The recent availability of stellar parallaxes provided by the Hipparcos star catalogue (ESA 1997) enables an accurate determination of the positions of single field giants in a theoretical H-R diagram and a reliable estimate of their masses. The present study combines these new astrometric data with previously published X-ray fluxes and rotational velocities. The results confirm the existence o...

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The ISOGAL mid-infrared survey of areas close to the Galactic Plane aims to determine their stellar content and its possible bearing on the history of the Galaxy. The NGC 6522 and Sgr I Baade's Windows of low obscuration towards the inner parts of the Bulge represent ideal places in which to calibrate and understand the ISOGAL colour-magnitude diagrams, which are more diicult to interpret in he...

Results from high resolution spectroscopic analysis of HD 77361 are reported. The LTE analysis shows that HD 77361 is a K giant of atmospheric parameters: Teff = 4580 ± 75 K, log g = 2.5 ± 0.1, and ξt = 1.40 ± 0.5 km s . We found that the atmosphere of HD 77361 is highly enriched in Li with log ǫ (Li) = 3.82 ± 0.1. With this finding the total number of super Li-rich K giants (log ǫ(Li) ≥ 3.3 IS...

Three-dimensional stellar modeling has enabled us to identify a deep-mixing mechanism that must operate in all low mass giants. This mixing process is not optional, and is driven by a molecular weight inversion created by the He(He,2p)He reaction. In this paper we characterize the behavior of this mixing, and study its impact on the envelope abundances. It not only eliminates the problem of He ...

I demonstrate that the two unexpected results in the local universe-(1) anomalous intrinsic (V-I&parr0;0 colors of the clump giants and RR Lyrae stars in the Galactic center, and (2) very short distances to the Magellanic Clouds (LMC, SMC) as inferred from clump giants-are connected with each other. The (V-I&parr0;0 anomaly is partially resolved by using the photometry from phase II of the Opti...

We have computed a grid of high resolution synthetic spectra for cool stars (2500 < Teff < 6000 K) in the wavelength range λλ 6000 – 10200 Å, by employing an updated line list of atomic and molecular lines, together with state-of-the-art model atmospheres. As a by-product, by fitting TiO bandheads in spectra of well-known M giants, we have derived the electronic oscillator strengths of the TiO ...

We present computations of nucleosynthesis in red giants and asymptotic giant branch stars of Population I experiencing extended mixing. The assumed physical cause for mass transport is the buoyancy of magnetized structures, according to recent suggestions. The peculiar property of such a mechanism is to allow for both fast and slow mixing phenomena, as required for reproducing the spread in Li...

We present Keck 10-meter / LRIS spectra of candidate red giants in the halo of M31, located at a projected radius of R = 19 kpc on the minor axis. These spectroscopic targets have been selected using a combination of UBRI-based and morphological screening to eliminate background galaxies. Radial velocity measurements are used to separate M31 halo giants from foreground Milky Way dwarf stars, M3...