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Astron. Astrophys. 324, 1083-1090

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A stellar coronograph
for the COME-ON-PLUS adaptive optics system*

II. First astronomical results

D. Mouillet1, A.-M. Lagrange1, and J.-L. Beuzit1,2, and N. Renaud1

1Laboratoire d'Astrophysique de l'Observatoire de Grenoble, UMR 5571, Université J. Fourier, BP 53, F-38041 Grenoble Cedex 9, France
2DESPA, Observatoire de Paris, URA 264, Place J. Janssen, F-92195 Meudon Cedex, France

Received 4 September 1996 / Accepted 3 February 1997


We present here the first scientific results obtained with the coronograph described by Beuzit et al. (1996, hereafter paper I), developed to be used together with the COME-ON-PLUS /ADONIS adaptive optics (AO) system. Two IRAS excess Main Sequence (MS) stars, namely HR 4796 and HR 2020 ( FORMULA Pictoris), have been observed.

No circumstellar disk is detected around HR 4796, down to 2 FORMULA 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 faint companion located at 4.7 FORMULA .

The FORMULA Pictoris disk is detected through scattered light as close as 1.5 FORMULA from the star. We derive the radial mid-plane brightness from 1.5 FORMULA to 6 FORMULA , and the FWHM from 2 FORMULA to 6 FORMULA . We compare our results with other observations: here, the disk appears thinner than previously, and its surface brightness radial distribution gets flatter in the inner part. These results are then discussed in terms of density of the circumstellar matter.

Key words: stars: circumstellar matter - stars: imaging - stars: individual: FORMULA Pictoris

Send offprint requests to: D. Mouillet
*Based on observations collected at the European Southern Observatory, La Silla, Chile

© European Southern Observatory (ESO) 1997