Title of article :
An analysis of the optical spectra of the post-asymptotic giant branch stars LSIV -12 111 and HD 341617
Author/Authors :
Keenan، F. P. نويسنده , , Hubeny، I. نويسنده , , Dufton، P. L. نويسنده , , Rolleston، W. R. J. نويسنده , , Ryans، R. S. I. نويسنده , , Mooney، C. J. نويسنده , , Lanz، T. نويسنده ,
Issue Information :
روزنامه با شماره پیاپی سال 2003
Abstract :
The binary X-ray pulsar Her X-1 shows a variety of time variations both in luminosity and its pulse features. For the first time an about 600 days long anomalous low state was seen in the light curve of ASM on board RXTE during the period MJD 5120051800. We observed the source in the 20-200 keV energy band during its second main-on in the post anomalous state on November 21, 2000. The source was found to be extremely bright at high energies and a total of 26 000 photons from the source were detected during the 35 min snapshot observation. The cyclotron absorption line at ~ 34 keV and its second harmonics were clearly detected in the data. We present the spectral details and discuss its implication in terms of the geometrical properties of the source.
Keywords :
stars , fundamental parameters , supergiants , early-type , Abundances
Journal title :
Astronomy and Astrophysics
Journal title :
Astronomy and Astrophysics