Barium stars and technetium-poor, extrinsic S stars are binary systems with a white dwarf companion, and with orbital elements similar to those of symbiotic systems. One may thus wonder whether these various families of binary systems involving red giant stars are somehow related. This question is actually twofold: (i) Do barium and binary S stars exhibit some symbiotic activity? (ii) Do symbio...

Fluorine (F) abundances are derived in a sample of 6 bulge red giants in Baade’s Window. These giants span a factor of 10 in metallicity and this is the first study to define the behavior of F with metallicity in the bulge. The bulge results show an increase in F/O with increasing oxygen. This trend overlaps what is found in the disk at comparable metallicities, with the most oxygen-rich bulge ...

The mechanism behind the Long Secondary Period (LSP) observed in pulsating red giants still remains unknown. In this work, I investigate connection between Red Giant Branch and Asymptotic evolution appearance of LSP - phenomenon a large fraction giants. use OGLE-III sample OSARG variables Large Magellanic Cloud. construct density maps period-luminosity as well color-magnitude planes for stars s...

We investigate the tidal interactions of a red giant with a main sequence in the dense stellar core of globular clusters by Smoothed Particle Hydrodynamics method. Two models of 0.8M⊙ red giant with the surface radii 20 and 85R⊙ are used with 0.6 or 0.8M⊙ main sequence star treated as a point mass. We demonstrate that even for the wide encounters that two stars fly apart, the angular momentum o...

Stellar photometry of nearby irregular galaxies of the Local Group is used to identify and study the young and old stellar populations of these galaxies. An analysis of the spatial distributions of stars of different ages in face-on galaxies shows that the young stellar populations in irregular galaxies are concentrated toward the center, and form local inhomogeneities in star-forming regions, ...

The behaviour of the ∆ν=2 CO bands around 2.3 μm was examined by comparing observed and synthetic spectra in stars in globular clusters of different metallicity. Changes in the C/C isotopic ratio and the carbon abundances were investigated in stars from 3500–4900 K in the galactic globular clusters M71, M5, M3 and M13, covering the metallicity range from –0.7 to –1.6. We found relatively low ca...

Infrared J and K photometry has been obtained of all red giants in the half square degree region of the LMC bar searched for variables using the MACHO database by Wood et al. (1999). The K–logP diagram shows the five distinct period–luminosity sequences which are also evident in the MACHO photometry. The K–logP plot allows identification of the Mira sequence from among the five observed sequenc...

We analyse the kinematics of ∼ 400 000 stars for which the RAdial Velocity Experiment (RAVE) has obtained spectra. These stars, half giants and half dwarfs, mostly lie within 2.5 kpc of the Sun. We decompose the sample into hot and cold dwarfs, red-clump and non-clump giants. The kinematics of the clump giants are consistent with being identical with those of the giants as a whole. Without binn...

cluding red giants, asymptotic giant branch (AGB) stars, massive stars, and classical novae. In particular, the ratio between reaction rates of 17O(p,α)14N (Q = 1.2 MeV) and 17O(p,γ)18F (Q = 5.6 MeV) channels on 17O is one of the most important parameters for the galactic synthesis of 17O, the stellar production of radioactive 18F, and for predicted O isotopic ratios in presolar grains. The LUN...

Observational arguments supporting the binary explanation of the long secondary periods (LSP) phenomenon in red giants are presented. Photometry of about 1200 semiregular variables with the LSP in the Large Magellanic Cloud are analyzed using the MACHO and OGLE photometry. For about 5% of these objects additional ellipsoidal-like or eclipsing-like modulation with the same periods as the LSP is ...