Bibcode
in't Zand, J. J. M.; Hulleman, F.; Markwardt, C. B.; Méndez, M.; Kuulkers, E.; Cornelisse, R.; Heise, J.; Strohmayer, T. E.; Verbunt, F.
Referencia bibliográfica
Astronomy and Astrophysics, v.406, p.233-243 (2003)
Fecha de publicación:
7
2003
Revista
Número de citas
41
Número de citas referidas
34
Descripción
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
1036 erg s-1) 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 104. The period is
P=0.514980303(7) d. We do not detect a period derivative with an upper
limit of |dot {P}/P|=3*E-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.