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Multiwavelength studies of her x-1
| Content Provider | NASA Technical Reports Server (NTRS) |
|---|---|
| Author | Voges, W. Dennerl, K. Vrtilek, Saeqa Dil Truemper, J. Kahabka, P. Serlemitsos, P. |
| Organization | The National Aeronautics and Space Administration (NASA) |
| Copyright Year | 1996 |
| Abstract | The ROSAT observations were part of an extensive multiwavelength campaign of the X-ray, pulsar system Her X-1/HZ Her conducted in 1993 August. The source was found in an anomalous low state detected only once before. Characteristics observed during anomalous low states include a substantial, unexpected drop in flux at X-ray energies, with no change in absorbing column density; an increase in the pulse period from the previous measurement, contrary to the usual spin-up; no pulsed emission above 0.9 keV; and optical fluxes that continued to show 1.7 day modulation attributed to X-ray heating of the companion star. The 1993 campaign also detected a significant reduction in UV flux during eclipse ingress and egress. Comprehensive modeling of the ultraviolet and optical continuum flux suggests that the ultraviolet and optical lightcurves can be reproduced by assuming variations in mass-accretion rate alone; however, changes in accretion rate are insufficient to account for the observed drop in X-ray flux. Shifts in disk inclination angle and changes in mass accretion rate can consistently explain the observed changes in X-ray, ultraviolet, and optical fluxes. The changes in mass accretion rate and disk inclination angle may be related to shifts in the 35-day precession period, with the average mass accretion rate corresponding to the average 35-day period. The rapid fluctuations in soft X-ray flux observed several times during the campaign may be caused by rapid variation of the mass accretion rate. To date a total of eight publications (refereed papers and conference reports) have resulted utilizing data obtained in connection with this grant, a ninth is in preparation. These publications are listed in this report. |
| File Size | 96465 |
| File Format | |
| Alternate Webpage(s) | http://www.archive.org/details/nasa_techdoc_19960014642 |
| Archival Resource Key | ark:/13960/t8rb7xm05 |
| Language | English |
| Publisher Date | 1996-01-01 |
| Publisher Institution | Goddard Space Flight Center |
| Access Restriction | Open |
| Subject Keyword | Aerospace Engineering Systems Management Aerospace Industry Contractors Deployment Lubrication Mechanical Devices Surveys Tribology Artificial Satellites Mechanical Engineering Nasa Programs Problem Solving Satellite Control Satellite Design Space Mechanics Systems Analysis Ntrs Nasa Technical Reports Server (ntrs) Nasa Technical Reports Server Aerodynamics Aircraft Aerospace Aeronautic Space Science |
| Content Type | Text |
