Volume 537, January 2012
|Number of page(s)||11|
|Section||Stellar structure and evolution|
|Published online||09 January 2012|
Properties and nature of Be stars
Astronomical Institute of the Charles University, Faculty of
Mathematics and Physics, V
Holešovičkách 2, 180
2 Astronomical Institute of the Academy of Sciences, 251 65 Ondřejov, Czech Republic
3 Department of Physics and Astronomy, University of North Carolina at Greensboro, Greensboro, NC 27402, USA
4 Physics & Astronomy Department, University of Victoria, PO Box 3055 STN CSC, Victoria, BC, V8W 3P6, Canada
5 Association des Utilisateurs de Détecteurs Électroniques (AUDE), 28 rue du Pic du Midi, 31130 Quint-Fonsegrives, France
Received: 20 August 2011
Accepted: 12 October 2011
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 Hα 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 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.
Key words: binaries: spectroscopic / stars: early-type / stars: emission-line, Be
Based on new spectral and photometric observations from the Castanet-Tolosan, Dominion Astrophysical, Haute Provence, Hvar, Ondřejov, and Ritter Observatories.
Tables 2 and 3 are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (18.104.22.168) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/537/A59
Appendix A is available in electronic form at http://www.aanda.org
© ESO, 2012
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.