Stars are variable sources over timescales which depend on the phenomena triggering this variability. These phenomena are typically produced by the interaction between the stellar magnetic field and its plasma. Typical examples, observed and studied in great details in the Sun, are: flares (sudden release of a large amount of energy by the magnetic field which heats the gas in
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The search for young exoplanets is crucial to our understanding of the planetary formation process and the early evolution of planets. The disc of gas and dust from which planets form, in fact, typically disperse in a few million of years. Before that, the young planets interact with all the material orbiting around the star within the disk, triggering important
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Some of the 4903 exoplanets discovered and confirmed so far (https://exoplanets.nasa.gov/) orbit very close to their stars. We learnt with the very first planet discovered around a star different than the Sun (51 Pegasi b, discovered in 1995) that planets with very close orbits are possible in nature. 51 Pegasi b, in fact, orbits at about 0.05 Astronomical Units (AU,
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LBV (Luminous Blue Variable) stars are massive and unstable stars characterized by large mass-lost due to intense stellar winds and aperiodic bursts. Due to their instability, LBV stars are also variable, with quasi-periodic oscillations of their luminosity of the order of 0.5-2 magnitudes. Typical examples of this class of stars are: the supergiant S Doradus in the Large Magellanic Clouds,
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M stars are the most common stars in the Universe. They have a mass ranging between 0.6 and 0.08 Solar masses in the main sequence, and an effective temperature ranging between 3900 K and 2400 K. In these stars, the signals due to the presence of planets, such as radial velocity (periodic oscillations of the star from its rest position
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Protoplanetary disks are disk-like structures that are found in low-mass stars younger than 10 million of years, typically called “pre-main sequence stars”. These disks are also the sites where planets formation occurs. In the last years, scientists have devoted a large effort to study the evolution and dispersion of protoplanetary disks. This has been possible also thanks to facilities such
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The study of planets orbiting around young stars (younger than 100 million years) can help astronomers understanding the physical processes setting the early evolution of planetary systems. However, young stars are typically characterized by rapid rotation and intense magnetic activity, phenomena which produce photometric and spectroscopic signals that can mimic and confuse those due to the presence of planets. It
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Supernova remnants are clouds in rapid expansion formed by supernova explosions. Typically, these remnants are very inhomogeneous. These inhomogeneity is the result of the interaction between the expanding remnant and the surrounding material, and, in particular when they are generated by core-collapse supernova explosions (which are the supernova triggered by the gravitational collapse of the cores of massive stars), also to anisotropies formed
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Supernova remnants are clouds in rapid expansion produced by supernova explosions. They are often characterized by a complex morphology, resulting from the interaction between the expanding remnants and surrounding clouds. Supernova remnants also emit radiation on a wide band of the electromagnetic spectrum. This is due to the variety of phenomena occurring in these objects, and because of the different
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Since astronomers captured the bright explosion of a star on February 24, 1987, researchers have been searching for the squashed stellar core that should have been left behind. A group of astronomers using data from NASA space missions and ground-based telescopes may have finally found it. [Continue reading at this link]
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