Astrophys. J., 687, 425-432 (2008/November-1)
Resolving a class I protostar binary system with Chandra.
HAMAGUCHI K., CHOI M., CORCORAN M.F., CHOI C.-S., TATEMATSU K. and PETRE R.
Abstract (from CDS):
Using a subpixel event repositioning technique, we spatially resolved X-ray emission from the infrared double system IRS 5 in the R Corona Australis molecular cloud with ∼0.8" separation. As far as we know, this result–obtained from eight Chandra archival observations between 2000 and 2005–is the first X-ray study of individual sources in a Class I protostar binary system with a projected separation of less than 200 AU. We extracted light curves and spectra of the individual sources using a two-dimensional image-fitting method. IRS 5a at the south, the source that was brighter in the near-infrared, showed three X-ray flares lasting >20 ks, reminiscent of X-ray flares from pre-main-sequence stars, while the northern source (IRS 5b) was quiescent in X-rays in all the observations except for a 2005 August 9 observation with a factor of ∼2 flux enhancement. In quiescence, these sources showed almost identical X-ray spectra, with NH∼4x1022/cm2, kT∼2 keV, and logLX∼30.2-30.3 ergs/s. IRS 5a showed plasma at temperatures up to kT∼5-6 keV during flares, while the column density of IRS 5b increased by a factor of 2 during an observation on 2005 August 9. We discuss the evolutionary stages and variation of the X-ray activity of these sources.
Stars: Binaries: Visual - Stars: Magnetic Fields - Stars: Pre-Main-Sequence - Techniques: High Anular Resolution - X-Rays: Stars
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