Polaris may be losing mass each year

Science : A new analysis of observations made over the last 160 years suggests that Polaris, also called the North Star, is losing nearly the equivalent of Earth’s mass, or just under one millionth of its own mass, every year. Hilding Neilson of the University of Bonn in Germany and colleagues studied the variation in Polaris’s pulse—the approximately four-day cycle over which the star grows dimmer and brighter—and found that it’s slowing by about 4.5 seconds every year. In 1844, however, it was about 12 minutes slower than it is now. If Polaris is an older star that’s burning helium nuclei in its core, then its pulse is decreasing at a faster rate than it should, according to the standard model of stellar evolution. Loss of mass is the only thing that can account for the discrepancy, according to Neilson.