Brown Dwarf With Water Clouds Tentatively Detected Just 7 Light-Years From Earth 85
sciencehabit (1205606) writes Astronomers have found signs of water ice clouds on an object just 7.3 light-years from Earth — less than twice the distance of Alpha Centauri. If confirmed, the discovery is the first sighting of water clouds beyond our solar system. The clouds shroud a Jupiter-sized object known as a brown dwarf and should yield insight into the nature of cool giant planets orbiting other suns.
Is this the missing "dark matter"? (Score:2, Insightful)
There was not enough mass in what we can see from the galaxies. And people came up with strange theories like dark matter.
Now we have an (arguably not so super heavy, but nonetheless) object just around the corner. Could it be that there's no dark matter, but that simply the galaxies are full of these things?
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Re:Is this the missing "dark matter"? (Score:5, Informative)
No, the amount of missing matter is far to great to be contained in such small objects even if they were incredibly numerous.
Consider the entire mass of the asteroid belt is estimated to be only 4% of the Moon's mass, and the Moon's mass is only 1/81 of the Earth's.
Dark matter, meanwhile, is thought to have a total mass more than 5 times greater than that of normal matter.
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Logic fail. Dark matter can be explained by such small objects if they are incredibly numerous. It's just math: divide the missing mass by the mass of one brown dwarf to get the number needed. If you want to disprove the brown dwarf explanation you need to explain why the number that is needed contradicts something.
Re:Is this the missing "dark matter"? (Score:5, Insightful)
Logic fail. Dark matter can be explained by such small objects if they are incredibly numerous. It's just math: divide the missing mass by the mass of one brown dwarf to get the number needed. If you want to disprove the brown dwarf explanation you need to explain why the number that is needed contradicts something.
The hypothesized dark matter does not emit or absord any type of electromagnetic radiation, in other words it does not interfere with or react to light. Numerous small objects would. Also, and this is the most important bit in your logic fail fail, if you have enough small objects to account for five times the mass of the visible universe, you would have something five times more visible than the visible universe. Matter attracts other matter (which is why there is a dark matter hypothesis to begin with, something invisible attracts the visible) and such a copious amount of "small objects" would form larger objects. Which is how stars and planets form to begin with.
Re:Is this the missing "dark matter"? (Score:5, Informative)
Its not a simple argument but if you look at:
http://en.wikipedia.org/wiki/D... [wikipedia.org]
dark matter composed of bits of normal baryonic matter is not consistent with observations / simulations
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No, they have not eliminated the possibility that dark matter does interact with electromagnetism weakly
If it's violating Maxwell's laws, then 1) whatever else it is it's not ordinary matter, and 2) that's far-fetched and cool the same way the dark matter hypothesis is.
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Whether it has or has not been eliminated, idle speculation isnt compelling. If you havent studied this and / or had extensive experience with it, you probably shouldnt be composing theories on dark matter.
Re: Is this the missing "dark matter"? (Score:1)
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". You build a theory by standing on the shoulders of others and learning."
Yes. But if you don't even stand on the shoulders of the giants in a field, then you should probably shut the fuck up.
"Learning is the asking of questions."
Yes, but it isn't throwing out ideas so off base they aren't even wrong, and then telling people to show you why they can't be when the idea being stated makes no sense at all. AC who posted that question clearly doesn't know the first thing about dark matter. Frankly, the poster
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Yeah, I liked the MACHO idea many years ago, they may still account for some of the gravity yet, but the position is more or less untenable at this stage both empirically and theoretically.
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No matter how cold it is, it would STILL interact with light (being cold does not make something invisible). And given the number of cold brown dwarfs it would take to make up the difference, it would be virtually impossible to NOT have seen them (if they were in fact the the culprits of dark matter) as others have alluded to in this thread.
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Re:Is this the missing "dark matter"? (Score:5, Interesting)
Similar inane arguments were aimed at Newton, plenty of 15th century scholars thought that the fact a bird can fly disproved the theory of gravity. We still don't know what the hell gravity is (other than a property of matter) but we no longer question it's existence and have developed a very good understanding of how it behaves. Dark matter is harder to wrap one's head around because it's effects can not be observed in everyday human experience. However the effects are real and the tag scientists have given them is "dark matter".
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We still don't know what the hell gravity is (other than a property of matter) but we no longer question it's existence and have developed a very good understanding of how it behaves.
Maybe not so good. ts possible that dark matter is just a fudge factor tat we need to apply to Newton's inverse square law over larger distances or for larger masses.
Here's an interesting thought puzzle: Assume the effects of gravity are caried by some yet to be discovered particle/wave (gravitons) and these 'particles' are subject to the same laws of physics that all other partices are (photons, for example). Then how do they escape the gravitational pull of a black hole? If photons can't get out, then ho
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You think your argument is strong with Sun containing 98% of the Solar system's total mass? It is actually something like 99.8%!!
Yep. Here's a good source for the relative masses of the solar system object: http://en.wikipedia.org/wiki/List_of_Solar_System_objects_by_size#List [wikipedia.org]. It does not include the Oort Cloud, which is though to contain about 5 Earth masses of material.
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the Sun holds 98% of all the matter in our solar system. If the "missing mass" were normal cold matter, such a great quantity would effectively block the light of the stars we can see
This simply doesnt compute unless you make assumptions about the distribution of the missing mass, and in this case your argument assumes its distributed evenly (nebula) while also taking advantage of the fact that the actual visible mass (stars) isnt.
Let me translate the flaw so you understand: You are claiming that there is no place to put 100 of these brown dwarfs near a star that wouldnt block the stars light from reaching any of the rest of the universe. (and before you go there, I didnt pull 100 ou
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"Now dont discuss this subject any more unless you learn at least a few basic things."
You should follow your own advice. Most brown dwarves are glowing away nicely in infrared. If there were triillions of them they'd be lighting up the sky in that band. They arn't, so unless something has cooled them all down to absolute zero (yeah, right), they don't exist. Back to school for you.
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Now dont discuss this subject any more unless you learn at least a few basic things.
Your post was interesting and informative but my reaction to this parting shot is - go fuck yourself you arr
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Shouldn't have an impact on the mass estimation of other galaxies, so no.
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I'm pretty sure that's where Lando lives.
Occam's razor. (Score:3, Insightful)
Could it be that there's no dark matter, but that simply the galaxies are full of these things?
Could it be that all the cosmologists and physicist who have been looking at this for a couple of decades somehow missed that blindly obvious "possibility". Or is it more likely you are simply unaware of the evidence [wikipedia.org] that forces these people to dismiss the obvious "common sense" answer?
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I'd be un-surprised when it leads a half-dozen "gotcha" worded follow ups from someone who clearly has no interest in Googling their own ideas first.
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Re:Occam's razor. (Score:4, Insightful)
If you feel a gentler more informative answer can be provided then why not provide it? I'm sure the OP is quite capable of defending himself against my prose if it has unintentionally offended him in some way that I'm unaware of. What I'm not so sure of is why do you feel the need to be offended on his behalf?
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Posters do not have to pander to idiots just to be civil. There is nothing wrong with a bit of boisterous prose.
The associated subject of the impossibility of human interstellar travel is another one that people never admit
Mind you it is a bit dull realizing that the human race is stuck in this solar system forever, never mind just for now.
Re:Occam's razor. (Score:4, Interesting)
Occam's Razor has always been applied here, and that is why it is still an open question, because the simple and obvious answer (MACHO) is not working and extraordinary evidence is being found, eg the Physic's Nobel Prize 2011 [wikipedia.org].
This article is not about MACHO vs WIMP. It says they found a nearby MACHO with water vapor, and that is very interesting for life questions, not dark matter questions.
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Could it be that there's no dark matter, but that simply the galaxies are full of these things?
Could it be that all the cosmologists and physicist who have been looking at this for a couple of decades somehow missed that blindly obvious "possibility".
Because cosmologists are never finding anything new? Im not trying to stir anything up, especially since you seem to have an emotional stake on this topic.
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No, Dark matter does not interact with normal matter. We can "See" light and radiation pass unimpeded through areas that contain detected dark mater. It does not reflect, bounce off of or interact in any other way... except it's gravitational pull. That's why it's called "Dark" Moving light/radiation will bend around it, but not bounce off of it.
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Like dimples in space.
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Like letting the air out of a balloon!
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And how do magnets work, HMMM?????
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No.
Dark matter is matter that does not interact with electromagnetic forces. It isn't mass that's gone missing.
First non-cloud candidate (Score:4, Interesting)
Is this the same brown dwarf that... (Score:1, Offtopic)
Wants to know what Willis is talkin' bout?
The theorized nemesis star? (Score:1)
It's been said that the sun might have a brown dwarf that orbits it. Seven light years isn't that far off.
Re:The theorized nemesis star? (Score:4, Interesting)
The brown dwarf that orbits the sun is called Jupiter.
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There's a mass and temperature difference between gas giants and brown dwarf stars. The cutoff is whether the object in question has any fusion going on at all. At about 13x Jupiter mass it's big enough to fuse deuterium, and at 65x it can fuse lithium. If it's massive enough to fuse hydrogen, you've crossed into Red Dwarf territory (oh smeg!).
No form of sustained fusion has ever been detected within Jupiter, so it's not a brown dwarf, just a gas giant planet.
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Seven light years is that far off. There's multiple star systems between us and it, which would interfere with it's orbit.
Going to Battle (Score:2)
From the article;
"I went to battle at the telescope to try and get this detection," Faherty says. "I wanted to put war paint under my eyes and wear a bandanna, because I knew this was not going to be an easy thing to do."
Who said astronomy was dull? There has to be a TV series to had here. Action Astronomer wields her mighty War Telescope!
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Episode 16: The missing TPS cover sheet
Moons? (Score:2)
I wonder if it has any Earth sized moons. Maybe one close in could be kept warm(ish) by tidal heating.
Re:Moons? (Score:4, Informative)
Indeed it does. I haven't published yet, but I detected one a few days ago (I work out of a valley in Iceland). I observed the brown dwarf in question (right ascension 08h 55m 10.83s, declination -07 14 42.5") and detected a large, earth-sized body occluding the star during my brief observations.
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Ahhh ... Slashdot ... where some posts are impossible to differentiate between humor and sheer awesomeness.
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Could that body have been... The Earth? The same thing happens whenever I try to look at Paris from Australia.
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Well, it's funny you say that.
We saw two moons. One of which wasn't in earlier detections, and as it came around the brown dwarf, it just exploded. weird.
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Its clearly a trap.