J/A+A/363/1040 DB white dwarfs from the Hamburg/ESO survey (Friedrich+, 2000)
Cool helium-rich white dwarfs from the Hamburg/ESO survey.
Friedrich S., Koester D., Christlieb N., Reimers D., Wisotzki L.
<Astron. Astrophys. 363, 1040 (2000)>
=2000A&A...363.1040F 2000A&A...363.1040F
ADC_Keywords: Stars, white dwarf ; Spectroscopy ; Effective temperatures
Keywords: surveys - stars: fundamental parameters - white dwarfs
Abstract:
We present an analysis of 40 cool helium-rich white dwarfs found in
the Hamburg/ESO survey. They were selected for follow-up spectroscopy
because of their U-B colour below -0.18, the absence of strong
absorption lines, and a continuum shape similar to that of a quasar.
Effective temperatures for individual stars were determined by fitting
model atmospheres of nearly pure helium with a small admixture of
hydrogen. As a consequence of the selection criteria all but one
sample stars have Teff below 20000K. Four stars clearly show helium
and hydrogen lines in their spectra. In the spectra of another three,
helium, hydrogen, and metal lines can be detected. For these stars
hydrogen and metal abundances were also determined by fitting
appropriate model atmospheres containing these elements. Seven sample
stars most likely have helium-rich atmospheres but do not show any
helium lines. They either have featureless spectra or show calcium
lines.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table2.dat 134 40 Coordinates, magnitudes, cross-references and
spectral types, if already existing,
for the observed objects.
table3a.dat 155 33 Results from the temperature and logg
determination and derived spectral types
for the analyzed stars.
spectra.dat 24 40 List of data files for spectrum
fig/* . 40 Individual spectra
--------------------------------------------------------------------------------
See also:
III/210 : Spectroscopically Identified White Dwarfs (McCook+, 1999)
J/A+AS/115/235 : The Hamburg/ESO survey for bright QSOs. II. (Reimers+, 1996)
J/A+A/358/77 : Hamburg/ESO survey for bright QSOs. III. (Wisotzki+, 2000)
Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 12 A12 --- HES HES name (Hamburg/ESO Survey)
14- 32 A19 --- Name Other name of object (1)
34 I1 --- n_Name [2/4]? Notes on other names (2)
37- 39 A3 --- SpType Spectral type
41 I1 --- n_SpType [1]? Note on SpType (3)
44- 46 I3 --- Field Number of ESO/SERC atlas field
48- 49 I2 h RAh Right ascension (J2000)
51- 52 I2 min RAm Right ascension (J2000)
54- 57 F4.1 s RAs Right ascension (J2000)
59 A1 --- DE- Declination sign (J2000)
60- 61 I2 deg DEd Declination (J2000)
63- 64 I2 arcmin DEm Declination (J2000)
66- 67 I2 arcsec DEs Declination (J2000)
69- 72 F4.1 mag BJmag BJ magnitude
74- 86 A13 --- Campaign Year, month and telescope of the
first observation
88- 91 I4 s ExpTime Exposure time
93-105 A13 --- Campaign2 Year, month and telescope of the
second observation
107-110 I4 s ExpTime2 ? Exposure time for campaign 2
112-124 A13 --- Campaign3 Year, month and telescope of the
third observation
126-129 I4 s ExpTime3 ? Exposure time for campaign 3
--------------------------------------------------------------------------------
Note (1): Cross-references were taken from the Simbad database and
McCook & Sion (1999ApJS..121....1M 1999ApJS..121....1M, Cat. III/210). Most of the EC
objects are listed in Kilkenny et al. (1997MNRAS.287..867K 1997MNRAS.287..867K). Details
of individual observing campaigns can be found in Table∼1. The survey
fields, given in column ``field'', are ESO/SERC atlas fields. The BJ
magnitudes are accurate to better than 0.2mag
Note (2): Notes on other names:
2: Mistakenly identified as PHL1201 in Lamontagne et al.
(2000AJ....119..241L 2000AJ....119..241L)
3: Coincidences with PHL objects (PHL3345, PHL1477, PHL166, PHL363)
have been rejected using finding charts provided by E. Chavira
4: Finding chart from Jaidee & Lynga (1969ArA.....5..345J 1969ArA.....5..345J)
Note (3): Individual Note:
1: Classified as magnetic WD without detectable polarization in
McCook &Sion (1999ApJS..121....1M 1999ApJS..121....1M, Cat. III/210).
Magnetic white dwarf with a polar field strength of 176MG
(Reimers et al. 1996A&A...311..572R 1996A&A...311..572R)
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table3a.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 12 A12 --- HES HES name (Hamburg/ESO Survey)
14- 17 A4 --- Type Derived spectral type
19- 23 I5 K Teff Derived effective Temperature
25- 28 I4 K e_Teff rms uncertainty on Teff
30- 33 F4.2 [cm/s2] logg Derived log g
35- 38 F4.2 [cm/s2] e_logg rms uncertainty on logg
40- 44 I5 K Teff8 Derived effective temperature for logg=8 (fixed)
46- 49 I4 K e_Teff8 rms uncertainty on Teff8
51-155 A105 --- Rem Equivalent widths (in Å) of spectral lines
and remarks on individual stars
--------------------------------------------------------------------------------
Table 3b: Possible helium-rich stars without helium lines
--------------------------------------------------------------------------------
Name Type Teff(logg=8) Rem
--------------------------------------------------------------------------------
HE 0052-2511 possibly DC or magnetic
HE 0122-2244 DZ 10000+2000-1000 W(CaII)=18.4+3-5/19.0±2 (Oct97/Nov98)
HE 0309-2105 DC
HE 0442-3027 possibly DC or DQ
HE 0453-4423 DC
HE 1146-0109 DQ C2 bands
HE 2237-3630 DC binary
--------------------------------------------------------------------------------
Byte-by-byte Description of file: spectra.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 12 A12 --- HES HES name (Hamburg/ESO Survey)
14- 22 A9 --- File Associated spectrum file name in "fig" subdirectory
--------------------------------------------------------------------------------
Byte-by-byte Description of file: fig/*
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 F9.4 0.1nm Lambda Wavelength
11- 24 E14.7 10mW/m2/nm Flux Flux (erg/cm2/s2/Å)
--------------------------------------------------------------------------------
Acknowledgements: Susanne Friedrich
References:
Hagen et al., Paper I 1995A&AS..111..195H 1995A&AS..111..195H
(End) Patricia Bauer [CDS] 16-Nov-2000