AAS 206th Meeting, 29 May - 2 June 2005
Session 31 Highlights in Laboratory Astrophysics
Topical Session, Wednesday, 8:30-10:00am, 10:45am-12:30pm, 2:30-4:00pm, 4:15-6:00pm, June 1, 2005, 102 D

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[31.07] Pressure-broadened Alkali Resonance Lines as Diagnostics in Brown Dwarfs and Extra-solar Planets

K. Kirby, J. Babb, C. Zhu, R. Santra, A. Dalgarno (Harvard-Smithsonian Center for Astrophysics)

The resonance lines of Na and K dominate the visible and near-infrared spectrum of substellar objects such as cool brown dwarfs and extra-solar planets. The lines are significantly broadened due to collisions with molecular hydrogen and helium, and the wings extend as much as 100 nm. either side of line core. Detailed knowledge of the line profiles as a function of temperature and pressure can be obtained from quantum mechanical calculations, using accurate molecular potential energy curves and dipole transition moments for the alkali- perturber system. The line profiles can then be used as valuable diagnostics of the atmospheres of brown dwarfs and extra-solar planets.

This work is supported by NASA grant NAG5-12751.

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