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Session 111 - Pulsars.
Display session, Saturday, January 10
Exhibit Hall,

[111.04] Discovery of Quasi-Periodic Oscillations from X Persei

T. Takeshima (NASA GSFC (USRA))

The Rossi X-ray Timing Explorer (RXTE) observed low luminosity Be X-ray binary pulsar X Persei on March 19 and April 1 1996 with the Proportional Counter Array (PCA). In addition to the coherent pulsations, quasi-periodic oscillations (QPO) are observed during the March 19 observation.

QPO are so far reported from eight X-ray binary pulsars. All of these pulsars have relatively short or moderate pulse period and are believed to be disk-fed pulsars. Since the QPO detected from X Persei have typical parameters of QPO from X-ray binary pulsars, QPO from X Persei seem to have the same origin as those observed from other X-ray binary pulsars.

On the other hand, X Persei has a pulsation period of \sim838 sec, which is the longest period among the binary pulsars. From the facts that X Persei is a low luminosity Be X-ray binary system, the Roche lobe is not filled, and that the random-walk like behavior of pulse period change in relatively short time scale similar to Vela X-1 is known, the mass accretion onto the compact object in X Persei is considered as a wind-fed system. These facts suggest that the QPO from X Persei might be different phenomena from the QPO from other binary pulsars.

In the meeting, we will present the results of the QPO from X Persei and compare the QPO and binary system characteristics between X Persei and other binary pulsars exhibiting QPO.

Program listing for Saturday