We present an implementation of stellar evolution and chemical feedback for smoothed particle hydrodynamics simulations. We consider the timed release of individual elements by both massive (Type II supernovae and stellar winds) and intermediate-mass stars (Type Ia supernovae and asymptotic giant branch stars). We illustrate the results of our

We have computed the Galactic Habitable Zones (GHZs) of the Andromeda galaxy (M31) based on the probability of terrestrial planet formation, which depends on the metallicity (Z) of the interstellar medium, and the number of stars formed per unit surface area. The GHZ was obtained from a chemical evolution model built to reproduce a metallicity

Chariklo is known to possess an exotic ring system and we show indications from several distinct data sets that Chiron also has a ring system with similar features to that of Chariklo, although its case is somewhat more complex because Chariklo has never shown cometary-like activity, whereas Chiron has.

As a result of a major program of spectral observations using the CAT 1.4 m telescope and Coude Echelle Spectrograph at ESO, La Silla, 68 high resolution profiles of the 3968.5 A Ca H resonance line have been obtained for 16 late type stars (dwarfs and subgiants, including the sun) ranging from F9 to K5, selected to be representative of a wide span

High resolution, high signal to noise spectral profiles of the 8498 and 8542 A lines of the Ca II infrared triplet (IRT) have been obtained for a sample of late type dwarfs, with a wide range of levels of chromospheric activity, in the spectral range F9 to K4/5. These profiles, and the difference profiles for selected active and quiescent objects

This article shows how some recent developments in the observation and theoretical modeling of weak polarization signals in chromospheric spectral lines are facilitating fundamental new advances in our ability to investigate the magnetism of the solar outer atmosphere via spectropolarimetry.