J/A+A/470/1079 UVES/VLT spectroscopy of white dwarfs (Voss+, 2007)
High-resolution UVES/VLT spectra of white dwarfs observed for the ESO
SN Ia progenitor survey. II. DB and DBA stars.
Voss B., Koester D., Napiwotzki R., Christlieb N., Reimers D.
<Astron. Astrophys., 470, 1079-1088 (2007)>
=2007A&A...470.1079V 2007A&A...470.1079V
ADC_Keywords: Stars, white dwarf; Magnitudes; Effective temperatures
Keywords: stars: white dwarfs - methods: observational -
stars: fundamental parameters - stars: atmospheres
Abstract:
We present a detailed spectroscopic analysis of the stars with
helium-dominated spectra in the ESO Supernova Ia Progenitor Survey
(SPY).
Atmospheric parameters, masses, and abundances of trace hydrogen are
determined and discussed in the context of spectral evolution of white
dwarfs.
The spectra are compared with theoretical model atmospheres using a
χ2 fitting technique, leading to determinations of effective
temperature, surface gravity, and hydrogen abundance.
Our final sample contains 71 objects, of which 6 are new detections
and 14 are reclassified from DB to DBA because of the presence of H
lines. One is a cool DO with weak HeII lines, 2 are composite DB+dM.
55% of the DB sample show hydrogen and are thus DBA, a significantly
higher fraction than found before.
Description:
We fit the data with model spectra from six different grids of helium
atmosphere models with different hydrogen abundances, from H/He=10-2
down to H/He=10-7, and with a grid of pure He atmosphere models. The
grids cover a range of temperatures from 10000K to 50000K and
logarithms of the surface gravities from 7.0 to 9.0.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 123 31 Properties and parameters of the DB stars
without visible hydrogen
table2.dat 192 38 Properties and parameters of the DB stars with
hydrogen features in their spectra
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See also:
III/235 : Spectroscopically Identified White Dwarfs (McCook+, 2008)
J/A+A/378/556 : UVES/VLT spectra of white dwarfs (Koester+, 2001)
J/A+A/505/441 : UVES/VLT spectra of white dwarfs (Koester+, 2009)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 12 A12 --- Name Object name
14- 15 I2 h RAh Right ascension (J2000)
17- 18 I2 min RAm Right ascension (J2000)
20- 24 F5.2 s RAs Right ascension (J2000)
26 A1 --- DE- Declination sign (J2000)
27- 28 I2 deg DEd Declination (J2000)
30- 31 I2 arcmin DEm Declination (J2000)
33- 36 F4.1 arcsec DEs Declination (J2000)
38 A1 --- n_mag [BVy] Observed band for magnitude (G1)
39 A1 --- --- [=]
40- 44 F5.2 mag mag Magnitude in band specified in n_mag
46- 72 A27 --- ONames Other name(s)
74- 78 I5 K Teff Effective temperature
80- 84 F5.3 [cm/s2] logg Surface gravity
86- 90 F5.3 Msun M ? Stellar mass
92-109 A18 --- Com Comments
111 I1 --- Note [2/4]? Note (1)
113-117 I5 K Teff2 ? Teff from fit (2)
119-123 F5.3 [cm/s2] logg2 ? Surface gravity from fit (2)
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Note (1): Notes as follows:
2 = Beauchamp et al. (1999ApJ...516..887B 1999ApJ...516..887B) list WD 1326-037 as a DBA; however
no H is visible in the SPY spectra. According to Bergeron (2007, priv.
comm.), the Beauchamp data show no hydrogen features and thus this
object appears as a DBA in their paper due to a mis-classification.
3 = Temperatures were determined from the equivalent widths of HeI 5876Å.
The surface gravity was assumed to be logg=8.0.
4 = Fitted with the alternate set of models with van der Waals line
broadening. The surface gravity was kept fixed at logg=8.0 for these
fits.
Note (2): For hot objects (Teff>20000K), result of a fit with H/He=10-5
models to check the influence of possible admixtures of invisibly small
amounts of hydrogen.
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 13 A13 --- Name Object name
15- 16 I2 h RAh Right ascension (J2000)
18- 19 I2 min RAm Right ascension (J2000)
21- 25 F5.2 s RAs Right ascension (J2000)
27 A1 --- DE- Declination sign (J2000)
28- 29 I2 deg DEd Declination (J2000)
31- 32 I2 arcmin DEm Declination (J2000)
34- 37 F4.1 arcsec DEs Declination (J2000)
39- 40 A2 --- n_mag [BVy mc] Observed band for magnitude (G1)
41 A1 --- --- [=]
42- 46 F5.2 mag mag Magnitude in band specified in n_mag
48- 77 A30 --- ONames Other name(s)
79 A1 --- u_[H/He] [~] Uncertain H abundance
80- 84 F5.2 [-] [H/He] H abundance: log(H/He)
86- 90 I5 K Teff Effective temperature
92- 96 F5.3 [cm/s2] logg Surface gravity
98-102 F5.3 Msun M ? Stellar mass
104-108 F5.3 10+8yr Age ? Age
110-118 E9.4 Msun MH ? H mass
120-148 A29 --- Com Comments
150-152 A3 --- Note ? Note (2)
154-158 F5.2 [-] [H/He]2 ? log(H/He) from second spectrum (3)
160-164 I5 K Teff2 ? Teff from second spectrum (3)
166-170 F5.3 [cm/s2] logg2 ? Surface gravity from second spectrum (3)
172-176 F5.3 Msun M2 ? Stellar mass from second spectrum (3)
178-182 F5.3 10+8yr Age2 ? Age from second spectrum (3)
184-192 E9.4 Msun MH2 ? H mass from second spectrum (3)
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Note (2): Notes as follows:
1 = First reported as a DBA here; previously known as DB.
2 = Since WD 0853+163 is a magnetic DBA, the fit is uncertain because the
Zeeman-splitted lines were fitted with a non-magnetic model.
3 = Temperatures and hydrogen abundances where determined from the
equivalent widths of He I 5876Å and Hα, respectively.
The surface gravity was assumed to be logg=8.0.
4 = WD 1134+073 and WD 1421-011 show Ca II lines but are not mentioned among
the SPY DBZ/DBAZ objects of Koester et al. (2005b).
5 = WD 2142-169 shows a He I-dominated spectrum with Balmer lines and
HeII 4686Å .
6 = Fit using the alternate set of models with van der Waals line broadening.
The surface gravity was kept fixed at logg=8.0 for these fits.
Note (3): For some objects, two set of data are given, for the analysis
results of each of the two independent SPY spectra of the star.
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Global notes:
Note (G1): Band as follows:
V = V magnitude from SIMBAD or MCS (McCook & Sion, Cat. III/235)
B = either Johnson B magnitude or, in most cases, a photographic
magnitude from the MCT (Montreal-Cambridge-Tololo survey, see
1990ApJ...351..271D 1990ApJ...351..271D), HQS, or HES surveys
y = Stromgren y magnitude
mc = Greenstein multichannel V magnitude, obtained from the MCS catalog
(McCook&Sion, Cat. III/235)
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History:
From electronic version of the journal
References:
Koester et al., Paper I 2001A&A...378..556K 2001A&A...378..556K, Cat. J/A+A/378/556
Koester et al., Paper III 2009A&A...505..441K 2009A&A...505..441K, Cat. J/A+A/505/441
(End) Patricia Vannier [CDS] 14-Feb-2014