We show evidence that the red giant star ξ Hya has an oscillation mode lifetime , τ, of about 2 days significantly shorter than predicted by theory (τ = 17 days, Houdek & Gough 2002). If this is a general trend of red giants it would limit the prospects of asteroseismology on these stars because of poor coherence of the oscillations.

We present 8–13 μm spectra of eight red giants in the globular cluster 47Tucanae (NGC104), obtained at the European Southern Observatory 3.6m telescope. These are the first mid-infrared spectra of metal-poor, low-mass stars. The spectrum of at least one of these, namely the extremely red, large-amplitude variable V1, shows direct evidence of circumstellar grains made of amorphous silicate.

We report the first abundance analysis of 14 M giant stars in the Galactic bulge, based on R = 25, 000 infrared spectroscopy (1.5−1.8 μm) using NIRSPEC at the Keck telescope. Because some of the bulge M giants reach high luminosities and have very late spectral type, it has been suggested that they are the progeny of only the most metal rich bulge stars, or possibly members of a younger bulge p...

The origin of gas falling from the halo toward the disk of the Milky Way is still largely unclear. Here the amount of gas shed by the (older) halo red giants is estimated. The distribution of red giants (RGs) in the halo is not known but that of a subset of stars in the post RG phase, the sdB stars of the horizontal-branch (HB), is. Using the mid-plane density and z-distribution of sdB stars, t...

We present first results from a spectroscopic survey designed to examine the metallicity and kinematics of individual red giant branch stars in the outer halo of the Andromeda spiral galaxy (M31). This study is based on multislit spectroscopy with the Keck II 10-m telescope and Low Resolution Imaging Spectrograph of the Ca ii near-infrared triplet in 99 M31 halo candidates in a field at R = 19 ...

HST high resolution spectra of metal-deficient field giants more than double the stars in previous studies, span ∼ 3 magnitudes on the red giant branch, and sample an abundance range [Fe/H]=−1 to −3. These stars, in spite of their age and low metallicity, possess chromospheric fluxes of Mg II (λ2800) that are within a factor of 4 of Population I stars, and give signs of a dependence on the meta...

We present period–luminosity relations for more than 23 000 red giants in the Large Magellanic Cloud observed by the OGLE-II microlensing project. The OGLE period values were combined with the 2MASS single-epoch JHKS photometric data. For the brighter stars we find agreement with previous results (four different sequences corresponding to different modes of pulsation in asymptotic giant branch ...

The properties of 322 intermediate-mass late-G giants (comprising 10 planet-host stars) selected as the targets of Okayama Planet Search Program, many of which are red-clump giants, were comprehensively investigated by establishing their various stellar parameters (atmospheric parameters including turbulent velocity fields, metallicity, luminosity, mass, age, projected rotational velocity, etc....