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It has been suggested that stars formed from the same molecular cloud should share the same primordial chemical abundances. This has led several authors to consider the possibility that stars formed in a star forming region now disappeared could be identified by studying their chemical composition (chemical tagging theory, Freeman & Bland-Hawthorn 2002). However, the evolution of chemical abundances of

Stellar clusters are important targets for the study of stellar evolution, since their members constitute a sample of stars, sometime even richer than few thousands, with similar age but covering a wide range of masses. The most widely used method to determine clusters age consists in comparing magnitudes and colors of their stars with those predicted by stellar evolutionary models.

The discovery of hot Jupiters (e.g. Jupiter-like exoplanets with orbital period shorter than 10 days) was completely unexpected since no such planets are present in the Solar System. This has forced us to change our view of how giant planets can form.   Two hypotheses are used to explain how hot Jupiters form. The most accredited theory is that hot

The Solar System is particularly ordered, with the small rocky planets lying close to the Sun and the giant gaseous planets (with a radius larger than 3.9 R⊕) orbiting at larger distances. The study of exoplanets, however, has thought to us that the architecture of exoplanetary systems can be very different than that of our Solar System.   Considering planets between

di Mario Giuseppe Guarcello    ( segui mguarce)     Un’esplosione di supernova lascia due residui che possono essere osservati ed analizzati: mentre il nucleo della stella progenitrice si contrae fino a formare un oggetto compatto, la sua atmosfera viene proiettata nello spazio circostante formando un resto di supernova in rapida espansione. Quando interagiscono con con il mezzo circostante, i resti