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Spectra of Her X-1 near a turn-on in the 35-day cycleX-ray spectra for Her X-l are presented for times before, during, and after a turn-on in the 35 day on-off cycle, as well as during an anomalous dip in the X-ray intensity. All four spectra are well represented by a power law of number index approximately .9 with a high energy cutoff near 20 keV. However, the column density of cold matter along the line of sight as estimated by the low energy cutoff varies substantially among the four intervals. The low level flux present prior to turn-on does not pulse and shows very little low energy absorption, in contrast to the X-rays observed during the turn-on and the anomalous dip. It seems likely that the pre-turn-on flux is composed of X-rays scattered into the line of sight by material away from the accretion disk.
Document ID
19770004992
Acquisition Source
Legacy CDMS
Document Type
Preprint (Draft being sent to journal)
Authors
Becker, R. H.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Boldt, E. A.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Holt, S. S.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Pravdo, S. H.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Rothschild, R. E.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Serlemitsos, P. J.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Smith, B. W.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Swank, J. H.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Date Acquired
September 3, 2013
Publication Date
October 1, 1976
Subject Category
Astronomy
Report/Patent Number
X-661-76-217
NASA-TM-X-71213
Report Number: X-661-76-217
Report Number: NASA-TM-X-71213
Accession Number
77N11935
Funding Number(s)
CONTRACT_GRANT: NGR-21-002-316
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
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