Astronomers Finally Image Betelgeuse’s Elusive Companion After a Century

Astronomers using the Very Large Telescope in Chile have captured the clearest image ever of Betelgeuse B, a massive companion star orbiting the famous red supergiant Betelgeuse, according to an announcement by the observation team led by astronomer Miguel Montargès. The detection, based on data and images gathered in December 2024 using the SPHERE instrument, resolves a century-long quest to spot the elusive companion hidden beneath the supergiant’s immense brightness and dynamic stellar atmosphere.

Direct Imaging of Betelgeuse B With the Very Large Telescope

The companion star, nicknamed Siwarha, was photographed when it was predicted to be at its furthest point from Betelgeuse as viewed from Earth. According to Miguel Montargès, the observation team expected the target to be much dimmer based on earlier predictions. Instead, observations revealed that Betelgeuse B weighs in at roughly two to three times the mass of the Sun, making it a young B-type main-sequence star with a mass calculated between 2.6 and 3.1 solar masses. Study co-author Anthony Boccaletti noted that advanced post-processing techniques and extreme adaptive optics originally designed for finding exoplanets made the direct imaging possible despite the blinding luminosity of the primary star.

Overcoming Stellar Dimming and Dust Ejections

Locating Betelgeuse B proved exceptionally difficult because Betelgeuse is a pulsating variable star whose brightness fluctuates as its size and temperature change. Furthermore, the supergiant sits inside an asymmetric envelope of material thrown off as hydrogen fusion stopped in its core. In 2019, the star underwent an unexpected dimming phase. Hubble Space Telescope observations subsequently showed that hot material cooled and formed a temporary dust cloud that blocked starlight, while other data revealed a dense trail of gas swirling through the atmosphere. According to astronomers, this atmospheric wake is churned up by the orbital passage of Betelgeuse B as the two stars circle a common center of gravity.

Impact on the Anticipated Betelgeuse Supernova

The discovery of the companion star has triggered new scientific interest regarding how its presence might influence Betelgeuse’s eventual death. While the 2019 dimming event initially sparked speculation that the star stood on the precipice of a supernova, researchers determined that dust clouds were the primary culprit. According to Miguel Montargès, it remains an open question whether Betelgeuse B will alter the evolutionary timeline or the eventual collapse of the red supergiant. When Betelgeuse finally undergoes its catastrophic mass-loss phase, its core will compress into a neutron star or a black hole, an event that could either destroy the companion or leave a remnant of it behind.

Frequently Asked Questions

What is Betelgeuse B?

Betelgeuse B, nicknamed Siwarha, is a young B-type main-sequence star orbiting the red supergiant Betelgeuse with an estimated mass of two to three times that of the Sun.

How did astronomers finally image Betelgeuse B?

Astronomers directly imaged the companion using the SPHERE instrument on the European Southern Observatory’s Very Large Telescope in Chile, applying extreme adaptive optics and advanced image processing to peer through the glare of the primary star.

Will the companion star survive the Betelgeuse supernova?

Researchers are still studying whether Betelgeuse B will be completely destroyed when Betelgeuse explodes as a supernova in the next 100,000 years, or if a remnant of the companion might survive the blast.