Pre-Main Sequence stars are young stars whose nuclei are still not hot enough to trigger the thermonuclear reactions that will produce energy for the rest of their existence. Some of these stars are called “T Tauri”, and they are surrounded by a protoplanetary disk made of gas and dust, where planetary systems may form. T Tauri stars were classified for
Solar corona is the outer atmosphere of our star. Extended for several solar radii, it is made of million degrees plasma, thus being hotter than the gas in the photosphere (about 5600 degrees). Several scientist have tried understanding the mechanism responsible for the heating of coronal plasma, but it is has been an open issue for decades. The most promising
The architecture of planetary systems is result from both the planet formation process and a complex mechanism of radial migration of planets. This has occurred also in the Solar System, whose final architecture resulted from the migration of the gaseous giants. In particular, the theories describing the formation and migration of super-Earths and Neptunian planets predict different configurations of the
Several astronomical studies rely on the precise determination of the chemical abundances of stars. For instance, the determination of chemical abundances of stars in different sites of the Milky Way, or with different age or evolutionary phase, can provide precious information on the evolution of our Galaxy. However, recently it has been discovered that spectroscopic determination of stellar chemical abundances
The number of known exoplanets discovered so far (4197 planets, updated at 2020/August/4th, from NASA) is large enough to allow us to study their global properties. One of these properties, still lacking a proper explanation, is the so-called “Neptunian desert”, e.g. the lack of intermediate planets with orbital periods shorter than 3 days. One of the hypotheses that can explain the Neptunian
To understand how planets form, it is mandatory to study the evolution of protoplanetary disks, e.g. disks of gas and dust grains orbiting around stars during the first 3-5 million years of their evolution, a that may evolve into planetary systems. In the last years, several observations have been done in order to detect the molecules, mainly organic, in these
Terrestrial planets are common in the Milky Way. It has been estimated, in fact, that at least 30% of stars in the Solar neighborhood host a terrestrial planet, and this fraction increases to 40% considering the habitable zone around all M stars (e.g. stars with effective temperature between 2400 and 3700 degrees) of the Galaxy. The habitable zone is defined
The Solar System is populated by a variety of objects: gaseous giants, rocky planets, dwarf planets, moons, asteroids, comets, and dust. To date, more than 4000 planets orbiting around other stars were identified, and the presence of planets seems to be ubiquitous in stars of our Galaxy. Are the other class of objects that we observe in the Solar System
Supernova remnants are nebulae created by supernova explosions. These expanding clouds are formed by the interstellar medium shocked and heated up by the expanding shock produced by the explosion, and the knots of material launched by the exploding star, called ejecta. These ejecta are located behind the expanding shock, traveling with lower velocity, and they are heated up by the reverse shock:
