FUSE Observations of a Full Orbit of Hercules X-1: Signatures of Disk, Star, and Wind

Abstract

We observed an entire 1.7 day orbit of the X-ray binary Hercules X-1 with the Far Ultraviolet Spectroscopic Explorer (FUSE). Changes in the O VI 1032,1037 line profiles through eclipse ingress and egress indicate a Keplerian accretion disk spinning prograde with the orbit. These observations may show the first double-peaked accretion disk line profile to be seen in the Hercules X-1 system. Doppler tomograms of the emission lines show a bright spot offset from the Roche lobe of the companion star HZ Her, but no obvious signs of the accretion disk. Simulations show that the bright spot is too far offset from the Roche lobe to result from uneven X-ray heating of its surface. The absence of disk signatures in the tomogram can be reproduced in simulations which include absorption from a stellar wind. We attempt to diagnose the state of the emitting gas from the C III 977, C III 1175, and N III 991 emission lines. The latter may be enhanced through Bowen fluorescence.

arXiv commentAccepted for publication in The Astrophysical Journal

References in corpus (14)

• Overview of the Far Ultraviolet Spectroscopic Explorer Mission
• On-Orbit Performance of the Far Ultraviolet Spectroscopic Explorer (FUSE) Satellite
• Warped accretion discs and the long periods in X-ray binaries
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• High-Resolution X-ray Spectroscopy of Hercules X-1 with the XMM-Newton RGS: CNO Element Abundance Measurements and Density Diagnostics of a Photoionized Plasma
• Identification of an Extended Accretion Disk Corona in the Hercules X-1 Low State: Moderate Optical Depth, Precise Density Determination, and Verification of CNO Abundances
• The He II Fowler lines and the O III and N III Bowen fluorescence lines in the symbiotic nova RR Tel
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• Hot Outflowing Gas from the X-ray Binary Hercules X-1
• Hercules X-1: Empirical Models of UV Emission Lines
• Eclipsing Broad Emission Lines in Hercules X-1: Evidence for a Disk Wind?

Cited by in corpus (8)

• SPH simulations of irradiation-driven warped accretion discs and the long periods in X-ray binaries
• The Photoionized Accretion Disk in Her X-1
• An ionised accretion disc wind in Hercules X-1
• Dynamical Ne K Edge and Line Variations in the X-Ray Spectrum of the Ultra-compact Binary 4U 0614+091
• Vertical wind structure in an X-ray binary revealed by a precessing accretion disk
• Variable O VI and N V Emission from the X-ray Binary LMC X-3: Heating of the Black Hole Companion
• FUSE Observations of a Full Orbit of Scorpius X-1
• Phase-Resolved Spectroscopy of the Low-Mass X-ray Binary V801 Ara