AAS Meeting #194 - Chicago, Illinois, May/June 1999
Session 52. White Dwarfs, Neutron Stars and Pulsars
Display, Tuesday, June 1, 1999, 10:00am-7:00pm, Southeast Exhibit Hall

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[52.15] Yet Another Multi wavelength Campaign on Hercules X-1/HZ Herculis

S.D. Vrtilek (SAO), B. Boroson, M. Still (GSFC), H. Fiedler (UM), H. Quaintrell (OU), K. O'Brien (St.~Andrews)

Preliminary results are presented from an extensive multi wavelength campaign (July 10-13, 1998) to observe the binary X-ray pulsar system Her X-1/ HZ Her. Data were obtained with three satellites (the STIS on HST, the PCA and ASM on RXTE, and EUVE), and several ground-based observatories (including La Palma and Calar Alto). The system was observed during the latter half of the short-on state of the 35-day cycle. A similar campaign to cover the main-on state is scheduled for July 1999. The STIS observations covered over a full binary orbit. The STIS data show variable line emission during eclipse and eclipse egress and clearly show the narrow and broad N~V line features (associated respectively with the companion star and the accretion disk) observed with the GHRS in 1995. The orbital phase dependent behavior of the N~V emission observed in 1995 persists. The STIS TIME-TAG mode data clearly show pulsations around 1.237 sec in the UV Continuum; and there is some evidence for pulsations in the lines; the pulse period was also clearly observed in the optical data. The X-ray/EUV/UV/Opt continuum data are consistent with models incorporating a precessing accretion disk and X-ray heating of HZ Her but the observed UV/Opt line emission presents some problems for this interpretation.

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