IAU Circ., 8068, 2 (2003/February-0)
Flaring object in Orion cluster.
GETMAN K.V., FEIGELSON E.D., GARMIRE G., MURRAY S.S. and HARNDEN F.R.Jr
Abstract (from CDS):
On behalf of a large collaborative team, K. V. Getman, E. D. Feigelson, and G. Garmire, Pennsylvania State University; and S. S. Murray and F. R. Harnden, Jr., Smithsonian Astrophysical Observatory, report the detection of an x-ray flare from the radio- flaring object reported on IAUC 8055 and 8060, as seen with the Chandra X-ray Observatory (+ ACIS-I detector) during an ultradeep observation of the Orion nebula during Jan. 8-22. The x-ray variability has a complex morphology: it is approximately constant around 0.04 counts/s from Jan. 8.9 to 16.3 UT, rapidly rising to 0.19 counts/s starting Jan. 16.3, falling to 0.11 counts/s by Jan. 16.7 (where it remained constant for a day), rising to 0.35 counts/s and higher over several hours starting Jan. 17.7, falling to 0.2 counts/s over one day (and remaining at that level for a half day), rising again to 0.35 counts/s and higher starting Jan. 19.7, and falling to 0.2 counts/s over one day by the end of the observation. Preliminary spectral analysis confirms the previous Chandra findings (Feigelson et al. 2002, Ap.J. 574, 258) that the source is deeply embedded in a molecular cloud with a column density of log N_H about 22.6 cm**-2 and with absorption-corrected luminosities of log L_x about 31.3 and about 32.0 erg/s, for the quiescent and flaring phases, respectively. As this source does not have a near-infrared excess (Muench et al. 2002, Ap.J. 573, 366), it may be an extreme example of a magnetically active weak- line T-Tau star, such as V773 Tau or DoAr 21 (cf. Feigelson and Montmerle 1985, Ap.J. 289, L19), rather than a rare radio flaring protostar (e.g., IRS 5 near R CrA; cf. Taylor and Storey 1984, MNRAS 209, 5P).
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