In 1995, after many years of intense observational efforts, brown dwarfs were finally discovered in a star cluster and also orbiting a star. The work that led to the discovery and characterization of the brown dwarf Teide 1 is described here. This very red object was detected in optical images of the central region of the Pleiades cluster obtained

Various aspects of the magnetism of the quiet sun are reviewed. The suggestion that a small scale dynamo acting at granular scales generates what we call the quiet sun fields is studied in some detail. Although dynamo action has been proved numerically, it is argued that current simulations are still far from achieving the complexity that might be

We present a detailed and uniform study of oxygen abundances in a large sample of solar-type stars. EW measurements were carried out for the [OI] 6300 Å and the OI 6158 Å lines and LTE abundance results for these indicators were obtained in 611 and 535 stars respectively. 411 stars have oxygen derived from both indicators, which allows us to

The reduction of integral field spectroscopy (IFS) data requires several stages and many repetitive operations to convert raw data into, typically, a large number of spectra. Instead there are several semiautomatic data reduction tools and here we present this data reduction process using some of the Image Reduction and Analysis Facility (IRAF)

In order to build more realistic single stellar population (SSP) models with variable α-enhancement, we have recently determined [Mg/Fe] in a uniform scale with a precision of about 0.1 dex for 752 stars in the MILES empirical library. The [α/Fe] abundance ratio is commonly used as a good temporal scale indicator of star formation, taking Mg as a

We report our investigation of the first transiting planet candidate from the YETI project in the young (˜4 Myr old) open cluster Trumpler 37. The transit-like signal detected in the lightcurve of F8V star 2M21385603+5711345 repeats every 1.364894±0.000015 days, and has a depth of 54.5±0.8 mmag in R. Membership in the cluster is supported by its