2001/07/26 by C. O. Heinke, P. D. Edmonds, J. E. Grindlay · 1 citation
Physics and Astronomy · #Astronomy #Astrophysical Phenomena and Observations #Astrophysics #Astrophysics and Star Formation Studies #Bremsstrahlung #Galaxy #Globular cluster #Luminosity #Neutron star #Photon #Physics #Stars #Stellar, planetary, and galactic studies #X-ray binary #astro-ph
paper · pdf · doi:10.1086/323493
14 pages, 3 figures, accepted by Astrophysical Journal
arxiv created 2001/07/26 · openalex publication_date 2001/11/20 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
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 ~ 4.7), suggested by Deutsch and coworkers as the optical candidate for the LMXB, is identified (<0 3) not with the LMXB, but with another, newly detected source (B). Using archival Hubble Space Telescope ( HST ) images, we identify (<0 3) the LMXB (A) and one of the remaining new sources (C) with blue variable optical counterparts at M V ~ 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 × 10 20 , source A has intrinsic luminosity L X ~ 5.3 × 10 35 ergs s -1 . Assuming a 1 keV thermal bremsstrahlung spectrum, B has L X ~ 4.1 × 10 33 ergs s -1 , while C and D have L X ~ 8 × 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.