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Flaring history of IGR J17544-2619 unveils stellar wind clumping

ATel #1269; R. Walter (ISDC, Geneva), J. Zurita (CEA, Saclay)
on 10 Nov 2007; 08:30 UT
Credential Certification: Roland Walter (Roland.Walter@obs.unige.ch)

Subjects: X-ray, Gamma Ray, Binary, Transient

To follow on ATEL#1265 and ATEL #1266 we point out that Walter & Zurita (2007, in press; astro-ph 0710.2542) have reported 8 flares of IGR J17544-2619 detected by INTEGRAL/ISGRI for a total effective exposure time (corrected for the variation of the sensitivity with off-axis angle) of about 76 days. About one flare is detected every 10 days of observation on average. IGR J17544-2619 is one of the supergiant fast X-ray transient system featuring the largest variability factor. Its variability characteristics can be used to derive parameters of the stellar wind of the O9Ib companion in particular its clumping structure (see Walter & Zurita 2007 for more details).