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arXiv · 0903.4814

X-ray variability of sigma Orionis young stars with ROSAT

J. A. Caballero·J. Lopez-Santiago·E. de Castro·M. Cornide
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Abstract

We used the Aladin Virtual Obsrvatory tool and High Resolution Imager ROSAT archival data to search for X-ray variability in scale of days in 23 young stars in the sigma Orionis cluster and a background galaxy. Five stars displayed unambiguous flares and had probabilities p_var >> 99% of being actual variables. Two of the detected flares were violent and long-lasting, with maximum duration of six days and amplitude of eight times above the quiescent level. We classified another four stars as possible X-ray variables, including the binary system formed by the B2Vp star sigma Ori E and its close late-type companion. This makes a minimum frequency of high-amplitude X-ray variability in excess of a day of 39% among sigma Orionis stars. The incidence of this kind of X-ray variability seems to be lower among classical T Tauri stars with mid-infrared flux excesses than among fast-rotating, disk-less young stars.

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J. A. Caballero, J. Lopez-Santiago, E. de Castro, M. Cornide. 2009-03-27. X-ray variability of sigma Orionis young stars with ROSAT. https://doi.org/10.1088/0004-6256/137/6/5012

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