Beppo-SAX observations of AR lacertae

We present the results of an X-ray observation of the binary system AR Lace rtae (HD 210334) obtained with the Low and Medium Energy Concentrator Spect rometers (LECS & MECS) and with the Phoswich Detector System (PDS) on board the Beppo-SAX satellite. Two flare episodes with comparable peak luminosities were detected, one in each of the two runs into which the observations were split. Several low am plitude flares appear to be superimposed on a rotational modulated light cu rve. A very tight and shallow primary eclipse was observed, which is differ ent from primary eclipses observed at other epochs by other X-ray telescope s. No sign of secondary eclipse can be inferred from these data. The PDS data show that the emission in the 15-300 keV range is generally no t detectable, but there is convincing evidence of hard photons during the o nset of a flare on Nov 4 and during the flare on Nov 11. There was no signi ficant emission in the 15-300 keV range during the major flare on Nov 4. The AR Lac spectrum between 0.1 and 9 keV is well fit by a two component op tical-thin plasma model based on the MEKAL plasma emission code with subsol ar metal abundances. We also performed spectral analyses of the two separat e segments of data, and found that the plasma temperatures, abundances and emission measures did not significantly change between the two time interva ls. Hints of possible H I absorption in corona or in the circumstellar environm ent are also discussed.