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HARD X-RAY EMISSION ASSOCIATED WITH WHITE DWARFS. III.
被引:21
作者:
Bilikova, Jana
[1
]
Chu, You-Hua
[1
]
Gruendl, Robert A.
[1
]
Maddox, Larry A.
[1
]
机构:
[1] Univ Illinois, Dept Astron, Urbana, IL 61801 USA
关键词:
binaries: general;
stars: coronae;
stars: late-type;
white dwarfs;
X-rays: general;
HUBBLE-SPACE-TELESCOPE;
BINARY-SYSTEM;
CATALOG;
STARS;
COMPANIONS;
HOT;
DISCOVERY;
MASS;
SPECTROSCOPY;
SPECTRA;
D O I:
10.1088/0004-6256/140/5/1433
中图分类号:
P1 [天文学];
学科分类号:
0704 ;
摘要:
Hard X-ray emission associated with white dwarfs (WDs) can be used to diagnose the presence of late-type binary companions, mass accretion from companions, or physical processes with unknown origins. Since our previous systematic searches for hard X-ray emission associated with WDs, the Galactic WD catalog has been augmented by >10,000 new WDs from the Sloan Digital Sky Survey and new X-ray point-source catalogs from XMM-Newton and ROSAT have become available. Therefore, we have extended the search using the updated catalogs, and found 17 new cases of WDs associated with hard X-ray emission. The 32 WDs associated with hard X-ray emission, from the current and previous searches, can be divided into five categories: (1) binary WD with a coronal companion, (2) binary WD with mass transfer from a companion, (3) single hot WD with a hard X-ray component peaking near 1 keV in addition to a soft photospheric component, (4) two PG 1159 stars with very faint X-ray emission in the 0.9-2.0 keV band, and (5) two DA WDs whose photospheric emission component has a hard shoulder extending to 0.5-0.9 keV. The origin of the hard X-ray emission in the latter three categories is not yet known. Deeper X-ray observations with higher angular and spectral resolutions are needed to help us understand these WDs' hard X-ray emission.
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页码:1433 / 1443
页数:11
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