Bursts, eclipses, dips and a refined position for the luminous low-mass X-ray binary in the globular cluster Terzan 6
Abstract
GRS 1747-312 is a bright transient X-ray source in the globular cluster Terzan 6 with quasi-periodic outbursts approximately every 4.5 months. We carried out 2-60 keV target-of-opportunity observations during eight outbursts with the Proportional Counter Array on the RXTE satellite, for a total exposure time of 301 ks, and detect the first unambiguous thermonuclear X-ray bursts from this source. This identifies the compact accretor in this binary as a neutron star. The neutron star identification implies that twelve out of thirteen luminous (above 10^36 erg/s X-ray sources in Galactic globular clusters harbor neutron stars, with AC211's nature (in M15) remaining elusive. We observed 24 transitions of eclipses of the X-ray emitting region by the companion star and are able to improve the accuracy of the orbital period by a factor of 10^4. The period is P=0.514980303(7) d. We do not detect a period derivative with an upper limit of |\dot{P}/P|=3X10^-8 yr^{-1}. Archival Chandra data were analyzed to further refine the X-ray position, and the cluster's center of gravity was re-determined from optical data resulting in a correction amounting to 2 core radii. We find that GRS 1747-312 is 0.2+/-0.2 core radii from the cluster center.
Cite
@article{arxiv.astro-ph/0302417,
title = {Bursts, eclipses, dips and a refined position for the luminous low-mass X-ray binary in the globular cluster Terzan 6},
author = {J. J. M. in 't Zand and F. Hulleman and C. B. Markwardt and M. Mendez and E. Kuulkers and R. Cornelisse and J. Heise and T. E. Strohmayer and F. Verbunt},
journal= {arXiv preprint arXiv:astro-ph/0302417},
year = {2011}
}
Comments
Accepted by A&A