Poster Abstracts

Name/Affiliation:  Rachel Koncewicz (Oxford)

Title:  CO Fluorescence and 2D Atmospheric Models of two Cool Stars

Infrared absorption spectra of CO have been well observed in cool stars and the Sun, and used to estimate filling factors of active regions. UV emission lines were observed in IUE spectra, and, following GHRS observations, identified as fourth positive lines, pumped by the O I (uv2) resonance triplet (McMurry & Jordan 2000). The O I triplet itself is a product of pumping by H Ly $\beta$. Here, we present new calculations of CO UV emission lines in $\alpha$ Tau and $\alpha$ Boo using O I profiles calculated including full Partial Redistribution (PRD) in the hydrogen lines (Koncewicz & Jordan 2007). We use these results to produce new two-dimensional models of the chromospheres of $\alpha$ Tau and $\alpha$ Boo.