Flares are among the most energetic magnetic phenomena occuring in stars. They are triggered by a sudden release of energy previously stored in the stellar magnetic field, and then they culminate with the formation of magnetic loops in the stellar coronae filled by X-ray and UV emitting plasma at million degrees. Sometimes, these magnetic structures erupt, releasing in the surrounding
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Supernova remnants (expanding clouds produced by the explosion of massive stars) are fascinating objects. Their study, in fact, can unveil the physical processes working during supernova explosions and even the properties of the stellar progenitors. To these aims, of particular importance is the analysis of the physical and chemical properties of the ejecta (which are the fragments of the dying
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Almost all stars in the Universe produce their own magnetic field with a process called stellar dynamo, whose basic ingredients are stellar rotation and convection. In general, magnetic fields are produced and are affected by charged particles, which is what stellar plasma is made of. In stars the magnetic field and plasma thus interact, producing a class of transient phenomena
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X-ray astronomy explores the high-energy Universe. X-rays are, in fact, high energy photons emitted by very hot gas (with temperature of some milion degrees) or by processes involving relativistic particles. Some astronomical sources of X-rays radiation are: accreting black holes, such as the supermassive black holes at the center of active galaxies, stellar coronae, supernova remnants, and clusters of galaxies.
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Our planet is constantly bombarded by energetic particles (mainly protons) called “cosmic rays“. The study of cosmic rays is a leading science topic given its importance in several fields, such as the study of the effects on instrumentation and astronauts in space, where the natural protection against these particles provided by the magnetic field of Earth is low or null.
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After their formation, during the first few million of years (how many? it depends on the mass: the larger the stellar mass the faster is their evolution) stars continue to contract under their the action of their own gravity, rising their temperature and density. During this phase, their nuclei have not started yet the thermonuclear reactions that will power the
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SN1987A, the supernova exploded in the Large Magellanic Cloud (at about 170000 light years of distance) on February 23rd 1987, was an iconic event for the study of supernovae and supernova remnants. In fact, it is the only case where it was possible to observe (with telescopes) the explosion and to follow with periodic observations the evolution of the supernova
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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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