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back to article Galaxy is teeming with homeless planets

The galaxy – and presumably, if we’re in a normal-enough galaxy, the rest of the universe – has a bit less empty space than we thought, according to a study by the Kavli Institute for Particle Astrophysics (KIPAC). The research suggests the Milky Way could hold many millions of “nomad planets” – many thousands existing for each …

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How do they confirm the planet?

As I understand it they confirm planets they've spotted by the microlensing method by seeing regularly repeated events (at the orbital period of the planet). With nomad planets they would presumably see only a single event, so how do they confirm it isn't just a glitch?

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Re: How do they confirm the planet?

Perhaps by multiple observations of the microlensing event from different sites, followed by a sufficiently long period of no microlensing event, also confirmed by multiple sites?

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Re: Re: How do they confirm the planet?

Having glanced through a paper on this (http://arxiv.org/abs/1105.3544), it seems that they grab a series of images - the lensing varies with time (it brightens the background star), so they can plot the light received versus time and compare with models of what a lensing event should look like. The paper takes some time to discuss how they tried to cut out other events that look similar (supernovae, cataclysmic variables).

For completion, the paper the article is about is available at http://arxiv.org/abs/1201.2687 (not all their references are about gravitational microlensing - Bihain et al 2009 seems to have chosen to look in the infrared to find suitably cool objects)

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Re: Re: How do they confirm the planet?

They could do that if they had sufficient warning of the event to train a lot of instruments on it. But since it's effectively random there's no way to predict it. You have to know that the planet is there before you can look for the planet!

Also these events are often a *long* way away - it works much further than the other planet-finding methods. So there would be very little difference between different observations.

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Boffin

Does this answer some of that unexplained mass

Wasn't one reason for dark matter to explain the fact that galaxies are heavier than they look. Maybe some of it is just rock.

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Re: Does this answer some of that unexplained mass

I've often wondered about this - just because it's missing doesn't necessarily mean it has to be something exotic, right?

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Holmes

Re: Re: Does this answer some of that unexplained mass

Yes and No! We are talking MACHOs. But there are limits on these...

See

http://en.wikipedia.org/wiki/Baryonic_dark_matter

http://en.wikipedia.org/wiki/Nonbaryonic_dark_matter

"A small proportion of dark matter may be baryonic dark matter: astronomical bodies, such as massive compact halo objects, that are composed of ordinary matter but which emit little or no electromagnetic radiation. Consistency with other observations indicates that the vast majority of dark matter in the universe cannot be baryons, and is thus not formed out of atoms. It also cannot interact with ordinary matter via electromagnetic forces; in particular, dark matter particles do not carry any electric charge."

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Re: Does this answer some of that unexplained mass

Those planets (MACHOs) can explain just some of the dark matter.

From the analysis of the Cosmic Microwave Background radiation, we know that barionic (normal) matter is just 5% of the matter-energy of the universe, while gravitational matter is around 30%. So most of the matter of the universe has to be some kind of exotic (non baryonic) matter.

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Re: Re: Re: Does this answer some of that unexplained mass

Maybe discoveries such as this will prompt new thought on these THEORIES.

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Re: Does this answer some of that unexplained mass

It might, however it would help explaining the trend to concentrate more on the outskirts of the spiral galaxies. Since this is what you have to accept to save Kepler's Laws (more precisely, its modification for the spread-out mass of the galactic mass)

PS Yes and see other comments about more reasons.

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@myself

I meant to say "it would NOT help explain the trend of the DM to..."

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Coat

Re: Does this answer some of that unexplained mass

Well, a nomad planet is going to be mainly rock (solid, maybe a liquid rock/metal core) but since it's got to be pretty far from any stars, yeah, that would make it quite dark. And matter.

Mines the one with baryonic decontamination scanner in the pocket.

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FAIL

Well, duh!

The shadows aren't invisible planets, they're Dalek Motherships assembling for the exit of Amy and Rory...

You know it's gonna be Daleks...

nK

</coat>

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Coat

Re: Well, duh!

Daleks? There's some Cybermen from Mondas here who disagree...!

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Makes sense...

Planetes (πλανητες) originally meant Wanderer after all

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Re: Makes sense...

So you are postulating that the ancient Greeks knew about these nomad planets (and hence came up with the name planetes) and that modern science is only now catching up with them?

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Windows

Re: Re: Makes sense...

Of course he isn't, don't be silly. He's postulating that the Greeks knew about dark matter and were offering huge grants to anyone who could write papers on it.

The papers were all lost in one of the many sackings of Alexandria. Nobody cared.

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Unhappy

Re: Re: Re: Makes sense...

Bad news if you've written a paper on dark matter. The Greeks haven't any money left.

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Mushroom

Re: Re: Makes sense... @Condiment

I think you forgot the Sarcastic icon on your post...it's obvious that some people need to get out more...

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Windows

Easy to spot surely

Just look for where they stash their cardboard boxes at night time.

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Bloody migrant planets

Coming over here, stealing all our sunshine. They should piss off back to the Orion Nebula where they came from, etc.

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Joke

"Honey, do you remember where we parked the planet?"

Beep Boop

"Ahh nm found it with the keyfob..."

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Joke

Well it is 2012 after all..

...the boffins just need to look behind the sun to find the nearest wandering planet that's about to destroy all life as we know it... apparently....

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Coat

Death Stars.

Obviously.

Daleks indeed.

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I'm not surprised

In star formation, supergiant stars like Rigel and Deneb are rare but massive, then as you go down the Hertzsprung-Russell diagram (W to O to B to A to F to G to K to M) the star types become more common as mass/size/brightness decreases. Blue B-type stars like Rigel are less common than G-stars like the Sun; stars like the Sun are less common than M-type red dwarfs like Wolf 359 or Proxima Centauri.

The numbers increase exponentially, too: for every Rigel there's a thousand Suns, but a million Proxima Centauris.

So it follows that if smaller = a LOT more common, then it's logical that free-formed planet-sized bodies should outnumber stars, even red dwarfs, by thousands to one.

By this hypothesis, many, if not most of these planets are quite likely to have formed independently of any star system, rather than having been expelled from one in the early stages of it's formation. This is borne out by the sheer number of them alluded to in the article; if they all came from star systems, there would be thousands of planets per star, which is not feasible.

Without nearby stars to blow off their atmospheres with stellar wind during their formation, these planets are also likely to have immense, nebulous atmospheres tens or even hundreds of thousands of kilometres deep, such that their outer surfaces may be far less distinguishable than even Jupiter or Saturn's. A photo of such a world would be an intriguing sight indeed.

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Re: I'm not surprised

"A photo of such a world would be an intriguing sight indeed."

Sez you. The opinion of those forced to sit through your slideshow of "wandering planets I saw on my hols" may differ.

Mine's the one with the projector, screen and two boxes of 35mm colour slides of a family holiday in Alicante in the pocket......

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Re: I'm not surprised

LOL! Makes me think of Moonbase Alpha....

Maybe the chafing film producers just got a new spin from you to start their re-imagined Space: 1999. Maybe in this case, descendants abandoned the Moon and moved on to a planet the Moon gravitated toward, but then the Moon disintegrated after most of the transfer is finished...

IIRC, a similar revival idea is out there, on Youtube...

Of course, by this point, I'm re-reading your post about the atmosphere being immensely thick.

It would be interesting to find nomad planets without any tidal-lock effects but having oceans and vegetation on spectral scans/images. Even without any signs of more than vegetation, that would be an IMMENSELY profound catalyst for rethinking science as we know it.

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Mushroom

No reference to Flash Gordon???

Mongo is coming...

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Coat

Re: No reference to Flash Gordon???

Mongo is coming...

No.

Mongo straight.

Guess which DVD's in my pocket?

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Re: Re: No reference to Flash Gordon???

Mongo only pawn in game of life...

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Re: Re: Re: No reference to Flash Gordon???

If you shoot him, you'll just make him mad.

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Wandering star?

Uh ... Shirley you were discussing wandering planets?

Not exactly the same thing ...

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xyz
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Niburu; the pikey planet?

So....the universe is full of these gyppo planets just roaming about looking for trouble and you can't really see them until they show up on your doorstep trying to nip off with your orbit or tarmac your moon. Maybe the Mayans were right all along.

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Nibiru related theory?

It is a very interesting theory but in the end I get the idea its nothing more but a wild educated guess. After all; we also used to have the idea that a solar system would only consist of one star with a few planets, but in the mean time we've also witnesses systems which had 2 stars.

If the scenario of 2 stars is possible, then it wouldn't surprise me if it would also be possible for 2 solar systems to "intermingle" with each other. In other words; sharing a part of space. I'm not familiar with the full math equations here, but it is possible for an object to escape gravitational forces by sheer momentum. And if this would happen in the far outer regions of a solar system then the effect could be so minimal that such a situation could be sustained for a long time.

Still, if this theory does turn out to hold truth then it would be a boon for the Nibiru theorists. As such I also can't help wonder if this new theory is related to it.

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Re: Nibiru related theory?

You made me look up Nibiru on Wikipedia.

I want the last two minutes of my life back.

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Re: Re: Nibiru related theory?

No, Dan 55, you made you look up Nibiru on the wikithingy.

As penance: Nothing better than Bass Ale for a fortnight.

Next time, use a proper library ...

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Re: Nibiru related theory?

" I'm not familiar with the full math equations here"

Get familiar. They do not support your flight of fancy at all.

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Re: Re: Re: Nibiru related theory?

Surely that is a 'Cruel and unusual punishment' and against some sort of convention or human rights or some other 'let's be nice to people' law. I'm not sure even the BOFH would stoop that low!

.

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Trollface

@jake

You got me until you said I should look up Nibiru in "a proper library".

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@Dan 55

You have issues with proper research?

Ok. Carry on.

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Happy

A reason

for the wandering bits and pieces, space 1999 perhaps?

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Anonymous Coward

oooerrr

anyone remmeber the film 'when worlds collide'? I hope none of those wandering planets are called Bella....

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Anonymous Coward

Looks like Lars von Trier was ahead of the curve on this on

Hopefully, Melancholia won't be coming our way ...

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Re: Poul Anderson used these things as plot points twice

I vaguely remember a scifi story I read in the '80s about a wandering planet that was outside the galactic disk, so the inhabitants had no concept of what "stars" were, and had immense culture shock when visited. Wish I could remember what it was called.

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Alien

Re: Re: Poul Anderson used these things as plot points twice

Crikkit?

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Mushroom

For The World Is Hollow & I Have The Sky

It's Mondas.

Z Bomb is not required.

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Meh

Melancholia here we come!

Splat! http://www.imdb.com/title/tt1527186/

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