L’emissione ad alta energia da parte delle stelle può avere un impatto importante sulle atmosfere dei pianeti. Per comprendere questo effetto a fondo, è necessario tenere conto di come questa emissione varia nel tempo. Negli ultimi anni, le stelle di piccola massa di classe spettrale M hanno assunto una notevole importanza nella ricerca e caratterizzazione degli esopianeti. Questo perché
A star hosting six terrestrial-type planets and showing intense X-ray emission, with a cyclic behavior on a timescale of about two years, which may have a significant impact on the properties of the planets and their atmospheres. The magnetic activity of a star manifests itself through a variety of high-energy phenomena that produce X-ray and UV radiation. Studying this
Measured the amount of plasma between 10000 and 30 million degrees—responsible for the emission of extreme UV radiation and soft X-rays—in a sample of Sun-like and low-mass stars. Sun-like stars (spectral classes FGK) and low-mass stars (spectral class M) host in their outer atmospheres (the corona) plasma at temperatures of millions of degrees. Such high temperatures are reached through
Analysis of X-ray observations of the SN1987A supernova remnant, obtained by the XMM-Newton satellite, provides new insights into the interaction between the supernova shock wave and the circumstellar material, as well as the oxygen abundance in the remnant. The SN1987A supernova remnant is undoubtedly one of the most iconic objects for studying supernovae, their remnants, and the final stages
Despite the wide array of telescopes and satellites available to the astronomical community, there is a type of radiation to which we are virtually blind: the extreme UV band. This is high-energy radiation with a wavelength that ranges from the Lyman-α emission, caused by hydrogen atoms whose electron transitions from the innermost orbital (the ground state) to the second (n=2),
Supernova remnants, which are nebulae produced by explosion of supernovae and undergoing rapid expansion, typically serve as intense sources of high-energy radiation, particularly in the form of X-ray emissions. This radiation can be of two different types: thermal and non-thermal. Thermal radiation is emitted by dense material and is contingent upon the temperature of the emitting gas. To emit X-rays,
The corona is the outermost part of the atmosphere of the vast majority of stars, where the plasma is heated to millions of degrees by stellar magnetic activity. Since both the intensity and the topology of the stellar magnetic fields depend on the internal structure of stars, the study of coronal activity allows astronomers to better understand both the high-energy
Flares are transient and energetic phenomena that occur in most stars and can be observed with high spatial and temporal resolution in the Sun. These phenomena are triggered by a sudden release of energy previously stored in the star’s magnetic field, which, after a sequence of events, leads to extreme heating of the stellar plasma. The heated plasma then rapidly
Cosmic rays are high-energy charged particles which continuously hit our planet. These particles are accelerated up to such high velocities in different astronomical environments, among which supernova remnants seems to be particularly important. These objects are nebulae in rapid expansion generated by the explosions of very massive stars. In supernova remnants, particle acceleration seems to occurr along the expanding shock
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.
