A COMPREHENSIVE SPECTROSCOPIC ANALYSIS OF DB WHITE DWARFS

By Pierre Bergeron, F. Wesemael, Patrick Dufour, A. Beauchamp, C. Hunter, R. Saffer, A. Gianninas, M. Ruiz, M. Limoges, G. Fontaine and 1 more. 2011

260 citations recorded by the source corpus.

We present a detailed analysis of 108 helium-line (DB) white dwarfs based on model atmosphere fits to high signal-to-noise optical spectroscopy. We derive a mean mass of 0.67 M☉ for our sample, with a dispersion of only 0.09 M☉. White dwarfs also showing hydrogen lines, the DBA stars, comprise 44% of our sample, and their mass distribution appears similar to that of DB stars. As in our previous investigation, we find no evidence for the existence of low-mass (M < 0.5 M☉) DB white dwarfs. We derive a luminosity function based on a subset of DB white dwarfs identified in the Palomar-Green Survey. We show that 20% of all white dwarfs in the temperature range of interest are DB stars, although the fraction drops to half this value above Teff ∼ 20,000 K. We also show that the persistence of DB stars with no hydrogen features at low temperatures is difficult to reconcile with a scenario involving accretion from the interstellar medium, often invoked to account for the observed hydrogen abundances in DBA stars. We present evidence for the existence of two different evolutionary channels that produce DB white dwarfs: the standard model where DA stars are transformed into DB stars through the convective dilution of a thin hydrogen layer and a second channel where DB stars retain a helium atmosphere throughout their evolution. We finally demonstrate that the instability strip of pulsating V777 Her white dwarfs contains no non-variables, if the hydrogen content of these stars is properly accounted for.

Subfields: Astronomy and Astrophysics, Education, Instrumentation

View Paper: https://www.semanticscholar.org/paper/abd9342ebef494ad34bb8126d05b595f03abcd0e

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In Astronomy and Astrophysics

1. Pierre Bergeron
2. P.-E. Tremblay
3. J. Farihi
4. A. Gianninas
5. B. Gänsicke
6. D. Koester
7. Patrick Dufour
8. M. Ruiz

In Education

1. L. Chomiuk

In Instrumentation

1. Pierre Bergeron
2. P.-E. Tremblay
3. A. Gianninas
4. J. Farihi
5. B. Gänsicke
6. M. Ruiz
7. Patrick Dufour
8. D. Koester

Citations in the corpus

• SDSS DR7 WHITE DWARF CATALOG (2012, background): “8 through their analysis of the convection zone for the pulsating DB white dwarf, GD 358 while Bergeron et al. (2011) justify this value in their atmospheric modeling.”
• KNOW YOUR NEIGHBORHOOD: A DETAILED MODEL ATMOSPHERE ANALYSIS OF NEARBY WHITE DWARFS (2012, methodology): “Our WDLF is also compared with that obtained by Harris et al. (2006) using the SDSS sample, and with that derived by Bergeron et al. (2011) using the DA and DB stars identified in the PG survey (see their Figure 24).”
• Three Hypervelocity White Dwarfs in Gaia DR2: Evidence for Dynamically Driven Double-degenerate Double-detonation Type Ia Supernovae (2018, methodology): “Using publicly available DB WD cooling tables1 (Holberg & Bergeron 2006; Kowalski & Saumon 2006; Tremblay et al. 2011; Bergeron et al. 2011), we find that a 0.6 (1.0)M WD that has cooled for 1 Gyr since its birth has an absolute visual magnitude of 12.9 (12.8).”
• New white dwarf stars in the Sloan Digital Sky Survey Data Release 10 (2014, result): “…high S/N sample, we obtain 〈log gDB〉 = 8.122±0.017. and a corresponding mean mass of 〈MDB〉 = 0.696±0.010M⊙ , similar to the results from gravitational redshift by Falcon et al. (2012) and Bergeron et al. (2011), and to 〈MDB〉 = 0.685 ± 0.013M⊙ for the 191 DBs with S/N> 15 of Kleinman et al. (2013).”
• The Sirius System and Its Astrophysical Puzzles: Hubble Space Telescope and Ground-based Astrometry (2017, methodology): “These tables are based on evolutionary sequences and model atmospheres calculated by Holberg & Bergeron (2006), Kowalski & Saumon (2006), Tremblay et al. (2011), and Bergeron et al. (2011). measure 89.60± 0.75 km s−1.”
• A SPECTROSCOPIC SURVEY AND ANALYSIS OF BRIGHT, HYDROGEN-RICH WHITE DWARFS (2011, methodology): “The helium models we have employed are described in Bergeron et al. (2011), which are based on the updated grid of white dwarf models described in TB09 in which the improved Stark profiles of neutral helium of Beauchamp et al. (1997) have been incorporated.”
• On the Spectral Evolution of Hot White Dwarf Stars. I. A Detailed Model Atmosphere Analysis of Hot White Dwarfs from SDSS DR12 (2020, methodology): “Consequently, for our pure-helium grid, we adopted the following strategy: we employ the non-LTE, strictly radiative models of TLUSTY/SYNSPEC for Teff>40,000K, and the LTE, convective models of Bergeron et al. (2011) for Teff 40,000K.”
• AGaiaData Release 2 catalogue of white dwarfs and a comparison with SDSS (2018, methodology): “We have also computed synthetic magnitudes for He-atmosphere models (Bergeron et al. 2011) using a mass-radius relation for thin hydrogen layers (Fontaine et al. 2001, MH/MWD = 10−10).”
• The frequency of planetary debris around young white dwarfs (2014, methodology): “…computational tools: several white dwarfs with close Mdwarf companions (drawn from Schreiber & Gänsicke 2003 and Farihi et al. 2010b), two recently discovered metal-polluted DA white dwarfs from Vennes et al. (2010, 2011b), and a small number of bright DB white dwarfs from Bergeron et al. (2011).”