EDP Sciences
Free access
Volume 441, Number 1, October I 2005
Page(s) 261 - 269
Section Stellar structure and evolution
DOI http://dx.doi.org/10.1051/0004-6361:20053335

A&A 441, 261-269 (2005)
DOI: 10.1051/0004-6361:20053335

INTEGRAL observations of the Be/X-ray binary EXO 2030+375 during outburst

A. Camero Arranz1, C. A. Wilson2, P. Connell1, S. Martínez Núñez1, P. Blay1, V. Beckmann3, 4 and V. Reglero1

1  GACE, Instituto de Ciencias de los Materiales, Universidad de Valencia, PO Box 20085, 46071 Valencia, Spain
    e-mail: Ascension.Camero@uv.es
2  XD12 NASA Marshall Space Flight Center, Huntsville, AL 35812, USA
3  NASA Goddard Space Flight Center, Code 661, Greenbelt, MD 20771, USA
4  Joint Center for Astrophysics, Depart. of Physics, University of Maryland, Baltimore County, MD 21250, USA

(Received 28 April 2005/ Accepted 5 June 2005 )

We present a type-I outburst of the high-mass X-ray binary EXO 2030+375, detected during INTEGRAL's Performance and Verification phase in December 2002 (on-source time about 106 s). In addition, six more outbursts have been observed during INTEGRAL's Galactic Plane Scans. X-ray pulsations have been detected with a pulse period of  $41.691798\,\pm\,0.000016$ s. The X-ray luminosity in the 5-300 keV energy range was $9.7\,\times\,10^{36}$ erg s-1, for a distance of 7.1 kpc. Two unusual features were found in the light curve, with an initial peak before the main outburst and another possible spike after the maximum. RXTE observations confirm only the existence of the initial spike. Although the initial peak appears to be a recurrent feature, the physical mechanisms producing it and the possible second spike are unknown. Moreover, a four-day delay between periastron passage and the peak of the outburst is observed. We present for the first time a 5-300 keV broad-band spectrum of this source. It can be modelled by the sum of a disk black body ( $kT_{\tt BB} \sim8$ keV) with either a power law model with $\Gamma =2.04 \pm0.11$ keV or a Comptonized component (spherical geometry, $ kT_{\rm e}=30$ keV, $\tau=2.64$, $kT_{\rm W}=1.5$ keV).

Key words: accretion, accretion disks -- stars: binaries: close -- stars: individual: EXO 2030+375 -- X-rays: binaries

SIMBAD Objects

© ESO 2005