Observations of short-duration X-ray transients by WATCH on Granat

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dc.creatorCastro-Tirado, Alberto
dc.creatorBrandt, Soeren
dc.creatorLund, Niels
dc.creatorSunyaev, Rashid
dc.date1999-05-06
dc.date.accessioned2026-07-07T02:31:31Z
dc.date.available2026-07-07T02:31:31Z
dc.descriptionDuring 1990-92, the WATCH all-sky X-ray monitor on Granat discovered six short-duration X-ray transients. In this paper we discuss their possible relationship to peculiar stars. Only one of the fast (few hours) X-ray transients (GRS 1100-771) might be tentatively ascribed to a superflare arising from a young stellar object in the Chamaeleon I star-forming cloud. At the distance of 150 pc, Lx = 1.35 x 10E34 erg/s (8-15 keV), or 2.6 x 10E34 erg/s (0.1-2.4 keV) assuming a thermal spectrum with kT = 10 keV, a temperature higher than those previously seen in T Tauri stars (Tsuboi et al. 1998). The peak X-ray luminosity is at least 2 times higher than that derived for the protostar IRS 43 (Grosso et al. 1997) which would make -to our knowledge- the strongest flare ever seen in a young stellar object. However, the possibility of GRS 1100-771 being an isolated neutron star unrelated to the cloud cannot be excluded, given the relatively large error box provided by WATCH. Regarding the longer duration (about 1 day) X-ray transients, none of them seem to be related to known objects. We suggest that the latter are likely to have originated from compact objects in low-mass or high-mass X-ray binaries, similarly to XTE J0421+560.
dc.descriptionAccepted for publication in Astronomy and Astrophysics (5 pages, 2 figures)
dc.identifierhttps://arxiv.org/abs/astro-ph/9905078
dc.identifierhttp://arxiv.org/abs/astro-ph/9905078
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/14178
dc.subjectAstrophysics
dc.titleObservations of short-duration X-ray transients by WATCH on Granat
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