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Planets can be spawned in the same way as stars
by Marcus Chown
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x Marcus Chown   - at 1:19 am on Thursday November 27 2003 x
x The process by which planets are made x
x Marcus Chown our solar system USA - Planets can be spawned by the same process that makes stars, say astronomers who have discovered a developing planet floating alone in a stellar nursery.

"It's a planet but it has all the hallmarks of an embryonic star," says Jane Greaves of the Royal Observatory in Edinburgh (ROE).

Until recently, it was thought that planets could only build up, or "accrete", from gas and dust swirling in a disc around a newborn star. But everything changed in 2000 with the discovery of isolated planets without parent stars in the Sigma Orionis star cluster. "Their existence strongly suggested there was another way of making planets," says Greaves.

Now, Greaves and ROE colleague Wayne Holland, together with Marc Pound of the University of Maryland at College Park, have looked at the Rho Ophiuchus B star-forming region, which is 500 light years away, only one-third as far from us as the famous star nursery of the Orion nebula.

Using the James Clerk Maxwell Telescope in Hawaii, they have found a dozen isolated planetary objects, including one they have named Rho Ophiuchus B-11, an object nine times the mass of Jupiter.

Jet stream

Crucially, the astronomers have seen evidence of a "bipolar outflow", a fast stream of gas jetting from the polar regions of Rho Ophiuchus B-11.

"This is a key characteristic of forming stars," says Greaves. "Though Rho Ophiuchus B11 is planet-sized, it is in the process of condensing from an isolated gas cloud in exactly the same way as a young star." This poses a big mystery, because gas clouds condense into dense objects only when the gravity trying to shrink the cloud is greater than the force of the hot gas pushing outwards.

"The gravity of objects as small as Rho Ophiuchus B-11 would appear to be too weak to overcome the outward gas pressure," says Greaves. Some unknown factor must be at work here, she suggests.

If the team is right, it means that a single process can make bodies all the way from planets with just one per cent of the mass of the Sun, equivalent to the mass of Jupiter, to stars 10 times the mass of the Sun.

It is also possible that the planets observed by the team began forming in discs around stars and were then catapulted into the void by close encounters with sibling planets.

However, Greaves says the fact that orphan planets are so common in Rho Ophiuchus B makes this unlikely. In fact, there are so many, say the astronomers, that there could be as many lone planets as stars wandering in our galaxy.





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Journal reference: Monthly Notices of the Royal Astronomical Society (vol 346, p 441)
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x Unread post xjj_4487   - at 1:19 am on Thursday November 27 2003 x
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x jj_4487 I really am bored...

Oh well, enjoy the latest dtring of articles smile
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x x View the profile for jj_4487 x
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x Unread post xZoe   - at 5:21 am on Thursday November 27 2003 x
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x Zoe i think the colours on the planets look amazing

all pwetty
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x x View the profile for Zoe x
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x Unread post xSmila   - at 5:23 am on Thursday November 27 2003 x
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x Smila space is my fav topic.....we should explore our minds with space trivia.....what is at the end of space....i know i know...its a wall...but whats beyond the wall.....i know i know......heaven.....but whats beyond etc etc etc fuck off smila
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x x View the profile for Smila x
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x Unread post xjj_4487   - at 5:24 am on Thursday November 27 2003 x
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x jj_4487 No, don't... I have an article on space and the formation of the universe, but I'm not yet awake enough to type it out.. it will be up by tomorrow if you're interested?
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x x View the profile for jj_4487 x
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x Unread post xSmila   - at 5:35 am on Thursday November 27 2003 x
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x Smila i truely truely truely love space topics.....i havent mentioned it before coz i thought it was too nerdy for UM but your my saviour......i know everything about space....only thing i havent done is gone there but maybe one day (looks up dreamily)......i sadly even know the names of all the satelites in order that have been put in orbit.....
smila's interesting fact no. 1)...on the surface of venus it is 260C
now theres a tan ready to happen
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x x View the profile for Smila x
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x Unread post xjj_4487   - at 5:41 am on Thursday November 27 2003 x
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x jj_4487 lol I'll put it up by tomorrow morning then, then we can have a nice debate smile
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x x View the profile for jj_4487 x
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x Unread post xxSmila   - at 5:46 am on Thursday November 27 2003 x
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x Smila i like MASS debating....i would make a good american senator.....right i'm off to work but before i go it thik UM deserves interesting fact no.2)
the whole origianl moon landing was a hoax and when i have time i'll tell you why
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x x View the profile for Smila x
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x Unread post xjj_4487   - at 5:47 am on Thursday November 27 2003 x
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x jj_4487 Yeah I'd be most interested to hear why that is so...
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x x View the profile for jj_4487 x
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