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Evidence for variability of the hard X-ray feature in the Hercules X-1 energy spectrumThe hard X-ray spectrum of HER X-1 was measured for the first time with a high resolution (1.4 keV FWHM) germanium spectrometer. The observation was performed near the peak of the on-state in the 35 day cycle and the 1.24 pulsations were observed between the energies of 20 keV and 70 keV. The feature corresponds to an excess of 7.5 sigma over the low energy continuum. Smooth continuum models are poor fits to the entire energy range (chance probabilities of 2 percent or less). The best fit energies are 35 keV for an absorption line and 39 keV for an emission line. These are significantly lower energies than those derived from previous experiments. A direct comparison of the data with the results of the MPI/AIT group shows statistically significant variations which strongly suggest variability in the source. Previously announced in STAR as N83-37036
Document ID
19840050308
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Tueller, J.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Cline, T. L.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Teegarden, B. J.
(NASA Goddard Space Flight Center Laboratory for High Energy Astrophysics, Greenbelt, MD, United States)
Paciesas, W. S.
(Maryland, University College Park, MD, United States)
Boclet, D.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Durouchoux, PH.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Hameury, J. M.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Prantzos, N.
(Commissariat al'Energie Atomique, Centre d'Etudes Nucleaires de Saclay, Gif-sur-Yvette Essonne, France)
Haymes, R. C.
(Rice University Houston, TX, United States)
Date Acquired
August 11, 2013
Publication Date
April 1, 1984
Publication Information
Publication: Astrophysical Journal, Part 1
Volume: 279
ISSN: 0004-637X
Subject Category
Astrophysics
Accession Number
84A33095
Distribution Limits
Public
Copyright
Other

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