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Measurement of coronal X-ray emission lines from CapellaThe Einstein Observatory's Focal Plane Crystal Spectrometer has detected X-ray emission lines due to O VIII, Fe XVII, and Fe XX, from the binary star system Capella. Line luminosities are well fitted by an emitting plasma at a single temperature of 6.29 + or - 0.01 - 0.03 million K, and a volume emission measure of about 8.6 x 10 to the 52nd/cu cm, corresponding to the low temperature component previously observed. A high temperature component is undetectable, since the observed lines are not produced in plasma at temperatures above about 20 million K. Nearly isothermal plasma would be expected if many of the magnetically confined coronal loops have similar sizes and pressures, and a second population of longer loops would be required to account for the hotter component. An alternative interpretation of the observed X-ray line emission and upper limit is that the plasma contains a continuous distribution of emission measure versus temperature that rises sharply to 3 million K and then falls by nearly a decade to 16 million. An extrapolation of the loop sizes suggested by this alternative to hotter, longer loops may also account for the higher temperature emission.
Document ID
19830060414
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Vedder, P. W.
(MIT Cambridge, MA, United States)
Canizares, C. R.
(Massachusetts Inst. of Tech. Cambridge, MA, United States)
Date Acquired
August 11, 2013
Publication Date
July 15, 1983
Publication Information
Publication: Astrophysical Journal, Part 1
Volume: 270
ISSN: 0004-637X
Subject Category
Astrophysics
Accession Number
83A41632
Funding Number(s)
CONTRACT_GRANT: NAS8-30752
Distribution Limits
Public
Copyright
Other

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