AAS 207th Meeting, 8-12 January 2006
Session 14 Highlights and Discoveries from INTEGRAL
Poster, Monday, 9:20am-7:00pm, January 9, 2006, Exhibit Hall

## [14.04] INTEGRAL Observations of the Be star \gamma Cassiopeiae

S. J. Sturner, C. R. Shrader (USRA, NASA/GSFC)

We present the results of hard X-ray observations of the Be star \gamma Cassiopeiae made with the INTEGRAL observatory. This star is a known, moderately strong (L\rm x \approx 1033\ {\rm erg\ s-1}) X-ray source that has recently been shown to be part of a binary system with a 203.59 day orbital period. The secondary was shown to have a mass of ~1\ M\odot, consistent with a white dwarf, a neutron star, or a normal late-type dwarf, however no orbital modulation of the X-ray intensity has been identified. This result has fueled debate as to whether the X-ray emission is due to accretion onto a compact companion or magnetic activity near the surface of the Be star. The detection of flaring activity in the hard X-ray domain could lend support for the stellar activity hypothesis. We present IBIS/ISGRI and SPI hard X-ray spectra of the system. We also calculate light curves in an effort to search for flares and long timescale flux variations. The results are compared with those of previous hard X-ray missions such as BeppoSAX and RXTE and conclusions are drawn as to the origin of the hard X-ray emission.

Bulletin of the American Astronomical Society, 37 #4
© 2005. The American Astronomical Soceity.