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The delta upsilon = 1 fundamental bands of carbon monoxide in late-type starsA program was begun to develop the fundamental vibration-rotation bands of CO near 4.7 micron, as a tool to investigate the properties of late type stellar atmospheres. The strong delta v = 1 lines are sensitive probes of the thermal structure of the outer layers, which can be strongly affected by the CO, itself: cooling in the fundamental lines can depress the surface temperature to low values that are in sharp contrast with those derived from chromospheric diagnostics like Ca II K and Mg II k. Cool atmospheric models are being constructed to reproduce observed high resolution CO spectra of several late-type stars. The sensitivity is illustrated of CO LTE spectra to variations in T sub eff, log g, (Fe/H), and isotopic abundances of C and O for a grid of such models. In parallel, the assumptions of LTE line formation are tested using newly available cross sections for translational-to-vibrational energy exchange in collisions of atomic H on CO. In addition, spectra of CO and Ca II K calculated from semi-empirical UV based hot chromospheric models are used to estimate geometrical filling factors for the CO dominated and chromospheric regions on the stellar surface, in the spirit of Ayres' thermal bifurcation scenario.
Document ID
19880003795
Acquisition Source
Legacy CDMS
Document Type
Conference Paper
Authors
Wiedemann, G.
(Colorado Univ. Boulder., United States)
Ayres, T.
(Colorado Univ. Boulder., United States)
Saar, S.
(Joint Inst. for Lab. Astrophysics Boulder, Colo., United States)
Jennings, D.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Date Acquired
September 5, 2013
Publication Date
July 1, 1987
Publication Information
Publication: Colorado Univ., 5th Cambridge Workshop on Cool Stars, Stellar Systems and the Sun
Subject Category
Astronomy
Accession Number
88N13177
Funding Number(s)
CONTRACT_GRANT: NSF AST-85-07029
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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