28. Implications of systematic observations for the nature of the multiple system with the Be star o Cassiopeæ and its circumstellar environment
Astronomical Institute, Academy of Sciences of the Czech Republic,
251 65 Ondřejov, Czech Republic e-mail: email@example.com
2 European Organisation for Astronomical Research in the Southern Hemisphere, Karl-Schwarzschild-Str. 2, 85748 Garching bei München, Germany
3 Astronomical Institute of the Charles University, Faculty of Mathematics and Physics, V Holešovičkách 2, 180 00 Praha 8 - Troja, Czech Republic
4 Department of Physics, Central Michigan University, Mount Pleasant, MI 48859, USA
5 Institute of Astronomy, Madingley Road, Cambridge, UK
6 University of Victoria, Dept of Physics and Astronomy, PO Box 3055 Victoria, BC V8W 3P6, Canada
7 Hvar Observatory, Faculty of Geodesy, Zagreb University, Kačiceva 26, 10000 Zagreb, Croatia
8 US Naval Observatory, Flagstaff Station, 10391 West Naval Observatory Road, Flagstaff, AZ 86001, USA
Accepted: 19 April 2010
The analysis of radial velocities of the Be star o Cas from spectra taken between 1992 and 2008 at the Ondřejov Observatory and the Dominion Astrophysical Observatory allowed us to reconfirm the binary nature of this object, first suggested by Abt and Levy in 1978, but later refuted by several authors. The orbital parameters of this SB1 system imply a very high mass function of about one solar mass. This in turn leads to a very high mass of the secondary, possibly higher than that of the primary. In order to look for such a massive secondary, o Cas was observed with the Navy Prototype Optical Interferometer, which allowed the binary components to be spatially resolved for the first time. The interferometric observations lead to the detection of a secondary, about 3 mag fainter than the primary. The possible properties of this peculiar binary system and the reasons why the massive secondary does not dominate the optical spectrum are discussed.
Key words: binaries: close / binaries: spectroscopic / stars: emission-line, Be / stars: fundamental parameters / stars: individual: o Cas
Based on new spectroscopic, photometric and interferometric observations from the following observatories: Dominion Astrophysical Observatory, Herzberg Institute of Astrophysics, National Research Council of Canada, Hvar, Navy Prototype Optical Interferometer, and Astronomical Institute AS CR Ondřejov.
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© ESO, 2010