AAS 201st Meeting, January, 2003
Session 12. Activity in Cool Stars
Poster, Monday, January 6, 2003, 9:20am-6:30pm, Exhibit Hall AB

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[12.07] The Quiescent and Flaring Atmosphere of the dMe Flare Star EV Lacertae

R.A. Osten (NRAO), S.L. Hawley (Univ. of Washington), C.M. Johns-Krull (Rice University), A. Brown, T.R. Ayres (CASA, Univ. of Colorado), C. Ambruster (Villanova Univ.)

We report on a multi-wavelength campaign to observe flares on the dM4.5e flare star, EV ~Lac, in 2001 September. The campaign utilized the Chandra ACIS-HETGS, HST-STIS, VLA, and optical photometry and spectroscopy with the McDonald Observatory's 2.1 and 2.7m telescopes. The goal of the campaign was to characterize EV~Lac's dynamic outer atmosphere and study the characteristics of magnetic energy release processes in a completely convective star. X-ray grating observations confirm the quiescent underabundance of iron deduced from previous low spectral resolution observations and show evidence of enhanced and variable Ne/Fe abundance ratios. Numerous flares were observed in the 100 ksec X-ray pointing; UV observations overlap one impulsive event, while radio and optical observations reveal impulsive flare signatures during a moderate X-ray flare. Preliminary results from a time-resolved spectroscopic analysis of the X-ray data will be presented, including determination of changing abundances, density, and temperature structure of the coronal plasma in EV~Lac. The timing of flares in radio, UV, and optical will be compared against X-ray variations. A discussion of the observed multi-wavelength temporal trends will be given, and comparison made to solar flares.

RAO acknowledges support from Chandra grant G01-2014A and HST grant GO-08880.04-A, as well as support from NRAO through a Jansky fellowship.

The author(s) of this abstract have provided an email address for comments about the abstract: rosten@nrao.edu

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Bulletin of the American Astronomical Society, 34, #4
© 2002. The American Astronomical Soceity.