PROPERTIES OF THE BE STARS IN THE FIELD OF THE SMALL MAGELLANIC CLOUDCLUSTER NGC-330

The blue globular cluster NGC 330 in the Small Magellanic Cloud is one of the few SMC clusters to be rich in young luminous stars. The incid ence of Be stars in the cluster is known to be high (Feast 1972; Grebe l et al. 1992). Medium resolution, high signal-to-noise (S/N) optical spectra of many of the brightest blue stars in the cluster have been o btained, and for some of the stars high resolution, high S/N spectra h ave also been acquired. New Johnson U and B photometry has also been o btained. Spectroscopy shows that even stars that were not classified a s Be photometrically do have emission at least in H alpha, so that the vast majority of the early B-type, non-supergiant stars in the cluste r are Be (13 stars out of 14 in our sample). The physical parameters ( effective temperature, surface gravity) of the stars have been determi ned, and their emission properties (full-width-half-maximum, emission equivalent width of the B aimer lines) have been investigated. The Her emission flux appears to be proportional to the value of the FWHM, an d, by inference, to that of upsilon sin i. All Be stars have similar, single-peaked H alpha emission profiles, regardless of emission streng th and stellar upsilon sin i. This is in some sense an unexpected resu lt, and may be taken to indicate that the extension of the discs surro unding the stars, whence the H alpha emission is supposed to arise, de pends on the rotational velocity of the stars (which would explain the absence of broad double peaks). The possible absence of double-peaked profiles of any separation, if confirmed, may also indicate that the Be stars in NGC 330 are observed under roughly the same inclination an gle, or that they are all surrounded by extended and optically thick d iscs.