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We introduce a new parameter Δξ-the difference in magnitude between the red giant branch (RGB) bump and the point on the main sequence (MS) at the same color as the bump (which we call the "benchmark")-to estimate the helium content in old stellar systems. The Δξ parameter is a helium indicator, since an increase in helium makes, at fixed age and

Stellar clusters with the same general physical properties (e.g., total mass, age, and star-formation mode) may have very different stellar mass spectra due to the incomplete sampling of the underlying mass function; such differences are especially relevant in the high-mass tail of the mass function due to the smaller absolute number of massive

The study of stellar parameters of planet-hosting stars, such as metallicity and chemical abundances, help us to understand the theory of planet formation and stellar evolution. In this poster, we present a catalog of accurate stellar atmospheric parameters and iron abundances for a sample of 257 K and G field evolved stars that are being surveyed

We investigated the absolute age of the Galactic globular cluster M71 (NGC 6838) using optical ground-based images (u\prime ,g\prime ,r\prime ,i\prime ,z\prime ) collected with the MegaCam camera at the Canada–France–Hawaii Telescope (CFHT). We performed a robust selection of field and cluster stars by applying a new method based on the 3D (r\prime

A continuum intensity-magnetic field distributions are presented for a decaying sunspot. It is shown that a very simple model accounts for the observed correlation. The Wilson depression is determined.