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## Massive Exoplanet Discovered, Challenges Established Planet Formation Theories129

sfcrazy writes "A giant exoplanet that is in the most distant orbit ever seen around its host star, has been recently discovered. Dubbed HD 106906 b, the newly discovered planet is relatively young (13 million years old, compare this to our 4.5 billion years old Earth) and bigger than any other planet discovered till date. It is 11 times the size of Jupiter, and that's what makes it a most singular discovery."
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## Massive Exoplanet Discovered, Challenges Established Planet Formation Theories

• #### Can someone who knows about astronomy fill me in? (Score:5, Interesting)

on Monday December 09, 2013 @10:45AM (#45639169)
How do astronomers calculate the age of a distant planet? I can see how they'd get distance from host star (orbital period) and mass (displacement of host star) but how on earth do you work out the age?
• #### Re:Can someone who knows about astronomy fill me i (Score:5, Funny)

on Monday December 09, 2013 @10:50AM (#45639215) Homepage Journal

By counting the rings, obviously ;)

• #### Re: (Score:1)

That only works if you can cut it in half first.

• #### Re:Can someone who knows about astronomy fill me i (Score:4, Insightful)

on Monday December 09, 2013 @10:53AM (#45639247)

Guesswork. They take what they think they know and use it to make a guess that will change every time they find out what they thought they knew was wrong. It's fun to follow but don't put too much faith in it.

• #### Re: (Score:2, Insightful)

by Anonymous Coward

If you don't have any information to provide, please don't try to act like you do.

"They take what they think they know and use it to make a guess"

Thanks for that brilliant insight.

• #### Re: (Score:2)

Am I wrong? It's exactly what happens. A guess based on the slimmest of knowledge. I can't count how many times I've seen these sudden bursts of enlightenment get changed when everything they thought they knew gets turned upside down. It's a guess and only by the loosest term an educated one. I'm sorry if the facts hurt your feelings.

• #### Re:Can someone who knows about astronomy fill me i (Score:4, Funny)

on Monday December 09, 2013 @10:54AM (#45639251) Homepage
• #### Re:Can someone who knows about astronomy fill me i (Score:5, Informative)

on Monday December 09, 2013 @10:55AM (#45639269)
• #### Re:Can someone who knows about astronomy fill me i (Score:5, Interesting)

on Monday December 09, 2013 @11:41AM (#45639803)
Nice article, but that only says how they get the age of a star. I suppose that puts an upper limit on the age of the planet.
• #### Re: (Score:1)

Nice article, but that only says how they get the age of a star. I suppose that puts an upper limit on the age of the planet.

More than an upper limit. Unless the planet is a captured rogue, knowing the age of the star gives you the age of the planet, pretty much. If you know the age of someone's heart, you know the age of their head, too (transplant patients excepted).

• #### Re: (Score:2)

Couldn't a pre-existing planet be captured by a new star? I can imagine a situation where a star going dark sends its planets drifting through deep space only to be captured again later.

• #### Re: Can someone who knows about astronomy fill me (Score:1)

Even if it's dark, it's star would still be there, same mass bending space time to form a gravity well. If tinge star blew up, it would probably destroy the planet. If it escaped, you have an 11 jupiter sized bowling ball just waiting to be captured by another star, at just the right angle for a stable orbit?
• #### Re: (Score:2)

In a huge universe, anything's possible ...

• #### Re: (Score:3)

How do astronomers calculate the age of a distant planet? I can see how they'd get distance from host star (orbital period) and mass (displacement of host star) but how on earth do you work out the age?

They can't accurately predict it to a degree of 100% certainty. However they can guess based on it's radiation level and it's decay of said rad signal. They can also compare it to surrounding star systems and see if they have been influenced for an extended period of time or more recent (recent as in millions of years ago instead of billions of years).

It's not an exact science but at least it gives them a ballpark figure until they can manage to actually get to that planet and get samples. However, that

• #### Re: (Score:3)

The problem in this case is that the discovery supposedly has the potential to challenge existing planet formation theories. If that is true, then the methodology to calculate this planet's age may be flawed.

• #### Re:Can someone who knows about astronomy fill me i (Score:5, Informative)

on Monday December 09, 2013 @11:47AM (#45639869)

OK I answered my own question with some googling.

The age of the exoplanet is not independently derived, but instead, taken from the age of the host star. This too can be difficult to determine. For isolated stars, there are precious few methods (such as gyrochronology) and they generally have large errors associated with them. Thus, instead of looking for isolated stars, astronomers searching for young exoplanets have tended to focus on clusters which can be dated more easily using the main sequence turn off method.

http://www.universetoday.com/76495/the-hunt-for-young-exoplanets/ [universetoday.com]

• #### Re: (Score:2)

A paper by Bailey et al. is here... http://arxiv.org/abs/1312.1265

The age is estimated from the primary star. Presumably the system formed all at the same time, star and planet together. (It's difficult to gain a planet in some other way, such as "capture," especially in such a short period of time since the star's birth.)

The planet's mass is estimated from the brightness and color of the planet. HD 106906 b is a rare case where the companion can be resolved from its primary so a spectrum can be measure

• #### Re: (Score:2)

I'm guessing you meant 1800 arcseconds, unless the moon really let itself go while I wasn't looking and is now several thousand light years across. :)

• #### Re: (Score:3)

but how on earth do you work out the age?

Umm, the same way you work it out on other planets??

[ducks]

• #### Upper limit on planets? Lower limit on stars (Score:2)

Becoming a star requires at a minimum many times the mass of jupiter. As small stars exist, there's therefore a likelihood that there are gas giants almost as big a the minimum to make a star.

A quick google seems to suggest that's 8% the size of the son

As Jupiter is 0.1% size the son, 11x the size of jupiter doesn't seem that big. We should be able to find "planets" up to almost 80x larger

• #### Re:Upper limit on planets? Lower limit on stars (Score:4, Funny)

by Anonymous Coward on Monday December 09, 2013 @11:02AM (#45639337)

that's 8% the size of the son

Or 0.003% the size of yo momma.

• #### Re:Upper limit on planets? Lower limit on stars (Score:4, Funny)

on Monday December 09, 2013 @12:00PM (#45640021)

Yo mama so fat, if she was any bigger she'd start fusing hydrogen.

• #### Re: (Score:2)

Yo mama so fat, if she was any bigger she'd start fusing hydrogen.

Yo momma SO fat, every time I am done visiting her, I have to break orbit.

• #### Re: (Score:2)

Wikipedia says that at 13 times the size of juptiter you get something that can ignite and you get a brown dwarf.. How that is calculated is beyond me..

• #### Re: (Score:1)

My brown dwarfs are typically much smaller than that.
• #### Re: (Score:2)

the Tall Man can do custom orders?

• #### Re:Upper limit on planets? Lower limit on stars (Score:5, Informative)

on Monday December 09, 2013 @12:07PM (#45640075)

That's the mass threshold for deuterium fusion. No fusion = planet, deuterium fusion = brown dwarf, hydrogen fusion = main sequence star.

So at 11 Jovian masses, the planet is close, but not quite big enough to reach brown dwarf status.

• #### Re: (Score:2)

How that is calculated is beyond me

A certain amount of mass equals a certain amount of pressure, which is what's required to start hydrogen fusing.

• #### Re: (Score:2)

Wikipedia says that at 13 times the size of juptiter you get something that can ignite and you get a brown dwarf.. How that is calculated is beyond me..

From hydrostatics: the more mass you build up, the higher the pressure --and the temperature-- becomes in the core, and then you reach a point where the temperature is high enough to start fusing stuff up (as per definition of 'a star'). This, for hydrogen, happens at some mass limit or other which is at around a few Jupiter masses.

It is a back-of-the-envelope calculation really, though there are a few other, more sophisticated models, around.

• #### Re:Upper limit on planets? Lower limit on stars (Score:5, Interesting)

on Monday December 09, 2013 @11:10AM (#45639419)

Well, mass and size get thrown around a lot semi-interchangeably which they're most definitely not.

80x the MASS of Jupiter and something becomes a star, but the established theory IIRC was that until you get to that point you keep cramming things in and the planet itself just kinda compresses more and doesn't get much bigger than Jupiter. If it ever gets big enough to become a star and achieve fusion then the pressure pushes it out and then it gets better.

So if it is as the summary says and the planet is literally 11 times the size of Jupiter then that's quite a find. It basically says that there's either something wrong with either a) our understanding of planet formation or b) there's something wrong with how we measured this and the data is just wrong.

If its 11 times the mass then yeah - kind of boring and expected.

• #### Re:Upper limit on planets? Lower limit on stars (Score:4, Funny)

on Monday December 09, 2013 @11:54AM (#45639973)

"If it ever gets big enough to become a star and achieve fusion then the pressure pushes it out and then it gets better."

Unless you live there. Then it gets worse. Much worse.

• #### Re: (Score:2)

Ah. Typing goof. Meant to say bigger, not better. Often times those are as misused as the mass and size situation though :).

• #### Re: (Score:2)

So if it is as the summary says and the planet is literally 11 times the size of Jupiter then that's quite a find. It basically says that there's either something wrong with either a) our understanding of planet formation or b) there's something wrong with how we measured this and the data is just wrong.

Maybe it's just 11x closer than they think it is, and moving away faster than expected. Would still be an interesting system to find.

• #### Re: (Score:3)

Bad summary. The point of the article is that:

- the distance the planet is orbiting its primary is much farther out than current planet formation theories support.
- the planet is not massive enough compared to the primary to fit the theories on binary star formation.

• #### Re: (Score:2)

Becoming a star requires at a minimum many times the mass of jupiter. As small stars exist, there's therefore a likelihood that there are gas giants almost as big a the minimum to make a star.

A quick google seems to suggest that's 8% the size of the son

As Jupiter is 0.1% size the son, 11x the size of jupiter doesn't seem that big. We should be able to find "planets" up to almost 80x larger

Those are objects known as Brown Dwarfs which would put them at a different category than Jovian planet. I believe that the minimum mass to establish fusion is something on the order of one tenth solar mass. Brown Dwarves radiate Infared radiation due to heat from residual gravitational collapse. Presumably the standard is considerably higher than Jupiter which also radiates more heat than it absorbs from the Sun.

• #### Re: (Score:2)

Brown dwarfs are substellar objects too low in mass to sustain hydrogen-1 fusion reactions in their cores, unlike main-sequence stars, which can. They occupy the mass range between the heaviest gas giants and the lightest stars, with an upper limit around 75[1] to 80 Jupiter masses (MJ). Brown dwarfs heavier than about 13 MJ are thought to fuse deuterium and those above ~65 MJ, fuse lithium as well.[2] Brown dwarf [wikipedia.org]

There is a class of objects between planets and red dwarf binaries.

• #### 11 times the size of Jupiter? (Score:2)

The Gravity must be immense, we'll need to ban their Olympic athletes from participating in the summer games.

• #### Re:11 times the size of Jupiter? (Score:5, Informative)

on Monday December 09, 2013 @11:30AM (#45639655)

If it's 11 times the diameter, then gravity would be pretty tame at the surface unless it's extremely dense. For example, Jupiter's diameter is 11.2 times that of Earth, but the surface gravity is only 2.64 times that of Earth. Saturn and Uranus both have equatorial surface gravities roughly equal to Venus, in spite of being 9.44 and 4 Earth diameters, respectively.

Source: http://www.windows2universe.org/our_solar_system/planets_table.html [windows2universe.org]

• #### Re: (Score:2)

If it's 11 times the diameter

It's not - it's 11 times the mass.

• #### So if we send out the black monolith now (Score:1)

it should get there at just about the right time to teach the pre-dawn humans about the wonders of violence. How about instead we fill this one with Youtube cat videos and see how the planet evolves?
• #### Re: (Score:3)

It's been done. Except when it came their turn to do it, they sent back telephone sanitization kits.

• #### That's no Exoplanet! (Score:2)

Just kidding . . . but, seriously, I am really not looking forward to when they actually do discover a death star . . .
• #### Re: (Score:2)

So your guess on humanity's reaction to discovering a stellar engine, ringworld or similar megastructure would be...?

• #### Is is most singular is right (Score:1)

by Anonymous Coward

whatever that means.

• #### Huh? (Score:3)

"Most singular" does not mean anything. It's gratuitous gibberish.

Most is a superlative, it only makes sense when comparing 3 or more things (plural.) No comparing was being done here, and "singular" is a word whose meaning allows no opportunity to augment it with a superlative. There is no more or less singular, no least or most singular, singular is simply singular.

It's not exactly shocking to see poor English in a slashdot writeup, but this one manages to be even worse than expected.

• #### Re: (Score:1)

That was a most satisfying demonstration that your pedantry outstrips your knowledge of the English language./pL

• #### Singular discovery (Score:2)

It is 11 times the mass [FTFY] of Jupiter, and that's what makes it a most singular discovery.

Much as I enjoy the Sherlockian prose, every time we discover a new most massive planet, it's going to be a singular discovery.

The missing context here is: how massive was the previous recorder holder?

• #### Not size - mass (Score:2)

It is 11 times the size of Jupiter, and that's what makes it a most singular discovery.

Oh dear. Do we have to have the talk again?

• #### Re: (Score:2)

Whooops. Yes, sorry. See comment below. :(

• #### Size? (Score:2)

I wonder, when astronomers say 11 times the size of Jupiter, does that mean 11 times the radius, the mass, or that you could fill the sphere of its volume with 11 jupiters? Or the circle area as seen from earth?

• #### Re: (Score:2)

In order to answer this, I plugged "size" into a dictionary and used the result easiest to work with.

"2. each of the classes, typically numbered, into which garments or other articles are divided according to how large they are.
"I can never find anything in my size""

In other words, if Jupiter wears size 10 pants, this new planet wears size 110. Fatass spacerock needs to lay off the Mars bars.

• #### Re: (Score:2)

I expect astronomers would normally specify mass or radius/diameter rather than use size ambiguously. And the article doesn't use the word size, so can't fault the journalist. Summary writers, however ...

(11 x mass BTW)

• #### Re: (Score:2)

I wonder, when astronomers say 11 times the size of Jupiter, does that mean 11 times the radius, the mass, or that you could fill the sphere of its volume with 11 jupiters? Or the circle area as seen from earth?

It would always be by mass, since it's pretty much nearly impossible to actually get a reading on the radius. Also physics pretty much determines what happens when you've got a gas giant of that mass.

• #### Re: (Score:2)

I hereby name this planet, Planet Enzyte.

• #### Of course planet formation theory will need fixing (Score:2)

As the set of planets grows, theories will have to change as we have based the original ones on a single sample that may or may not be representative of the full set.

It's like basing an entire theory of construction of buildings on De Aar, South Africa and while it may explain most small towns, the suburbs of most cities, it will fall apart completely when you try and explain Manhatten or wooden houses in the US with it.

• #### Re: (Score:1)

This object is in an ugly middle between being a separate star or just a planet. Are there any models that consider both star and planet formation as the same process? If we built our programs to model one or the other, it's easy to see why we wouldn't have predicted distant but non-fusing binary partners. Note, it seems that 650 AU is quite distant even for a binary companion, alpha centauri A and B wobble between 16-32 or so AU between them, and have a larger orbit than most.
• #### headline isn't quite correct (Score:5, Informative)

<thebadastronomer@nOsPam.gmail.com> on Monday December 09, 2013 @12:08PM (#45640083) Homepage
The headline as submitted isn't really correct. The planet is not the biggest found; there are several whose mass may be larger, like the exoplanets announced just last week (and this planet has 11 times the mass of Jupiter; we don't know its actual size). The real issue with HD 106906 b is that it is so far out from its parent star, much farther out than planets with that ass should form. Either it formed farther in and got tossed out (which is unlikely) or it formed where it was, which current theories say is difficult; usually objects forming that far out have much higher mass. I explain all this in my own blog post about it [slate.com].
• #### Very Young (Score:3)

on Monday December 09, 2013 @12:23PM (#45640279)

So are you saying it's a Day Zero Exoplanet?

• #### How old is the star? (Score:2)

I read both articles but did not see how old the star it's orbiting is. Pardon me if I missed it, I just woke up. It sounds to me like a failed star from the same general region drifted into the gravity well of the star in question, and found a cozy place that far out. Even if the star it is orbiting is much older, they could have still formed from the same gas cloud. Just because it has taken up orbit, does not mean formed there. Perhaps it's mass results in some kind of wild slingshot orbit... perhaps, pe
• #### Re: (Score:2)

If it had drifted in it would have a rather non-circular (eccentric) orbit.

And because this planet seems to have a regular orbit we can consider it formed at the same time it's sun was formed, that's what solar systems typically do.

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