Betelgeuse revelation: Giant star is actually a binary system
After centuries of observation, the red supergiant star Betelgeuse, one of the most visible points in the constellation Orion, finally had one of its mysteries unveiled. Astronomers confirmed, on July 29, 2026, that the celestial body is not alone in space. It is accompanied by a companion star that is hotter, brighter and significantly more massive than previously thought, defying predictions from astronomical models.
An ancient quest and the challenge of observing Betelgeuse
The idea that Betelgeuse could have a companion has been around for many years, with the first suggestions emerging in the 20th century. However, confirming the presence of another star proved to be a complex task. Betelgeuse is a red supergiant of immense proportions, with a mass between 16.5 and 19 times that of the Sun and hundreds of times larger in diameter. Its surface is marked by gigantic convective cells, pulsations and ejections of material, in addition to being surrounded by a dense dusty atmosphere. All this intense activity and changing structure can easily overshadow or mimic the signal from a nearby object.
On the same topic: Unpublished telescope images show Betelgeuse as a double star, solving ancient mystery
Identification of the companion Betelgeuse B
Confirmation of the existence of the companion star, nicknamed Betelgeuse B, came with the use of the European Southern Observatory’s Very Large Telescope, located in Chile. Researchers were able to obtain the sharpest image ever recorded of a faint light source in the vicinity of Betelgeuse. The object was found almost exactly where predictions indicated a possible companion star would be. To ensure detection, two independent image processing methods were employed, allowing the star to be recovered from the intense glow emitted by the red supergiant.
New Star’s Surprising Mass Questions Models
Initially, astronomers speculated that Betelgeuse B would have a mass similar to that of our Sun. However, new observations have revealed that the companion star is much larger than expected, with a mass between 2.6 and 3.1 times the solar mass. This data is crucial, as it challenges existing theoretical models on the formation and evolution of binary systems and red supergiants. The discovery indicates that the interaction and development of these celestial bodies may be more complex than previously thought.
Miguel Montargès, lead author of the new study, who is part of LIRA at the Paris-PSL Observatory, expressed his surprise at the finding. He said he did not believe the equipment’s sensitivity would be sufficient to detect Betelgeuse B as predicted. “As it is more massive than predicted, we see it!” said Montargès, underlining the importance of the unexpected mass for detection.
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More on this story: European telescope records Betelgeuse’s companion star and solves mystery
Characteristics of the Betelgeuse binary system
The discovery of Betelgeuse B brings new perspectives to understanding the Orion constellation and complex stellar systems. The main features of the newly discovered binary system are:
- Betelgeuse A (the red supergiant):
- Betelgeuse B (the companion star):
* Mass: Approximately 16.5 to 19 times the mass of the Sun.
* Size: Hundreds of times larger than the Sun.
* Behavior: Pulses, ejects material and has a dense atmosphere.
* Type: Hot young star.
* Mass: Between 2.6 and 3.1 times the mass of the Sun (more massive than expected).
* Orbit: Revolves around the red supergiant at a distance similar to that between Saturn and the Sun.
The identification of Betelgeuse B and the determination of its mass paves the way for more in-depth studies on the dynamics of these systems and the impact of the companion on the evolution of the red supergiant itself, which is known for its variations in brightness and mass ejection events.
