James Webb finds six orphan planets, shedding new light on star birth

James Webb has discovered something special again: six orphan planets, not gravitationally bound to a star, but floating freely. The space telescope has also found the lightest object ever found with a dust disk around it.

The celestial bodies provide new evidence that the same cosmic processes that form stars also play a role in the formation of objects slightly larger than Jupiter. “We are studying the outer limits of star formation,” says lead researcher Adam Langfield, an astrophysicist at the center. Johns Hopkins University“If you have an object like a small Jupiter, could it become a star under the right conditions? This is important for better understanding the formation of stars and planets.

NGC1333
Web did what he did. Special discovery In the young reflection nebula NGC1333, a star-forming cluster located about a thousand light-years away in the constellation Perseus. A new image released today by the European Space Agency shows NGC1333 as a glowing region of interstellar dust and clouds.

The worlds discovered are likely to be gas giants with masses five to ten times that of Jupiter. This is called rogue worlds They are among the lightest objects ever found, and are remarkably formed by a process that typically produces brown dwarfs, objects smaller than a star but larger than a gas giant. The mass is insufficient to initiate proton fusion.

infrared sensitivity
“We used Webb’s unparalleled sensitivity at infrared wavelengths to search for the faintest members of a young star cluster in an attempt to answer a fundamental question in astronomy: What is the light like for a body that is forming as a star?” says astrophysicist Ray Jayawardhana of Johns Hopkins University. “It turns out that the smallest free-floating objects form when stars in the cluster overlap with giant exoplanets orbiting neighboring stars.”

The telescope found no objects lighter than five times the mass of Jupiter. This is a clear sign, the researchers conclude, that lighter stellar objects likely form in the same way as planets. “Our observations confirm that nature produces planetary-mass objects in at least two different ways: through the collapse of a cloud of gas and dust, during star formation, and in disks of gas and dust around young stars, such as Jupiter in our own solar system,” Jayawardhana said.

1600 land
The most interesting of the starless objects is the lightest example, estimated to have a mass of five Jupiters (about 1,600 Earth masses). The presence of a dust disk almost certainly means the object formed similarly to a star, since space dust typically orbits a central body in the early stages of star formation, the researchers say.

Disks are also a prerequisite for planetary formation, so Webb’s observations could have important implications for potential small planets. “These small bodies with masses similar to the giant planets could form their own planets,” adds astrophysicist Alex Scholtz of the Space Center. University of St Andrews “This could be a fertile ground for a miniature planetary system, on a scale much smaller than our solar system.”

New brown dwarf
Using Webb’s NIRISS instrument, astronomers measured the infrared light spectrum of each object in the observed portion of the cluster and reanalyzed 19 known brown dwarfs. They also discovered a new brown dwarf with a planetary-mass companion, a rare finding that challenges theories about how binary systems form. “It is possible that such a pair formed like a binary star system, through a cloud that broke apart as it collapsed,” Jayawardhana says.

Planning fades away
Orphan planets can form from collapsed molecular clouds that lack the mass needed for the nuclear fusion that powers stars, but they can also form when gas and dust in disks around stars clump together into planet-like spheres that are eventually ejected from their galaxy, likely through gravitational interactions with other objects.

What’s unique about these free objects is that they blur the classification of celestial objects, because their mass overlaps with that of both gas giants and brown dwarfs. They are, by the way, less rare than expected. In the star clusters Webb examined, they make up about 10 percent of the total number of celestial objects.