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Project Progress

The high energy process in the young stellar environment would be important in stimulating chemical reaction of molecules and producing pre-biotic materials. In 2005, we approached this problem from two directions: study of mechanism and history of X-ray emission from young low and intermediate mass stars; study of interaction of circumstellar materials with stellar winds from observations of a comet.

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As members of an international team, we continuously monitored the young stellar object V1647 Ori, which had a mass accretion outburst 2 years ago (Figure 1). The X-ray activity gradually declined during 2005 as the optical outburst fades. This result strongly suggests that the X-ray activity has a strong connection with the mass accretion activity. We observed the eclipsing binary TY CrA during primary and secondary eclipsing phases. Our current analysis suggests that TY CrA has two levels of X-ray activity: high temperature and high luminosity and vice versa. We found the X-ray intensity enhanced apparently coincident with eclipse phase during the high state. This may mean that the X-ray activity and orbital phase have some connection. We observed young intermediate mass stars with Chandra and XMM-newton with the collaboration with Carol Grady, who is a member of the GSFC Astrobiology team. Both observations detected X-ray emission from both pre-main-sequence stars and young stars with intermediate mass (Figure 2). We made a systematic survey of intermediate mass young stars Herbig Ae/Be stars with Chandra.

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On May and June 2006, we observed X-ray emission from the comet 73P/SCHWASSMANN-WACHMANN3 with the Suzaku observatory, whose observations were coordinated with optical/IR observations lead by the GSFC astrobiology team. Suzaku detected clear X-ray emission from the comet. A preliminary analysis showed a significant depletion in oxygen. This result is consistent with abundance in solar winds during the Suzaku observations and the comet itself.