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Artist's conception of a planet like HD106906 b. Visible in the picture is a debris disk and its distant host star. Credit: NASA/JPL-Caltech

This Exoplanet Is Turning Planetary Formation Scenarios Upside Down

6 Dec , 2013

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What the heck is that giant exoplanet doing so far away from its star? Astronomers are still trying to figure out the curious case of HD 106906 b, a newly found gas giant that orbits at an astounding 650 astronomical units or Earth-sun distances from its host star. For comparison, that’s more than 20 times farther from its star than Neptune is from the sun.

“This system is especially fascinating because no model of either planet or star formation fully explains what we see,” stated Vanessa Bailey, a graduate astronomy student at the University of Arizona who led the research.

HD 106906 b is 11 times the size of Jupiter, throwing conventional planetary formation theory for a loop. Astronomers believe that planets gradually form from clumps of gas and dust that circle around young stars, but that process would take too long for this exoplanet to form — the system is just 13 million years old. (Our own planetary system is about 4.5 billion years old, by comparison.)

The discovery image of HD 106906 b, shown in thermal infrared light from instruments on the Magellan telescope at the European Southern Observatory in Chile. The image has been changed to take out light from its very bright host star. The planet orbits more than 20 times farther from its host star than Neptune does from the sun. (AU = astronomical units, or Earth-sun distances). Credit: Vanessa Bailey

The discovery image of HD 106906 b, shown in thermal infrared light from instruments on the Magellan telescope at the European Southern Observatory in Chile. The image has been changed to take out light from its very bright host star. The planet orbits more than 20 times farther from its host star than Neptune does from the sun. (AU = astronomical units, or Earth-sun distances). Credit: Vanessa Bailey

Another theory is that if the disc collapses quickly, perhaps it could spawn a huge planet — but it’s improbable that there is enough mass in the system for that to happen. Perhaps, the team says, this system is like a “mini binary star system”, with HD 106906 b being more or less a failed star of some sort. Yet there is at least one problem with that theory as well; the mass ratio of the planet and star is something like 1 to 100, and usually these scenarios occur in ratios of 1 to 10 or less.

“A binary star system can be formed when two adjacent clumps of gas collapse more or less independently to form stars, and these stars are close enough to each other to exert a mutual gravitation attraction and bind them together in an orbit,” Bailey stated.

“It is possible that in the case of the HD 106906 system the star and planet collapsed independently from clumps of gas, but for some reason the planet’s progenitor clump was starved for material and never grew large enough to ignite and become a star.”

Young binarys stars: Image credit: NASA

Young binary stars: Image credit: NASA

Besides puzzling out how HD 106906 b came to be, astronomers are also interested in the system because they can clearly see leftovers or a debris disk from the system’s formation. By studying this system further, astronomers hope to figure out more about how young planets evolve.

At 2,700 degrees Fahrenheit (1,500 degrees Celsius), the planet is most easily visible in infrared. The heat is from when the planet was first coalescing, astronomers said.

The astronomers spotted the planet using the Magellan telescope at the European Southern Observatory’s Atacama Desert in Chile. It was visible in both the Magellan Adaptive Optics (MagAO) system and Clio2 thermal infrared camera on the telescope. The planet was confirmed using Hubble Space Telescope images from eight years ago, as well as the FIRE spectrograph on Magellan that revealed more about the planet’s “nature and composition”, a press release stated.

The research paper is now available on the prepublishing site Arxiv and will be published in a future issue of Astrophysical Journal Letters.

Source: University of Arizona

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David English
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David English
December 6, 2013 11:02 AM

I have to say the quality of writing is getting very good! Reference to the papers is a great thing.

cptdavep
Member
cptdavep
December 6, 2013 11:34 AM

Could it be a rogue planet that was caught by the gravity of the star?

Bariman43
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Bariman43
December 6, 2013 4:49 PM

Considering the amount of heat coming off of the planet, that’s extremely unlikely. If it were a rogue, it would have cooled off from formation before it ever got captured. Here we can see temps indicative of early formation.

Dean Brown
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Dean Brown
December 8, 2013 6:36 AM

Perhaps it wasn’t rogue very long. Or maybe a near-rogue, just teetering on the line of breaking free from the formation of the system, and then thought -‘nah stuff this for a lark, too much effort’.
Or got dragged back in.

Brandyn
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Brandyn
December 6, 2013 1:06 PM

I agree, rogue planet seems to be the most likely case. Can’t believe astronomers who make a profession on the study of space failed to think of that possibility.

Bariman43
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Bariman43
December 6, 2013 4:46 PM

Here’s a hint for how to be successful in life: stop pretending to know more than the people who make this their career. Those people didn’t spend 6+ years of their life earning their degrees for some random internet person to come by and present his own hypotheses as immediate fact. Watch yourself.

angel wines
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angel wines
December 7, 2013 10:39 AM

no offense,but there are alot of smart people who can figure this out better than someone with a so called degree…

Lorin Ionita
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Lorin Ionita
December 9, 2013 2:29 AM

Yes there are… but I doubt those scientists have just a “so called degree”

magnus.nyborg
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magnus.nyborg
December 7, 2013 12:56 PM

Assessing likelyhood without performing an actual analysis seems assinine to me…
Besides, likelyhood does not imply what the actual case is, something proffesionals learn.

alan martin
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alan martin
December 6, 2013 1:56 PM

On the Origin of Planets at Very Wide Orbits from the Recapture of Free Floating Planets

http://arxiv.org/abs/1202.2362

person3triple0
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person3triple0
December 6, 2013 4:10 PM

The planet may have been caught in the star’s debris field and was then bombarded by said debris, causing the planet to slow enough to form an orbit. I wouldn’t be surprised if we found out the planet was on the very edge of the Star’s influence. The planet was probably from a nearby system that recently went supernova, probably 5-8mil years ago. The loss of gravity would’ve sent the planet at a constant speed straight into the path of this new system.

magnus.nyborg
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magnus.nyborg
December 7, 2013 12:53 PM

If the planet was an escapee from a nearby system, it would not be bound to this particular system and would continue on its way alone. Orbital capture requires a 3rd object interacting.

person3triple0
Guest
person3triple0
December 8, 2013 9:28 AM

The third object you mention is the debris orbiting the star. The closer that planet comes to the star, the more matter it encounters and collects. Eventually, the mass would increase the Gravitational attraction between the planet and the star enough to hold the planet in order. There may also have been celestial bodies involved, such as a stray comet or asteroid.

magnus.nyborg
Guest
magnus.nyborg
December 9, 2013 11:00 AM
The debris must both be of comparable mass to the planet, and interact directly with the planet (most likely ejected from the system) in order for the planet to become gravitationally bound. I am sorry, but I dont see this as a probable conjecture. The planet is too massive, and too far away from the star, and with a lack of supporting evidence in favor of capture. Not ruled out, just not probable. Be aware that 1 Jupiter mass of debris being ejected could fail at gravitationally capturing this planet. If indeed the planet is orbiting ofc, if it is a rogue nearby planet then ofc it might simply be on its way elsewhere. But then it still… Read more »
Wouter Vanbelleghem
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Wouter Vanbelleghem
December 6, 2013 4:29 PM

Well if it is a rogue planet, how do you explain the heat? Rogue, being a planet swung out of it host system, must have traversed “cold dead space”…

what about a rogue “failed binary star”? I never see someone offer this as an explanation… they talk about rogue planets, but what about a failed star in a binary system that got swung out of that system into this one (a rogue star?)

fabuchachi
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fabuchachi
December 6, 2013 9:56 PM

The universe never fails to surprise us.

Dav_Daddy
Member
December 6, 2013 11:47 PM

My guess would be a small brown dwarf that got caught up by the star.

Isn’t 12 X Jupiter mass about where the planet/star boundary is usually at when we find something that isn’t bound to another star?

ProfressorDetective
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ProfressorDetective
December 7, 2013 2:08 PM

#GallifreyFallsNoMore

hyperion8
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hyperion8
December 7, 2013 6:06 PM

That’s no moon. It’s a space station!

InTheory
Member
InTheory
December 7, 2013 8:15 PM

It’ll be interesting to see what further observations show us. I’d be interested to learn of the eccentricity of HD 106906 b’s orbit and if there any other large bodies in the system. It would also be interesting to watch HD 106906 b carefully to see if there’s anything large orbiting it.

Snowball Solar System
Member
Snowball Solar System
December 9, 2013 2:54 AM
Alternative Gas Planet Formation Mechanism: The distance of the gas giant merely represents the angular momentum of the system; however, neither core accretion or disk instability will accommodate this distance for an isolated planet, and the planet/star size ratio is prohibitively small for direct wide-binary formation by gravitational instability within the bok globule. So we may be seeing the degenerate end product of a more complex solar system that created this outcome. The large amount of angular momentum in this system would typically spawn a binary star system in which excess angular momentum would have caused the collapsing bok globule to fragment into a close-binary protostar. But even after fragmenting, contracting binary protostars must rid themselves of additional… Read more »
Sam Cashion
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Sam Cashion
December 9, 2013 4:59 AM

Could this have anything to do with the “halo of oligarchs” theory? It’s the only extant theory I can think of that resembles this at all. However, “oligarchs” are supposed to be even farther away from their parent stars, if I remember correctly.

zig rivers
Guest
zig rivers
December 10, 2013 1:29 AM

I’m trying to understand this.

if it is so far from the star, how do they know is is not free floating and not orbiting anything? that ‘orbit; is so huge how can they determine this since it would take hundreds of years to make a single transit around once

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