view Abstract Citations (280) References (94) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Scanner Abundance Studies. I. an Investigation of Supermetallicity in Late-Type Evolved Stars Spinrad, Hyron ; Taylor, Benjamin J. Abstract In this paper we describe a new technique for obtaining differential abundances This technique utilizes the following information : (1) Accurate measures of line and molecular-band strengths, obtained by using a photoelectric spectrum scanner in a manner analogous to that of the Cambridge observers; (2) a self-consistent relative temperature scale based on measures of the star's continuum in the yellow, red, and infrared regions of the spectrum, also obtained with a scanner. With these data, stars may be ordered in terms of their molecular abundances; moreover, quantitative relative abundances may be derived from the measures of atomic-line strengths by using the additional information described below; (3) a simple theoretical treatment for the interpretation of the measured line strengths; (4) at least one com- parison star with standard abundances in the temperature range considered. We also describe results we have obtained to date from an application of this technique to K giants and subgiants These results include the following: 1. Evolved K stars with metal abundances greater than those of the Hyades exist in substantial numbers This conclusion is derived from the individual strong-feature data, and is confirmed by blanket- ing measures and by spot checks with slit spectrograms. Conclusive evidence exists that this interpreta- tion of the data is not confused by variations in microturbulence or surface gravity, and that the abun- dances found are primordial, not the result of self-enrichment; moreover, there is good indication that high metallicities, not low hydrogen contents, are involved. The abundances found range as high as 4 times the solar values for Ca, Mg, and Na. The cool evolved stars in M67 and NGC 188 have generally 3 times the solar abundances of the above elements; independent data on the hotter stars in M67 indicate that this is probably true of them, also 2 The tendency for the range of abundances in K giants to cause systematic errors in MK spectral classification of these stars makes supplementary red photometry necessary. 3 At least one significant source of error exists in standard differential curve-of-growth and model- atmosphere techniques for giants cooler than about KO. 4 A tight correlation exists between N, Na, and Fe abundances for the stars studied, and is pre- sumably of general validity. This correlation does not, however, extend in full strength to Ca and Mg 5 K giants and subgiants exist which have solar or higher abundances and orbital eccentricities up to 0 5 or maximum heights above the galactic plane of 1.5 kpc. The velocity-abundance correlations found previously by others for G dwarfs are not completely valid for evolved K stars and are probably not strictly valid generally 6. A relatively abrupt cutoff in the production of stars with abundances similar to or higher than those in M67 took place shortly after the epoch of formation of M67 itself. From this result and the results of other investigations, it is concluded that uniform enrichment was probably important during the forma- tion of the halo but has played no significant role in the history of the disk Publication: The Astrophysical Journal Pub Date: September 1969 DOI: 10.1086/150154 Bibcode: 1969ApJ...157.1279S full text sources ADS | data products SIMBAD (73) CDS (2) Related Materials (5) Catalog: 2002yCat.2047....0S Part 2: 1970ApJS...22..177T Part 3: 1971ApJ...163..303S Part 4: 1972ApJ...173..619T Part 5: 1972ApJ...171..403S