Astronomers have identified Elias 2-24 b, a newly confirmed exoplanet that is less than 1 million years old, making it the youngest planet ever recorded. The world remains encased in the gas and dust of its forming disk, providing researchers with an unprecedented opportunity to observe planet formation in real time.
The discovery was detailed in a study published September 16 in The Astrophysical Journal Letters. Researchers utilized archived observations from the W. M. Keck Observatory in Hawaii, which operates under a cooperative agreement with NASA. These archives contained data from coronagraph observations of seven young stars, each surrounded by debris disks containing dust, gas, and icy or rocky fragments.
Andrea Bernardi, a doctoral candidate at the Universidad Diego Portales in Chile and lead author of the study, explained that the team targeted gaps within these disks, as forming planets are expected to carve out such spaces. “The planets should be found within the gaps, since they are carving them,” Bernardi said. “And that’s exactly where we found Elias 2-24 b.”
Elias 2-24 b is approximately the mass of Jupiter and orbits a star located about 450 light-years from Earth. Because the system is so nascent, it offers a glimpse into the early conditions of our own solar system billions of years ago.
Lucas Cieza, a professor at the Instituto de Estudios Astrofísicos in Chile and co-author of the paper, noted that the find challenges existing theories. Previous records for the youngest planets involved four-way ties between planets orbiting PDS 70 and WISPIT 2, all of which are over 5 million years old. “Elias 2-24 b shows us that even our best planet-formation models are still missing some important processes,” Cieza said.
The confirmation also resolves a decade-long debate. Earlier data from the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile revealed a gap in the disk around Elias 2-24, and subsequent observations from the European Southern Observatory’s Very Large Telescope detected a faint light source within that gap. However, current models suggested a Jupiter-sized planet could not form so quickly at such a vast distance—roughly 55 times the Earth-Sun distance—when it typically takes about 5 million years for such a planet to form at Jupiter’s distance.
To verify the object was indeed a planet and not an imaging artifact or background star, Bernardi and colleagues analyzed data from the Keck Observatory Archive collected in 2018 and 2020. By tracking the object’s movement over time, they confirmed it was orbiting the star.
“We usually hear about telescopes working separately, but this confirmation was possible only by using multiple telescopes together,” Bernardi said. He added that while Elias 2-24 b sits at the detection limit of current instruments, upcoming technology will improve findings significantly.
NASA’s Nancy Grace Roman Space Telescope, which launched on August 30, features an advanced coronagraph designed to detect fainter, closer-orbiting planets that are currently obscured by stellar glare. While Elias 2-24 b orbits about 10 times farther from its star than Jupiter does from the Sun, Roman’s sensitivity could reveal true Jupiter analogs and other young planets during their earliest formation stages.
“This is just the beginning of a new era of discovery,” Cieza said. “It’s incredible that with modern technology, we are actually able to see planet formation in action, and Roman will take planet hunting to the next level.”
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