Philip Massey

Spectroscopic studies of Wolf-Rayet stars. V - Optical spectrophotometry of the emission lines in Small Magellanic Cloud stars

Spectrophotometry of the strongest emission-line features for the eight known WR stars in the SMC is presented. Seven are relatively early WN types; and one is a WO. These are compared to stars of similar spectral types in the Galaxy and the LMC. The hydrogen-burning CNO cycle equilibrium nitrogen abundance with respect to helium appears to be similar to that in WN stars of the Galaxy and LMC even though the SMC objects presumably began their lives with appreciably smaller CNO content. 28 refs.

The Hydrogen/Helium Ratio on the Surface of Wolf-Rayet Stars

As yet there have been few detailed analyses of Wolf-Rayet (WR) emission line spectra. Such analyses must certainly take account of line transfer in a spherically extended, expanding medium, a problem not yet completely addressed in the complexity of WR envelopes. However, visual examination of optical spectra suggests real differences in line strengths among the Balmer and Pickering series lines in WN stars. If hydrogen is present, the Balmer lines will be stronger than the adjacent Pickering lines of ionized helium; if hydrogen is weak or absent, then there will be a smooth transition in intensities along the Pickering series with no additional contribution from the Balmer lines at alternatively blending wavelengths (Underhill 1967).

The O-type Spectroscopic Binary System HD 149404

HD 149404 (HR 6164) was noted to have double lines by Conti, Leep and Lorre (1977). The spectrum has been previously classified as 09Ia, and shows strong Si IV λ4089, 4116 absorption, He I stronger than He II, N III λ4634,41 weakly in emission, He II λ4686 “filled in,” and all the Balmer lines through H13 in absorption except Hα, which is strongly in emission.