Hubble Finds a Planet Forming in an Unconventional Way


NASA’s Hubble Space Telescope has directly photographed evidence of a Jupiter-like protoplanet forming through what researchers describe as an “intense and violent process.” This discovery supports a long-debated theory for how planets like Jupiter form, called “disk instability.”

“Interpreting this system is extremely challenging. This is one of the reasons why we needed Hubble for this project – a clean image to better separate the light from the disk and any planet.”

Thayne Currie, lead researcher on the study

The new world under construction is embedded in a protoplanetary disk of dust and gas with distinct spiral structure swirling around surrounding a young star that’s estimated to be around 2 million years old. That’s about the age of our solar system when planet formation was underway. (The solar system’s age is currently 4.6 billion years.)

“Nature is clever; it can produce planets in a range of different ways,” said Thayne Currie of the Subaru Telescope and Eureka Scientific, lead researcher on the study.

All planets are made from material that originated in a circumstellar disk. The dominant theory for jovian planet formation is called “core accretion,” a bottom-up approach where planets embedded in the disk grow from small objects – with sizes ranging from dust grains to boulders – colliding and sticking together as they orbit a star. This core then slowly accumulates gas from the disk. In contrast, the disk instability approach is a top-down model where as a massive disk around a star cools, gravity causes the disk to rapidly break up into one or more planet-mass fragments.

The newly forming planet, called AB Aurigae b, is probably about nine times more massive than Jupiter and orbits its host star at a whopping distance of 8.6 billion miles – over two times farther than Pluto is from our Sun. At that distance it would take a very long time, if ever, for a Jupiter-sized planet to form by core accretion. This leads researchers to conclude that the disk instability has enabled this planet to form at such a great distance. And, it is in a striking contrast to expectations of planet formation by the widely accepted core accretion model.

The new analysis combines data from two Hubble instruments: the Space Telescope Imaging Spectrograph and the Near Infrared Camera and Multi-Object Spectrograph. These data were compared to those from a state-of-the-art planet imaging instrument called SCExAO on Japan’s 8.2-meter Subaru Telescope located at the summit of Mauna Kea, Hawaii. The wealth of data from space and ground-based telescopes proved critical, because distinguishing between infant planets and complex disk features unrelated to planets is very difficult.

Researchers were able to directly image newly forming exoplanet AB Aurigae b over a 13-year span using Hubble’s Space Telescope Imaging Spectrograph (STIS) and its Near Infrared Camera and Multi-Object Spectrograph (NICMOS). In the top right, Hubble’s NICMOS image captured in 2007 shows AB Aurigae b in a due south position compared to its host star, which is covered by the instrument’s coronagraph. The image captured in 2021 by STIS shows the protoplanet has moved in a counterclockwise motion over time.Credits: Science: NASA, ESA, Thayne Currie (Subaru Telescope, Eureka Scientific Inc.); Image Processing: Thayne Currie (Subaru Telescope, Eureka Scientific Inc.), Alyssa Pagan (STScI)

“Interpreting this system is extremely challenging,” Currie said. “This is one of the reasons why we needed Hubble for this project – a clean image to better separate the light from the disk and any planet.”

Nature itself also provided a helping hand: the vast disk of dust and gas swirling around the star AB Aurigae is tilted nearly face-on to our view from Earth.

Currie emphasized that Hubble’s longevity played a particular role in helping researchers measure the protoplanet’s orbit. He was originally very skeptical that AB Aurigae b was a planet. The archival data from Hubble, combined with imaging from Subaru, proved to be a turning point in changing his mind.

“We could not detect this motion on the order of a year or two years,” Currie said. “Hubble provided a time baseline, combined with Subaru data, of 13 years, which was sufficient to be able to detect orbital motion.”

“This result leverages ground and space observations and we get to go back in time with Hubble archival observations,” Olivier Guyon of the University of Arizona, Tucson, and Subaru Telescope, Hawaii added. “AB Aurigae b has now been looked at in multiple wavelengths, and a consistent picture has emerged – one that’s very solid.”

The team’s results are published in the April 4 issue of Nature Astronomy.

“This new discovery is strong evidence that some gas giant planets can form by the disk instability mechanism,” Alan Boss of the Carnegie Institution of Science in Washington, D.C. emphasized. “In the end, gravity is all that counts, as the leftovers of the star-formation process will end up being pulled together by gravity to form planets, one way or the other.”

Understanding the early days of the formation of Jupiter-like planets provides astronomers with more context into the history of our own solar system. This discovery paves the way for future studies of the chemical make-up of protoplanetary disks like AB Aurigae, including with NASA’s James Webb Space Telescope.

The Hubble Space Telescope is a project of international cooperation between NASA and ESA (European Space Agency). NASA’s Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope. The Space Telescope Science Institute (STScI) in Baltimore, Maryland, conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy, in Washington, D.C.

Illustration Credit: NASA, ESA, Joseph Olmsted (STScI)

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April 6, 2022 10:07 pm

in an Unconventional Way

Titled, no doubt, by a NASA PR news flack with a poor understanding of what unconventional means. The word New would have sufficed.
One thing it doesn’t mean is a new discovery of a process that doesn’t conform to theory. But does this mean that Hubble space telescope isn’t following the science? Cancel the telescope’s twitter account, now!

Chris Hanley
April 6, 2022 10:49 pm

Awesome, in the true sense of the word.

April 6, 2022 10:57 pm

Could it be possible that this is a rogue planet that formed in another solar system and was ejected and captured by AB Aurigae, the host star now? It is hypothesized that there are billions of rogue planets in the MilkyWay galaxy alone, and there may be more planets (both rogue and formed in situ) than all the stars in the universe.

Astronomers have discovered at least 70 new free ranging planets that wander through space without a parent star, in nearby region of the Milky Way known as the Upper Scorpous OB stellar association.

paranoid goy
April 7, 2022 1:06 am

Where do we draw the line between theory, conjecture and wishful thinking?
I mean, after millions of years watching planets form in the conventional way, I have to find out there is another way?
Will the wonders of navel gazing ever end?

April 7, 2022 1:07 am

… and here we have a problem with Identity Theorem: it is forming this way and doing so naturally so is thus conventional by definition. No aliens have shown up to fling giant clusters of electrostatically charged hair into the accretion disk. There was no collision of giant space-worthy turtles with small planes of soil sloshing with light on their backs. The Nothing did not cough up a giant hair-ball for lack of a regular diet to assist it’s normal peristalsis.

It has happened and continues to happen on its own and is thus absolutely conventional and it is the catastrophysicists who are, again, too galled up on bullshit fantasies about how reality “should” work to even bother comprehending that 170% of their science is built on fantastic presumptions. To quote Zwicky, Spherical Bastards. One can only become truly spherical if one makes one’s spinal column a circumference in much the way of Ouroboros but with opposite polarity.

If only Zwicky knew the people he worked with were topologically inverted!

Interested Observer
April 7, 2022 1:11 am

When all you have is a hammer, everything looks like a nail.

It’s possible another force is at play but, they can’t bring themselves to even contemplate it.

The giveaway: “… gravity is all that counts…”! So, let’s make up some wild-ass idea that might, just might explain this phenomenon that may be more easily explained by the theory that no one dare speak of in astronomical circles.

A planet “…nine times more massive than Jupiter and orbits its host star at … over two times farther than Pluto is from our Sun.” That sure is some massive “disk instability”. Even a captured planet seems more credible than this idea.

Tom Abbott
Reply to  Interested Observer
April 7, 2022 6:17 am

“Even a captured planet seems more credible than this idea.”

Yes, I think they need to fire up the Webb telescope and get us a better picture.

How many giant planets form at this distance from their planet?

The star would have to have a pretty big disk of gas and dust to form something so big, so far away from the star.

I don’t think they have distinguished between a “bottom up” and a “top down” method of formation.

Ed Zuiderwijk
April 7, 2022 2:24 am

How can anybody know what is ‘unconventional’ planet formation? That process has been going on for at least 10 billion years, while we have observed it for 20 years at best and theorised about it for 200 years.

Reply to  Ed Zuiderwijk
April 8, 2022 3:34 am

You are absolutely right! There is still no complete clarity about what processes take place during the formation of planets and which of them dominate. What tradition are we talking about?

April 7, 2022 3:34 am

“Nature is clever”

Not according to conservationists and climate scientists (the priesthood).

“orbits its host star at a whopping distance of 8.6 billion miles”

So what is the size or mass of the host star?  A little context helps.

Richard Page
Reply to  fretslider
April 7, 2022 6:54 am

You are, perhaps, aware of the internet? There is a lot of information on AB Aurigae (the star in question, mentioned several times in the main post) that you can very easily research all on your very own. A ridiculously quick and easy search, for example, turns up the fact that it is 2.4 x Sol’s mass. If you want context it won’t be hard to find for yourself.

Reply to  Richard Page
April 9, 2022 6:19 am

Then why even bother posting the article on wuwt? All this info was already on the internet…

April 7, 2022 5:32 am

13 years observing a process that takes millions of years?

Astronomy isn’t one of my pet topics. I don’t follow the sources dedicated to studying and publishing the latest in the field.

I get my education here from the articles and comments from the many readers here who are in the field or are keenly interested. So, I’m not totally ignorant on the topic. There has been much written here to explain the “inside baseball” aspects of the rest of the universe even as we struggle just to understand our Planet Earth.

So back to my questioning. After 13 years, how much of this is rank speculation based on a little observation and a lot of assumptions, and how much is good, solid conclusions?

Peter Fraser
Reply to  H.R.
April 7, 2022 12:34 pm

Strange how Hubble, after a period of quiescence, has come to life after the James Webb telescope was launched.

Dave Fair
Reply to  H.R.
April 7, 2022 9:39 pm

“There is something fascinating about science. One gets such wholesale returns of conjecture out of such a trifling investment of facts.” Now who would have said such a silly thing considering the rectitude of current scientists?

Pat Frank
Reply to  H.R.
April 8, 2022 6:31 pm

The 13 years was enough to detect motion, and so allowed deducing the orbit. The violent disarray of the gas cloud likely was the source of the disc instability hypothesis.

A core must form at some point. Maybe it’s still early in planetary formation, and the core forms by infall from the local gas gyre that produces the planet.

April 7, 2022 7:30 am

what researchers describe as an “intense and violent process.”

I’m fairly certain that any reaction in space—read “sans friction”—is going to be intense and violent.

David Anderson
April 7, 2022 8:29 am

“Nature is clever”

Belief in “The gods” must be hardwired in us.

Reply to  David Anderson
April 7, 2022 9:58 am

Humanizing phenomenae seems to be related to sitting at a desk or telescope, or something similar, waiting for something to happen. Then, especially after a long wait, the previously unobserved “happening” has got to be important.

April 7, 2022 9:41 am

Not being up to speed on the mechanics of stars and their planets, a orbital radius of 8.6 billion miles must result in a helluva long solar year for such a planet. I looked up Pluto and its solar year is 248 earth years. I am guessing that, just based upon geometry alone, having twice the orbital radius of Pluto it’s year must be 1/2 pi (about 1.57) times the radius increase squared or 6+ times as long – or somewhere around 1,500+ earth years. I don’t know how orbital velocity varies with orbital radius.

Reply to  Duane
April 7, 2022 10:41 am

In any case, that would really suck if you’re looking forward to your next birthday anniversary.

OTOH, for the guys, you never reach the point where you have to remember it’s your wedding anniversary… yesterday, and that’s why the door was bolted and your burned dinner was set out on the porch.

Dave Fair
Reply to  H.R.
April 7, 2022 9:51 pm

During a family move to Alaska I went ahead to start my job while my wife stayed to sell the house. My wife didn’t say anything before such time, but did mention when I wished her a happy anniversary that it was four days late. Being the couple that we are, I still wish her a happy anniversary annually four days late, but I’m sure woe would be upon me if I ever again forget the real date and fail to acknowledge it.

Michael S. Kelly
Reply to  Duane
April 15, 2022 4:20 am

Orbital period varies as the 3/2 power of the semi-major axis. Though the eccentricities may vary a lot, we can just assume all circular orbits for comparison. A planet at twice Pluto’s orbital radius would have an orbital period 2.828 times that of Pluto, or about 700 years.

April 7, 2022 10:21 am

I find it interesting that the authors of this article didn’t even bother to suggest a captured planet is a possibility (confirmation bias, anyone?).

Regardless, when I read this article, the first thing I thought of was a special I saw about a mysterious plant X in our solar system WAY out beyond Pluto. On one hand, a captured planet also seems likely in that scenario, assuming planet X even exists.

On the other hand, I find it ironic that, during that show, they speculated wildly on how the planet could have formed in the inner solar system and was ejected into the nether regions. Never once did they mention the possibility that disk instability could also explain the assumed planet’s distant location.

Seems to me that they missed at least two possible alternate explanations for how something came to be. Kind of sounds like modest atmospheric warming, no?

Reply to  NavarreAggie
April 7, 2022 7:01 pm

Captured from what?

The theory of star system formation is well defined based mostly on gravity induced by, initially, just clouds of gas and dust produced in the Big Bang, or later on by the bursting of super novas which recycle the base material (hydrogen and helium) plus other heavier elements formed via fusion inside those earlier generation stars that gets recycled. Gravity causes the gases and dust to coalesce into rotating discs. Then within those discs, gravity and chaotic collisions between solid materials eventually produces a star, which holds the disc tighter together, then eventually either gas giant planets or rocky planets eventually form.

For a planet to be “captured” by a star it would have had to have been formed elsewhere outside the solar disc within another relatively dense solar cloud or disc, and then somehow have wandered on a path that would take it into the gravity field of the nearest star. That is certainly theoretically possible, but given the vast expanses of empty space that exist between solar discs and clouds if star-forming gas and dust, it is of extremely low probability.

April 7, 2022 3:49 pm

Cosmostrology often reminds me of climastrology with its endless realm of conjecture.

Reply to  Slowroll
April 7, 2022 7:05 pm

Nope – Cosmology or astrophysical science is based upon both a keen understanding of the proven laws of physical science, and direct empirical observation – the diametric opposite of “conjecture”.

Reply to  Duane
April 7, 2022 10:09 pm

Using the proven laws of physics for things that have been empirically verified in reality is indeed science. Trying to define how events happen and apply physical laws to things that are light years away or that happened billions of years ago is conjecture. Virtually no cosmological “laws” have been unequivocally proven. Even the Hubble constant is suspect, according to Hubble himself. And, if one challenges the standard models, one is ostracized and banned, just like climastrology. Look at the case of Halton Arp, for example.

Reply to  Slowroll
April 9, 2022 7:56 am

There are always layers of details that can be debated, such as the size of a constant, or whether there is such a thing as dark matter or dark energy that explains gaps in our understanding of science.

But we’ve actually observed, using telescopes (optic as well other types), on land and from the Hubble telescope in space, stars being formed, solar discs being formed, planets being formed, super novas exploding, vast fields of star-forming gases that coalesce due to gravity, that all fit exactly within our understanding of the applicable laws of physical science.

There is no conjecture whatsoever about those processes.

April 7, 2022 11:24 pm

“This result leverages ground and space observations …”

What do they mean by “leverages”?

Interested Observer
Reply to  RoHa
April 8, 2022 1:18 am

Merriam-Webster provides 3 definitions but, I think this one sums up what they mean nicely:

“The use of credit to enhance one’s speculative capacity.”

In other words, they are using the credit of other people’s observations to enhance their own speculations. “Disk instability” is a new wild-ass guess hypothesis, after all.

April 8, 2022 4:48 am

“Interpreting this system is extremely challenging. This is one of the reasons why we needed Hubble for this project – a clean image to better separate the light from the disk and any planet.”

Thayne Currie, lead researcher on the study”

Typical of current day NASA; assume, presume and then speculate. All from a static image they can barely image.

The size of their alleged protoplanet is the only reason they can detect it, not because they can clearly define and identify it.

Pat Frank
April 8, 2022 6:23 pm

Pluto averages 3.67 billion miles from the sun. At 8.6 billion miles AB Aurigae b is 2.3 times further away. Richard Page above found that AB Aurigae is 2.4 times the solar mass.

So, with respect to the local stellar gravitational gradient, AB Aurigae b is forming just about where Pluto did.

Interested Observer
Reply to  Pat Frank
April 8, 2022 8:57 pm

I would have thought that the inverse square rule applies to this and AB Aurigae would need to be ~4 – 5 times the solar mass for the orbits to be equivalent.

Also, that doesn’t address the discrepancy between a planet 9 times bigger than Jupiter, orbiting so far away from its parent star, and tiny little Pluto.

My suggestion is that we wait until we have another few centuries worth of observations before we start speculating about what’s going on in this system (the same suggestion I make for climate studies on this planet).

Pat Frank
Reply to  Interested Observer
April 9, 2022 11:47 am

You’re right, IO. I was too hasty. The gravitational gradient at AB Aurigae b is more like 0.4x the gradient at Pluto.

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