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Astron. Astrophys. 347, 137-150 (1999)

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5. Conclusions

A new search for IRAS counterparts of the galactic early-type emission-line stars (Wackerling 1970) resulted in the discovery of two HAEBE candidates, BD[FORMULA] and MQ Cas. The follow-up photometric and spectroscopic observations of these stars and 6 other recently suggested HAEBE candidates revealed the presence of a near-IR excess in 3 of them (AS 116, AS 117, and BD[FORMULA]). The objects' spectral types were predicted from the UBV photometry and, in 8 cases, determined from classification-resolution spectra. Six were found to be late B-type - early A-type stars, one, Hen 938, is most likely an early B-type star, and one, HDE 290380, is an F6-type star. V1012 Ori was classified as A3 II shell?, however, it might have a lower luminosity if one takes into account the possible presence of the shell emission in the Balmer lines.

All objects except Hen 938 are most likely pre-main-sequence stars, while the observed characteristics of Hen 938 are more consistent with those of B[e] supergiants or post-AGB stars. Photometric variations, similar to those of HAEBEs, were found for MQ Cas and V1012 Ori. GSC 1811-0767, BD[FORMULA], and HDE 244604 are located in regions which contain other young stars, making the suggestion about their youth more reliable.

Nevertheless, additional observations are needed to extend our knowledge about these objects. In particular, higher resolution spectroscopy will provide us with quantitative information about their circumstellar envelopes and help to refine their distances. Long-term photometric monitoring will be capable of revealing brightness variations, which are expected for low-temperature HAEBEs. IR spectroscopy may place constraints on the chemical composition of the circumstellar dust.

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© European Southern Observatory (ESO) 1999

Online publication: June 18, 1999