Neutral Metals Research Articles

The Spectrum of XX Ophiuchi in 1949 and 1950.

view Abstract Citations (32) References Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The Spectrum of XX Ophiuchi in 1949 and 1950. Merrill, Paul W. Abstract During 1949 and 1950 the spectrum of XX Ophiuchi, then in the bright-line state, was photographed from x 3600 to H with a dispersion of 10 A/mm; from H to Ha with 15 A/mm. Of the emission lines listed in Table 2, 29 are of II, 14 of He I, 72 of neutral metals, 441 of ionized metals, 11 miscellaneous, and 10 unidentified. The total number, 577, is possibly the greatest yet measured in any stellar spectrum. Lines of Fe ii dominate the spectrum; certain multiplets are observed more completely than in the laboratory. The D lines of sodium are conspicuous in emission-a rare occurrence in stellar spectra. The velocities from the bright lines have not changed markedly since 1921; in 1949 weak absorption components on the shortward edges of bright metallic lines had but a slight effect. H and [0 2] lines yield the same velocities as metarnc lines. In 1949 the H and K lines of Ca ii had well-defined, greatly displaced absorption components something like those in the spectrum of HD 190073. In XX Ophiuchi these lines are subject to large variations. The bright metallic lines are stronger than in other 3e stars exhibiting the same range of atomic excitation. This indicates a larger emitting atmosphere. Publication: The Astrophysical Journal Pub Date: July 1951 DOI: 10.1086/145449 Bibcode: 1951ApJ...114...37M full text sources ADS | data products SIMBAD (3)

Line-Intensities in Stars of Type G5 to K5

The paper presents results of measured intensities of certain lines, in the green-yellow region, of 78 stars of type G5 to K5. Homogeneity of the material has been ensured by using the same 2-prism spectrograph throughout at an unchanged setting. Quantitative mean variations with spectral type and absolute magnitude (based on Mt. Wilson and Victoria classifications) are derived. The deviations from these means are studied statistically and the observed dispersion is found in most cases to exceed slightly that attributable to observational errors ; in particular, the excess dispersions of Hβ and Mg 5183 are more than twice their standard errors. The numerous physical factors contributing to line-intensities are briefly discussed. But, provided the abundance of the relevant element makes no significant contribution to the atmospheric opacity nor to the classification of type and luminosity, such residual dispersions indicate upper limits to the dispersion in abundance for stars of the same type and luminosity. The upper limits so found amount to ± 18, ± 20 and ± 29 per cent for the abundance of Na , Mg and H respectively. The approximate nature of these results is stressed, especially for H . Corrections to types and absolute magnitudes, as well as observed deviations in individual stars, are listed in Table IV. One outstanding case is ζ Aurigae whose visual spectrum at phase 0.69 is that of a normal giant ( M v = + 0.5). The existence of a number of sub-giants is confirmed. The following results in connection with the variations with type and luminosity are noteworthy: (1) the strength of certain satellite lines of a low-level Fe multiplet in supergiants, (2) the strength of Mg 5183 in dwarfs, (3) the failure of subordinate lines of the neutral metals to show a maximum earlier than K5, (4) the strengthening of Cr lines from Ko to K5 compared with the relative insensitivity of Ti lines.