AAS 197, January 2001
Session 43. High Mass Star Formation
Display, Tuesday, January 9, 2001, 9:30am-7:00pm, Exhibit Hall

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[43.14] HST/WFPC2 Images of the Circumstellar Environment of V376 Cas and V633 Cas

F. Menard (Canada-France-hawaii Telescope), K.R. Stapelfeldt (JPL / Caltech), J.E. Krist (STScI), D.L. Padgett (SIRTF Science center, Caltech), W. Brandner (U. of Hawaii)

V376 Cas is an Herbig AeBe stars that is associated with a complex reflection nebula and shows signs of HH flows (Corcoran et al., 1995, A&A, 293, 550; Aspin & Reipurth 2000, MNRAS, 311, 522). On the basis of seeing limited images taken at CFHT, Asselin et al. (1996, ApJ, 472, 349) claimed that V376 Cas was seen close to edge-on with the two sides of the bipolar nebula surrounding a minimum in the isophotal contours. That interpretation was further supported by the extremely large optical linear polarisation (>20% in I-band) measured in an 8" diaphragm centered on the star and also by polarisation maps showing aligned vectors at the position of the minimum (Asselin et al. 1996), where the equatorial plane is expected. That interpretation was later challenged by Piirola et al. (1992, Nature, 359, 399) based on lower resolution images.

In this poster we show our recent HST/WFPC2 images of the V376 Cas/ V633 Cas (LkHa 198) region. They show that V376 Cas is not made of point sources (as would be expected for a binary) and that a "dark lane" is crossing the reflection nebula at a position angle in complete agreement with the one measured from polarisation measurements. We therefore suggest that V376 Cas is indeed seen edge-on. The exact nature of this "dark lane" needs to be confirmed before it is firmly interpreted in terms of a disk however, e.g. by millimeter mapping.

Nevertheless, if the case for disks around solar-type and A-type pre-main sequence stars is well established (e.g., Ménard & Stapelfeldt, 2000, proc. of IAU Symp. 200, in press), it is much less secure for the more massive B stars. V376 Cas is then especially attractive in that context given its B5e spectral type (Thé et al. 1994, A&AS, 104, 315). If this classification is confirmed, the results presented here would provide a good case to study the survival of an opaque dust "disk" in the harsh circumstellar environment of massive star.

The author(s) of this abstract have provided an email address for comments about the abstract: menard@cfht.hawaii.edu

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