Red clump giants in the Galactic bulge occupy a distinct region in the colour magnitude diagram. They have a very small spread in intrinsic luminosities and their number counts have a well defined peak. We show that these characteristics can be used to constrain the differences in the streaming motions of stars on the near side and those on the far side. We propose two methods to select two sam...

The Hipparcos Intermediate Astrometric Data for carbon stars have been reprocessed using an algorithm which provides an objective criterion for rejecting anomalous data points and constrains the parallax to be positive. New parallax solutions have been derived for 317 cool carbon stars, mostly of types R and N. In this paper we discuss the results for the R stars. The most important result is t...

The asteroseismology of red giant stars has continued to yield surprises since the onset of high-precision photometry from space-based observations. An exciting new theoretical result shows that the previously observed suppression of dipole oscillation modes in red giants can be used to detect strong magnetic fields in the stellar cores. A fundamental facet of the theory is that nearly all the ...

Context. Observations during the first long run (∼150 days) in the exo-planet field of CoRoT increase the number of G-K giant stars for which solar-like oscillations are observed by a factor of 100. This opens the possibility to study the characteristics of their oscillations in a statistical sense. Aims. We aim to understand the statistical distribution of the frequencies of maximum oscillatio...

We present a homogeneous photometric and spectroscopic analysis of 18 stars along the evolutionary sequence of the metal-poor globular cluster NGC 6397 ([Fe/H]≈−2), from the main-sequence turnoff point to red giants below the bump. The spectroscopic stellar parameters, in particular stellarparameter differences between groups of stars, are in good agreement with broad-band and Strömgren photome...

The onset of variability in red giant stars is studied from the data collected by the ‘Long-Term Photometry of Variables’ project which operates at ESO (La Silla) since 1982. The differential nature of the observations combined with a multinight reduction algorithm enables to study the variability of over 50 red giants with an accuracy of the order of 2 to 3 millimagnitudes on time scales rangi...

We investigate the evolution of metal deficient stars, presentingH-burning isochrones covering cluster ages from800 Myr to 7 Gyr. Evolutionary evidences for selection effects in the metallicity distribution of very metal poor H-burning red giants are reported. The evolution of stars during central and shell He burning is further investigated, discussing the occurrence of He burning pulsators as...

We show that collisions with stellar–mass black holes can partially explain the absence of bright giant stars in the Galactic Centre, first noted by Genzel et al. (1996). We show that the missing objects are low–mass giants and AGB stars in the range 1 − 3M⊙. Using detailed stellar evolution calculations, we find that to prevent these objects from evolving to become visible in the depleted K ba...

Context. The CoRoT 5-month long observation runs provide us with the opportunity to analyze a large variety of red-giant stars and derive their fundamental parameters from their asteroseismic properties. Aims. We perform an analysis of more than 4600 CoRoT light curves to extract as much information as possible. We take into account the characteristics of both the star sample and the method to ...

We present the results of a narrow-band infrared imaging survey of a narrow strip (12 ′ wide) around the galactic equator between 6 • and 21 • of galactic longitude aimed at detecting field stars with strong CO absorption, mainly late-type giants and supergiants. Our observations include follow-up low resolution spectroscopy (R = 980) of 191 selected candidates in the H and K bands. Most of the...