J/A+A/342/736 Pre-eclipse dip of Her X-1 (Stelzer+ 1999)
Evolution of spectral parameters during a pre-eclipse dip of Her X-1
Stelzer B., Wilms J., Staubert R., Gruber D., Rothschild R.
<Astron. Astrophys. 342, 736 (1999)>
=1999A&A...342..736S 1999A&A...342..736S (SIMBAD/NED BibCode)
ADC_Keywords: Binaries, X-ray ; Accretion
Keywords: stars: individual: Hercules X-1 - X-rays: stars - stars: neutron -
accretion, accretion disks
Abstract:
We report on a pre-eclipse dip of the X-ray binary pulsar Her X-1
observed by the Rossi X-ray Timing Explorer (RXTE) in 1996 July. The
energy spectra in the 3-18keV range can be described by the sum of two
power-laws, one of which is modified by photoelectric absorption and
by Thomson scattering in cold material, plus an iron emission line at
6.7keV. We present the evolution of the spectral parameters with a
temporal resolution of 16s and show that the varying flux and spectrum
can be interpreted solely by a time varying column density. The data
do not appear to require non-solar abundances in the absorbing
material, although a slight over-abundance of the metals cannot be
ruled out. We also find that the lightcurve is characterized by
symmetric substructures which can be successfully modeled by Gaussian
profiles. The recurrence time of these substructures is on a timescale
of a few minutes.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 36 38 Parameters of Gaussians fitted to the first
half of the dip lightcurve
table2.ps 72 234 PostScript version of table2
table2.tex 78 56 LaTeX version of table2
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 2 I2 --- Nsub Numeration of substructures observed in
the lightcurve
3 A1 --- n_Nsub [*] Note on Nsub (1)
5- 11 F7.2 ct/s Norm Normalization (depth of the Gaussian)
13- 28 F16.8 d Tcenter JD time of the line center
30- 36 F7.2 s FWHM FWHM of Gaussian
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Note (1): Gaussians marked by an asterisk describe the underlying continuous
intensity modulation and have been held fixed in the fit.
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Acknowledgements: Beate Stelzer
(End) Patricia Bauer [CDS] 30-Nov-1998