Study of candidate Be stars in the Magellanic Clouds using NIR
  photometry and optical spectroscopy
  Mennickent et al.and Sabogal et al.identified a large number of Classical Be
(CBe) candidates in the L&SMC based on their photometric variability using the
OGLEII database. They classified these stars into four different groups based
on the appearance of their variability. We studied the infrared properties of
the sample as well as the spectroscopic properties of a subsample. We
cross-correlated the optical sample with the IRSF catalog to obtain the J, H,
Ks magnitudes of all the four types of stars in the L&SMC. Spectra of 120 stars
belonging to the types 1, 2 and 3 were analysed to study their spectral
properties. Among the four types, the type 4 stars is the dominant group. The
NIR colour-colour diagrams suggest that the type 4 stars in the LMC have a
subclass, which is not found in our Galaxy or in the SMC. The main type 4
sample which is \sim 49% of the total sample has NIR properties similar to the
Galactic CBe stars and the SMC type 4 stars. Though the new subclass of type 4
stars have high E(B - V) \sim 0.75, they are not located close to regions with
high reddening. The type 3 stars (\sim 6% & 7.3% in the L&SMC) are found to
have large H{\alpha} EW in the SMC and some are found to have large NIR excess.
This small fraction of stars are unlikely to be CBe stars. The type 2 stars are
found in larger fraction in the SMC, when compared to the LMC. The
spectroscopic and the NIR properties suggest that these could be CBe stars. The
spectroscopic sample of type 1 stars which show H{\alpha} in emission and
confirmed as CBe stars are more abundant in the SMC by a factor of 2.6. If the
effect of metallicity is to cause more CBe stars in the SMC, when compared to
the LMC, then type 1, type 2 and type 4 stars follow this rule, with an
enhancement of 2.6, 2.4 and 1.3 respectively.
