The Astrophysical Journal, 621:398–416, 2005 March 1 # 2005. The American Astronomical Society. All rights reserved. Printed in U.S.A. FROM RADIO TO X-RAY: FLARES ON THE dMe FLARE STAR EV LACERTAE Rachel A. Osten1, 2 National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903;
[email protected] Suzanne L. Hawley2 Astronomy Department, Box 351580, University of Washington, Seattle, WA 98195;
[email protected] Joel C. Allred Physics Department, Box 351560, University of Washington, Seattle, WA 98195;
[email protected] Christopher M. Johns-Krull2 Department of Physics and Astronomy, Rice University, 6100 Main Street, Houston, TX 77005;
[email protected] and Christine Roark3 Department of Physics and Astronomy, University of Iowa, 203 Van Allen Hall, Iowa City, IA 52245 Received 2004 June 23; accepted 2004 November 5 ABSTRACT We present the results of a campaign to observe flares on the M dwarfflare star EV Lacertae over the course of two days in 2001 September, utilizing a combination of radio continuum, optical photometric and spectroscopic, ultraviolet spectroscopic, and X-ray spectroscopic observations to characterize the multiwavelength nature offlares from this active, single, late-type star. We find flares in every wavelength region in which we observed. A large radio flare from the star was observed at both 3.6 and 6 cm and is the most luminous example of a gyrosynchrotron flare yet observed on a dMe flare star. The radio flare can be explained as encompassing a large magnetic volume, comparable to the stellar disk, and involving trapped electrons that decay over timescales of hours.