Overview
- A CfA-led team tracked Betelgeuse for nearly eight years with Hubble and ground-based telescopes, finding repeatable changes tied to a companion star named Siwarha.
- Ultraviolet Fe II measurements showed stronger blueshift when the companion was in front of Betelgeuse, then muted as its trailing wake absorbed the emission.
- The wake appears shortly after each transit roughly every 2,100 days, offering a robust explanation for Betelgeuse’s long secondary period in brightness.
- The results were presented at the AAS 247 meeting and accepted by The Astrophysical Journal, with the full analysis available on arXiv.
- Siwarha is currently obscured by Betelgeuse, and teams plan focused attempts to isolate it around 2027, following a tentative 2025 Gemini ‘Alopeke’ sighting.