Identification of the low-mass X-ray binary and faint X-ray sources in NGC 6652

被引:41
作者
Heinke, CO [1 ]
Edmonds, PD [1 ]
Grindlay, JE [1 ]
机构
[1] Harvard Smithsonian Ctr Astrophys, Cambridge, MA 02138 USA
关键词
binaries : close; binaries : eclipsing; globular clusters : individual (NGC 6652); novae; cataclysmic variables; stars : neutron; stellar dynamics; X-rays : binaries;
D O I
10.1086/323493
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
We have detected three new X-ray point sources, in addition to the known low-mass X-ray binary (LMXB) X1832-330, in the globular cluster NGC 6652 with a Chandra 1.6 ks HRC-I exposure. Star 49 (M-V similar to 4.7), suggested by Deutsch and coworkers as the optical candidate for the LMXB, is identified (<0.<double prime>3) not with the LMXB, but with another, newly detected source (B). Using archival Hubble Space Telescope (HST) images, we identify (<0.<double prime>3) the LMXB (A) and one of the remaining new sources (C) with blue variable optical counterparts at M-V similar to 3.7 and 5.3, respectively. The other new source (D) remains unidentified in the crowded cluster core. In the 0.5-2.5 keV range, assuming a 5 keV thermal bremsstrahlung spectrum and N-H = 5.5 x 10(20), source A has intrinsic luminosity L-X similar to 5.3 x 10(35) ergs s(-1). Assuming a 1 keV thermal bremsstrahlung spectrum, B has L-X similar to 4.1 x 10(33) ergs s(-1), while C and D have L-X similar to 8 x 10(32) ergs s(-1). Source B is probably a quiescent LMXB, while source C may be either a luminous cataclysmic variable or a quiescent LMXB.
引用
收藏
页码:363 / 367
页数:5
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