Inhomogeneous Stellar Atmospheres

University Of Colorado At Boulder, Boulder CO

Investigators

Abstract

Ayres, Thomas "Inhomogeneous Stellar Atmospheres" AST-9987414 Dr. Ayres is investigating the atmospheres of solar-type stars using observational and theoretical data for carbon monoxide (CO). The presence of relatively cool (T~3500K) CO molecules at high altitudes in the hot (T~7000K) solar atmosphere is a long-standing puzzle in solar physics, since in this region only hot chromospheric gas should exist and molecules are quite unexpected. In the Sun CO is found in the middle of the transition region that separates the kinetically controlled plasma of the photosphere and the magnetically controlled gas of the corona. This region is expected to provide important diagnostic clues to Solar activity levels and, indirectly, to the Sun-Earth interactions during the solar activity cycle. Dr. Ayres is extending this research to other solar-type stars using observations at the 5 micron infrared region where CO transitions are detectable to probe the cool side of this magnetic transition zone. This complements the visible and ultraviolet observations that probe the hotter regime. The primary objectives of this work are to: (1) use CO observations to investigate solar active regions; (2) investigate the low chromospheric structure at the solar limb; (3) survey the CO spectra of solar type stars; and (4) construct two-dimensional static models of the solar and stellar atmospheres that incorporate dynamic CO formation and destruction processes. Funding for this project was provided by the NSF program for Stellar Astronomy & Astrophysics (AST/SAA).