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K. Ishibashi, D. Dewey (MIT/CSR)
Capella consists principally of two cool giants (G8III + G1III) that have evolved in a very similar manner. It is a bright object at all energies; and the physical parameters of the system are accurately known. These respects make Capella an ideal stellar laboratory to study the differences in chromospheric and magnetic activities of the two similar stars.
In the last five years of its operation, the Chandra X-ray Observatory has observed the Capella system once or twice annually. Using the High Energy Transmission Grating Spectrometer (HETGS), we have successfully measured the change in apparent Doppler motion of the Capella system and identified that the primary G8III star is the principal source of its emission line spectrum in X-rays. This presentation describes our analysis method and the physical implication of our finding.
This research is supported by NASA through the SAO contract SV3-73016 for the Chandra X-ray Center and Science Instruments.
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Bulletin of the American Astronomical Society, 37 #2
© 2005. The American Astronomical Soceity.