A Cessation of X-ray Dipping Activity in X1254-690
Abstract
We present results from a campaign of simultaneous X-ray and optical observations of X1254-690 conducted using the Rossi X-ray Timing Explorer and the CTIO 1.5m telescope. We find that the usually-observed deep X-ray dipping is not seen during the times of our observations, with an upper limit of ~2% on any X-ray orbital variation, and that the mean optical variability has declined in amplitude from 0.40+-0.02 mag (in V) to 0.28+-0.01 mag. These findings indicate that the vertical structure on the disk edge associated with the impact point of the accretion stream has decreased in angular size from 17-25 degrees to <10 degrees, and support the suggestions of previous modeling work that the bulge provides 35-40% of the contribution to the overall optical modulation. The average optical and X-ray brightnesses are comparable to their values during dipping episodes, indicating that the mean accretion rate and disk radius remain unchanged.
Keywords
Cite
@article{arxiv.astro-ph/9907327,
title = {A Cessation of X-ray Dipping Activity in X1254-690},
author = {Alan P. Smale and Stefanie Wachter},
journal= {arXiv preprint arXiv:astro-ph/9907327},
year = {2009}
}
Comments
6 pages, 3 figures, accepted for publication in ApJ