Place: Deep space
Drifting Jupiter-sized planet.
Music: They call me the wanderer yeah the wanderer. I roam around around around...
A team of astronomers has identified a novel new kind of galactic wanderer - lone, Jupiter-sized planets expelled from forming solar systems and drifting in the empty void between the stars. The researchers, led by Takahiro Sumi of Japan's Osaka University, spotted 10 such free-floating "orphan planets" in data from a 2006-7 …
I remember going to lectures on this some years ago.
Perhaps it's bad translation but his statement should read:
"The existence of free-floating planets has been predicted by planetary formation theory, but nobody knows how many there are."
because we still don't know how many there are, he only spotted a few. The hunt for "dark matter" is still on and according to some lectures I went to the lack of "dark matter" has lead to the theory predicting it being questioned.
dark matter is not 'dark' simply because we cant see it, (say because it happens to be out in deep space and not near anything shiny like a sun)., it is 'dark' because it is not see-able. ie it does not emit or reflect electromagnetic radiation.
the planets in the article have been "expelled from forming solar systems" and are adrift between stars, making them merely hard to see. but if you shine a torch on one of these planets you will see it. if you shine a torch on dark matter you wont.
the mass of these planets may well account for some of the 'missing mass' that is needed to make the edges of galaxies rotate at the speed they do, but these planets are not made of dark matter.
it would not be sufficient to make up the gap between directly observed mass and the mass apparent from gravitational pull of galaxies. This is because Jupiter-sized planets are only a fraction of the mass of a star, and there is a huge amount of missing mass (only 6% is observable, might become 12% with the lone planets, but still 88% missing). On the other hand, our model of gravity may be wrong.
Jupiter is less than 0.1% the mass of the Sun. A couple of these per star is several orders of magnitude less mass than required to make up the missing mass. When your grasp of such basic facts is so weak perhaps you shouldn't be labeling as lunacy the views of the experts that spend their whole career studying the area.
Er, no. The problem here is that even after you take into consideration the mass of all the Galaxies in the Universe (which, by definition, includes any loose planets wandering about in them), we're still a shedload short.
I believe that you'd have to postulate that were more planets wandering around untethered in intergalactic space than there are in Galaxies for that to be a runner. IIRC, that would put something of a nasty dent in the Standard Model.
"Could this help account for some of the "missing" mass out there? Maybe we can get over this last 20 years of dark matter lunacy?"
Wouldn't even scratch the surface - dark matter is around 80% of the observable universe. So you'd need to billions of these planets for each star out there, given the size of planets.
A Jupiter size planet is a star that didn't get enough matter to "switch on", so isn't it awfully expected? Heck, there's probably some cooled down red dwarves among them as well. And all these probably have smaller satelites planets as well. First to say it, PM me so I can give you the address where to send my PhD certificate. Kthx.
"...several orders of magnitude less mass than required to make up the missing mass."
If they can just-now, just-barely detect just-some of just-the-biggest-ones (using gravitatinal lensing), then how many undetectable smaller ones must there be?
Assume some reasonable distibution (fewer biggies, vastly more smallies, all the way down to atoms...), then perhaps we can get within an order of magnitude or so of the 'missing' (now partially found?) Dark Matter.
My guess? They just found 32.75% of the Dark Matter. Worth celebrating.
And I'm not coming out until all the pictures of Jupiter with "Forever Alone" 'shopped onto it have disappeared beneath the steady flow of cats dancing with octopi, moonwalking stick insects, and orange reality-show celebs.
I need a drink. Several large ones in fact. Hold the parmo.
If these planets were gas giants and became disconnected from a host star wouldn't they cool down and reduce in volume. If they remained hot due to spinning or some other reason would they be 'visible'. How different in power output and temperature spectrum would they be and would this make them easier to detect than by using light being bent around them.....
What have I missed here?
Er, that nowhere in the article does it say they are gas giants, or indeed, anything-giants. The only available data so far is that they have mass of the same order as a known gas giant, but that doesn't necessarily imply that they have similar size. They could be microscopic fragments of collapsed matter.
But it always looked a *very* long shot IRL.
Think about it.
a) A formed planet (and a *big* one) has to be given enough force to reach solar escape velocity.Note it's *very* unlikely that a planet would be able to form on its own.
b) it forms in deep space on its *own*.with a bit of velocity to get it moving.
Neither of these really sounds very plausible.
So superficially this should be *very* unlikely and yet it's happening.
Either the common public view of how planets form is a *major* mis representation of how things work or the current model needs some *serious* rethinking.
Given the detection method and how long we've been watching them I assume there is no velocity data. Can we say for sure they're on there own? Or could some be in very long, very eccentric eliptical orbits around their parent star. Such a body might fit well with the 'dark companion' nemesis theory of mass extinctions. Even without them being in orbit how often would we expect one to wander close enough for interesting effects?
Presumably ones that escaped a low mass star might eventually be captured by a higher mass star? A possible explanation for any planets found in a 'backwards' orbit?
1. The Ancient Greeks were more right than they knew: Planet = "Wandering Star" indeed.
2. @John Smith: I favor the idea of an external force breaking a planet free of its star. Such as a rogue planet. Which would make the rogue planet generation mechanism resemble a nuclear fission reaction: split up one atom, let loose three extra neutrons that go and burst other atoms, freeing more neutrons, etc. Soon the universe will be uniformly filled with rogue planets, including our own.