Color Anomalies and Metal Deficiencies in Solar-Type Disk Population Stars.

Abstract

view Abstract Citations (4) References Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Color Anomalies and Metal Deficiencies in Solar-Type Disk Population Stars. Conti, Peter S. ; Deutsch, Armin J. Abstract Many solar-type stars of the disk population have spectral lines that are systematically weaker than those in the Hyades dwarfs of the same temperature. Small line-weakening has often been inferred from a photometric determination of, say, an ultraviolet color excess 8 (U-B), a low m, index, or some other comparable color anomaly. The line weakening is, in turn, usually attributed to a small metal deficiency. But a direct calculation shows that the small metal deficiencies which have been spectroscopically established in some of these stars can directly weaken the lines by far too little to produce the color anomalies observed. More than half the line absorption in the near ultraviolet and violet spectra of these stars is caused by lines that lie on the "flat" part of the curve of growth and that are very insensitive to small changes in abundance. However, the strengths of these saturated lines are directly proportional to the velocity parameter. In fact, the color anomalies observed among most solar-type stars appear to arise primarily from differences in turbulence. The correlations among line strengths, kinematics, and age imply that turbulence decays with age. High turbulence is responsible for a large part of the photometric anomalies that distinguish many metallic4ine stars. In these objects, however, duplicity also plays an important role in perturbing the photometric indices and in making them unreliable indicators of metallicism. Publication: The Astronomical Journal Pub Date: 1965 DOI: 10.1086/109655 Bibcode: 1965AJ.....70S.670C full text sources ADS |