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Consequences of a chromospheric temperature gradient on the width of H Alpha in late-type giantsAn analytic expression for the integrated H alpha optical depth profile is derived for a one dimensional slab geometry model chromosphere, with electron temperature increasing as a power law with height. The formula predicts H alpha opacity and profile width to be sensitive functions of the thermal gradient. Application of the model to observation reveals that broad H alpha absorption widths in G and K giant stars are consistent with a mean H alpha chromospheric optical depth of 50, while narrower widths in M stars indicate slightly lower opacities. It is proposed that differences in H alpha width between late-type giants of similar spectral type may be due, in part, to differences in their chromospheric thermal gradient, and associated H alpha opacity.
Document ID
19840011192
Acquisition Source
Legacy CDMS
Document Type
Contractor Report (CR)
Authors
Zarro, D. M. (California Inst. of Tech. Pasadena, CA, United States)
Date Acquired
September 4, 2013
Publication Date
February 1, 1984
Subject Category
Astrophysics
Report/Patent Number
NAS 1.26:173359
NASA-CR-173359
BBSO-0230
Accession Number
84N19260
Funding Number(s)
CONTRACT_GRANT: NSF ATM-82-11002
CONTRACT_GRANT: NGL-05-002-034
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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