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Frigid Brown Dwarf Found Only 7.2 Light-Years Away
An anonymous reader writes "Astronomer Kevin Luhman just found the 7th closest star to the sun. It's a mere 7.2 light-years away, discovered using NASA's Spitzer and WISE telescopes. How could it exist so close for so long without us knowing? It's a brown dwarf — barely a star at all. 'Brown dwarfs are star-like objects that are more massive than planets, but not quite massive enough to ignite sustained fusion in their cores. Hydrogen fusion is what powers the Sun, and makes it hot; it's the mighty pressure of the Sun's core that makes that happen. Brown dwarfs don't have the oomph needed to keep that going.' This small almost-star is downright chilly at around 225-260 Kelvin. That's -48 to -13 C (or -54 to 9 F). As Phil Plait points out, that's not much different from the temperature in the freezer in your kitchen. He adds, 'It implies this object is very old, too, because it would've been a few thousands degrees when it formed, and would take at least a billion years to cool down to its current chilly temperature. It's hard to determine how old it actually is, but it's most likely 1-10 billion years old. It has a very low mass, too, probably between 3 and 10 times the mass of Jupiter. That's pretty lightweight even for a brown dwarf. And here's another amazing thing about it: It might be a planet. What I mean is, it may have formed around a star like a planet does, then got ejected by gravitational interactions with other planets.'"
No, it might have been a planet once, but its not orbiting a star now so its not a planet.
You try spotting something that cold and not much bigger than jupiter 7 light years away! I'm incredibly impressed they've managed to spot it at all and should be congratulated since it'll barely even register in the infrared never mind visible light.
I keep hearing about "Dark Matter" as an explanation for how galaxies don't fly apart due to the force generated by their rotation, but I can't help thinking that all that mass we're looking for in galaxies could be stuff like this. Regular matter that just doesn't generate enough heat or light for us to have noticed prior to this.
Could the question of how galaxies rotate be answered by large quantities of objects such as these?
"...most likely 1-10 billion years old."
That doesn't narrow it down much, given everything in the universe is in the 0-13.8 billion year range.
Astronomer Kevin Luhman just found the 7th closest star to the sun.
Damn your reading comprehension sucks.
Sorry for the double-post, didn't realize I wasn't logged in when I posted this previously
I keep hearing about "Dark Matter" as an explanation for how galaxies don't fly apart due to the force generated by their rotation, but I can't help thinking that all that mass we're looking for in galaxies could be stuff like this. Regular matter that just doesn't generate enough heat or light for us to have noticed prior to this.
Could the question of how galaxies rotate be answered by large quantities of objects such as these?
TFS mentions it is the "7th closest star to the sun"
Sleep your way to a whiter smile...date a dentist!
My personal experiences, have been very much, the opposite.
Kudos for writing 225-260 Kelvin and not 'degree Kelvin' or 'Kelvins' in the summary. Slate f'ed up though. They wrote 'Kelvins'. I have seen even reputable scientific writings using degrees prefix with Kelvin. It's very disheartening to see that even some scientists don't get it that you don't use degrees when talking about absolute temperature.
Could it be the Nemesis Star that orbits the Sun from far away, and maybe responsible for periodic extinctions here on earth? Probably not. :)
wouldn't that be the 8th closest star to Earth?
Google that without SafeSearch. ewwww.
Traveling at 25 m/s, the speed of the current fastest man made object, it would take 55,885 years to reach this star. It's understandable why we haven't noticed it till now.
Or, he should simply rotate his screen about 20 degrees clockwise to see the 7 under the right angle.
Ezekiel 23:20
no, because when it is the 8th closest star to earth, we need to be on the other side of our orbit around the sun, and we couldn't see it anymore, because the sun is in the way. duh.
Sleep your way to a whiter smile...date a dentist!
I don't think brown dwarf stars are really going to be much of a problem. They're hard to spot when they're 7 light years away, but they're still really big objects that are highly likely to appear to be moving through space from the perspective of any interstellar craft. Any such craft can be expected to have telescopes and something like this is virtually certain to show up through the telescope occluding other objects when it's closer. At the kinds of distances where it would be obvious there's still plenty of time to make a tiny course correction which will allow the craft to dodge it entirely. Heck, you can still make such a course correction when it's close enough to spot by the naked eye as a hole in the field of stars.
So, unless the the interstellar craft is effectively just drifting blind, I'm going to have to conclude that objects like this are basically a 0% risk for a direct collision. The smaller objects you mention are definitely the only real risk.
Sure, right after we finish mining Jupiter and develop FTL drives to get there.
--- Most topics have many sides worth arguing, allow me to take one opposite you.
Two elements of TFA caught my eye:
micrometers
Together, these figures are within the range for a type I (or, maybe even a type II) Dyson sphere.
And, it is only 7.2 light years away?
Yes, it is very probably the Brown Dwarf that the astronomers think it is.
But, imagine. It could be a Dyson sphere; our first evidence of advanced life beyond the earth.
"values of beta will give rise to dom!"
Well, I hear the collision with the Andromeda galaxy will shake things up a bit in interstellar space in about 4 billion years...
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Well maybe, but if this thing was never fusing was it ever really a star? And if it was fusing, but has now completely stopped, then the question is did it stop being a star while still orbiting it's primary, and thus become a planet first, or did it get ejected as a star and become a planet later? For that matter is there really such a thing as a rogue planet? Planet means wandering star, and we now know that it's only the act of orbitting a star that causes a planet to "wander" across the stellar background - without a star a rogue "planet" will maintain formation on the relevant timescales, just like the visible stars.
Or we could all sit down like adults and recognize that words draw distinctions that are often completely arbitrary and do not reflect any fundamental physical distinctions, and will thus potentially be ill-suited to discussing phenomena near the boundaries of their arbitrarily-constructed and potentially overlapping definitions.
--- Most topics have many sides worth arguing, allow me to take one opposite you.
You don't need line-of-sight for something to exist. What are you, a 2 year old?
Brown dwarves are not stars, this astronomer did not find a star nor the 7th furthest star from the Sun. Brown dwarves are known as "sub-stellar objects". No fusion, no star.
well, a 2 year old would equate "couldn't see it anymore" with not existing...
Sleep your way to a whiter smile...date a dentist!
Well, I hear the collision with the Andromeda galaxy will shake things up a bit in interstellar space in about 4 billion years...
And by then the sun will be a red giant with a radius as large of not larger than the earth's orbit. We're going to be pretty well fried by then.
In a time of universal deceit, telling the truth is a revolutionary act. George Orwell
The Sun is ~1 AU away, the three Alpha Centauri stars are 4.24 to 4.37 l.y. away, Bernard's star is just under 6 l.y. away, and the two Luhman 16 brown dwarfs are just over 6.5 l.y. away. The position of Earth in its orbit is not enough to make any of those exceed 7.2 light years. this is either the 8th closest star that we know of, or it is not considered a star at all if you don't want to count brown dwarfs (or might be pushing the lower limit of what is a brown dwarf).
it may have formed around a star like a planet does, then got ejected by gravitational interactions with other planets.
But if Jupiter interacts with anything, Jupiter isn't going to get ejected. The remaining object must have been a sizeable star.
This star must be warm deeper down. I wonder if it is a good place for life.
http://michaelsmith.id.au
It's a super-giant planet or a super-dwarf star.
If it is big enough to ignite fusion, then it is a star. A mass of about J8 (eight Jupiters) is needed to fuse deuterium. Most likely, that is not happening, or it would not be so cold. So it is not a star. But I don't think it is a planet either, because it is only a planet if it is orbiting a star. So I don't know what it is called.
http://en.wikipedia.org/wiki/R...
Per the article, it could also be a "sub-brown dwarf".
It doesn't hurt to be nice.
The Wikipedia article on rogue planets discusses ways in which they could retain an atmosphere, warmth, and liquid water. If we knew one of these was in the neighborhood, and knew it was going somewhere interesting, we could use it as a ship. It's possible that we could get to one in a few centuries of travel, and then perhaps colonize it, and ride it the rest of the way to our ultimate destination. That's assuming wherever the rogue planet was going was more interesting and/or less deadly than wherever Earth was going at the time.
It doesn't hurt to be nice.
Well, it's only 7.2 lightyears away, so you don't need an FTL drive, you just need a LOT of patience. But what you really need is some way to cheaply get the mass away from a star's gravitational field. True, it's quite a small star, but at 3-10 times Jupiter's mass, it will take 9-90 times as much energy to extract it. (That's an estimate, not a calculated answer...but escape velocity goes up faster than the mass, or you'd almost never get a black hole.)
I think we've pushed this "anyone can grow up to be president" thing too far.
Actually estimates are that the red giant transition is 4 to 7 billion years out, so the Andromeda collision will roughly coincide with the lower end of estimates of our sun's lifespan in it's current state. It could also turn out that it will have another 3 billion years after the the collision begins.
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Talk about a killer commute...
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Obviously, but what worries me is that Relativity is correct that any form of FTL travel can inherently be repurposed as a time machine to travel into your own past. The integrity of lottery will be destroyed forever, and the complete collapse of civilization can't be far behind.
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Even if we solve the propulsion problem, there's another problem--uncharted objects like this.
If we could actually speed a ship up to anywhere near the speed of light, even hitting a pebble is likely to blow up your spaceship.
Not any form of FTL travel. Warp drives as currently proposed don't allow travelling into the past and
there might be tweaks to relativity or other as yet unknown methods like worm holes, etc.. that allow
faster travel.
I think I read somewhere that the inner core temperature of Jupiter is higher than it should be, and chemical engineering 101 says if heat out minus heat in not equal zero, then there is heat generated. The inner lava temperature of Earth is sustained mostly by K40 and U235 decay, besides minor asteroid impacts. So the inner temperature of Jupiter is also sustained probably by the same thing, and not fusion, as it is hard to imagine Jupiter without an iron-nickel core, and lava, and then a hydrogen atmosphere. Ditto for this "nonstar," it's hot for the same reasons that the inside of the Earth and Jupiter is hot, mostly K40 and U235.
That's amazing! That is the exact name I had for my ex wife!
There are reasons to think that Jupiter's heat is sustained by simple gravitational collapse, as its core gets slowly transformed into metallic hydrogen.
Since the sun gets about 10% brighter every billion years we'll be dead long before either of those things happen.
If this is correct, then why not.
"Consensus" in science is _always_ a political construct.
You obviously haven't tried to hide something from a 2yo.
And did you exchange a walk on part in the war for a lead role in a cage? - Pink Floyd.
If this were an object that coalesced away from any (other) protostellar discs, it may conceivably have small objects orbiting it. Since there wouldnt have been a "fusion event" to blow away the remaining gas and dust of the original cloud it formed from, any objects that coalesced near to the central sub-brown dwarf would not have been pushed out by the radiation pressure.
This means that gravitationally bound satellites close enough to be quite warm indeed just from tidal heating could be possible with "object systems" like this. (With small objects orbiting large ones at close distances, the odds of the objects being tidally locked increases greatly. However, without the sudden application of solar wind gusting through the accretion disc, the number of small rocky bodies would be much higher, meaning orbital resonances could help prevent this tide locking, should a sufficient number of such objects be at work-- planetoids with lots of "comparitively large moons" tugging on the planetoid's centers of mass, preventing tide locking.)
The compact size of this dense object may suggest that the object is metal rich. That would indicate a reasonable probability for rocky terrestrial type objects orbiting it.
Discounting the system as being too cold for life as we know it is premature. Tidally heated satellites with liquid oceans are possible, even with this very dark "star" overhead. (EG, look at Io around jupiter. Despite being waaay more than 1AU from the sun, the surface is totally motlen rock. Jupiter is smaller/lighter than this object.)
Being a non-fusing object, this object can theoretically last for hundreds of billions of years-- much longer than our sun will live. If I were a member of an interstellar capable species looking for a "Long term solution", I would be very interested in systems like this one, and in red dwarf systems for this very reason. Artificial biospheres powered by thermal energy equilibrium (which itself is generated by gravitational tidal forces and radio-isotope decay) exploitation would be just as comfy for energy hungry lifeforms as a sunny planet like earth-- and be far more abundant for possible building sites.
I find it highly foolish to just write off systems like this one as being "too cold for life".
A cold brown dwarf star?
Did they name it "Gary Coleman"?
I say we completely ignore it from now it it's not really worthy of our attentions is it within its' rotten miserable failure to be anything important?
Actually, probably not. There wasn't much potassium and uranium at the orbital position where proto-Jupiter formes, compared to water ice. So most models of the formation of Jupiter (and the rest of the Solar system) have a proto-Jupiter forming largely of water-ice, then going into runaway growth at about that mass and building up huge additional amounts of hydrogen and helium from the Solar nebula.
Some models still have Jupiter collapsing from the crystallisation of metallic hydrogen in Jupiter's core, which releases heat (as says). Other models ahve that heat generated because of the gravitational settling of helium into Jupiter's core (rather analogous to the settling of iron into the Earth's core). And it's possible that both processes are going on ; we don't know the equations of state of hydrogen and helium well enough at these pressures to be really sure.
Birds are not dinosaur descendants;birds are dinosaurs, for all useful meanings of "birds", "are" and "dinosaurs"
True, but that's a separate issue from our sun exploding into a red giant. And really, both problems have the same relatively simple solution - move the Earth. It should be possible to start the process even with technology currently being developed - fusion-powered ion drives on the moon could slowly tug the Earth further from the sun. Sure it'd be incredibly slow, but we've got billions of years to get the job done. If we eventually master mass-energy conversion (a domesticated black hole should do the job nicely) then we'll have effectively unlimited energy to work with - more than enough mass on the moon to raise the Earth's orbit arbitrarily. In fact throw some massive lights on the near side to mimic sunlight and we could fly the whole planet between stars. Might want to grab a couple extra moons on our way the way out of the system just as backup batteries though. Maybe snare the other rocky planets as well - no sense leaving them to be devoured. Then again by that point they'll probably have been moved to more favorable orbits and colonized, and may well want to set of in their own directions.
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AC is correct, both of those forms do still allow at the very least communication with the past if employed in a larger construct. Basically in the simplest form it relies on the fact that at relativistic speeds the Lorentz transformation rotates the space-time axes such that if some sublight traveler is moving at relativistic speeds relative to Earth, then certain directions that they perceive as space will be perceived by us as time. An FTL traveler departing from that relativistic frame can then travel along those spatial directions fast enough to travel into what we perceive as the past. With a cleverly constructed FTL communication loop between two frames of reference traveling at relativistic speeds relative to each other, you can then easily transfer information from one frame into it's own past.
--- Most topics have many sides worth arguing, allow me to take one opposite you.
Considering we've given these guys the rest of eternity you'd think they would visit once in a while? They don't even write.
It's your own fault for not reading the flyers. They're going to throw a big bash downtown yesterday, you should come.
--- Most topics have many sides worth arguing, allow me to take one opposite you.
How about "Frigid brown dwarf revolves around hot star," is it porn or astronomy?
The idea here was NOT that the central object needs to be hot.
The idea was that if it is metal rich, then the chances of rocky bodies that are much smaller/less dense than it can be tidally heated, and with that tidal heating, be able to support life. (say, chemotrophic microbes.)
Spectroscopic analysis of the object will only reveal its atmospheric composition. Lensing analysis (from a transit) would better refine mass estimates, which could help refine the internal composition, but much like our own gas giants much closer by, we can only speculate as to what is deep below the clouds.
Detecting orbiting bodies in this system is a non-starter with current technology, because the parent object is too dim to do effective transit light dimming measurements. The whole system would have to transit a very bright and distant system, and then if there are any large transiting objects in that distant system, interval periodicity will be suspect/difficult to refine.
I still hold that systems like this one should be of considerable interest, and not passively written off as "too cold."
Wikipedia geothermal_gradient#Heat_Sources, http://en.wikipedia.org/wiki/G... says the top heat producer on Earth is
Th232 3.27 × 10^-12 W/kg mantle, then
U238 2.91 × 10^-12 , and only then
K40 1.08 × 10^-12, and then
U235 0.125 × 10^-12.