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Odd Planet Confuses Scientists
Posted by
samzenpus
on Wed Oct 08, 2008 06:55 PM
from the that's-no-moon dept.
from the that's-no-moon dept.
eldavojohn writes "While there's been a lot of debate about what is a planet, there is a recent discovery that has scientists even more confused. COROT (COnvection ROtation and planetary Transits) spotted an object that appears to be the size of Jupiter yet is 21.6 times more massive ... and orbits its star in a mere four days and six hours. Now, the other piece of the puzzle is that the star it orbits is more massive and only slightly larger than our Sun. But they can't describe this thing orbiting it. So far they think it is more likely to be a 'failed star' but have settled with 'member of a new-found family of very massive planets that encircle stars more massive than the sun' to describe it accurately."
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IAU Demotes Pluto to 'Dwarf Planet' Status 424 comments
davidwr writes "It's official. Pluto's been demoted. It's now one of several 'dwarf planets.' I guess we can drop the 'Period' from 'Mary's violet eyes make John stay up nights.'" (Of course, no one says you have to privately agree with the International Astronomical Union.) Several readers have contributed links to the BBC's coverage of the downgrade, as well as the usefully illustrated story at MSNBC.
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I hate to say it.. (Score:3, Funny)
... but that's no moon.
Re:I hate to say it.. (Score:5, Funny)
Parent
Is orbital mechanics fractal? (Score:3, Interesting)
One thing I've wondered about: Does orbital mechanics lead to fractal planetary arrangements?
If so, binary stars and star/gas-giant planetary systems are just points in a continuum.
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No, thank you for not adding anything to the discussion. If you can explain what was meant, please do. If not, please don't bother posting.
But seriously, a continuum of what? What the hell does fractal geometry apply to planetary arrangements? To me those two sentences are nonsense. As I see it, fractals just don't apply. It's like asking if we'll have a long winter because a groundhog sees its shadow.
If I'm wrong, please enlighten me. That was the hope of my original post.
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The aspect of "fractal" I had in mind was "equivalently arranged across large variations in scale".
I.e. a gas giant and its moons are just a small version of a star and its planets, etc.
Of course you do get a discontinuity between a star that ignites and a gas giant that does not. For instance: A star's heat drives more volatiles off the orbiting rocky objects than a gas giant's warmth does. Solar wind tends to clear out small debris. (And t
Re:Is orbital mechanics fractal? (Score:4, Interesting)
A usual property of fractal dimensions is they aren't integers. Cases with interger dimensionality in articles and books on fractals are simplified or 'degenerate' fractals. If scientists found themselves relying on math that involved non-integral dimensions to describe planetary systems, I could definitely see there being 'fractal planetary arrangements', but baring that, similarities across scales aren't enough to throw around a word such as fractals.
The idea sounds like an extension of Bode's law, by people who are trying to modernize the old model. The original Bode's law may have been a case of people seeing patterns that aren't really there in reality at all, simply an overfunctioning of the brain's pattern detecting apparatus. Knowing there's a temptation to interpret the data this way, I'd be cautious trying to stretch fractal math to fit unless all of it fits.
Parent
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Re:Is orbital mechanics fractal? (Score:4, Funny)
My bet is that they just misplaced a decimal point somewhere. It's always some mundane detail like that.
Parent
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Re:Is orbital mechanics fractal? (Score:5, Interesting)
Does orbital mechanics lead to fractal planetary arrangements?
Good, question, but my "shooting at the hip" answer is that while there may be some tendencies toward that kind of arrangement, that applies to certain conditions that are limited. Roughly, around our star, each planet ~2x the distance as the previous, out to Neptune or so.
I'd guess that while it happened here, that it won't happen everywhere, or that there's only a tendency toward this.
I think the idea of trying to define a planet vs asteroid vs planetoid vs failed star is kind of like trying to define the difference between a pebble", a rock, a stone, and a boulder. When does a pebble become a rock? When does a rock become a stone, and when does a stone become a boulder?
There's no clear line, and there doesn't need to be. Seriously: why do we care?
Parent
Re: (Score:3, Funny)
I don't get it. Can you please re-frame your example using a car analogy?
That's no planet. (Score:5, Funny)
"the size of Jupiter yet 21.6 times more massive.. and orbits its star in a mere four days and six hours."
That's New Year roughly twice a week, by Jove.
Party on ; ).
Re:That's no planet. (Score:4, Funny)
He capitalized it. Maybe that's the name of his cat.
Parent
You know, the way we're going... (Score:2, Funny)
...before long astrophysicists will have more words for things that orbit other things than the Inuit have for snow.
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What's it made of? (Score:3, Interesting)
Re:What's it made of? (Score:5, Interesting)
Metallic Hydrogen? Though you would think that it would begin to fuse at that kind of mass-density. Then again, 26 times the mass of Jupiter is still less than 3% the mass of the sun so perhaps not. My guess is that this is the edge case. If there were even a little more mass it would have collapsed into a red dwarf and started fusing hydrogen.
Parent
Don't think so (Score:5, Informative)
Actually, I don't think that metallic hydrogen is twice as dense as solid lead.
If you look at most metals, the higher the atomic weight, the higher the density of the solid. Depleted uranium is heavy, while Aluminium is lightweight, and Lithium is half the density of water, for example. So for hydrogen, metallic or not, to be denser than lead, you need it to be packed tighter than, I think, is physically possible.
At some quick maths, a hydrogen atom is 1, lead is 207-208 (82 protons and a load of neutrons.) I know that some mass is actually in the binding energy between those, but for some quick and very approximative maths let's say a lead atom is 200 times heavier than a hydrogen one. (Plus/minus something.) At the same distance between atoms, lead will be 200 times heavier than hydrogen. To go for twice as heavy, you need the hydrogen atoms to be packed at over 7 times less distance from each other than lead atoms are.
At a quick googling, the estimated range of densities for metallic hydrogen is anywhere between 0.4g per cubic centimetre (less than lithium) and 4g per cc (4 times as heavy as water), with apparently 0.8 being the most likely candidate for where it turns metal. Compress it any denser and it'll start to fuse. And we're still nowhere near as heavy as we need for that planet.
What throws a further spanner into it, is that our own gas giants _already_ have a core of metallic hydrogen. That' what's in the middle of Jupiter and Saturn. So something 26 times heavier, hmm, must be something else.
Parent
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Re:What's it made of? (Score:4, Interesting)
I wonder if this is just a result of some weird gravitational lensing effect? I'm not very familiar with the technique, but from what I understand, its kind of like looking at a shadow in order to try and figure out the shape of an object... except the light source is light years away and the object is equally far away.... I'm sure as time goes by and our observation techniques improve, we are going to see many different things that we never thought would be possible. Yes yes... physics is physics, but humanity has a problem with adjusting to scales, and space is a very, very big thing.
There is little way to control the environments in order to do controlled experiments, all we have are observations... which at such great distances, must be very susceptible to nearly infinite sources of interference that we simply cannot identify with present means.
With that said... a new category of planets off of one object? Getting carried away much...?
Parent
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Well, they only have two options. They can redefine an existing, well-defined and -populated category to also encompass this one mysterious planet, or they can (perhaps temporarily, pending further observations) give it its own new category. You really the the latter is more drastic?
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Apart from no-one understanding what formed this planet and why it is so dense, I don't see ho
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AOL CD's aren't that dense. It's the AOL USERS that are dense.
Needs more vowels (Score:2)
Bad Data (Score:5, Interesting)
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Re:Bad Data (Score:4, Informative)
Uh, we know of a bunch of Jupiter or larger sized planets in closer than Mercury orbits. This isn't anywhere near the first. It's density is it's unique trait.
Parent
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This was followed up on the astro mailing lists as faulty data -- the observers mistook sunspot-dimming for a planet passing in front of the star. The correction hasn't made it to journalists yet and the science article is still in draft, so no link-to-reference, sorry!
The same thing happened 3-4 weeks back with TW Hydrae b [universetoday.com].
NASA and the ESA's sites still claim this one is valid.
Maybe you could post an excerpt from one of the emails?
Hold on a minute here... (Score:5, Interesting)
The density of Jupiter is about 4/3, so 21 times that would put it at 28 and change. That means it would have to be significantly denser than Iridium (about 22). That means it would have to be either:
Guess where I'd put my money...
--MarkusQ
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given that the entire planet is appearing smaller than it should be, could it not just be further away?
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My first thought is similar to yours - if it's that far out of the norm, it's probably a calculation error.
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The core of a brown dwarf has a density somewhere between 10 and 10^3 g/cm^3. That means the cores of brown dwarfs have to be either:
Guess where I'd put my money....
Seriously: brown dwarfs all have about the same radius as Jupiter, but range in mass up to about 60 times that
How dense is the Death Star? (Score:2)
How dense is the Death Star?
I bet more than 4/3....
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This kind of density boggles the mind. What could have this density? Tungsten, Platninum? Osmium is not getting close.
Considering the mind boggling surface gravity of a object like this, we don't know how many materials behave under incredible pressure, for example the centre core of the earth, while largely iron, is more like crystal. The core of jupiter might be shrouded in metallic hydrogen. Indeed we understand
Caught me (Score:3, Informative)
In some systems, yeah, it is. Set c=1 (space-time unification), measure masses and energies in the same units (E=mc^2), and so on. But I (obviously) wasn't using one of those systems, I was using g/cm^3, as you probably realized.
--MarkusQ
Re:Caught me (Score:4, Informative)
Density isn't exactly dimensionless, but if you set things up so the density of water is 1 in a system of measurements, the densities of other things (i.e. Lead, Iridium, or this planet) will come out the same numbers, regardless of the units used. So it's not necessary to really specify the units, just that H2O at STP = 1 in whatever system you are using.
Parent
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Admittedly I'm just eyeballing it, but I can't see how you can make that work. Remember the T part of P=T/V works against you here; the higher temperature should make it less dense, which both reduces the gravitational forces on the outer portions (larger r) and increases their area and thus the amount of energy those on the sunwar
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I can see how you could get the core density up that high, but not the total density. Remember, the sun, for all it's size and mass, is only a few percent more dense than Jupiter.
The Sun also is thought to be around 150 million kelvin in the interior. It'd be a lot more dense if it weren't for the high temperature.
Good point (Score:3, Insightful)
Good point. This planet should be about
(0K+6000K)/2
------------------
150000000K
or about 1/50000 the temperature and thus could on that basis be up to 50000 times as dense.
But that can't be the whole picture. At those pressures you'd no longer be dealing with a gas--the volume-per-atom of He would be way out of line. A helium atom occupies about (3.1e-9 cm)^3 or 3e-26 cm^3, and has a mass around 4 * 1.66e-27 kg = 6.66e-24 g, for a per-atom density of about 222 g/cm^3.
So if you could get a core m
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Maybe they don't "see" them with the naked eye, but they observe wobbles in the position of a star or observe when the planet occludes the star. How is that so far removed from when you look at any other picture? All you're really seeing is light reflected off the developed photograph. You're not "seeing" the light that hit the negative, but rather you're getting light that is a few steps removed conceptually from the original photons. Does that mean there's no evidence that what's in the picture actual
Detecting Exoplanets (Score:5, Informative)
1. Wobbles -- what you explained: watch a star for deviations in its orbit by observing tiny redshifts and blueshifts. Our own sun does a little jiggle thanks mostly to Jupiter.
2. Dimness -- what they did for this object. Watch a star for dimming as something passes in front of it, although you have to be careful of other causes of temporary decreases in luminescence (like sunspots).
In both cases, it really needs repeated observations over time to establish that it's an orbital event and not something random. In the good ol' days of exoplanet discovery when the equipment wasn't so hot & we expected to find planets pretty much like ours, it took a whole lot of observations before anyone was willing to take the risk of announcing a discovery. Now, with better equipment making it easier to detect hiccups in a star's routine and a more open attitude about how planets behave, discoveries are being announced a lot earlier in the observation process.
To be fair, TFA does give itself a whole lot of wiggle room in interpreting the data. It just fails to mention that follow-up observations aren't confirming the orbital parameters of the assumed planet.
Parent
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Not really, planets don't move at relativistic speeds. However according to you standard physics text books trains do. Oh and TFS said 4 days not hours
Re:why not classify them with letters? ala star tr (Score:5, Funny)
Because the astrological community is too busy hoodwinking people with talk of Jupiter in the Second House, and horoscopes, and other nonsense.
Parent
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Yeah, well all you people born with Sedna in Puppis think astrology is bunk. Bet you've got Quaor in your House of Pancakes too.
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Comprised of PS3? It will be hotter than the sun if someone turns that thing on and starts folding!
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Sun in the middle, Sun in the middle
Dyson Sphere's got the Sun in the middle, and a great big bubble all around.
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How do you know? Maybe Athiesm is a new religion they made up, where his god is contained in a Coca Cola bottle with a misspelled label....