JWST discovers six new ‘rogue worlds’, not a planet or a star

In their quest to understand the many mysteries of the universe, astronomers are looking for potentially trillions of elusive space objects called rogue worlds. These stellar objects blur the boundaries between planet and star – to better understand the cosmic processes that shape both.

A team of astronomers using the James Webb Space Telescope (JWST) recently discovered six new rogue worlds in a young nebula. The findings are detailed in a study published on August 27 in The astronomical magazine and indicate that rogue worlds can help create celestial bodies even larger than the planet Jupiter. These newly discovered worlds can even be gas giants 5 to 10 times larger than the largest planet in our solar system.

[Related: Space probably has way more ‘rogue planets’ than we thought.]

“We are testing the limits of the star formation process,” study co-author and Johns Hopkins University astrophysicist Adam Langeveld said in a statement. “If you have an object that looks like a young Jupiter, is it possible that it could have become a star under the right conditions? This is an important context for understanding the formation of both stars and planets.”

What are rogue worlds?

Also called rogue planetsthese free-floating celestial bodies have a mass comparable to that of planets. However, unlike planets, they are not bound by the gravity of a central star, the way Earth is bound by the Sun’s gravity. Instead, they are cast adrift in space.

However, their formation and size make them resemble stars. Most rogue worlds are formed by material ejected during the early stages of planet formation, when matter collides more frequently. They may also have disks of space dust around them, which is crucial for the formation of both stars and planets. Others may come from collapse molecular clouds that don’t have enough mass to generate the nuclear fusion that powers stars. Even with these similarities, they are still on the border between what is considered a star and a planet.

While there are approximately 70 to 170 known or suspected rogue planetsSome scientists estimate that there could be trillions in the Milky Way.

Importantly, rogue worlds blur classifications because their masses overlap with gas giants like Saturn and Jupiter and brown dwarf stars. Although rogue worlds are rare in our own Milky Way Galaxy, the new JWST data indicate that they make up about 10 percent of the celestial objects in a recently observed focused star cluster.NGC1333.

Villainous worlds in a young nebula

In the studythe team used data from the JWST’s deepest survey of the young nebula NGC1333. This star-forming cluster is about 1000 light years away from Earth in the constellation Perseus. A newly released image of NGC1333 included in the study shows the nebula glowing with dramatic displays of interstellar dust and clouds.

[Related: The Ring Nebula is a glowing gas-filled donut in the latest JWST snap.]

“We used Webb’s unprecedented sensitivity at infrared wavelengths to search for the faintest members of a young star cluster, answering a fundamental question in astronomy: how does light form an object like a star?” study co-author and Johns Hopkins astrophysicist and provost Ray Jayawardhana said in a statement. “It turns out that the smallest free-floating objects that form as stars overlap in mass with giant exoplanets orbiting nearby stars.”

In the observations, the team has not detected any objects with masses less than five Jupiterseven though JWST has the sensitivity necessary to detect such bodies. This indicates that stellar objects lighter than this threshold are more likely to form as planets do, unlike stars.

“Our observations confirm that nature produces planetary mass objects in at least two different ways – through the contraction of a cloud of gas and dust, the way stars form, and in disks of gas and dust around young stars, such as Jupiter in our own solar systems . system did,” Jayawardhana said.

Dusty discs

The most intriguing of these starless objects also happened to be the lightest. It has an estimated mass of about five Jupiters, or about 1,600 Earths, and a dusty disk of material nearby.

According to the study, the presence of a disk indicates that the object may have formed like a star does. This type of space dust typically orbits a central object in the early stages of star formation.

Disks like these are also a prerequisite for planet formation, and this could also have important implications for the formation of potential ‘mini’ planets.

“These small objects with masses similar to those of giant planets may be able to form their own planets,” said Aleks Scholz, co-author and astrophysicist at the University of St. Andrews in Scotland. said in a statement. “This could be a nursery for a miniature planet system, on a much smaller scale than our solar system.”

[Related: Astronomers spot an extragalactic star with a disc around it for the first time.]

With the NIRISS instrument on board the JWSTthe astronomers measured the infrared light profile (or spectrum) of every object in the observed part of the cluster and reanalyzed 19 known brown dwarf stars. They also found a new brown dwarf with a planetary mass companion. According to the team, this is a rare finding that challenges a number of theories about the formation of binary systems.

“It is likely that such a pair formed as binary star systems do, from a cloud that fragmented as it contracted,” Jayawardhana said. “The diversity of systems that nature has produced is remarkable and is pushing us to refine our models for star and planet formation.”

In future studies, the team plans to continue examining more atmospheres of the faint objects and comparing them to the atmospheres of more massive brown dwarfs and gas giant planets. They will also use the JWST to study similar objects with dusty disks, exploring the possibility that these disks form miniplanetary systems similar to the numerous moons of Jupiter and Saturn.