A quest for PMS candidate stars at low metallicity: Variable HAe/Be and Be stars in the Small Magellanic Cloud
Résumé
We report the discovery of 5 new Herbig Ae/Be candidate stars in the Small Magellanic Cloud in addition to the 2 reported in Beaulieu et al. (\cite{Beaulieu01}). We discuss these 7 HAeBe candidate stars in terms of (1) their irregular photometric variability, (2) their near infrared emission, (3) their Hα emission and (4) their spectral type. One star has the typical photometric behaviour that is observed only among Pre-Main Sequence UX Orionis type stars. The objects are more luminous than Galactic HAeBe stars and Large Magellanic Cloud HAeBe candidates of the same spectral type. The stars were discovered in a systematic search for variable stars in a subset of the EROS2 database consisting of 115 612 stars in a field of 24x 24 arcmin in the Small Magellanic Cloud. In total we discovered 504 variable stars. After classifying the different objects according to their type of variability, we concentrate on 7 blue objects with irregular photometric behaviour. We cross-identified these objects with emission line catalogues from Simbad and JHK photometry from 2MASS. The analysis is supplemented with obtained narrow and broad band imaging. We discuss their variability in terms of dust obscuration and bound-free and free-free emission. We estimate the influence of metallicity on the circumstellar dust emission from pre-main sequence stars.
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