THE WHITE DWARFS WITHIN 25 pc OF THE SUN: KINEMATICS AND SPECTROSCOPIC SUBTYPES

Sion, E. M.; Holberg, J. B.; Oswalt, Terry D.; McCook, G. P.; Wasatonic, R.; Myszka, Janine

doi:10.1088/0004-6256/147/6/129

Cited by 65 publications

(69 citation statements)

References 40 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…A recent hypothesis for strong magnetic fields in single WDs considers a magnetic dynamo generation during a CE-merger in a binary (Tout et al 2008). The fraction of magnetic WDs amongst all WDs is poorly estimated due to selection effects, but it ranges from 21 ± 8% within 13 pc and 13 ± 4% within 20 pc from Kawka et al (2007), to 8% from Sion et al (2014). This is consistent with the incidence of mergers in our models, but see Briggs et al (2015) for a more detailed study.…”

Section: Single White Dwarfssupporting

confidence: 88%

“…As such the 50 pc sample has the potential of breaking the degeneracy between the synthetic models. Giammichele et al (2012), with additions of Limoges et al (2013), Sion et al (2014), and Limoges et al (2015).…”

Section: Resultsmentioning

confidence: 99%

“…Much time and effort has been devoted to create a complete and volume-limited sample of WDs in the Solar neighbourhood (e.g. Holberg et al 2002;Vennes & Kawka 2003;Kawka et al 2004;Farihi et al 2005a; Kawka & Vennes 2006;Subasavage et al 2007Subasavage et al , 2008Holberg et al 2008b;Sion et al 2009;Giammichele et al 2012;Sayres et al 2012;Limoges et al 2013Limoges et al , 2015Sion et al 2014). The advantage of the Solar neighbourhood is that even the coolest WDs can be identified with relative ease at these short distances from us (e.g.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

The binarity of the local white dwarf population

Toonen

Hollands

Gänsicke

et al. 2017

A&A

174

194

View full text Add to dashboard Cite

Context. As endpoints of stellar evolution, white dwarfs (WDs) are powerful tools to study the evolutionary history of the Galaxy. In particular, the multiplicity of WDs contains information regarding the formation and evolution of binary systems. Aims. Can we understand the multiplicity of the local WD sample from a theoretical point of view? Population synthesis methods are often applied to estimate stellar space densities and event rates, but how well are these estimates calibrated? This can be tested by a comparison with the 20 pc sample, which contains ≃ 100 stars and is minimally affected by selection biases. Methods. We model the formation and evolution of single stars and binaries within 20 pc with a population synthesis approach. We construct a model of the current sample of WDs and differentiate between WDs in different configurations, that is single WDs, and resolved and unresolved binaries containing a WD with either a main-sequence (MS) component or with a second WD. We also study the effect of different assumptions concerning the star formation history, binary evolution, and the initial distributions of binary parameters. We compile from the literature the available information on the sample of WDs within 20 pc, with a particular emphasis on their multiplicity, and compare this to the synthetic models. Results. The observed space densities of single and binary WDs are well reproduced by the models. The space densities of the most common WD systems (single WDs and unresolved WD-MS binaries) are consistent within a factor two with the observed value. We find a discrepancy only for the space density of resolved double WDs. We exclude that observational selection effects, fast stellar winds, or dynamical interactions with other objects in the Milky Way explain this discrepancy. We find that either the initial mass ratio distribution in the Solar neighbourhood is biased towards low mass-ratios, or more than ten resolved DWDs have been missed observationally in the 20 pc sample. Furthermore, we show that the low binary fraction of WD systems (∼25%) compared to Solartype MS-MS binaries (∼50%) is consistent with theory, and is mainly caused by mergers in binary systems, and to a lesser degree by WDs hiding in the glare of their companion stars. Lastly, Gaia will dramatically increase the size of the volume-limited WD sample, detecting the coolest and oldest WDs out to ≃ 50 pc. We provide a detailed estimate of the number of single and binary WDs in the Gaia sample.

show abstract

Section: Single White Dwarfssupporting

confidence: 88%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

The binarity of the local white dwarf population

Toonen

Hollands

Gänsicke

et al. 2017

A&A

174

194

View full text Add to dashboard Cite

show abstract

“…The incidence of magnetism is a matter of debate. In volume-limited surveys-those that select stars within a maximum distance from the Sun-the incidence of magnetism is~20% (Kawka et al 2007;Giammichele et al 2012;Sion et al 2014), while for magnitude-limited surveys-those selecting stars brighter than a given apparent magnitude-it is~8% (Liebert et al 2003;Kepler et al 2013Kepler et al , 2016. Nevertheless, because a population of white dwarfs with magnetic fields weaker than ∼1 kG may exist, the fraction of magnetic white dwarfs could be larger (Koester et al 2011;Kawka & Vennes 2012;Ferrario et al 2015).…”

Section: Introductionmentioning

confidence: 99%

A Common Origin of Magnetism from Planets to White Dwarfs

Isern

Garcı́a–Berro

Külebi

et al. 2017

ApJL

111

View full text Add to dashboard Cite

Isolated magnetic white dwarfs have field strengths ranging from kilogauss to gigagauss. However, the origin of the magnetic field has not been hitherto elucidated. Whether these fields are fossil, hence the remnants of original weak magnetic fields amplified during the course of the evolution of their progenitor stars, or are the result of binary interactions, or, finally, they are produced by other internal physical mechanisms during the cooling of the white dwarf itself, remains a mystery. At sufficiently low temperatures, white dwarfs crystallize. Upon solidification, phase separation of its main constituents, 12 C and 16 O, and of the impurities left by previous evolution occurs. This process leads to the formation of a Rayleigh-Taylor unstable liquid mantle on top of a solid core. This convective region, as it occurs in solar system planets like the Earth and Jupiter, can produce a dynamo able to yield magnetic fields of strengths of up to 0.1 MG, thus providing a mechanism that could explain magnetism in single white dwarfs.

show abstract

“…In addition, Brinkworth et al (2013) find 1%-2% variability in 2/3 of their B100 kG magnetic white dwarf sample, implying an overall variability fraction of 10%. Sion et al (2014) find the fraction of magnetic white dwarfs in the 25 pc local sample to be 8%, but Liebert et al (2003) demonstrate that the fraction could be substantially higher than 10% for B>10 kG. Hence, with a 1% precision at r=21 mag, the LSST may find ∼10 5 white dwarfs that show variations on hour/day timescales due to the presence of magnetic fields.…”

Section: Implications For the Kepler/k2 Missions And The Lsstmentioning

confidence: 95%

A Dark Spot on a Massive White Dwarf

Kilic

Gianninas

Bell

et al. 2015

ApJ

View full text Add to dashboard Cite

We present the serendipitous discovery of eclipse-like events around the massive white dwarf SDSS J152934.98 +292801.9 (hereafter J1529+2928). We selected J1529+2928 for time-series photometry based on its spectroscopic temperature and surface gravity, which place it near the ZZ Ceti instability strip. Instead of pulsations, we detect photometric dips from this white dwarf every 38 minutes. Follow-up optical spectroscopy observations with Gemini reveal no significant radial velocity variations, ruling out stellar and brown dwarf companions. A disintegrating planet around this white dwarf cannot explain the observed light curves in different filters. Given the short period, the source of the photometric dips must be a dark spot that comes into view every 38 minutes due to the rotation of the white dwarf. Our optical spectroscopy does not show any evidence of Zeeman splitting of the Balmer lines, limiting the magnetic field strength to B<70 kG. Since up to 15% of white dwarfs display kG magnetic fields, such eclipse-like events should be common around white dwarfs. We discuss the potential implications of this discovery on transient surveys targeting white dwarfs, like the K2 mission and the Large Synoptic Survey Telescope.

show abstract

THE WHITE DWARFS WITHIN 25 pc OF THE SUN: KINEMATICS AND SPECTROSCOPIC SUBTYPES

Cited by 65 publications

References 40 publications

The binarity of the local white dwarf population

The binarity of the local white dwarf population

A Common Origin of Magnetism from Planets to White Dwarfs

A Dark Spot on a Massive White Dwarf

Contact Info

Product

Resources

About