X-ray observations of the slowest known Be/X-ray pulsars RX J0146.9 6121 and X Persei
F. Haberl 1,
L. Angelini 2, 3,
C. Motch 4 and
N.E. White 2
Received 28 July 1997 / Accepted 1 September 1997
We present ASCA and ROSAT observations of the Be/X-ray binary pulsars RX J0146.9 6121 and X Persei between 1994 and 1996. Measuring the neutron star spin period and X-ray luminosity of X Persei shows that the episode of low X-ray luminosity and monotonic spin-down since 1978 continued to at least August 1995. ASCA and ROSAT HRI observations of RX J0146.9 6121 detected the pulsar with the longest known neutron star spin period at low luminosities after the X-ray outburst seen by EXOSAT in August 1984. The large spin period decrease seen between 1984 and 1993 has nearly stopped at a period of 1407.3 s in February 1996. We discuss that the X-ray outburst behaviour of X Persei with respect to its Be star phase changes observed in the optical can be caused by an asymmetry in the matter distribution around the Be star.
Key words: stars: emission-line, Be stars: individual: RX J0146.9+6121, X Persei stars: neutron X-rays: stars
Send offprint requests to: F. Haberl (firstname.lastname@example.org)
This article was processed by the author using Springer-Verlag LATEX A&A style file L-AA version 3.
© European Southern Observatory (ESO) 1998
Online publication: January 8, 1998