Building on prior disk observations from the ALMA telescope, scientists have used archival W. M. Keck Observatory data to confirm the direct near-infrared detection of the protoplanet Elias 2-24 b developing in the ring of dust around the young star Elias 2-24.
Being less than one million years, the newly discovered planet sets a record for its age compared to other planets discovered in the past.
Its mass is currently being accumulated by adding gas and dust, and it gives us a rare opportunity to observe how planets are born.
Discovering infant protoplanets inside young stellar disks
A compact circumstellar disc of matter in the form of gas and dust particles revolves around stars within formative star systems.
Planet formation takes place right after aggregation in the formation zones.
It is quite hard to detect new planets since dust clouds prevent astronomers from observing the inner disks.
High-resolution radio interferometry with ALMA initially revealed a narrow gap in the circumstellar disk.
However, direct confirmation of the embedded protoplanet required high-contrast near-infrared imaging using the W. M. Keck Observatory’s NIRC2 vortex coronagraph (analyzing archived 2018 and 2020 epochs) to pierce the dense dust shroud.
Detection of gravitational disturbances in the dust cloud suggests the presence of a growing planet embryo.
Sizing up the record-breaking newborn world
Physical features of baby planets can be calculated by studying the emission of dust and the changes in the velocity of gas within the local region.
By comparing near-infrared photometry from Keck Observatory with evolutionary models, scientists estimate the planet’s mass to be approximately 1.9–4.0 Jupiter masses at a projected separation of 54.9 ± 4.3 AU, though this remains a model-dependent estimate.
This giant is orbiting its parent sun at an enormous distance equal to that in outer solar systems.
Its large size promotes fast gravitational accretion due to the accumulation of dust and gas.
Based on age calculations, scientists estimate that the planet is less than one million years old.
A new chronological record may soon be confirmed.
Analyzing gas accretion within circumstellar disk gaps
Protoplanets undergo very quick growth processes by acquiring the materials from their surroundings via annular gaps that have been created around them.
The centrifugal force as well as tidal interaction work to repel the gases and dust from the orbit around the planet.
While the planet’s extreme youth and disk context strongly point to ongoing growth through accretion, the Bernardi et al. confirmation study specifically relied on direct near-infrared point-source detection, astrometry, and photometry rather than mapping local gas chemistry or direct spiral feeding flows.
Challenging traditional timescales for gas giant formation
Core accretion theory typically demands millions of years to accumulate enough solid planetesimals before enveloping the gases around them.
The presence of planets that have already formed in systems younger than one million years forces the scientists to reconsider their formation periods.
Models that rely on gravitational instability indicate that the gas giants might condense rapidly in extremely dense outer disc regions.
A quick gravitational contraction accounts for the fast formation of gas giants ahead of the time when the winds from the stars will disperse the discs.
Rethinking theories of planetary formation is an important step to understanding exoplanets’ formation process.
Outlining the limits of high-resolution radio astronomy surveys
Finding baby protoplanets is proof that there exists highly advanced astronomical technology, but the limitations associated with the procedure are huge.
Radio interferometers rely on thousands of observation hours to identify small structures in distant star formation sites.
Dust extinction and intricate star magnetic fields create problems when determining the masses of the heavily embedded protoplanets.
It is uncertain whether giant outer disk planets move over millions of years in line with the orbit of their star, according to NASA Exoplanets.
Future observations will have to be conducted from telescopes in space and on the ground to make sure that astronomers are making the correct inferences.
All the details of the study can be found here: Bernardi, A., Zurlo, A., Cieza, L. A., Ruane, G., Christiaens, V., Dasgupta, A., … & Williams, J. P. (2026). Searching for Embedded Protoplanets with the Keck/NIRC2 Vortex Coronagraph: Confirmation of a Core-accretion Planet in the Narrow Gap of the Elias 2-24 Disk. The Astrophysical Journal Letters, 1009(1), L3.
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