J/AJ/125/2239 Hard X-ray emission from white dwarfs (O'dwyer+, 2003)
Hard X-ray emission associated with white dwarfs.
O'dwyer I.J., Chu Y.-H., Gruendl R.A., Guerrero M.A., Webbink R.F.
<Astron. J., 125, 2239-2254 (2003)>
=2003AJ....125.2239O 2003AJ....125.2239O
ADC_Keywords: X-ray sources ; Stars, white dwarf
Keywords: binaries: general - stars: coronae - stars: late-type - white dwarfs -
X-rays
Abstract:
Inspired by the hard X-ray emission from WD 2226-210, the central star
of the Helix Nebula, we have made a systematic search for similar
sources by correlating the white dwarf catalog of McCook & Sion
(1999, See Cat. III/235) and the ROSAT Position Senstive
Proportional Counter (PSPC) point-source catalog of White et al.
(2000, Cat. IX/31). We find 76 white dwarfs coincident with X-ray
sources at a high level of confidence. Among these sources, 17 show
significant hard X-ray emission at energies greater than 0.5keV.
Twelve of these white dwarfs with hard X-ray emission are in known
binary systems, in two of which the accretion of the close companion's
material onto the white dwarf produces hard X-ray emission, and in the
other 10 the late-type companions' coronal activity emits hard X-rays.
One apparently single white dwarf is projected near an active galactic
nucleus that is responsible for the hard X-ray emission. The remaining
four white dwarfs and two additional white dwarfs with hard X-ray
emission appear single.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 93 94 White dwarfs coincident with WGACAT X-ray sources
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See also:
IX/31 : The WGACAT version of ROSAT sources (White+ 2000)
III/235 : Spectroscopically Identified White Dwarfs (McCook+, 2006)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 9 A9 --- WD White dwarf number (3)
11- 23 A13 --- Name Common name
25- 34 A10 --- WDType White dwarf spectral type
36- 47 A12 --- WGACAT The WGA catalog number (1WGA)
49- 54 I6 --- ROR The ROSAT PSPC observation number
56- 59 F4.1 ks Exp The PSPC exposure time
61- 64 A4 --- PosCo Positional coincidence (1)
66- 72 I7 ct Soft The soft (0.1-0.4keV) band counts (2)
74- 77 I4 ct e_Soft Error in Soft
79- 82 I4 ct Medium The medium (0.4-0.9keV) band counts (2)
84- 85 I2 ct e_Medium Error in Medium
87- 90 I4 ct Hard The hard (0.9-2.4keV) band counts (2)
92- 93 I2 ct e_Hard Error in Hard
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Note (1): Between the X-ray source and the white dwarf;
U1 = The X-ray source is not convincingly centered on the white dwarf;
U2 = The position of the X-ray source is compromised by the occultation
of the PSPC window support structure or the superposition of a bright
background;
U3 = Multiple candidates of optical counterparts are present within
the PSPC PSF;
U4 = The X-ray source is too faint to be credible.
Note (2): As reported in the WGACAT, Cat. IX/31.
Note (3): Names based on J2000 where originally written with the 'J' at
the end of the name; the 'J' was moved to the first letter of the
name, to be compatible with the IAU conventions.
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Patricia Vannier [CDS] 28-Aug-2007