One of those next-generation facilities is ESO's Extremely Large Telescope (ELT), slated to achieve first light in 2026. "Next-generation facilities focused on monitoring stellar brightness over time, or on studying the signature of dust in the infrared spectra of stars, could prove invaluable for expanding the lessons learned here." She raises the prospect of other red supergiants also showing signs of dimming. "The lack of an explosive conclusion might seem disappointing, but results go beyond explaining one brief wink of a nearby star," University of Washington astronomer Emily Levesque (who is not a co-author) wrote in an accompanying Nature commentary. The ESO team found no evidence to support the impending supernova hypothesis. The astronomers speculate that a similar expelling of dust from cool stars could end up becoming building blocks of planets. When a convection-driven cold patch appeared on the surface, the local temperature decrease was sufficient to condense the heavier elements (like silicon) into solid dust, forming a dusty veil that obscured the star's brightness in its southern hemisphere. The ESO team concluded that a gas bubble was ejected and pushed further out by the star's outward pulsation. Those images, combined with earlier observations in January and December 2019, allowed astronomers to directly witness the stardust formation, matching the observations of Dupree and her colleagues last year. "For once, we were seeing the appearance of a star changing in real time on a scale of weeks," said coauthor Miguel Montargès, from the Observatoire de Paris, France, and KU Leuven, Belgium. The new Nature paper expands on those earlier observations due to images captured by the European Southern Observatory's (ESO) Very Large Telescope (VLT) in January and March 2020. Those two events combined pushed out sufficient material far enough from the star that it cooled down, forming stardust. While they're easy to track with ground-based telescopes, these shifts don't cause the sort of radical changes in the star's light that would account for the changes seen during the dimming event.ĭupree and her colleagues suggested that as the star expanded in one of its usual cycles, a portion of the surface accelerated much more rapidly, thanks to a convection cell that had traveled from the interior of the star to its surface. Layered on that is a shorter, more irregular cycle that takes anywhere from under a year to 1.5 years to complete. One of these cycles is fairly regular, taking a bit over five years to complete. Over time, the star cycles through periods when its surface expands and then contracts. The star has something akin to a heartbeat, albeit an extremely slow and irregular one. It's an old star that has reached the stage where it glows a dull red and expands, with the hot core only having a tenuous gravitational grip on its outer layers. Ars is owned by WIRED's parent company, Condé Nast.Īs Ars' John Timmer reported last year, Betelgeuse is one of the closest massive stars to Earth, about 700 light years away. This story originally appeared on Ars Technica, a trusted source for technology news, tech policy analysis, reviews, and more.
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