The red supergiant Betelgeuse, a prominent star in our night sky, has puzzled astronomers with its irregular dimming and brightening. While its primary pulsation cycle is approximately 420 days, a longer, 2,170-day cycle (known as the Long Secondary Period or LSP) has remained a mystery. A new theory suggests a companion star, roughly the size of our Sun, orbiting Betelgeuse could be the key to understanding this unusual behavior.
A Stellar Dance: Betelgeuse and its Potential Partner
The presence of a companion star, nicknamed “BetelBuddy,” could explain Betelgeuse’s LSP. As the two stars orbit their common center of mass, their gravitational interaction could influence the dust surrounding Betelgeuse, leading to the observed variations in brightness. This intriguing hypothesis, presented in a preprint paper on arXiv, awaits peer review but offers a fresh perspective on Betelgeuse’s complexities. According to László Mólnar, an astronomer at Hungary’s Konkoly Observatory, this potential companion “definitely changes how we look at Betelgeuse.” It’s surprising to consider a well-studied star like Betelgeuse might harbor a hidden companion.
The Ticking Clock of a Supergiant
Betelgeuse, a relatively young star at 10 million years old, is considerably more massive than our Sun, estimated to be between 15 and 20 times its mass. This immense size comes at a cost: Betelgeuse is rapidly burning through its fuel and is destined to end its life in a spectacular supernova explosion. The timing of this event is a subject of ongoing research. Meridith Joyce, an astronomer at the University of Wyoming and co-author of the study, explains that confirming the presence of “BetelBuddy” would solidify our understanding of Betelgeuse’s pulsation periods and place it firmly in its core helium burning phase. This phase suggests Betelgeuse has approximately 100,000 years remaining before its dramatic demise.
Betelgeuse (orange dot in top right) in the constellation Orion.
The Great Dimming and the Dust Cloud Enigma
Betelgeuse’s dramatic dimming event in late 2019 and early 2020, known as The Great Dimming, further complicated the picture. Scientists later attributed this dimming to a massive ejection of surface material that cooled into a dust cloud, obscuring Betelgeuse from Earth’s view. While previous theories suggested companion stars might drag dust, causing eclipses and dimming, the new research challenges this idea. Lead author Jared Goldberg from the Flatiron Institute points out that Betelgeuse and other stars with LSPs dim when their potential companions are behind them, ruling out the dust-dragging hypothesis. Instead, the team proposes that the companion star could be gravitationally modulating or irradiating the dust, rather than dragging it.
The Search for BetelBuddy
While the idea of a companion star is compelling, historical attempts to detect “BetelBuddy” have been unsuccessful. Miguel Montargès, an astronomer at the Sorbonne Université, acknowledges these past failures but emphasizes that a companion for Betelgeuse wouldn’t be unexpected, given that massive stars are rarely born alone. He further highlights the importance of this research for our understanding of red supergiants.
Implications for Betelgeuse’s Fate
While the presence of a companion doesn’t directly influence when Betelgeuse will go supernova, discovering it could refine our predictions. Finding “BetelBuddy” is a significant challenge due to Betelgeuse’s overwhelming brightness, which could easily mask a smaller companion. Goldberg suggests utilizing technologies similar to those used for directly imaging exoplanets to detect faint companions around bright stars. Further measurements of Betelgeuse’s brightness, coupled with careful analysis, could eventually reveal the presence of this hidden companion and shed more light on the final stages of this fascinating star.
Conclusion
The ongoing investigation into Betelgeuse’s behavior highlights the complexities of stellar evolution. While the existence of “BetelBuddy” remains hypothetical, its discovery would significantly advance our understanding of Betelgeuse and other red supergiants. The search for this elusive companion continues, promising valuable insights into the life and eventual death of one of the night sky’s most captivating stars.
