Institut für Astronomie und Astrophysik

Abteilung Astronomie

Preprint 11f/98

NEW OBSERVATIONS OF THE VELA X­1 CYCLOTRON LINES WITH RXTE ­ PRELIMINARY RESULTS

P. Kretschmar (1);(3) , J. Wilms (1) , R. Staubert (1) , E. Kendziorra (1) , I. Kreykenbohm (1) , D. Gruber (2) , W. Heindl (2) , R. Rothschild (2)

(1) Institut für Astronomie und Astrophysik, Astronomie, Universität Tübingen, Waldhäuser Str. 64, D-72076 Tübingen, Germany
(2) Center for Astrophysics and Space Science, UCSD, La Jolla, CA, USA
(3) INTEGRAL Science Data Center, 1290 Versoix, Switzerland

3rd Integral Symposium - The Extreme Universe, in press

Abstract. We present preliminary results from a new, extended RXTE observation of Vela X­1. The main goal of this observation was to settle the question of the existence and energy of the cyclotron line features in the high energy X­ray spectrum. Previous observations with RXTE and BeppoSAX (Kreykenbohm et al. 1998, Orlandini et al. 1998) have differed in their conclusions, emphasizing the uncertainties caused by the imperfect continuum description. While our results are still preliminary, they do indicate cyclotron lines at both 22 keV and 51 keV, confirming earlier results.

Key words: Pulsars: indvidual: Vela X­1 - Stars: neutron - Stars: magnetic fields - X­rays: stars

Paper (95k gzip'ed Postscript including figures)

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Jürgen Barnstedt (barnstedt AT astro.uni-tuebingen.de) Last updated 11-Dec-1998