J/AJ/126/1023 White Dwarfs in the SDSS (Harris+, 2003)
An initial survey of white dwarfs in the Sloan Digital Sky Survey.
Harris H.C., Liebert J., Kleinman S.J., Nitta A., Anderson S.F., Knapp G.R.,
Krzesinski J., Schmidt G., STrauss M.A., Vanden Berk D., Eisenstein D.,
Hawley S., Margon B., Munn J.A., Silvestri N.M., Smith J.A., Szkody P.,
Collinge M.J., Dahn C.C., Fan X., Hall P.B., Schneider D.P., Brinkmann J.,
Burles S., Gunn J.E., Hennessy G.S., Hindsley R., Ivezic Z., Kent S.,
Lamb D.Q., Lupton R.H., Nichol R.C., Pier J.R., Schlegel D.J., Subbarao M.,
Uomoto A., Yanny B., York D.G.
<Astron. J. 126, 1023 (2003)>
=2003AJ....126.1023H 2003AJ....126.1023H
ADC_Keywords: Stars, white dwarf
Keywords: Stars, dwarfs ; Photometry, SDSS ; Proper motions
Abstract:
An initial assessment is made of white dwarf and hot subdwarf stars
observed in the Sloan Digital Sky Survey. In a small area of sky (190
square degrees), observed much like the full survey will be, 269 white
dwarfs (WDs) and 56 hot subdwarfs are identified spectroscopically
where only 44 white dwarfs and five hot subdwarfs were known
previously. Most are ordinary DA (hydrogen atmosphere) and DB (helium)
types. In addition, in the full survey to date, a number of WDs have
been found with uncommon spectral types. Among these are blue DQ stars
displaying lines of atomic carbon; red DQ stars showing molecular
bands of C2 with a wide variety of strengths; DZ stars where Ca and
occasionally Mg, Na, and/or Fe lines are detected; and magnetic WDs
with a wide range of magnetic field strengths in DA, DB, DQ, and
(probably) DZ spectral types. Photometry alone allows identification
of stars hotter than 12000K, and the density of these stars for
magnitude g 15<g<20 is found to be ∼2.2deg-2 at Galactic latitudes
of 29°-62°. Spectra are obtained for roughly half of these hot
stars. The spectra show that for 15<g<17, 40% of hot stars are WDs,
and the fraction of WDs rises to ∼90% at g=20. The remainder are hot
sdB and sdO stars.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 83 249 DA and DB white dwarfs
table2.dat 84 69 Unusual white dwarfs
table3.dat 81 56 Hot subdwarfs
notes.dat 81 46 Notes on tables 1, 2, 3
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See also:
J/AJ/123/3409 : SDSS M, L, and T dwarfs (Hawley+, 2002)
Byte-by-byte Description of file: table*.dat
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Bytes Format Units Label Explanations
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1- 2 I2 h RAh Hour of right ascension (J2000) (1)
4- 5 I2 min RAm Minute of right ascension (J2000) (1)
7- 11 F5.2 s RAs Second of right ascension (J2000) (1)
13 A1 --- DE- Sign of the declination (J2000) (1)
14- 15 I2 deg DEd Degree of declination (J2000) (1)
17- 18 I2 arcmin DEm Arcminute of declination (J2000) (1)
20- 23 F4.1 arcsec DEs Arcsecond of declination (J2000) (1)
25- 29 F5.2 mag gmag SDSS g-band magnitude
31- 35 F5.2 mag u-g ? The SDSS (u-g) color
37- 41 F5.2 mag g-r The SDSS (g-r) color
43- 47 F5.2 mag r-i The SDSS (r-i) color
49- 53 F5.2 mag i-z The SDSS (i-z) color
55- 58 F4.2 mag Au Full SDSS u-band interstellar absorption (2)
60 A1 --- l_pm [≲] Limit or approximate flag on PM
64- 66 I3 mas/yr pm Total proper motion (3)
68- 70 I3 deg pmPA ? Position angle of the proper motion
72- 78 A7 --- SpType Spectral type (4)
80- 84 A5 --- Note Individual notes, detailed in file notes.dat
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Note (1): Object name is "SDSS J+" plus the coordinates.
Note (2): From Schlegel et al. (1998ApJ...500..525S 1998ApJ...500..525S).
Reddening can be calculated using E(u-g)=0.264Au, E(g-r)=0.202Au,
E(r-i)=0.129Au, and E(i-z)=0.119Au. For most stars at these high
latitudes, the reddening is small whether or not the full absorption
Note (3): Calculated using the USNO-A2.0 catalog (Monet et al., Cat. I/252)
for the first-epoch position. For a few stars not in the USNO-A
catalog, usually because they are too faint to be detected on both the
POSS-I blue and red plates, the first-epoch position is taken from the
USNO-B1.0 catalog (Monet et al., 2003, Cat. I/284). The proper
motions typically have errors of 6-8mas/yr rms. Where the motion is
less than 20mas/yr, it may not be real, and the position angle of the
motion is omitted.
Note (4): From our classification of the SDSS spectra.
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Byte-by-byte Description of file: notes.dat
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Bytes Format Units Label Explanations
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1- 2 I2 --- Note Note number (1-24 in table 1, 30-47 in table2,
46- 51 in table3)
4 A1 --- --- [=]
6- 81 A76 --- Text Text of the note
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Laurent Cambresy [CDS] 05-Sep-2003