![]() ![]() This result suggests that the strong CN absorption seen in VSLs is not the result of unusual mixing. The CNO abundances (normalized to the iron abundances) of the VSLs appear on average to be normal for G and K giants. Carbon, nitrogen and oxygen abundances are most sensitive to mixing as they more » are produced through nucleosynthesis at various depths beneath the star's surface. Red giants are believe to undergo mixing, thereby driving the surface abundances towards those of the stellar interior. Contrary to earlier suggestions, none of the heavier elements (Z > 10) appear selectivity enhanced. The author finds that when compared to normal stars, the VSL stars show a mean iron overabundance of 0.15 dex. Of these, 33 have been called Very Strong-Lined (or VSL) stars primarily because of their CN line strength. « lessĮffective temperatures and surface gravities have been derived for 52 G and K giants using model atmosphere. However, our sample is dominated by low-velocity solar-metallicity RHB stars their existence cannot be easily explained with standard stellar evolution. Up until now, RHB stars have been considered as members of the thick disk, and were expected to have large space velocities and sub-solar metallicities. Taking into account both the kinematics and probable evolutionary stages, we conclude that our sample contains 5 thick-disk and 13 thin-disk RHB stars. We also derived kinematics of the stars with available distance information. The C underabundance is about a factor of 20 larger than for normal giants and the C ratios, revealed the presence of 18 probable RHB stars in our sample. The results show that the atmospheres of weak G band stars are highly contaminated with CN-cycle products. Middle layers are added (13 <20 M ). Smith Telescope at the McDonald Observatory and derived spectroscopic abundances for C, N, O, and Li, as well as for selected elements from Na-Eu. The CNO cycle was at work here, so that the ejecta is more and more enriched in 13C and 14N, reducing C/N and log(12C/13C) ratios from 2 and 0:75 to 2:6 and 0:6 (see g.1). We have observed 24 weak G band stars with the 2.7 m Harlan J. We determined the chemical composition of a large sample of weak G band stars-a rare class of G and K giants of intermediate mass with unusual abundances of C, N, and Li. ![]()
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