0000000000073899
AUTHOR
Guillermo Bernabeu
Simultaneous uvbyβ Photometry and Hα Spectroscopy of Be Stars in Open Clusters
The usual methods of spectral clasification, equivalent widths of Balmer lines or photometric calibrations are not suitable for the determination of the astrophysical parameters of the underlying star in Be-type objects. The spectrum is distorted by the circumstellar envelope lines, while the contribution of the envelope continuum radiation contaminates the photometric indices.
Abundances of Be Stars in Very Young Open Clusters
The Be Phenomenon in Early-Type Stars, IAU Colloquium 175, ASP Conference Proceedings, Vol. 214, edited by Myron A. Smith and Huib F. Henrichs. Astronomical Society of the Pacific, ISBN 1-58381-045-5, 2000, p.59 We present here standard uvbyβ CCD photometry for five open clusters of the Galaxy in order to determine abundances of Be stars, as a function of age.
Be stars in open clusters. I. uvby $ ^{\bf \beta}$ photometry
We present uvby β photometry for Be stars in eight open clusters and two OB associations. It is shown that Be stars occupy anomalous positions in the photometric diagrams, which can be explained in terms of the circumstellar continuum radiation contribution to the photometric indices. In the - M V plane Be stars appear redder than the non emission B stars, due to the additional reddening caused by the hydrogen free-bound and free-free recombination in the circumstellar envelope. In the c 0 - M V plane the earlier Be stars present lower c 0 values than absorption-line B stars, which is caused by emission in the Balmer discontinuity, while the later Be stars deviate towards higher c 0 values,…
Be stars in open clusters
We present Hα line profiles (, at continuum level, for some objects) for 58 stars in 8 northern open clusters and associations, complemented with Hβ and Hγ profiles for 36 of them as well as Hδ and Hϵ for 16 programme stars. Our observations, though lower in resolution, yield results which are in good agreement with those obtained in earlier works based mainly on field Be stars. Our data suggest a similar spectroscopic behavior for both field and cluster Be stars. The line parameters (EW, FWHM , ) have been obtained for each line. Nearly the whole set of stars have previously published quasi-simultaneous photometry, so a study of reliable correlations between photometric and spectroscopic d…