2011ApJ...735...95C

Our 5 ks Chandra ACIS-S observation of the globular cluster NGC 6652 detected seven X-ray sources, three of which were previously unidentified. This cluster hosts a well-known bright low-mass X-ray binary, source A (or XB 1832-330). Source B shows unusual rapid flaring variability, with an average L_X(0.5-10 keV) ∼2x10³⁴ erg/s, but with minutes-long flares up to L_X= 9x10³⁴ erg/s. Its spectrum can be fit by an absorbed power law of photon index Γ ∼ 1.24 and hardens as the count rate decreases. This suggests that part or all of the variation might be due to obscuration by the rim of a highly inclined accretion disk. Sources C and D, with L_X ∼ 10³³ erg/s, have soft and unusual spectra. Source C requires a very soft component, with a spectrum peaking at 0.5 keV, which might be the hot polar cap of a magnetically accreting polar cataclysmic variable. Source D shows a soft spectrum (fit by a power law of photon index ∼2.3) with marginal evidence for an emission line around 1 keV; its nature is unclear. The faint new sources E, F, and G have luminosities of 1-2x10³² erg/s, if associated with the cluster (which is likely). E and F have relatively hard spectra (consistent with power laws with photon index ∼1.5). G lacks soft photons, suggesting absorption with N_H> 10²²/cm2.