EDP Sciences
Free access
Volume 508, Number 2, December III 2009
Page(s) 889 - 894
Section Stellar structure and evolution
DOI http://dx.doi.org/10.1051/0004-6361/200912739
Published online 15 October 2009
A&A 508, 889-894 (2009)
DOI: 10.1051/0004-6361/200912739

The nature of the X-ray binary IGR J19294+1816 from INTEGRAL, RXTE, and Swift observations

J. Rodriguez1, J. A. Tomsick2, A. Bodaghee2, J.-A. Zurita Heras1, S. Chaty1, A. Paizis3, and S. Corbel1

1  Laboratoire AIM, CEA/DSM – CNRS – Université Paris Diderot (UMR 7158), CEA Saclay, DSM/IRFU/SAp, 91191 Gif-sur-Yvette, France
    e-mail: jrodriguez@cea.fr
2  Space Science Laboratory, 7 Gauss Way, University of California, Berkeley, C1 94720-7450, USA
3  INAF-IASF, Sezione di Milano, via Bassini 15, 20133 Milano, Italy

Received 22 June 2009 / Accepted 9 October 2009

We report the results of a high-energy multi-instrumental campaign with INTEGRAL, RXTE, and Swift of the recently discovered INTEGRAL source IGR J19294+1816. The Swift/XRT data allow us to refine the position of the source to RAJ2000 = 19h 29m 55.9s DecJ2000 = +18° 18$\arcmin$38.4$\arcsec$ ($\pm$3.5$\arcsec$), which in turn permits us to identify a candidate infrared counterpart. The Swift and RXTE spectra are well fitted with absorbed power laws with hard ($\Gamma$ ~ 1) photon indices. During the longest Swift observation, we obtained evidence of absorption in true excess to the Galactic value, which may indicate some intrinsic absorption in this source. We detected a strong (P = 40%) pulsation at 12.43781 ($\pm$0.00003) s that we interpret as the spin period of a pulsar. All these results, coupled with the possible 117 day orbital period, point to IGR J19294+1816 being an HMXB with a Be companion star. However, while the long-term INTEGRAL/IBIS/ISGRI 18-40 keV light curve shows that the source spends most of its time in an undetectable state, we detect occurrences of short (~ 2000-3000 s) and intense flares that are more typical of supergiant fast X-ray transients. We therefore cannot make firm conclusions on the type of system, and we discuss the possible implications of IGR J19294+1816 being an SFXT.

Key words: X-rays: binaries -- accretion, accretion disks -- stars: individual: IGR J19294+1816 -- stars: individual: IGR J11215-5952 -- stars: individual: IGR J18483-0311

© ESO 2009