Spectroscopy of Be stars in the Small Magellanic Cloud cluster NGC 330

Citation
Sc. Keller et Ms. Bessell, Spectroscopy of Be stars in the Small Magellanic Cloud cluster NGC 330, ASTRON ASTR, 340(2), 1998, pp. 397-401
Citations number
20
Categorie Soggetti
Space Sciences
Journal title
ASTRONOMY AND ASTROPHYSICS
ISSN journal
00046361 → ACNP
Volume
340
Issue
2
Year of publication
1998
Pages
397 - 401
Database
ISI
SICI code
0004-6361(199812)340:2<397:SOBSIT>2.0.ZU;2-3
Abstract
The presence of an anomalously large population of Be stars in the young cl uster NGC 330 in the SMC has been noted by Feast (1972), Bessell & Wood (19 92), Grebel (1992) and most recently Keller et al. (1998). We present resul ts from follow-up medium resolution spectra of the bright Be stars identifi ed in Keller et al. (1998) and in the spectroscopic study of Mazzali et al. (1996). We find that the study of Mazzali et al. has overestimated the num ber of Be stars within NGC 330. Many of the bright B type stars identified by Mazzali et al, as Be stars show no signs of emission after correction fo r the diffuse HII emission pervading the cluster field. In the study of Mazzali et al. (1996) evidence is presented suggesting that till Be stars in NGC 330 have a common inclination of their rotation axes to the line of sight. For our sample of Be stars we present the emission eq uivalent widths and observed rotational velocities. An examination of these quantities shows that there is no evidence of a preferential alignment of the rotational axes, rather we are observing a population with random rotat ional axis alignment and dis k size.