Rotation velocities measured for 330 B-type stars in eight stellar clusters of the Carina complex, thanks to the Gaia-ESO Survey. Stars rotate on their axes. Some, such as young stars, spin very rapidly, with rotation periods as short as one or two days. In other cases, like red giant stars, rotation is much slower, with periods lasting several months.
The study of the X-ray emission from stars provides an unmatched view of those energetic phenomena occurring in stars. In massive stars (O and early B stars), soft X-ray photons (less energetic than about 1 keV) are emitted from shocks in stellar winds. More energetic photons (the hard X-ray emission) is due to colliding stellar winds in binary systems or
di Mario Giuseppe Guarcello ( segui mguarce) Le stelle possono essere enormi magneti. In particolare, stelle come il Sole riescono a produrre un intenso campo magnetico nella regione di separazione tra la regione radiativa, piu’ in profondita’, e quella convettiva, piu’ superficiale, chiamata “tachocline”. Il campo magnetico prodotto da una stella e’ necessario per la formazione della corona,
