James Webb Space Telescope discovers a possible newborn planet outside solar system

Astronomers said future observations are needed to see what exactly the object is

The formation of a gas giant planet embedded in the disk of dust and gas in the ring of dust around a young star. Photo: University of Michigan

Astronomers using the James Webb Space Telescope have discovered what they think could be a planet forming outside of the solar system.

A study led by the University of Michigan, University of Arizona and University of Victoria aimed the telescope at a planet-forming region that has been studied before and unexpectedly found a new planet candidate.

Three research papers that included the investigations were published in the Astronomical Journal earlier this month.

Future observations will help us understand exactly what we are looking at

Gabriele Cugno,
astronomer

Planets form in disks of dust and gas called protoplanetary disks that rotate around a central protostar (a young star) during its final assembly. The astronomers were hunting for a protostar called SAO 206462 but instead found the possible planet.

“Several simulations suggest that the planet (SAO 206462) should be within the disk, massive, large, hot, and bright. But we didn’t find it,” said astronomer Gabriele Cugno, who led the study.

“This means that either the planet is much colder than we think, or it may be obscured by some material that prevents us from seeing it.

“What we have found is a different planet candidate, but we cannot tell with 100 per cent certainty whether it’s a planet or a faint background star or galaxy contaminating our image.

“Future observations will help us understand exactly what we are looking at.”

New technology

The Hubble Space Telescope and ground-based telescopes have studied the same disk in the past, with observations that showed a disk composed of two strong spirals, usually launched by a forming planet.

The planet the researchers behind the recent study expected to find is similar to Jupiter – a gas giant of mostly hydrogen and helium.

“The problem is, whatever we’re trying to detect is hundreds of thousands, if not millions of times fainter than the star,” said Mr Cugno.

“That’s like trying to detect a little light bulb next to a lighthouse.”

The James Webb Space Telescope was launched into space on Christmas Day, 2021. AFP

To look more closely into the disk, the team used an instrument on the James Webb Space Telescope called NIRCam – a science camera that detects infrared light.

This helped initially to detect the planet by capturing its thermal radiation, as well as observing emission lines from materials that are falling on to the planet and hitting its surface with high velocity.

“When material falls on to the planet, it shocks at the surface and gives off an emission line at specific wavelengths,” said Mr Cugno.

“We use a set of narrow-band filters to try to detect this accretion. This has been done before from the ground at optical wavelengths, but this is the first time it’s been done in the infrared with JWST.”

Astronomers need to study new planets as it gives them data about the formation process and how chemical elements get distributed throughout a planetary system.

Studying gas giants like Jupiter, outside the solar system and how they shape disks, would help deepen scientists' understanding of planets.

Some astronomers think that these gas giants regulate the delivery of water to rocky planets that are forming in the inner parts of disks.

Learning this science could shed more light on the properties and evolution of protoplanetary disks that later give rise to rocky, Earth-like planets.