2004A&A...420.1079F

We report a flare on the M9 dwarf DENIS 104814.7-395606.1, whose mass places it directly at the hydrogen burning limit. The event was observed in a spectral sequence during 1.3h. Line shifts to bluer wavelengths were detected in H_α, H_β, and in the NaI D lines, indicating mass motions. In addition we detect a flux enhancement on the blue side of the two Balmer lines in the last spectrum of our series. We interpret this as rising gas cloud with a projected velocity of about 100km/s which may lead to mass ejection. The higher Balmer lines H_γ to H₈ are not seen due to our instrumental setup, but in the last spectrum there is strong evidence for H₉ being in emission.