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
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),
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
All the magnetic phenomena occurring in stars, such as flares and spots, are called “stellar activity”. Astronomers study stellar activity using different diagnostics such as X-ray emission from the coronae and spectroscopic indices like the R’HK measuring the chromospheric activity. This is an important research field in stellar astronomy, given that stellar activity is connected to the intensity and morphology
