* Astronomy

Blobrana · L

RE: IGR J17544-2619

Blobrana · L

Title: Discovery of the orbital period in the supergiant fast X-ray transient IGR J17544-2619
Authors: D. J. Clark (1), A. B. Hill (2), A. J. Bird (1), V. A. McBride (1), S. Scaringi (1), A. J. Dean (1) ((1) School of Physics and Astronomy, University of Southampton, UK (2) Laboratoire dAstrophysique de Grenoble, UMR 5571 CNRS, Universite Joseph Fourier, France)

The supergiant fast X-ray transient (SFXT) system IGR J17544-2619 has displayed many large outbursts in the past and is considered an archetypal example of SFXTs. A search of the INTEGRAL/ISGRI data archive from MJD 52698-54354 has revealed 11 outbursts and timing analysis of the light curve identifies a period of 4.926±0.001 days which we interpret as the orbital period of the system. We find that large outbursts occasionally occur outside of periastron and place an upper limit for the radius of the supergiant of <23R_{\sun}.

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Blobrana · L

The Swift satellite has observed the probable neutron star
Supergiant Fast X-ray Transient IGR J17544-2619 in outburst.
IGR J17544-2619 was discovered in September 2003 by the INTEGRAL satellite.

Position (2000): RA 17h 54m 25.28s, Dec -26° 19' 52.6"

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Blobrana · L

Title: IGR J17544-2619 in depth with Suzaku: direct evidence for clumpy winds in a supergiant fast X-ray transient
Authors: Rachel A. Rampy, David M. Smith, Ignacio Negueruela
(Version v2)

We present the first direct evidence for dense clumps of matter in the companion wind in a Supergiant Fast X-ray Transient (SFXT) binary. This is seen as a brief period of enhanced absorption during one of the bright, fast flares that distinguish these systems. The object under study was IGR J17544-2619, and a total of 236 ks of data were accumulated with the Japanese satellite Suzaku. The activity in this period spans a dynamic range of almost 10000 in luminosity and gives a detailed look at SFXT behaviour

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