B[e] phenomenon extending to lower luminosities in the Magellanic Clouds.

Abstract

An analysis of the four recently discovered B[e] stars HenS35, S59, S93, and S137 in the Large Magellanic Cloud has been carried out using low-resolution IUE spectra, ESO 3.6-m CASPEC spectra, and ESO 0.5-m and 1-m UBV and JHK photometry, respectively. LTE model atmospheres have been fitted to the observed continuum energy distributions in order to derive the stellar parameters. The results are T_eff_=22000K, R=28R_sun_, and logL/L_sun_=5.2 for HenS35, T_eff_=14000K, R=16R_sun_, and logL/L_sun_=4.0 for HenS59, and T_eff_=13000K, R=26R_sun_, and logL/L_sun_=4.2 for HenS137. The presence of absorption lines in the optical spectrum of the B9[e]Ib star HenS93 allowed an additional LTE line analysis for this star using Balmer, HeI, SIII, MgII, and FeII lines to derive T_eff_=10000K, R=73R_sun_, logL/L_sun_=4.7, logg=1.75, ξ=10km/s, vsin i=65km/s, and M>14M_sun_. Our investigation shows that the class of B[e] stars in the Magellanic Clouds extends to luminosities of about logL/L_sun_=4, i.e. much lower than those of the previously studied B[e] supergiants. This result reinforces the importance of axial symmetry in large regions of the Hertzsprung-Russell diagram.