Poster Abstracts

Name/Affiliation:  Paul Schmidtke (Arizona State University)

Title:  The Angular Diameters of Alpha Scorpii and Lambda Aquarii at High Spectral Resolution

Abstract:
Time-resolved, high-resolution spectra of the cool stars alpha Scorpii (M1.5 Iab-b) and lambda Aquarii (M2 III) have been obtained during a series of lunar occultations, with the goal of measuring the atmospheric extension of prominent photospheric lines. The spectral ranges include both the Na doublet (D lines) and Ca II near-infrared triplet. Using a uniform-disk model, the measured extension relative to continuum light is about 55-115% (depending on line) for alpha Sco and 15-25% for lambda Aqr.