Elias 2-24 b: The Youngest Confirmed Exoplanet Yet Found

Elias 2-24 b is a newly confirmed giant exoplanet that is less than 1 million years old—the youngest confirmed planet reported so far. About 450 light-years from Earth, it remains embedded in the gas-and-dust disk around its young host star, making it an unusually valuable system for studying planet formation as it happens. 1713

What astronomers found

The planet is described as Jupiter-sized or roughly Jupiter-mass and is still gathering material from the protoplanetary disk around Elias 2-24. 1317 It lies about 55 astronomical units (AU) from its star—roughly 55 times the Earth-Sun distance—inside one of the disk’s conspicuous gaps. Earlier analysis of the candidate’s brightness allowed a broad estimated mass range of about 0.5 to 5 Jupiter masses, depending in part on the contribution of a possible circumplanetary disk. 2

That location is central to the discovery’s significance. Disk gaps can be produced by several processes, but a planet in the gap offers a direct explanation for why that region is cleared or structured. Observations from Keck, ALMA, and the European Southern Observatory’s Very Large Telescope were combined in the reported study. 13

How archival Keck images confirmed the planet

The confirmation came from a fresh analysis of NASA-funded archival observations of seven young stars made with the coronagraph at the W. M. Keck Observatory in Hawaiʻi. A coronagraph suppresses the bright glare of a star, helping astronomers search for faint nearby companions. 17

For Elias 2-24, the relevant Keck observations were taken in 2018 and 2020. The multi-epoch record made it possible to test whether the point-like source was consistent with a companion in the system rather than a one-time artifact or an unrelated background source. Reports of the result describe the data as establishing the object’s motion and confirming the planet. 417

The result also illustrates the lasting scientific value of observatory archives: data collected years earlier can become decisive when researchers revisit them with improved analysis techniques and additional observations.

Why a planet this young matters

Most confirmed exoplanets are observed long after their natal disks have dispersed. Elias 2-24 b is different: it is both a giant planet and still surrounded by the material from which planets form. That provides a direct opportunity to connect a planet’s properties with the disk structure around it. 1317

Its age is the key result. NASA describes Elias 2-24 b as less than 1 million years old, while previous youngest-known record holders were estimated at around 5 million years old. 1710 A Jupiter-scale planet appearing this early puts strong emphasis on the timing of giant-planet formation. The observation does not, by itself, identify the mechanism that formed the planet, but it gives theorists a demanding real-world benchmark: any viable explanation must account for a massive planet while a system is still this young.

What the Roman Space Telescope could contribute

NASA’s Nancy Grace Roman Space Telescope has exoplanets among its main science themes. Its program includes broad surveys with the Wide Field Instrument and technology-demonstration observations with the Coronagraph Instrument. 2324

Roman will not make Elias 2-24 b less exceptional on its own, but broader exoplanet observations and high-contrast imaging capabilities could help build a larger context for systems like it. Finding and characterizing more young planets near planet-forming disks would allow astronomers to compare disk gaps, planet locations, masses, and evolutionary stages across many systems.

For now, Elias 2-24 b is a particularly clear snapshot of an early planetary system: a giant world identified within the disk that is still feeding it, confirmed in part by observations that had already been waiting in the archive. 1317