A couple months back, astronomers officially confirmed the existence of “Betelbuddy,” Betelgeuse’s long-suspected companion star. Since then, researchers have been toiling away at characterizing Betelbuddy—finding that with each observation, the star drifts further away from initial expectations.
A recent study published in The Astrophysical Journal presents a thorough analysis of Betelbuddy using data gathered by NASA’s Chandra X-ray Observatory and the Hubble Space Telescope. In the “deepest X-ray observations of Betelgeuse to date,” researchers found that Betelbuddy is most likely a young stellar object (YSO) about the size of our Sun.
This affirms a separate, earlier study that predicted Betelbuddy’s striking youth compared to Betelgeuse, a red supergiant nearing the end of its stellar lifespan. At the same time, the findings usurp several assumptions astronomers have made about the nature of Betelbuddy’s stellar composition.
Hold on, Betelbuddy!
The project was a “race against time,” the researchers describe in a statement, as it managed to catch Betelbuddy in the nick of time before it disappeared behind its companion for the next two years.
The Gemini North Telescope in Hawaii captured a faint image of Betelbuddy, which in itself was a miraculous feat, as the “brightness difference between Betelgeuse and this little companion is absolutely insane,” explained Anna O’Grady, study lead author and a postdoctoral researcher at Carnegie Mellon University, in the statement.
To put this into perspective, Betelgeuse is about 700 times the size of our Sun and thousands of times brighter. So, the team considered other methods for probing the tiny star: X-ray imaging and UV spectroscopy. That Chandra and Hubble accepted their proposals to view the same event testifies to the astrophysical community’s excitement about Betelbuddy, the researcher said.
“It turns out that there had never been a good observation where Betelbuddy wasn’t behind Betelgeuse,” O’Grady said. “The fact that we can now confirm something is there shows how far our science has come.”
An odd stellar pair
Once the data supported Betelbuddy’s existence, astronomers began to consider what kind of star it could have been. The most “standard” explanation would be that, given its small size and Betelgeuse’s age, Betelbuddy was a compact neutron star or white dwarf.
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