The Secret Companion of Betelgeuse: A Tiny Star with Big Implications
The night sky, a vast tapestry of twinkling stars, holds many mysteries. One particularly captivating object is Betelgeuse, a red supergiant that dominates the constellation Orion. This massive star, about 10 million years old and 15 to 20 times the mass of our own Sun, is already in its twilight years. It is destined to one day explode in a spectacular supernova, an event that will illuminate the night sky for weeks and leave behind a remnant—either a neutron star or a black hole.
While we know Betelgeuse is heading towards its dramatic end, the exact timing of this event remains elusive. However, recent research has thrown a new twist into the story, hinting at a companion star orbiting this red giant, potentially offering valuable insights into Betelgeuse’s future.
Dimming and Brightening: Unraveling Betelgeuse’s Secrets
Betelgeuse, easily visible to the naked eye, has been captivating astronomers for centuries. However, it wasn’t until recent years that scientists started noticing some peculiar behavior. From late 2019 to early 2020, Betelgeuse underwent a significant dimming event, known as The Great Dimming, which reduced its brightness by 40%. This sparked a flurry of speculation, with some even wondering if the star was nearing supernova.
The culprit, as it turned out, was a massive ejection of surface material, which cooled and formed a dust cloud obscuring the star from view. This event, however, revealed another fascinating aspect of Betelgeuse’s behavior: its long secondary period (LSP)—a 2,170-day (6-year) cycle during which the supergiant dims and brightens. This LSP is much longer than Betelgeuse’s fundamental mode (FM), the primary way a star pulsates or vibrates, which is only 420 days long. This disparity between the two cycles raised a significant question: What could be driving this long, rhythmic dimming and brightening?
Enter BetelBuddy: A Tiny Star with a Big Influence
A recent research paper, published on the preprint server arXiv, has proposed a captivating answer: a smaller, Sun-like companion star orbiting Betelgeuse. This companion, affectionately nicknamed "BetelBuddy" by the research team, could be the driving force behind the star’s LSP. The authors suggest that BetelBuddy, in its gravitational dance with Betelgeuse, could be influencing the dust surrounding the red giant, causing periodic obscurations that lead to the observed dimming.
"A companion will make both stars move around their common center of mass, explaining the velocity variations," says László Mólnar, an astronomer at Hungary’s Konkoly Observatory, in an email to Gizmodo. "And it will have an effect on the dust surrounding Betelgeuse, explaining the brightness variations. This definitely changes how we look at Betelgeuse: It was hard to grasp at first that a star this well studied might have a yet undiscovered companion!"
According to Meridith Joyce, a co-author of the study from the University of Wyoming, the discovery of BetelBuddy could also provide crucial insights into Betelgeuse’s evolutionary stage. “If alpha Ori B, to which our team has given the pet name ‘BetelBuddy,’ is discovered, it would absolutely confirm that the [long secondary period] is the 2100-day periodicity and the 420-day periodicity is the [fundamental mode], which places Betelgeuse firmly in its core helium burning phase,” she explains. “If Betelgeuse is in its core helium burning phase, it has about 100,000 years to go before a supernova.”
The Challenges of Unmasking BetelBuddy
While the companion hypothesis holds promise, finding conclusive evidence for BetelBuddy is no small feat. Betelgeuse is incredibly bright, making it hard to detect any fainter objects in its vicinity. "A smaller, Sun-sized star can actually be almost undetectable next to it," says Mólnar.
Previous attempts to identify a companion star around Betelgeuse have been unsuccessful, each claim proving false. However, the researchers remain optimistic, pointing out that the discovery of exoplanets by observing them transit in front of their host stars, blocking a portion of the star’s light, might provide a promising technique for finding BetelBuddy. The team plans to use similar methods, analyzing precise measurements of Betelgeuse’s brightness and carefully looking for any telltale dips caused by the companion’s passage.
Implications for Betelgeuse’s Future
Whether or not BetelBuddy exists, the recent research highlights the complexity of stellar evolution and the challenges of predicting supernova events. "The companion itself doesn’t impact whether Betelgeuse explodes tomorrow or in the year 102024," says Jared Goldberg, the lead author of the study, "However, discovering the companion helps us predict better when Betelgeuse will explode.”
The quest for BetelBuddy, therefore, is about more than just unraveling a stellar mystery. It’s a journey to understand the intricate workings of massive stars like Betelgeuse, their companions, and the dramatic, albeit distant, future that awaits them. As we continue to observe and analyze this red supergiant, we gain deeper insights into the dynamic universe around us and the processes that shape the fate of stars, including our own Sun.
The story of Betelgeuse is a captivating reminder of the universe’s grandeur and the myriad mysteries that still lie hidden within the depths of space. The search for BetelBuddy, a tiny star with potentially enormous implications for our understanding of stellar evolution, promises to be an exciting and ongoing scientific adventure.
