CXOU J005047.9-731817: a 292-s X-ray binary pulsar in the Small Magellanic Cloud. (arXiv:1306.1106v1 [astro-ph.HE])

CXOU J005047.9-731817: a 292-s X-ray binary pulsar in the Small Magellanic Cloud. (arXiv:1306.1106v1 [astro-ph.HE]):
We report on the discovery of a transient X-ray pulsars, located in the Small
Magellanic Cloud, with a pulse period of 292 s. A series of Chandra pointings
fortuitously recorded in 2010 April-May the occurrence of a two-weeks-long
outburst, during which the source luminosity increased by a factor of about
100, reaching a peak of ~1E36 erg/s (for a distance of 61 kpc). Complex-shape
and energy-dependent pulsations were detected close to the outburst peak and
during the very first part of its decay phase. During the outburst, the
phase-averaged spectrum of the pulsar was well described by an absorbed power
law with photon index ~0.6, but large variations as a function of phase were
present. The source was also detected by Chandra several times (during 2002,
2003, 2006, and 2010) at a quiescent level of ~1E34 erg/s. In 2012 we performed
an infrared photometric follow-up of the R ~ 15 mag optical counterpart with
the ESO/VLT and a spectroscopic observation by means of the CTIO telescope. The
optical spectra suggest a late-Oe or early-Be V-III luminosity-class star,
though a more evolved companion cannot be ruled out by our data (we can exclude
a luminosity class I and a spectral type later than B2). Finally, we show that
the outburst main parameters (duration and peak luminosity) can be accounted
for by interpreting the source transient activity as a type I outburst in a Be
X-ray binary.