A Red Dwarf is Taking its Time Eating a Brown Dwarf– www.universetoday.com

Most of what happens to any individual star during its lifetime is determined by its mass. Massive stars die young in supernova explosions, small red dwarfs linger for trillions of years, and mid-size stars like our Sun enjoy about ten billion years of fusion. But interactions between stars aren’t uncommon, and they shape stellar destinies, too.

Stars are born in clusters that slowly drift apart. But many stars stay bound to one another in binary systems. Astronomers observed one such binary star where the more massive of the pair, a small red dwarf (M dwarf) is very slowly consuming its companion. In this case, the companion is a brown dwarf. Putting aside the argument over whether a brown dwarf is truly a star or not, the pair, which is only about 300 light years away, is giving astronomers an opportunity to study stellar cannibalism.

New research in Nature Astronomy presents their observations and analysis. It’s titled “Stable mass transfer from a substellar object onto an M dwarf,” and the first author is Aaron Householder, a graduate student in MIT’s Department of Earth, Atmospheric and Planetary Sciences. Householder works with Kevin Burdge, assistant professor of physics at MIT.

Massive stars consuming less massive objects like planets is not rare. There are many examples of stars engulfing exoplanets. In those cases, the planet doesn’t last long before being drawn into the star and being destroyed. The only evidence of the engulfment is often an unusual concentration of metals in the star’s upper layer.