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Independence of Chromospheric Activity and Soft X-Ray Flaring on the Flare Star EV Lacertae

Published online by Cambridge University Press:  27 September 2017

C.W. Ambruster ,
B.R. Pettersen ,
S.L. Hawley ,
L.A. Coleman  and
S. Sciortino
C.W. Ambruster
Affiliation:
Department of Astronomy, Villanova University, Villanova, PA 19085
B.R. Pettersen
Affiliation:
Institute of Theoretical Astrophysics, University of Oslo
S.L. Hawley
Affiliation:
Astronomy Department, University of Texas, and McDonald Observatory
L.A. Coleman
Affiliation:
Dept. of Physics & Astronomy, U, of Arkansas
S. Sciortino
Affiliation:
Osservatorio Astronomico di Palermo

Abstract

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EXOSAT observed the flare star EV Lacertae for 17 hr over 2 days in October 1985. Two flaring episodes were recorded. During a significant fraction of these observations, IUE, photometric and spectroscopic coverage was available. A 2-hour long period of X-ray flaring was observed during which there was no U-band activity and almost no chromospheric activity. On the other hand, two ΔU ~ 1° m° 5 optical flares produced normal chromospheric enhancements, but only a weak X-ray response. We suggest that these and a few other observations of stellar flares may imply the occasional existence of magnetically isolated regions in M-dwarf atmospheres.

Type
Session I: Stellar Flares
Information
International Astronomical Union Colloquium , Volume 104 , Issue 2: Solar and Stellar Flares , 1989 , pp. 27 - 31
Copyright
Copyright © Kluwer 1989

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