J/A+A/628/A102 Carbon-rich (DQ) white dwarfs in SDSS (Koester+, 2019)
Carbon-rich (DQ) white dwarfs in the Sloan Digital Sky Survey.
Koester D., Kepler S.O.
<Astron. Astrophys. 628, A102 (2019)>
=2019A&A...628A.102K 2019A&A...628A.102K (SIMBAD/NED BibCode)
ADC_Keywords: Stars, carbon ; Stars, white dwarf ; Effective temperatures ;
Stars, masses ; Abundances
Keywords: stars: atmospheres - white dwarfs - stars: carbon
Abstract:
Among the spectroscopically identified white dwarfs, a fraction
smaller than 2% have spectra dominated by carbon lines, mainly
molecular C2, but also in a smaller group by CI and CII lines. These
are together called DQ white dwarfs. We derive atmospheric parameters
Teff, logg, and carbon abundances for a large sample of these stars
and discuss implications for their spectral evolution. Sloan Digital
Sky Survey spectra and ugriz photometry were used, together with Gaia
Data Release 2 parallaxes and G band photometry. These were fitted to
synthetic spectra and theoretical photometry derived from model
atmospheres. We found that the DQs hotter than Teff ∼10000K have
masses ∼0.4M☉ larger than the classical DQ, which have masses
typical for the majority of white dwarfs (∼0.6M☉). We found some
evidence that the peculiar DQ below 10000K also have significantly
larger masses and may thus be the descendants of the hot and warm DQs
above 10000K. A significant fraction of the hotter objects with
Teff>14500K have atmospheres dominated by carbon.
Description:
Table A1 gives SDSS names, Gaia parallaxes, and photometric data for
304 objects with carbon features. Also given are spectral types DQ
(normal DQ white dwarfs with C2 Swan bands), wDQ (warm DQ with CI
lines), hDQ (hot DQ with CI/CII lines), DQpec (peculiar DQ, with
shifted bands), and dC (dwarf carbon stars).
Table A2 gives results of the analysis of spectra and photometry for
221 DQ stars with Swan bands. Derived are effective temperature,
surface gravity, and abundance ratio by number of carbon to helium.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1.dat 66 304 Sample of SDSS objects with carbon features
tablea2.dat 71 221 Parameters for classical DQ
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See also:
http://skyserver.sdss.org : SDSS Home Page
Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
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1- 18 A18 --- SDSSJ SDSS name (HHMMSS.ss+DDMMSS.s)
20- 34 A15 --- P-M-F plate-epoch-fiber of spectrum
36- 41 F6.3 marcsec Plx Gaia parallax in milli-arcsec
43- 48 F6.3 mag gmag SDSS g magnitude
50- 55 F6.3 mag Gmag Gaia G magnitude
57- 60 F4.1 --- S/N Signal-to-noise of SDSS spectrum
62- 66 A5 --- SpType Spectral type (1)
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Note (1): Spectral types as follows:
DQ = normal DQ white dwarfs with C2 Swan bands
wDQ = warm DQ with CI lines
hDQ = hot DQ with CI/CII lines
DQpec = peculiar DQ, with shifted bands
dC = dwarf carbon stars
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Byte-by-byte Description of file: tablea2.dat
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Bytes Format Units Label Explanations
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1- 9 A9 --- SDSSJ Abbreviated SDSS name (HHMM+DDMM)
11- 25 A15 --- P-M-F Plate-epoch-fiber of spectrum
27- 30 I4 K Teff Effective temperature (Kelvin)
32- 34 I3 K e_Teff Error effective temperature
36- 40 F5.3 [cm/s2] logg log surface gravity in cgs
42- 46 F5.3 [cm/s2] e_logg Error log surface gravity
48- 53 F6.3 [-] [C/He] log(C/He) number abundance ratio
55- 59 F5.3 [-] e_[C/He] Error of abundance ratio
61- 65 F5.3 Msun Mass Mass in solar units
67- 71 F5.3 Msun e_Mass Error of mass
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Acknowledgements:
Detlev Koester, koester(at)astrophysik.uni-kiel.de
History:
* 13-Aug-2019: on-ligne version
* 08-Jul-2021: some declination sign corrected in SDSS J names of tablea1.dat
(End) Patricia Vannier [CDS] 01-Aug-2019