Betelgeuse’s Hidden Companion Star Siwarha Confirmed by Astronomers

Astronomers have identified a previously undetected companion star, named Siwarha, orbiting Betelgeuse. This finding is based on long-term observations and has been presented to the scientific community for further study.

The presence of Siwarha was confirmed through analysis of data collected from NASA’s Hubble Space Telescope and several ground-based observatories. Researchers observed changes in gas flow and spectral lines, which indicated the influence of a companion star within Betelgeuse’s extended atmosphere.

Siwarha was first directly imaged in July 2025 using the Alopeke speckle imager on the Gemini North telescope. The star is estimated to be about 1.5 times the mass of the Sun and appears roughly six magnitudes fainter than Betelgeuse itself.

The companion star’s movement through Betelgeuse’s atmosphere produces a dense wake of gas, which is detectable through variations in both ultraviolet and optical spectral lines. These observations were made possible by combining data from multiple observatories over several years.

What the numbers show

• Siwarha’s orbital period is about 2,100 days, or roughly six years
• Betelgeuse is located approximately 650 light-years from Earth
• The red supergiant’s volume could contain over 400 million Suns
• Siwarha was first directly imaged in July 2025

The name “Siwarha,” which means “her bracelet” in Arabic, was proposed by the discovery team and received official recognition from the International Astronomical Union in September 2025. The identification of Siwarha adds new detail to the understanding of Betelgeuse’s structure and behavior.

Spectroscopic analysis revealed that the presence of Siwarha is associated with a trailing and expanding wake, as indicated by changes in specific ultraviolet and optical spectral lines. These findings support the conclusion that the companion star interacts with Betelgeuse’s outer layers.

The research team presented their results at the 247th meeting of the American Astronomical Society. The study has also been accepted for publication in The Astrophysical Journal, providing a detailed account of the observational evidence and analysis.

Betelgeuse, a red supergiant in the constellation Orion, has been the subject of extensive study due to its size and variability. The confirmation of Siwarha’s existence contributes to ongoing research into the dynamics of massive stars and their companions.

* This article is based on publicly available information at the time of writing.