Stunning images of "baby planets" reveal surprising growth spurts

A team of astronomers has produced the sharpest-ever images of infant planets forming around a distant star, revealing rings of dust that could eventually spawn moons. 

Taking advantage of a state-of-the-art adaptive optics system called Magellan Adaptive Optics Xtreme (MagAO-X), the researchers examined two protoplanets orbiting PDS 70 – a star that is only about five million years old. 

Situated roughly 370 light-years away in the constellation Centaurus, this newborn system offers a rare window into the formative stages of planetary evolution.

Led by the University of Arizona, the research provides some of the clearest evidence to date that young planets can be surrounded by dense rings of dust. 

These disks are expected to collapse into moons over the next few million years. The team also noted surprising shifts in the brightness of the planets, suggesting highly turbulent conditions as they rapidly evolve.

Young stars and massive planets

The youth of PDS 70 makes it a valuable proxy for what our own solar system might have looked like billions of years ago. In contrast, our Sun – a “middle-aged” star at roughly 4.5 billion years old – has long since lost the fleeting features of its infancy.

“Multiple massive planets act kind of like brooms or vacuum cleaners. They basically scatter the dust away and clear the large gap that we observe in this great big disk of gas and dust that surrounds the star,” explained Laird Close, a professor of astronomy at the University of Arizona’s Steward Observatory.

Among thousands of confirmed exoplanets, very few are known to be in the protoplanetary stage.

The two planets orbiting PDS 70, known as PDS 70 b and PDS 70 c, stand out as a unique opportunity for astronomers to track how worlds and their moons take shape.

Major breakthrough in technology

Central to the team’s success is MagAO-X, an advanced adaptive optics system installed on the 6.5-meter Magellan Telescope at Las Campanas Observatory in Chile.

Adaptive optics counters the blurring effects of Earth’s atmosphere, which otherwise hinders ground-based observations.

With a deformable mirror that changes shape up to 2,000 times per second, MagAO-X can “untwinkle” stars in much the same way noise-cancelling headphones block ambient sound.

“This is a really great breakthrough in technology,” said Close, noting that the system achieves better resolution than even space-based telescopes like Hubble and the James Webb Space Telescope. 

“Because our technology removes disturbances from the atmosphere, it’s a bit like taking a 6.5-meter telescope mirror and putting it in outer space by clicking a computer mouse button.”

In practical terms, this heightened resolution means MagAO-X can pick out exceptionally fine details from 370 light-years away – akin to discerning whether someone holds a single quarter or two quarters while standing 125 miles off.

Young planets with dusty birthplaces

One of the major discoveries from these observations was the presence of bright, compact rings of dust around PDS 70 b and c. 

These rings are expected to fall in on themselves over time, eventually giving rise to new moons, much like how Jupiter’s and Saturn’s moon systems likely formed out of similar dust disks in the early solar system.

“We can see, for the first time, rings of dust surrounding protoplanets made visible by the bright starlight reflecting off of them,” said Jialin Li, a doctoral student in astronomy and one of the study’s co-authors.

Understanding these initial stages is vital, as the presence of dusty disks can affect how planets accumulate mass and whether substantial moons can form. 

Over the coming millions of years, these forming gas giants could end up with satellite systems similar in scale to those found around Jupiter or Saturn.

Surprising shifts in planet brightness

Another finding was how dramatically the planets varied in brightness over just three years. The team discovered that PDS 70 b dropped to about one-fifth of its original brightness, whereas PDS 70 c doubled in brightness over the same timeframe.

Close suggested these fluctuations are tied to changes in the hydrogen “waterfalls” streaming onto each planet. When hydrogen gas bombards a planet’s surface, it emits light at a wavelength known as H-alpha. 

Because the amount of hydrogen flowing onto a planet can change quickly, its brightness at that specific wavelength can swing just as rapidly.

“Essentially, one of the planets abruptly went on a diet while the other was feasting on hydrogen,” said Close.

Despite these observations, astronomers still are not entirely sure what triggers such abrupt fluctuations.

More continued monitoring of systems like PDS 70 may help clarify whether these brightness changes are typical for protoplanets or caused by particularly chaotic growth spurts.

The future of ground-based discoveries

MagAO-X has already broadened astronomers’ capabilities for examining protoplanets, and the team plans to search for additional infant worlds around other young stars. 

Although discovering more planets at such an early formation stage is technically challenging, improvements in adaptive optics and telescope design could make it increasingly feasible.

“One of our main goals is to demonstrate just how well these observations can be done with telescopes on the ground,” said Jared Males, MagAO-X’s principal investigator and an associate astronomer at Steward Observatory. 

“We can always build larger telescopes on the ground than in space, and this result shows how important it is to build the next generation of even larger telescopes and equip them with instruments like MagAO-X.”

By continuing to refine adaptive optics and other observational techniques, astronomers hope to fill in the missing details of how stars and their planets form. 

In the process, they can draw parallels back to our own solar system’s earliest days – insights that were essentially lost to time after 4.5 billion years of evolution.

The study is published in The Astronomical Journal.

Image Credit: Emmeline Close and Laird Close

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