Subdwarfs

ABSTRACT White dwarfs carry information on the structure and evolution of the Galaxy, especially through their luminosity function and initial-to-final mass relation. Very cool white dwarfs provide insight into the early ages of each population. Examining the spectra of all stars with 3σ proper motion in the Sloan Digital Sky Survey Data Release 14, we report the classification for 20 088 spectroscopically confirmed white dwarfs, plus 415 hot subdwarfs, and 311 cataclysmic variables. We obtain Teff, log  g, and mass for hydrogen atmosphere white dwarf stars (DAs), warm helium atmosphere white dwarfs (DBs), hot subdwarfs (sdBs and sdOs), and estimate photometric Teff for white dwarf stars with continuum spectra (DCs). We find 15 793 sdAs and 447 dCs between the white dwarf cooling sequence and the main sequence, especially below $T_\mathrm{eff}\simeq 10\, 000$ K; most are likely low-mass metal-poor main-sequence stars, but some could be the result of interacting binary evolution.

scholarly journals A Catalog of Spectroscopically Identified White Dwarf Stars in the First Data Release of the Sloan Digital Sky Survey

2004 ◽  
Vol 607 (1) ◽  
pp. 426-444 ◽  
Author(s):  
S. J. Kleinman ◽  
Hugh C. Harris ◽  
Daniel J. Eisenstein ◽  
James Liebert ◽  
Atsuko Nitta ◽  
...  
Keyword(s):  
White Dwarf ◽  
Sloan Digital Sky Survey ◽  
Dwarf Stars ◽  
White Dwarf Stars ◽  
Sky Survey ◽  
Data Release
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