¶The possibility that Betelgeuse has a companion was first raised roughly a century ago as a potential explanation for some of its changes in brightness. Despite decades of observations, astronomers had been unable to clearly detect such a star.

¶That changed after Two studies published in 2024 made strong predictions about where the suspected companion should be. The studies indicated that Betelgeuse B would reach its greatest apparent separation from Betelgeuse in December 2024, giving astronomers their best opportunity to see it.

¶Montargès and his colleagues observed Betelgeuse with ESO’s VLT that December. They then spent several months carefully processing and analyzing the observations.

¶“Honestly, I thought we did not have the sensitivity to detect Betelgeuse B as it was predicted,” explains Montargès. “Because it is more massive than predicted, we see it!”

¶Scientists had initially estimated that the companion would have roughly the same mass as the Sun. The new observations instead suggest that Betelgeuse B is considerably larger, with about two to three times the Sun’s mass.

¶Do we finally have evidence that Betelgeuse‘s infamous pulsing brightness is due to a companion star? Not yet, but we’re close. The strongest evidence will come if and when the newly discovered star is observed on the opposite side of Betelgeuse, which sounds to be about a year away. These things take time.