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Astron. Astrophys. 340, L5-L9 (1998)

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Letter to the Editor

Li I enhancement during a long-duration stellar flare

David Montes * 1, 2 and Lawrence W. Ramsey[FORMULA] 2

1 Departamento de Astrofísica, Facultad de Físicas, Universidad Complutense de Madrid, E-28040 Madrid, Spain (e-mail: dmg@astrax.fis.ucm.es)
2 The Pennsylvania State University, Department of Astronomy and Astrophysics, 525 Davey Laboratory, University Park, PA 16802, USA

Received 28 September 1998 / Accepted 14 October 1998

Abstract

We report the possible detection of a Li I [FORMULA]6708 Å line enhancement during an unusual long-duration optical flare in the recently discovered, X-ray/EUV selected, chromospherically active binary 2RE J0743+224. The Li I equivalent width (EW) variations follow the temporal evolution of the flare and large changes are observed in the intensity of the line. The maximum Li I enhancement (40% in EW) occurs just after the maximum chromospheric emission observed in the flare. A significant increase of the 6Li/7Li isotopic ratio is also detected. No significant simultaneous variations are detected in other photospheric lines. Neither line blends nor starspots seem to be the primary cause of the observed Li I line variation. From all this we suggest that this Li I enhancement is produced by spallation reactions during the flare.

Key words: stars: activity – stars: chromospheres – stars: binaries: spectroscopic – stars: flare – stars: abundances – stars: individual (2RE J0743+224)

* Guest observer at McDonald Observatory

Send offprint requests to: David Montes

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© European Southern Observatory (ESO) 1998

Online publication: November 3, 1998
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