Umbral flashes are sudden brightenings commonly visible in the core of some chromospheric lines. Theoretical and numerical modeling suggests that they are...

During the final stages of their lives, stars with masses between one and eight times the mass of the Sun evolve along the asymptotic giant branch (AGB). AGB...

The black holes at the centres of galaxies are the most mysterious objects in the Universe, not only because of the huge quantities of material within them...