[vsnet-chat 7097] X-ray Transient Source in M31

[Taichi Kato]

   What magnitude would be expected in outburst?  Worth watching for the
next outburst in the optical??

Paper: astro-ph/0506312
Date: Tue, 14 Jun 2005 15:58:33 GMT   (185kb)

Title: Optical Constraints on an X-ray Transient Source in M31
Authors: Benjamin F. Williams, Michael R. Garcia, Frank A. Primini, Jeffrey E.
  McClintock, and Stephen S. Murray
Comments: 15 pages, 3 figures, accepted for publication in ApJ
\\
  We have detected a transient X-ray source in the M31 bulge through a
continuing monitoring campaign with the Chandra ACIS-I camera. The source was
detected at R.A.=00:42:33.428 +/- 0.11'', Dec.=+41:17:03.37 +/- 0.11'' in only
a single observation taken 2004 May 23. Fortuitous optical HST/ACS imaging of
the transient location prior to the X-ray outburst, along with follow-up
HST/ACS imaging during and after the outburst, reveals no transient optical
source brighter than B (equivalent) = 25.5. The location of the source and its
X-ray properties suggest it is a low mass X-ray binary (LMXB). Assuming the
transient is similar to many Galactic X-ray novae, the X-ray luminosity of (3.9
+/- 0.5) X 10$^{37}$ erg s$^{-1}$ and the upper-limit on the optical luminosity
provide a prediction of <1.6 days for the orbital period of the binary system.
\\ ( http://arXiv.org/abs/astro-ph/0506312 ,  185kb)