Simulations have shown that a diverse range of extrasolar terrestrial planet bulk compositions are likely to exist based on the observed variations in host star elemental abundances. Based on recent studies, it is expected that a significant proportion of host stars may have Mg/Si ratios below 1. Here we examine this previously neglected group of systems. Planets simulated as forming within these systems are found to be Mg-depleted (compared to Earth), consisting of silicate species such as pyroxene and various feldspars. Planetary carbon abundances also vary in accordance with the host star

The best spectrographs are limited in stability by their calibration light source. Laser frequency combs are the ideal calibrators for astronomical spectrographs. They emit a spectrum of lines that are equally spaced in frequency and that are as accurate and stable as the atomic clock relative to which the comb is stabilized. Absolute calibration provides the radial velocity of an astronomical object relative to the observer (on Earth). For the detection of Earth-mass exoplanets in Earth-like orbits around solar-type stars, or of cosmic acceleration, the observable is a tiny velocity change

Context. We study the time history of the yellow hypergiant HR 8752 based on high-resolution spectra (1973-2005), the observed MK spectral classification data, B - V- and V-observations (1918-1996) and yet earlier V-observations (1840-1918). Aims: Our local thermal equilibrium analysis of the spectra yields accurate values of the effective temperature (T eff), the acceleration of gravity (g), and the turbulent velocity (v t) for 26 spectra. The standard deviations average are 82 K for T eff, 0.23 for log g, and 1.1 km s -1 for v t. Methods: A comparison of B - V observations, MK spectral

OCAM 2 cuadriplica la resolución y multiplica por tres la velocidad de instrumentos similares. Con este dispositivo, que se unirá al sistema óptico adaptativo del GTC, el mayor telescopio del mundo podrá vencer las turbulencias de la atmósfera terrestre y obtener imágenes con una nitidez similar a la del telescopio espacial Hubble.

El acto se llevará a cabo hoy martes, 13 de diciembre, a las 18:00 horas en la Sala de Grados de la Facultad de Ciencias Físicas de la Universidad Complutense de Madrid (UCM)

Los responsables de los ocho centros y unidades de investigación españoles distinguidos con la acreditación de excelencia Severo Ochoa recogieron ayer, 28 de noviembre, sus acreditaciones en la sede del Ministerio de Ciencia e Innovación