Context. The vast majority of the known stars of ultra low metallicity ([Fe/H] < -4.5) are known to be enhanced in carbon, and belong to the "low-carbon band" (A(C) = log(C/H)+12 ≤ 7.6). It is generally, although not universally, accepted that this peculiar chemical composition reflects the chemical composition of the gas cloud out of which these

El objetivo principal de esta tesis es estudiar la evolución de las galaxias formadoras de estrellas durante los últimos 7 Gyrs. Las galaxias formadoras de estrellas de alto desplazamiento al rojo (z>1) difieren de sus contrapartidas locales en varios aspectos clave. Sus regiones formadoras de estrellas son de un orden de magnitud más grandes y

El objetivo principal de esta tesis es estudiar la evolución de las galaxias formadoras de estrellas durante los últimos 7 Gyrs. Las galaxias formadoras de estrellas de alto desplazamiento al rojo (z>1) difieren de sus contrapartidas locales en varios aspectos clave. Sus regiones formadoras de estrellas son de un orden de magnitud más grandes y

The Λ cold dark matter (ΛCDM) paradigm of galaxy formation predicts that dense spheroidal stellar structures invariably grow at early cosmic time. These primordial spheroids evolve toward a virialized dynamical status as they finally become today's elliptical galaxies and large bulges at the center of disk galaxies. However, observations reveal

We report the discovery of two new pulsating extremely low-mass pre-white dwarf (pre-ELMV) candidates in the Transiting Exoplanet Survey Satellite (TESS) eclipsing binaries, TIC 149160359 and TIC 416264037. Their light curves show a typical feature of EL CVn-type binaries. The light-curve modeling indicates that they are both detached systems with