Absorption line intensities and spectral types for the O stars.

Abstract

view Abstract Citations References Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Absorption line intensities and spectral types for the O stars. Petrie, R. M. Abstract Total absorptions of eleven lines of hydrogen, neutral and ionized helium, ionized magnesium and triply-ionized silicon were measured for nineteen 0-type stars. The majority of the stars are of early 0-type, thus extending the work of Williams and Rudnick. Measured line intensities for twenty-eight O5-B I stars are now available for studies of classification and absolute magnitude. The three classification ratios HeI/HeI I, Hell/H and SiIV/HeII arranged the stars unambiguously in the O5-Bo sequence. It was found that the singlet-triplet ratio of the diffuse series of helium exhibited no variation throughout Class 0, so that this ratio cannot be used for the classification of the 0 stars. The absolute magnitudes of twenty stars were calculated from the measured intensities of the K-line of interstellar calcium. The mean absolute magnitudes are as follows: O~, -5.0 (3); 06, -5.0(3); 07, -4.8 (7); 08-09, -5.1 (7). Correlation diagrams between line intensity and absolute magnitude failed to indicate a spectroscopic criterion of absolute magnitude for these high temperature stars. Dominion Astrophysical Observatory, Victoria, B. C. Publication: The Astronomical Journal Pub Date: November 1944 DOI: 10.1086/105811 Bibcode: 1944AJ.....51...69P full text sources ADS |