The solar corona is a structure that extends for several solar radii and is filled with low-density plasma at temperatures of millions of degrees. What heats coronal plasma to such extreme temperatures? It appears to be a combination of complex magnetic phenomena. X-ray and UV observations of the Sun reveal an atmosphere rich in bright structures that host million-degree
A new star may soon light up our sky, becoming visible even at naked eye. It is T Coronae Borealis, a recurrent nova located just under 3000 light-years away from us. In fact, it is the closest known object of this class to Earth. A nova is a system characterized by periodic explosions accompanied by sudden increases in brightness. These
Theoretical analysis of the properties of the cloud of stellar fragments (i.e., the ejecta) populating the innermost region of the supernova remnant SN 1987A reveals a highly asymmetric explosion, dominated by two bipolar jets. The complex physics governing the core collapse of a massive star and the subsequent supernova explosion can be uncovered through detailed analysis of the physical
Hot Jupiters represent an interesting class of exoplanets that does not exist in the Solar System. These are giant gaseous planets that orbit at such close distances from their stars that their orbital periods are shorter than 10 days. Due to their proximity to their stars, these planets have very hot atmospheres, with temperatures exceeding 1500 K. For this reason,
The corona is the outermost part of the Solar atmosphere, filled with plasma at temperatures reaching several million degrees. The mechanism responsible for heating the Solar plasma to these temperatures is a long-standing problem. It began in the 1930s when physicists Bengt Edlen and Walter Grotrian proposed that the mysterious spectroscopic lines observed in the corona were not due to
Energetic particles, called “cosmic rays”, constantly rain down on our planet. Thanks to several years of theoretical studies and observations, we know that these particles can be accelerated by shocks propagating in certain astrophysical environments. The classical example of such environment are the supernovae remnants, which are expanding clouds created by supernova explosions, which are often interacting with surrounding material.
Supernova explosions are sorted into two categories: The thermonuclear explosions triggered by white dwarfs in close binary systems (type Ia) and those triggered by the gravitational collapse of the core of massive stars (type Ib/c and II). Because of the paucity of known supernova remnants younger than 1000 years, astronomers developed several models describing the evolution of supernova remnants to
Supernova explosions, occurring and the end of the life of massive stars, are ruled by a complex physics, and they can not be described by a simple spherically symmetric geometry. The rarity of these events make even more difficult to understand the physical processes involved during the explosions. For instance, on average only one supernova explodes in our Galaxy every
T Tauri stars are young low-mass stars (typically younger than 5 million of years), which are surrounded by a protoplanetary disk, e.g. a disk of gas and dust orbiting around the star. The disk material does not reach the central star: the dust component sublimates in the inner disk, where the temperature exceeds 1500 degrees, while the gas disk is truncated
Stars more massive than 9 solar masses end their evolution in spectacular supernova explosions. These explosions are triggered by the gravitational collapse of the core of such massive stars, once the thermonuclear reactions are exhausted and the core is not supported against gravity by the pressure produced by the reactions. Supernovae are not simple spherical explosions, but rather complex phenomena
