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Session 35 - Galactic X-Ray (XTE) Sources.
Display session, Tuesday, January 14
Metropolitan Ballroom,
We report preliminary results of a coordinated x-ray and optical study of the AM Her systems VV Pup, V834 Cen, and EF Eri. Simultaneous, high time-resolution observations of these sources were made during April, May, and August 1996, respectively, using the Rossi X-ray Timing Explorer (RXTE) and the 1-meter telescope of the Cerro Tololo Inter-American Observatory (CTIO). During the times of the observations, VV Pup was in a depressed optical state, approximately one magnitude fainter than its normal state. V834 Cen was in a typical high state. EF Eri was in an anomalously low faint state, m_V \sim 18.
The systems chosen for our study are all known sources of low-amplitude, 1 - 4 second, optical quasi-periodic oscillations (QPOs). VV Pup and V834 Cen both showed optical QPOs during our observations while the signal to noise for EF Eri was too low to allow detection of low amplitude QPOs. We present the results of our x-ray timing analysis, including a discussion of possible x-ray QPO activity in VV Pup and V834 Cen. Because AM Her systems are faint in the hard x-rays, a rigorous quantitative analysis of the x-ray data awaits the development of a reliable model for the background.
