SIMULTANEOUS H-ALPHA, NAID1, D-2, AND HEID3 OBSERVATIONS OF A FLARE ON THE RS CVN SYSTEM UX ARI

We present simultaneous H alpha, Na I D-1, D-2, and He I D-3 spectrosc opic observations on the RS CVn system UX Ari. We have found a dramati c increase in the excess H alpha emission equivalent width by a factor of 2 in an interval of 1 day that indicates the beginning of a strong flare in this system. The presence of the He I D-3 in emission in coi ncidence with the enhancement of the H alpha emission confirms the det ection of a flare. The application of the spectral subtraction techniq ue reveals that the core of the Na I D-1 and D-2 lines are also filled -in by chromospheric emission.