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Strange New 'Twin' Worlds Found
toomanyairmiles writes "The BBC reports on the the discovery of 'twin worlds' which orbit each other, successfully blurring the line between planets and stars. 'Their existence challenges current theories about the formation of planets and stars.' according to the Journal of Science article which reports their existence. 'The pair belongs to what some astronomers believe is a new class of planet-like objects floating through space; so-called planetary mass objects, or "planemos", which are not bound to stars.'"
Stars can only 'ignite' when enough mass accumulates. It would make sense that often there would be chunks of smaller mass just floating around until they scoop up enough matter into their gravity well to start fusion.
Other extra-solar planets were dicovered when the astronomers saw the doppler shift in their stars. These planets do not orbit stars (as far as I can tell from the article) so there's no light to see them and there isn't a star to see any "shifts". So how were these stars discovered? X-Rays? What?
Ok so our Solar System is mostly flat. I mean, the orbits of the planets tend to follow the same orbital plane, with a notable exception of course.
The reason the planets orbit in the same plane is the same reason rings around celestial bodies like Saturn eventually fall into a common orbital plane: gravity. As the mass collects there is something like a gyroscopic effect, causing a general influence towards the common plane.
But.. if that's the case, why do we have a planet that doesn't follow the plane? And, also, is it slowly falling into line with the rest? (I think the answer is yes, it is, but I don't know for sure.. at least I think it should be).
Which leads me to ask.. Was Pluto originally extra-solar? Could it have developed in this eccentric orbit if it were originally part of the solar system when it formed? Is it possible that Pluto somehow, amongst the billions of years our system has been around, floated into orbit here for good, from Out There?
And if so, if there are enough of these free-floating masses out there, what kind of percentage of the unobservable 'dark matter' might this account for?
Just a few of my questions,
TLF
I do not respond to cowards. Especially anonymous ones.
On the somewhat off-topic of dark matter, what is the big deal with scientists searching for all this matter that we can't see? Perhaps I'm missing something really important here, but why is it so important that there might be all this matter in the universe that we can't currently detect? So what if it doesn't glow, or emit x-rays, etc. Aren't we dark matter? It stands to reason to me that the majority of mass in the universe probably isn't glowing or burning, or emitting some cosmic ray that we can detect here on earth. Can somebody with a real clue on this subject chime in, tell me i'm an idiot, and why?
I dont like the name one bit... they have NOTHING to do with planets... they are stelar objects whos mass is simply to low to get their internal temperature high enough for hydrogen fusion.
IMHO better names would be: stellar dwarfs, non-fusion stars or something along those lines... they arnt planets.
The problem is collapsing the nebula to form the planemo. The prevailing logic is that this collapse mainly occurs in large gas clouds (like the Orion Nebula) and produces loose clusters of stars (like the Pleiades). The paradigm is that clumps of gas collapse under self-gravity, but these planemos would not have been sufficiently massive to have formed in this manner.
btw, kudos to RayJay.
This discovery does have some implications about how these very small objects form. The two theories are essentially (1) they form from very small clumps of dust and gas, just like our sun did but the initial clump is much smaller or (2) they started out as a larger clump, but while they are still trying to accrete much of their mass, a gravitational interaction with a larger star flings them away from the molecular cloud they were born in. Away from the main molecular cloud their is less material for them to accrete and they do not build up as much mass.
Now, if there was a gravitational interaction most binaries (like this one) would have been broken apart. Astronomers also see evidence for dusty disks around some of these small objects, which would be mostly destroyed if there was an interaction. I'm sure the theorists supporting 2 have some clever idea to explain all this but the evidence right now seem to point towards theory 1.
Although it's interesting that we've now been able to observe such a pair of dim objects in this configuration, I see nothing strange about its existence. Astronomers have known about binary (and trinary) star systems for ages, but those were always easy to spot because they're so luminous. Brown dwarfs, on the other hand, are much harder to find, but thanks to modern technology we've found quite a few and astronomers now believe that they are in general quite numerous. So, what's so strange about two brown dwarfs orbiting one another? Nothing, really. It may be the first time we've found a binary system like this, sure -- great! -- but it's not strange at all; that's just an adjective thrown in by the media to spice the story.