ALMA Returns to the Boomerang Nebula
The Boomerang Nebula is the coldest location in the known universe at roughly 2 degrees colder than empty space! This nebula is the result of the death of a red giant star, and the extreme temperature is caused by the rapid expansion of the nebula. According to thermodynamics, if you expand a gas you cool a gas (just try using one of those compressed air cans for cleaning electronics). However, according to astronomers, a single star's death could not account for a strong enough wind to create this expansion. Based on this hypothesis, and data from the ALMA observatory, astronomers now believe the expansion of the Boomerang Nebula is being driven by a companion star.