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Discovery of a Transition to Global Spin-Up in EXO 2030+375EXO 2030+375, a 42 second transient X-ray pulsar with a Be star companion, has been observed to undergo an outburst at nearly every periastron passage for the last 13.5 years. From 1994 through 2002, the global trend in the pulsar spin frequency was spin-down. Using RXTE data from 2003 September, we have observed a transition to global spin-up in EXO 203G+375. Although the spin frequency observations are sparse, the relative spin-up between 2002 June and 2003 September observations along with an overall brightening of the outbursts since mid 2002 observed with the RXTE ASM accompanied by an increase in density of the disk indicated by infrared magnitudes suggest that the pattern observed with BATSE of a roughly constant spin frequency, followed by spin-up, followed by spin-down is repeating. If so this pattern has approximately an 11 year period, similar to the 15 plus or minus 3 year period derived by Wilson et al. (2002) for the precession period of a one-armed oscillation in the Be disk. If this pattern is indeed repeating, we predict a transition from spin-up to spin-down in 2005.
Document ID
20050092349
Acquisition Source
Marshall Space Flight Center
Document Type
Preprint (Draft being sent to journal)
Authors
Wilson, Colleen A.
(National Space Science and Technology Center Huntsville, AL, United States)
Fabregat, Juan
(Valencia Univ. Spain)
Coburn, Wayne
(California Univ. Berkeley, CA, United States)
Date Acquired
August 22, 2013
Publication Date
January 1, 2005
Subject Category
Astronomy
Distribution Limits
Public
Copyright
Other

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