Betelgeuse, Betelgeuse! The red supergiant star that marks Orion’s left shoulder may have a small, invisible companion star.
Two independent studies have found evidence that a star with approximately the same mass as the Sun orbits Betelgeuse about every 2,100 days.
“This was a huge surprise,” said Morgan MacLeod, an astrophysicist at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts. If the star is real, “it’s like it’s hidden in plain sight.”
MacLeod and his friends Linking Betelgeuse’s 6-year cycle of brightening and dimmingIn a paper submitted to arXiv.org on September 17th, the researchers looked at the distance to the companion star that is tweaking its orbit. MacLeod looked at global historical measurements dating back to 1896.
Separately, Jared Goldberg of the Flatiron Institute in New York et al. Measurement results over the past 20 years The most accurate representation of Betelgeuse’s movements in the sky. The team also found evidence of peers pecking at bigger stars, submitted to arXiv.org on August 17th.
Previous observers noticed that Betelgeuse’s light changes on an approximately six-year cycle. In 1908, British astronomer Henry Coger Plummer suggested that this period could be due to the gravitational pull of a companion star pulling Betelgeuse back and forth.
In subsequent centuries, astronomers realized that there was even more going on at Betelgeuse. (SN: 8/15/22). That outside air boils like water in a pot. It pulsates on a 400-day cycle, with associated subcycles occurring every 200 days. And sometimes, material is sent into space in a huge explosion. (SN: 21/6/16). All these complications made the idea of ​​a companion star obsolete. There are many other explanations for Betelgeuse’s strange behavior.
However, interest in Betelgeuse has increased again since the Great Fainting in 2019, prompting astronomers to reconsider.
MacLeod’s team reasoned that if the six-year cycle was caused by companions, it should repeat steadily over centuries. Using 128 years of observations, the research team showed that the brightness cycle is as follows: authentic and trustworthy.
Combining those results with other measurements, they found that the companion star is about 0.6 times the mass of the Sun and orbits a distance just over twice the radius of Betelgeuse every 2,110 days. Goldberg’s data suggest that the star orbits every 2,170 days and has about 1.2 times the mass of the Sun.
“These are very exciting studies. We all want to find Betelgeuse’s companion star,” says Miguel Montalger of the Paris Observatory. “This could have implications for our understanding of red supergiants. But it would be very difficult, if not impossible, to test.”
Even if it were real, Betelgeuse’s companion is ultimately doomed. The star’s orbit is shrinking as Betelgeuse takes away angular momentum. In about 10,000 years, Betelgeuse will be completely consumed.
