Betelgeuse’s Mysterious Companion Star Finally Confirmed by Astronomers
Betelgeuse, one of the most peculiar stars in the night sky, has long puzzled astronomers with its erratic behavior. However, a recent breakthrough has shed light on one of its enduring mysteries – the presence of a small companion star that orbits the red giant, leaving a distinctive trail in its atmosphere.
Scientists have observed that Betelgeuse’s light exhibits two distinct cycles of variation. The first cycle, lasting about 400 days, has been linked to internal pulsations within the star. The second cycle, lasting around 2,100 days, has been more challenging to explain until now.
The leading theory suggests that a dim companion star orbits Betelgeuse closely, creating a ripple effect in its atmosphere. After years of observations using telescopes like the Hubble Space Telescope and observatories in Arizona and Spain, astronomers have finally confirmed the existence of this companion star, named Siwarha.
According to Andrea Dupree, an astronomer at the Harvard & Smithsonian Center for Astrophysics, “It’s a bit like a boat moving through water. The companion star creates a ripple effect in Betelgeuse’s atmosphere that we can actually see in the data. For the first time, we’re seeing direct signs of this wake, or trail of gas, confirming that Betelgeuse really does have a hidden companion shaping its appearance and behavior.”
Siwarha’s presence does not dim Betelgeuse’s light but alters its spectrum, particularly in UV wavelengths emitted by ionized iron. When the companion is in front of Betelgeuse, there is a strong peak in iron emission. However, as Siwarha passes behind the star, its trailing gas absorbs these wavelengths, leading to a shorter peak that eventually fades until the next lap, approximately 5.77 years later.
“With this new direct evidence, Betelgeuse gives us a front-row seat to watch how a giant star changes over time,” Dupree explains. “Finding the wake from its companion means we can now understand how stars like this evolve, shed material, and eventually explode as supernovae.”
Siwarha is set to reappear in August 2027 after its current eclipse behind Betelgeuse. The groundbreaking study detailing the confirmation of Betelgeuse’s companion star has been accepted for publication in The Astrophysical Journal.
