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EXTraS discovery of a peculiar flaring X-ray source in the Galactic globular cluster NGC 6540

EXTraS discovery of a peculiar flaring X-ray source in the Galactic globular cluster NGC 6540

Publication date: 11 August 2018

Authors: Mereghetti, S., et al.

Journal: Astronomy & Astrophysics
Volume: 616
Page: A36
Year: 2018

Copyright: © ESO, 2018

We report the discovery of a flaring X-ray source 7" from the center of the globular cluster NGC 6540 obtained during the EXTraS project devoted to a systematic search for variability in archival data of the XMM-Newton satellite. The source had a quiescent X-ray luminosity on the order of ~1032 erg s-1 in the 0.5–10 keV range (for a distance of NGC 6540 of 4 kpc) and showed a flare lasting about 300 s. During the flare, the X-ray luminosity increased by more than a factor 40, with a total emitted energy of ~1036 erg. These properties, as well as Hubble Space Telescope photometry of the possible optical counterparts, suggest the identification with a chromospherically active binary in the cluster. However, the flare luminosity is significantly higher than what is commonly observed in stellar flares of such a short duration, leaving open the possibility of other interpretations.

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Last Update: Sep 1, 2019 8:20:21 AM
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