Chemical Composition of the Atmospheres of Red Giants with High Space Velocities Yu. V. Pakhomov1 1Institute of Astronomy, Russian Academy of Sciences, Pyatnitskaya ul. 48, Moscow, 109017 Russia,
[email protected] The results of a comparative analysis of the elemental abundances in the atmospheres of 14 red giants with high Galactic space velocities are presented. For almost all of the chemical elements considered, the their abundance trends with metallicity correspond to those constructed for thick- disk dwarfs. In the case of sodium, the main factor affecting the [Na/Fe] abundance in the stellar atmosphere for red giants is the surface gravity that characterizes the degree of development of the convective envelope. The difference between the [Na/Fe] abundances in the atmospheres of thin-and thick-disk red giants has been confirmed. Keywords: stellar spectroscopy, stellar atmospheres, red giants, stellar evolution, kinematics, Galactic chemical evolution. PACS: 97.10.Cv, 97.10.Ex, 97.10.Ri, 97.10.Tk, 97.20.Li, 98.35.Bd, 98.35.Df, 98.35.Pr INTRODUCTION TABLE I: The list of studied stars with the membership probabilities (p) in some Galactic subsystems Our Galaxy is currently believed to be a set of sub- N HD α2000 δ2000 mV SpType p, % systems that differ by their sizes, locations in the Galaxy, thin Hercules thick characteristic stellar velocities, and stellar populations. ◦ ′ ′′ The best-known subsystems are the nucleus, the bulge, h:m:s : : disc stream disc the thick and thin disks, and the halo. Each subsystem 1 2901 00:32:47.6 +54:07:11 6.91 K2III - - 99 can contain dynamical stellar groups or streams (see, e.g., 2 10550 01:42:43.5 -03:41:24 4.98 K3II-III 27 58 13 [23], [24]).