Using the Enhanced Resolution Imager and Spectrograph (ERIS) instrument on ESO’s Very Large Telescope (VLT), two teams of astronomers have detected a protoplanet candidate embedded inside a disk spiral around the young star HD 135344B, as well asa substellar companion candidate (brown dwarf or large planet) around the young star V960 Mon.
This image shows a spiral disk around the young star HD 135344B. The image was obtained with the VLT’s Enhanced Resolution Imager and Spectrograph (ERIS) instrument, which found a candidate planet that may be sculpting the spiral features in the disk. The location of this planet is indicated with a white circle. Image credit: ESO / Maio et al.
“We will never witness the formation of Earth, but here we may be watching a planet come into existence in real time,” said Francesco Maio, a doctoral researcher at the University of Florence, Italy, and lead author of a paper published in the journal Astronomy & Astrophysics.
Maio and colleagues detected a protoplanet candidate within a protoplanetary disk around HD 135344B, a 11.9-million-year-old F8V star located at 135 parsecs (440 light-years) from the Sun in the constellation of Lupus.
The protoplanet is estimated to be twice the size of Jupiter and as far from its host star as Neptune is from the Sun.
It has been observed shaping its surroundings within the protoplanetary disk as it grows into a fully formed planet.
Protoplanetary disks have been observed around other young stars, and they often display intricate patterns, such as rings, gaps or spirals.
Astronomers have long predicted that these structures are caused by baby planets, which sweep up material as they orbit around their parent star.
But, until now, they had not caught one of these planetary sculptors in the act.
In the case of HD 135344B’s disk, swirling spiral arms had previously been detected by another team of astronomers using VLT’s SPHERE instrument.
However, none of the previous observations of this system found proof of a planet forming within the disk.
Using VLT’s ERIS instrument, Maio and co-authors may have found their prime suspect.
They spotted the planet candidate right at the base of one of the disk’s spiral arms, exactly where theory had predicted they might find the planet responsible for carving such a pattern.
“What makes this detection potentially a turning point is that, unlike many previous observations, we are able to directly detect the signal of the protoplanet, which is still highly embedded in the disk,” Maio said.
“This gives us a much higher level of confidence in the planet’s existence, as we’re observing the planet’s own light.”
This image shows a possible substellar companion orbiting the young star V960 Mon. The candidate object was found with ESO’s Very Large Telescope (VLT), using its new Enhanced Resolution Imager and Spectrograph (ERIS). The new ERIS data are shown here in orange, overlaid on older images of the dusty disk as seen with the VLT’s SPHERE instrument (yellow) and ALMA (blue). Image credit: ESO / A. Dasgupta / ALMA / ESO / NAOJ / NRAO / Weber et al.
In a separate study, Anuroop Dasgupta, a doctoral researcher at ESO and at the Diego Portales University, and colleagues used the ERIS instrument to observe another young star, V960 Mon, which is located 1637.7 parsecs (5,342 light-years) away in the constellation of Monoceros.
Earlier observations with the SPHERE instrument and the Atacama Large Millimeter/submillimeter Array (ALMA) revealed that the material orbiting V960 Mon is shaped into a series of intricate spiral arms.
They also showed that the material is fragmenting, in a process known as gravitational instability, when large clumps of the material around a star contract and collapse, each with the potential to form a planet or a larger object.
Dasgupta and co-authors were able to detect a substellar companion — a brown dwarf or a large planet — around V960 Mon.
“With ERIS, we set out to find any compact, luminous fragments signallng the presence of a companion in the disk — and we did,” said Dasgupta, first author of a paper published in the Astrophysical Journal Letters.
“We found a potential companion object very near to one of the spiral arms observed with SPHERE and ALMA.”
“This object could either be a planet in formation, or a brown dwarf — an object bigger than a planet that didn’t gain enough mass to shine as a star.”
“If confirmed, this companion object may be the first clear detection of a planet or brown dwarf forming by gravitational instability.”
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F. Maio et al. 2025. Unveiling a protoplanet candidate embedded in the HD 135344B disk with VLT/ERIS. A&A 699, L10; doi: 10.1051/0004-6361/202554472
Anuroop Dasgupta et al. 2025. VLT/ERIS Observations of the V960 Mon System: A Dust-embedded Substellar Object Formed by Gravitational Instability? ApJL 988, L30; doi: 10.3847/2041-8213/ade996
