For the first time we show the detailed, late-stage, chemical evolution history of a small nearby dwarf spheroidal galaxy in the Local Group. We present the results of a high-resolution (R ~ 20 000, λ = 5340-5620; 6120-6701) FLAMES/GIRAFFE abundance study at ESO/VLT of 81 photometrically selected, red giant branch stars in the central 25' of the

SDSS (II/294), 2MASS (II/246) and UKIDSS (II/304) photometry of 806 ultra-cool dwarfs. Proper motions are found by dividing the difference between the 2MASS and UKIDSS coordinates by the observational epoch difference. Spectral types are based on their SDSS spectra and the relationship between spectral type and SDSS and 2MASS colors. (1 data file).

En esta tesis estudiamos la propagación de ondas magneto-acústicas en manchas solares, desde debajo de la fotosfera hasta la cromosfera. La motivación de este estudio va más allá de la simple derivación de las propiedades de las oscilaciones, ya que las ondas pueden ser usadas como herramienta de diagnóstico independiente para derivar la estructura

Extreme ultraviolet (EUV) and X-ray emission is of great importance in several phenomena related to the formation of planetary systems and the atmospheres of planets. The atmospheric composition and the mass of an exoplanet are partly dependent on the X-ray and EUV radiation received during the first stages of formation and even during main

We use N-body simulations to explore the possibility that the Sagittarius (Sgr) dwarf galaxy was originally a late-type, rotating disc galaxy, rather than a non-rotating, pressure-supported dwarf spheroidal galaxy, as previously thought. We find that bifurcations in the leading tail of the Sgr stream, similar to those detected by the SDSS survey

We present the latest analysis and results from SEPPCoN (Survey of Ensemble Physical Properties of Cometary Nuclei). This on-going survey involves studying 100 JFCs - about 25% of the known population - at both mid-infrared and visible wave-lengths to constrain the distributions of sizes, shapes, spins, and albedos of this population. Having