Astronomers Photograph 'Toddler Planet' That May Still Be Growing

The binary star system CS Cha with its planet circled off to the right. The new object is likely about 20 times the mass of Jupiter. C. Ginski & SPHERE

Planets don't just come out of nowhere—they're slowly built up from a disk of material that gradually sticks together.

Now, astronomers think they've caught a glimpse of that process in action just hundreds of light-years away from Earth, according to a new paper accepted for publication by the journal Astronomy & Astrophysics.

The planet orbits a pair of stars known collectively as CS Cha, which are located about 538 light-years away from Earth and are only 2-3 million years old. The new object is likely about 20 times the mass of Jupiter, which puts it right at the border between being a very large planet and being a very small star. Whether a giant planet or a tiny star, the object is more than 200 times farther away from its stars than Earth is from the sun.

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"It could be a brown dwarf but also a super-Jupiter in its toddler years," lead author Christian Ginski, an astronomer at Leiden University in the Netherlands, said in a press release. "The classical planet-forming-models can't help us."

The problem is, they can't get a very clear look at the companion object—because it is blocked by the very thing that makes it so interesting, which astronomers are pretty sure is a disk-shaped cloud of dust. That would likely indicate that the object is a planet that's still growing, pulling together mass from that cloud.

The scientists mostly used an instrument called SPHERE attached to the Very Large Telescope located in Chile. But they also looked back as far as 19 years ago, comparing it with older images taken by the Hubble Space Telescope.

That two-decade perspective convinced the team that the likely planet really was orbiting the pair of stars, rather than the scientists just catching the three objects when they happened to be crossing paths. They also hope to continue the research into the future to get a better estimate of the new object's size and what's going on around it.