Montes Gutiérrez, DavidRamsey, Lawrence W.2023-06-202023-06-201998-120004-6361https://hdl.handle.net/20.500.14352/59977This work was supported by the Universidad Complutense de Madrid and the Spanish Direccion General de Investigación Científica y Técnica (DGICYT) under grant PB94-0263, and by National Science Foundation (NSF) grant AST 92-18008. We thank the staff of McDonald observatory for their allocation of observing time and their assistance with our observations.We report the possible detection of a Li I λ6708 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 Li^-6/Li^-7 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.engjournal articlehttp://aa.springer.de/papers/8340001/23000l5.pdfhttp://aa.springer.deopen access52© Springer VerlagA. G. T-tauri starsChromospherically active starsLithium isotope ratioRS-canum-venaticorumSolar-flaresAbundancesBinariesDwarfsPleiadesSampleAstrofísicaAstronomía (Física)