Issue |
A&A
Volume 365, Number 2, January 2001
|
|
---|---|---|
Page(s) | 78 - 89 | |
Section | Interstellar and circumstellar matter | |
DOI | https://doi.org/10.1051/0004-6361:20000328 | |
Published online | 15 January 2001 |
HST/NICMOS2 coronagraphic observations of the circumstellar environment of three old PMS stars: HD 100546, SAO 206462 and MWC 480*
1
Laboratoire d'Astrophysique de l'Observatoire de Grenoble, Université J. Fourier, CNRS, BP 53, 38041 Grenoble Cedex 9, France
2
Canada-France-Hawaii Telescope Corporation, PO Box 1597, Kamuela, HI 96743, USA
Corresponding author: J. C. Augereau, augereau@obs.ujf-grenoble.fr
Received:
16
August
2000
Accepted:
29
September
2000
The close environment of four old
Pre-Main Sequence stars has been observed
thanks to the coronagraphic mode of the HST/NICMOS2 camera at m.
In the course of this program, a cir cum stel lar annulus around HD 141569 was detected and has
already been presented in Augereau et al. ([CITE]b).
In this paper, we report the detection of an elliptical structure around the Herbig Be
star HD 100546 extending from the very close edge of the co mask (∼50 AU) to
350-380 AU (3.5-3.8″) from the star. The axis ratio gives a disk inclination
of
to the line-of-sight and a position angle of
,
measured east of north. At 50 AU, the disk has a surface brightness between 10.5 and
11 mag/arcsec2, then follows a
radial power law up to 250-270 AU
and finally falls as
. The inferred optical thickness suggests that
the disk is at least marginally optically thick inside 80 AU and optically thin further
out. Combined with anisotropic scattering properties, this could explain the shape of
a brightness asymmetry observed along the minor axis of the disk. This asymmetry needs
to be confirmed.
The cir cum stel lar disks around SAO 206462 and MWC 480 are not resolved, leading to constraints on the
dust distribution. A tight binary system separated by only
is nevertheless
detected in the close vicinity of SAO 206462.
Key words: stars: cir cum stel lar matter -stars: HD 100546, SAO 206462, MWC 480 -stars: pre-main sequence
© ESO, 2001
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