Properties and nature of Be stars 29. Orbital and long-term spectral variations of ? Cassiopeiae

UNCG Author/Contributor (non-UNCG co-authors, if there are any, appear on document)
Anatoly S. Miroshnichenko, Professor (Creator)
The University of North Carolina at Greensboro (UNCG )
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Abstract: A detailed analysis of more than 800 electronic high-resolution spectra of gamma Cas, which were obtained during a time interval of over 6000 days (16.84 yr) at several observatories, documents the smooth variations in the density and/or extent of its circumstellar envelope. We found a clear anticorrelation between the peak intensity and FWHM of the Ha emission, which seems to agree with recent models of such emission lines. The main result of this study is a confirmation of the binary nature of the object, determination of a reliable linear ephemeris Tmin.RV = HJD (245081.9 ± 0.6) + 203d ±0.d08) x E and a rather definitive set of orbital elements. We clearly demonstrated that the orbit is circular within the limits of accuracy of our measurements and has a semi-amplitude of radial-velocity curve of 4.30? ± ?0.09 km s-1. No trace of the low-mass secondary was found. The time distribution of our spectra does not allow a reliable investigation of rapid spectral variations, which are undoubtedly present in the spectra. We postpone this investigation for a future study, based on series of dedicated whole-night spectral observations.

Additional Information

Astronomy & Astrophysics, 537
Language: English
Date: 2012
binaries: spectroscopic, stars: early-type, stars: emission-line, Be

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