Astronomers have confirmed Elias 2-24 b as the youngest known planet, less than a million years old and still growing in its star’s gas and dust disk, NASA reported on September 16. About as massive as Jupiter, the world lies in a system roughly 450 light-years from Earth and offers a rare view of early planet formation.
Andrea Bernardi, a doctoral researcher at Chile’s Universidad Diego Portales, led the study published in The Astrophysical Journal Letters. According to NASA, the team examined archived observations of seven stars from Hawaii’s Keck Observatory. A coronagraph blocked the stars’ glare so researchers could search for much fainter planets within their surrounding disks.
The evidence connects observations from several telescopes. NASA said ALMA in Chile first revealed a gap in the disk, while the European Southern Observatory’s Very Large Telescope detected a faint point of light there. The team found the object again in Keck records from 2018 and 2020. Its motion over time supported a planet rather than a background star or an imaging defect.
NASA places the object about 55 times farther from its star than Earth is from the Sun. The agency says existing models require about five million years to form a Jupiter-size planet at Jupiter’s distance, and longer farther out. Finding such a young giant at this distance therefore poses a challenge for scientists trying to explain how quickly planets grow.
Co-author Lucas Cieza told NASA that current models still lack important processes. The discovery provides a way to test those models by observing formation in progress. Young planets are difficult to detect because dust conceals them; NASA says finding more will help researchers refine theories otherwise built from simulations and indirect evidence.
Keck says researchers seek spectra and better mass measurements to study the atmosphere, temperature and continued growth. NASA says more powerful coronagraphs, including the instrument aboard its Roman space telescope, could make such detections easier and reveal planets in smaller orbits.
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