An artist’s impression of huge star spots on the surface of Betelgeuse, areas of lower temperature that researchers say likely are responsible for the red giant’s recent dimming. Image: MPIA graphics department
The recent, unexpectedly pronounced dimming of the red giant Betelgeuse likely was caused by huge “star spots” and not by clouds of expelled gas, researchers conclude in The Astrophysical Journal Letters.
Betelgeuse, the red star marking one of Orion the Hunter’s shoulders, is about 20 times more massive than the Sun and on the order of 1,000 times larger. If placed in the center of our solar system, its outer layers would reach almost to the orbit of Jupiter.
Between October 2019 and April 2020, Betelgeuse unexpectedly dimmed by about 40 percent. Some observers speculated the star might be on the verge of blowing up in a supernova blast. Other suggested the dimming more likely was caused by the pulsing red giants undergo as they run out of nuclear fuel. Those pulsations blow off the star’s outer layers and as the gas cools, it transitions into compounds that form light-absorbing dust.
A team led by Thavisha Dharmawardena of the Max Planck Institute for Astronomy decided to test the ...