Very low-mass M-dwarfs are a missing link in our theory of stellar interiors. Stars this small probably have fully convective interiors, but we don’t have a complete understanding of how that affects global properties like radius or temperature. It’s important to get right, if for no other reason because lots of exoplanets orbit M-dwarfs.
Cepheids’ pulsing brightness variations happen because the star’s temperature and radius is changing, and they occupy a unique niche of stellar evolution. We can learn a lot about what is physically happening inside stars during this tumultuous time through close observations. Or rather, we could learn a lot about what happens inside Cepheid variable stars, if only we knew their masses.
You can’t model RW Aurigae as a single star with a disk of material around it, because there is a second star. And you can’t model it as a regular old binary system either, because there are interactions between the stars and the asymmetric disk. The authors of today’s paper create a comprehensive hydrodynamic model that considers many different observations of RW Aurigae.
While the Sun is an excellent starting point in a quest to understand magnetism, the authors of today’s paper want more. They take advantage of something only relatively cool stars can have in their atmospheres to study magnetic fields: molecules in starspots.
In today’s paper, Čechura and Hadrava examine what happens to the runaway gas from the surface of massive stars—the stellar wind. In particular, they look at systems with massive stars so close to a companion neutron star or black hole that the stellar wind is jarred into a new orbit and heated to the point of emitting X-rays.