2008/06/27 by Kenji Hamaguchi, Minho Choi, Michael F. Corcoran +5
Physics and Astronomy · #Astro and Planetary Science #Astrophysical Phenomena and Observations #Astrophysics and Star Formation Studies #astro-ph
paper · pdf · doi:10.1086/591544
14 pages, 5 figures, Astrophysical Journal in press
arxiv created 2008/06/27 · openalex publication_date 2008/10/24 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/31
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 N H ∼ 4 × 10 22 cm −2 , kT ∼ 2 keV, and log L X ∼ 30.2–30.3 ergs s −1 . 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.