Stunning new images from ESO's Very Large Telescope unveil the surface of Betelgeuse, explaining its mysterious brightness dips. The cause? A vast cloud of dust.
Betelgeuse, the iconic red supergiant in Orion, is nearing the end of its life and could explode as a supernova within the next 100,000 years. Astronomers were alarmed when this relatively nearby star—smaller than once thought—began showing irregular brightness dips starting in December 2019, hinting at potential instability.
Further significant dimming occurred between January and March 2020, dropping Betelgeuse from the 10th brightest star in the night sky to 21st.
Speculation arose: Was this an extreme fluctuation for this variable star, or had it ejected a massive gas cloud that obscured its light? A new study in Nature confirms the latter.
Led by Miguel Montargès, researchers used the SPHERE instrument on ESO's Very Large Telescope in Chile to image Betelgeuse's surface directly from December 2019 to March 2020. By April, the star had regained its normal brightness. These observations revealed that the dimming was due to a dusty veil shrouding the star.
Betelgeuse's surface is dynamic, with giant gas bubbles rising, contracting, and expanding. Here, one such bubble was ejected; as the star's surface cooled, it condensed into solid dust particles. "We directly witnessed the formation of 'stardust,'" says Dr. Montargès.
The team anticipates ESO's Extremely Large Telescope (ELT), which will offer unprecedented resolution. "The ELT will let us image Betelgeuse in exquisite detail and expand our view to more red supergiants, unlocking the secrets of their powerful stellar winds."
