A STELLAR CORONOGRAPH FOR THE COME-ON-PLUS ADAPTIVE OPTICS SYSTEM .2.FIRST ASTRONOMICAL RESULTS

We present here the first scientific results obtained with the coronog raph described by Beuzit et al. (1996, hereafter paper I), developed t o be used together with the COME-ON-PLUS/ADONIS adaptive optics (AO) s ystem. Two IRAS excess Main Sequence (MS) stars, namely HR 4796 and HR 2020 (beta Pictoris), have been observed. No circumstellar disk is de tected around HR 4796, down to 2'' from the star. This new constraint on its circumstellar environment is discussed. The photometry in the J , H, and K bands allows us to derive a G0 to G2 spectral type for a fa int companion located at 4.7''. The beta Pictoris disk is detected thr ough scattered light as close as 1.5'' from the star. We derive the ra dial mid-plane brightness from 1.5'' to 6'', and the FWHM from 2'' to 6''. We compare our results with other observations: here, the disk ap pears thinner than previously, and its surface brightness radial distr ibution gets flatter in the inner part. These results are then discuss ed in terms of density of the circumstellar matter.