The discovery of hot Jupiters (Jupiter-like exoplanets in close orbits) has changed our view of planet formation. It is still debated whether hot Jupiters form in the present-day orbits or they form at large distances from their star and then they migrate inward. (e.g. Maldonado et al. 2018). Planetary migration can be induced by several effects, mainly interaction between
di Mario Giuseppe Guarcello ( segui mguarce) La polvere interstellare e circumstellare svolge un ruolo importante in diversi processi astrofisici. Ad esempio, nei dischi protoplanetari: strutture che caratterizzano le stelle nella fase di pre-sequenza principale, tipicamente nei primi 10 milioni di anni di evoluzione, che sono il luogo della formazione planetaria. Infatti, anche se la massa dei dischi
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
di Mario Giuseppe Guarcello ( segui mguarce) A recent study by a team of researchers of INAF-Astronomical Observatory of Palermo, the University of Palermo, and the University of Madrid, recently published on the Astrophysical Journal, shows that enormous flares in the young stars in Orion are due to large magnetic loops connecting the stars and their protoplanetary disks,
In the last years the number of known exoplanets has grown quickly thanks to missions such as Kepler and CoRoT and instruments such as HARPS-N, mounted on the Telescopio Nazionale Galileo, which are designed to identify exoplanets with the method of transits or radial velocity. We have understood now that the presence of exoplanets is a common features in stars
The study of the variability of stars and compact objects is a powerful diagnostic to unveil their physical properties. For instance, it is typical not feasible to observe directly the presence of magnetic active regions on stellar surface, pulsations, very faint companions, or close circumstellar material. These properties, however, can be studied by the variability of the observed photometry or
All the magnetic phenomena occurring in stars, such as flares and spots, are called “stellar activity”. Astronomers study stellar activity using different diagnostics such as X-ray emission from the coronae and spectroscopic indices like the R’HK measuring the chromospheric activity. This is an important research field in stellar astronomy, given that stellar activity is connected to the intensity and morphology
