ALMA Images Gas Swirling Around a Baby Planet
Astronomers have long simulated how a newborn planet stirs the gas around it. Now they have a picture of it happening.
A team led by Myriam Benisty at the Max Planck Institute for Astronomy used the ALMA observatory in Chile to image gas swirling around WISPIT 2b, a gas giant with five times the mass of Jupiter. The planet sits in a disk of gas and dust about 430 light-years from Earth, and it is still growing.
What ALMA saw
Gas moving toward us shows up bluish and gas moving away shows up reddish. At WISPIT 2b, gas moves away on one side and toward us on the other, which points to gas swirling around the protoplanet. Benisty said the swirls match what disk-planet simulations predicted but nobody had actually seen before.
The data also show two planets shaping their surroundings. WISPIT 2c has carved a cavity near the star, and WISPIT 2b has carved a gap farther out, about 57 astronomical units from the central stars. That is almost twice the distance from the Sun to Neptune.
Why it matters
Astronomers had seen swirls like this in other disks before, but without spotting a planet. Some researchers argue such swirls signal an unseen planet, while others say turbulence in the disk can make them. WISPIT 2b is the first system where the swirl and the planet appear together. The team says that makes it the only protoplanet where researchers can see the disk, the planet, evidence it is still gathering gas and the gas interacting with it.
Stefano Facchini of the University of Milan, who led the ALMA proposal, hopes observations like this will teach astronomers to tell planet-caused disk features from ones that are not.
A hard target
At this distance, resolving a structure as large as the Earth-Sun distance is like reading an ordinary book from 5 kilometers away. ALMA’s 66 antennas can act as a single telescope up to 16 kilometers wide. The team observed in September 2025, with more data in November 2025 and March 2026. A separate study published in August 2026 found that the host is a very close pair of stars rather than a single one.
The full analysis is in an Astrophysical Journal Letters paper by Benisty and colleagues, which the Max Planck release links to as an arXiv preprint. The team says higher spectral resolution is still needed to separate the different sources of the emission near the planet.
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