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Star in Leo shouldn't exist
September 3, 2011 9:34 PM   Subscribe

ESO scientists have found an 'extremely primitive star' in the Milky Way's halo - 4/5 the size of the Sun, one of the oldest ever found - that theory says is impossible. It has fifty times less lithium in it than expected in the material produced by the Big Bang.

Project supervisor Piercarlo Bonifacio: "It is a mystery how the lithium that formed just after the beginning of the Universe was destroyed in this star." Less than 1 part in a million in the 13 billion year-old star is not hydrogen or helium. It has 20 000 times less 'metals' than the Sun. Current theory says that stars can't form in a region with so few 'metals'.
(SDSS J102915+172927. Nature abstract)

Observations are the mutagens that cause theory to evolve - if they're right. All the birds in the sky are making this a great time for astronomy.
posted by Twang (79 comments total) 34 users marked this as a favorite

 
Primordial star shouldn't exist — but whoot there it is
posted by Foci for Analysis at 9:43 PM on September 3, 2011


Wouldn't THAT be a clever clogs way for an alien civilization to contact others: make the signature of an impossible phenomenon.
posted by hanoixan at 10:00 PM on September 3, 2011 [59 favorites]


hanoixan: My first thought as well. I know I've read at least one story that uses a star with an impossible makeup to signal that aliens exist or existed. Nrgh, I can't remember what it was now.
posted by BungaDunga at 10:05 PM on September 3, 2011


Maybe the intelligent race of aliens took all the lithium from the universe. What's the deal with lithium? Some astronomers have told me that there isn't as much lithium in the universe as there should be, another told me that there's plenty of lithium.
posted by fuq at 10:10 PM on September 3, 2011


Something something Nirvana something.
posted by jokeefe at 10:22 PM on September 3, 2011 [5 favorites]


tweakers stole it
posted by Iron Rat at 10:22 PM on September 3, 2011 [10 favorites]


God did it, just like He put those fossils in the ground to trick us.
posted by kmz at 10:23 PM on September 3, 2011 [4 favorites]


As a star that shouldn't exist, I propose that we name it "Snooki."
posted by XMLicious at 10:28 PM on September 3, 2011 [68 favorites]


there's a star that shouldn't exist
but hey, there it is in the sky
against all odds, it's hanging around
and don't nobody know why
a primordial star, way out on the edge
out on the outskirts of heaven
but they really should give it a catchier name than
SDS J102915+172927
posted by flapjax at midnite at 10:35 PM on September 3, 2011 [43 favorites]


Wouldn't THAT be a clever clogs way for an alien civilization to contact others: make the signature of an impossible phenomenon.

Not just clever, but that's pretty much the only way to communicate. Your communication channel has to stand out from the background noise. What do you think radio broadcasts look like? They are quite a bit more complex and structured than natural signals.

Of course, it this could just be a natural phenomena that we aren't familiar with. We either get to learn new physics, or get our brains sucked out by alien overlords.
posted by b1tr0t at 10:39 PM on September 3, 2011


Galacticus is bipolar, that's all.
posted by Grimgrin at 10:42 PM on September 3, 2011 [11 favorites]


BungaDunga, you might be thinking of Greg Egan's novel Diaspora, which includes a beacon in the form of a planet made up exclusively of the heaviest isotopes of its elements.
posted by stebulus at 10:52 PM on September 3, 2011


It starts with electric cars, and the demand for batteries, and before you know it, you have a lithium economy, and since no-one pays attention to the sustainable growth chicken-littles, you gotta keep growing your economy, and the next thing you know, you've got floating rigs drilling your sun for the stuff, and suddenly crazy war-obsessed primitives orbiting another star are sitting up and taking notice, and it all just goes downhill from there.

Just say no to electric cars.
posted by -harlequin- at 10:57 PM on September 3, 2011 [6 favorites]


Maybe the intelligent race of aliens took all the lithium from the universe.

Despite the best alien technology, battery technology never really gets that much better.
posted by furiousxgeorge at 10:58 PM on September 3, 2011 [9 favorites]


Fascinating. But we know that the universe that formed after the Big Bang (and any subsequent fancy inflation) wasn't quite homogeneous. That is, the photons and quarks and whatnot were distributed a little bit unevenly. Then they cooled enough for atoms like hydrogen and helium and lithium to form.

So I guess what I'm asking is why those primordial atoms had to form in the same proportions everywhere. If a certain part of the universe had slightly less material in it (corresponding to a less dense part of the CMB), maybe certain reactions that required a higher binding energy happened less often. So you end up with metal poor "deserts," and stars that formed there followed suit. That still doesn't explain how how the star formed in the first place, but it might explain why.
posted by Kevin Street at 11:04 PM on September 3, 2011 [2 favorites]


excession
posted by dibblda at 11:05 PM on September 3, 2011 [12 favorites]


b1tr0t: Not just clever, but that's pretty much the only way to communicate.

Sure. But a many-bit message would have more room for error in the interpretation. As a singal increases in complexity, it approaches the signature of random noise. This is a 1-bit message where it is 0, and the rest of reality is 1. I think that's more clever.
posted by hanoixan at 11:12 PM on September 3, 2011 [3 favorites]


Despite the best alien technology, battery technology never really gets that much better.

The universe: it just keeps going... and going ... and going ... and going ...
posted by flapjax at midnite at 11:12 PM on September 3, 2011 [3 favorites]


Sorry, might explain why the star is so metal poor. That is, the lithium and other metals weren't necessarily destroyed - they just weren't available in the neighborhood when this star's parent stars were forming.

But now that I think about it, this doesn't make much sense, since the rest of the Milky Way galaxy has elements in normal proportion. Maybe this star formed in in another, metal poor galaxy, and was then captured by ours?
posted by Kevin Street at 11:14 PM on September 3, 2011 [2 favorites]


Rather than means of communication, it's a great way for some Kardashev Type 3 civilization to prank us lowly planet-bound peoples.

"Hey, let's engineer something that's impossible to form naturally. They'll waste decades trying to find out what's wrong with their theories before they finally accept the fact that it really did have to be manufactured!"
posted by chimaera at 11:17 PM on September 3, 2011 [2 favorites]


MetaFilter: We either get to learn new physics, or get our brains sucked out by alien overlords.

(Tried to come up with a hipster joke about the heat death of the universe involving "before it was cool." Failed. Everyone gets this instead.)
posted by tzikeh at 11:28 PM on September 3, 2011 [10 favorites]


A shockwave from a nearby supernova could increase density in a metal poor region enough locally for a star to form, yeah?
posted by empath at 11:30 PM on September 3, 2011


The idea that this is a signal or a by-product of some latent sign of intelligent life having done something or passed through that area of the Milky Way sends some serious chills up my spine.

On the other hand, I've always thought from what I learned that stars/suns produce all the "stuff" and materials in the universe found in the Periodic Table as products of fusion, so to have a star that would remain, or decay into, such a basic state of the most fundamental building blocks, Helium and Hydrogen, might simply be a symptom of a weak or a sick star. But then again if that was the case this would be a much more common occurrence.

Then again what if the Lithium was "mined" out of it?

Whatever it is, a supernova or some release of, or collusion with anti-matter something happened.
posted by Skygazer at 11:46 PM on September 3, 2011 [3 favorites]


Nature is so fucking awesome.
posted by Blazecock Pileon at 11:47 PM on September 3, 2011 [10 favorites]


hanoxian, did you RTFA?

1) This doesn't contradict "the rest of reality." Rather, it contradicts a few details of the prevailing theory of stellar formation (yet one among many).

2) The team has discovered several other stars which they suspect of displaying the same behavior, and they're waiting on telescope time to investigate.
posted by 7segment at 11:49 PM on September 3, 2011


BungaDunga: "I know I've read at least one story that uses a star with an impossible makeup to signal that aliens exist or existed."

Alastair Reynolds' Revelation Space involves a plot device rather like this.

[SPOILER BELOW]



Unfortunately for humanity, these bizarre celestial bodies are in fact traps or, more accurately, lures.
posted by Conrad Cornelius o'Donald o'Dell at 11:57 PM on September 3, 2011


Pulsar Transformed Into Small Planet Made of Diamond Discovered in Milky Way
posted by homunculus at 12:11 AM on September 4, 2011 [1 favorite]


Wouldn't THAT be a clever clogs way for an alien civilization to contact others: make the signature of an impossible phenomenon.

Or, uh, our current theories are wrong, which going by the history of our theories seems pretty likely.
posted by 3FLryan at 12:18 AM on September 4, 2011 [5 favorites]


"A shockwave from a nearby supernova could increase density in a metal poor region enough locally for a star to form, yeah?"

Absolutely, that's how earlier generations of stars help kick off the formation of their successors. But one of the big mysteries here is how any star could form with such a low proportion of elements heavier than helium. Like it says in the first link, atoms like carbon and oxygen are needed to help cool the primordial cloud so it can collapse inwards and ignite into a star.
posted by Kevin Street at 12:20 AM on September 4, 2011


None of the reports tell us just how far away this odd star is, only that it's in "the Milky Way's halo" (and "Leo constellation" is no help). Since we're over on one side of the galaxy, it could be anywhere from moderately far away to ridiculously far away. And as long as there is any chance that it could have been artificially created by an alien intelligence with a LOT of power, I'd feel more comfortable with 'ridiculously far away'. If only Jack Horkheimer were still alive, he could probably hustle this star down to my level...
posted by oneswellfoop at 12:27 AM on September 4, 2011


If I fire up comms, there's a reply of blue silence
The screen is no comfort, I can't speak my sentience
We need to light up heaven's gate so we can say 'hi'

If I work all day on the lithium mine
There'll be grork on the table tonight
And if I walk up and down on the lithium mine
There'll be credits in my pocket tonight

And now some have asked from a distant shore
'Who took all this lithium nobody wants?'
But nothing says 'hey there!'
Like a hole in a star
posted by obiwanwasabi at 12:52 AM on September 4, 2011 [7 favorites]


tzikeh: "(Tried to come up with a hipster joke about the heat death of the universe involving "before it was cool." Failed. Everyone gets this instead.)"

I was at the Big Bang show and knew that star before it was cool. I guess that makes me the oldest hipster in the universe, but whatevs 'cause I'm the only one with this shirt.
posted by iamkimiam at 1:09 AM on September 4, 2011 [1 favorite]


I, for one, welcome our new lithium-sucking star-devouring overlords.

Is there any reason this star couldn't be the result of an improbable-but-not-surprising event like a bigger star being disrupted? Say, a low-metal early star forms, burns off its lithium, is disrupted by an encounter with another star, and its remnant goes drifting off, too small to do much except confuse astronomers?
posted by hattifattener at 1:14 AM on September 4, 2011


Please try not to head off into OMG aliens la-la land, people. New discoveries happen, sometimes observations are flawed or misinterpreted, sometimes theories have to be changed, interest rates fluctuate.

This sort of cosmological observation is, of necessity, at the very limits of our experimental and observational capabilities. All data must be approached with due caution.
posted by Decani at 1:18 AM on September 4, 2011 [7 favorites]


lease try not to head off into OMG aliens la-la land

All data must be approached with due caution.


Absolutely. All aliens must be approached with due caution.

I've got my laser set to KILL.
posted by flapjax at midnite at 1:43 AM on September 4, 2011 [2 favorites]


Please try not to head off into OMG aliens la-la land, people.

This. Lithium levels fluctuate all the time. It's a natural cycle. It's arrogant to think puny lifeforms could have an effect on something the size of a star. It's a conspiracy to get us all to switch to beryllium. Scientists can't tell me how much lithium there'll be on Iota Carinae three days from now but you expect me to believe them when they trot out this sort of nonsense? And what sort of a name is SDS J102915+172927 anyway? I demand to see a birth certificate with notarised Bok globule data.
posted by obiwanwasabi at 2:33 AM on September 4, 2011 [3 favorites]


My phaser, too.
posted by flapjax at midnite at 2:41 AM on September 4, 2011


Not just clever, but that's pretty much the only way to communicate. Your communication channel has to stand out from the background noise. What do you think radio broadcasts look like? They are quite a bit more complex and structured than natural signals.

Recently came across this, which seems apropos.
posted by solotoro at 3:12 AM on September 4, 2011


I was having this conversation earlier tonight about Tsar Bomba, the most powerful nuclear weapon ever detonated, which had a destructive force of 50 megatons. By contrast, the bomb dropped on Hiroshima was about 0.03 megatons. By even greater contrast, the Chicxulub impact, which led to the extinction of the dinosaurs, had a destructive force of about 96 teratons, which is about 2 million times more powerful than the most powerful bomb ever detonated by humankind.

The effective energy needed to interfere with a star would be many orders of magnitude above all this.

I quiver with the thought that anybody is out there who could do that.
posted by twoleftfeet at 3:30 AM on September 4, 2011


I quiver with the thought that anybody is out there who could do that.

Find a way to make it profitable and your children will see the day it happens. Humanity has no lack of ambition when properly motivated. In billions of years, another sentient life form may detect our own incomprehensible feats and wonder themselves what it may mean.

That, or something a lot more mundane like our measurements are off or our models need adjustment. More likely, more boring.
posted by Saydur at 3:48 AM on September 4, 2011 [1 favorite]


Lithium and hydrogen and helium and noble gases from the universe!

Coz you know that's what Box is up to these days.
posted by PapaLobo at 4:11 AM on September 4, 2011 [1 favorite]


Some time, some way
Your dreams awaken
You will not be forsaken
And like a pheonix rising
Into the midnight skies
You will realise
There's Stardust in your eyes

posted by Meatafoecure at 4:47 AM on September 4, 2011


It makes perfect sense if the star in question is travelling backward through what we call "time".
posted by Renoroc at 4:55 AM on September 4, 2011 [2 favorites]


Great, Science, just great. You have found the star that should not be. Now all those Great Old Ones are gonna hear about it in their primordial necrotic slumbers, they are gonna stir in their sleep, then waken and devour the few last shrieking handfuls of humanity before rising to take their place in the Universe.

You had to go fucking around with telescopes, didn't you?
posted by GenjiandProust at 5:01 AM on September 4, 2011 [7 favorites]


It's arrogant to think puny lifeforms could have an effect on something the size of a star.

It's even more arrogant to think all lifeforms are as puny as us.
posted by DU at 5:07 AM on September 4, 2011 [10 favorites]


This sort of cosmological observation is, of necessity, at the very limits of our experimental and observational capabilities. All data must be approached with due caution.

Agreed. There are more things in heaven and Earth, as it were, than are dreamed of in our science. Assuming the data is correct, it means we need to determine whether this is a freak occurrence or whether its evidence that we need to re-examine our theories regarding the origin of the universe.
posted by Joey Michaels at 5:34 AM on September 4, 2011 [1 favorite]


The Kardashev scale isn't that well known on this planet. Probably because we're somewhere below Type I.
posted by twoleftfeet at 5:53 AM on September 4, 2011


Martin Blank: They told me you have been taking lithium.

Mrs. Blank: Yes. Oh, those blabbermouths.
posted by mr_crash_davis at 5:57 AM on September 4, 2011 [2 favorites]


flapjax at midnite: "but they really should give it a catchier name than SDS J102915+172927"
obiwanwasabi: "And what sort of a name is SDS J102915+172927 anyway?"

SDSS is the Sloane Digital Sky Survey (the article misprints this as SDS the first time, but gets it right later). Objects imaged by the SDSS are assigned names somewhat "automatically" so that they don't have to come up with billions of names for them. The format of the names is based on the exact location (using celestial coordinate system) of the object. This star is at (approximately) 10h 29m 15s right ascension, +17° 29' 27'' declination.
posted by Plutor at 6:15 AM on September 4, 2011 [4 favorites]


I almost named my kid SDS J102915+172927.
posted by mazola at 6:55 AM on September 4, 2011 [1 favorite]


Pfft. I named my kid SDSS J102915+172927'); DROP TABLE Stars;--
posted by ROU_Xenophobe at 7:15 AM on September 4, 2011 [5 favorites]


It's even more arrogant to think all lifeforms are as puny as us.

Yeah. Two million years ago, we looked like this. Try to imagine what we'll look like in a billion, if we live that long.
posted by EarBucket at 7:26 AM on September 4, 2011


This star is at (approximately) 10h 29m 15s right ascension, +17° 29' 27'' declination

Sure, but Snooki's in New York, but they still call her Snooki.
posted by buzzv at 7:53 AM on September 4, 2011


Conrad Cornelius o'Donald o'Dell: "BungaDunga: "I know I've read at least one story that uses a star with an impossible makeup to signal that aliens exist or existed."

Alastair Reynolds' Revelation Space involves a plot device rather like this.

[SPOILER BELOW]



Unfortunately for humanity, these bizarre celestial bodies are in fact traps or, more accurately, lures.
"

Fortunately for humanity, we have no way to get there any time soon, and if we ever are able to do so (i.e. we don't fuck ourselves over before then), I'll be long dead, so, I'll leave it to the fancy pants intergalactic genius starfaring species we miraculously evolved into to figure that part out. For now, I'll just freak out about possible asteroids, and global warming and republicans.
posted by symbioid at 8:09 AM on September 4, 2011


It has fifty times less lithium in it than expected in the material produced by the Big Bang.

They found the ending to Garden State.
posted by Sticherbeast at 8:33 AM on September 4, 2011


Probably not an alien signal -- if you want to make a stellar signature stand out on a spectrometer, it's going to be much easier to add an unlikely isotope than to remove stellar material selectively. On this theory, SETI researchers have searched a number of stars for the tritium hyperfine line (with no luck so far), as it is both rare enough to stand out, and fairly easily detectable through our atmosphere.
posted by dgoddathunda at 9:59 AM on September 4, 2011


Following the link earlier about Lithium Burning - surely this might just be a brown dwarf that grew in size.

Possible scenario: Two "lithium burning" brown dwarfs that weren't big enough to fuse hydrogen, burned all their lithium then crashed into each other, giving a star big enough to fuse hydrogen? (And possibly did something with the heavier elements at the same time like concentrate them in the core which is unusual in stars)?
posted by BigCalm at 10:10 AM on September 4, 2011 [1 favorite]


Ok, I assume most of the "OMG aliens" talk here is in good fun, but just in case some of it's not here's why that theory will not gain any traction with actual, working scientists. It has nothing to do with us being close-minded, but because it's a truly awful explanation of the facts.

First, let me talk about why this is actually interesting from an astronomy and astrophysics perspective. Note: am a particle physicists who just happens to get paid by astrophysicists without doing too much actual astrophysics, so this is a bit outside my wheelhouse; if there are more astro-y people around, chime in. The early Universe created stable elements up to Li (two isotopes, 6Li and 7Li) in a process called Big Bang Nucleosynthesis (BBN). My work actually cares a great deal about Li abundances, since additional energy injection (say, from annihilating dark matter) would change the Li created during BBN: creating more 6Li and destroying 7Li. The experimental problem is that Li is a very fragile element; it likes to fall apart (into 2 He nuclei, I'm guessing) in the presence of too much energy, like in a star. So measuring the initial abundance is really hard, and I really would like to know how stars process elements in the early Universe, in order to get a better picture of what happened in BBN.

Astronomers and stellar astrophysicists also will care a lot about this question because the presence of heavy elements will change the story of how the generations of stars formed. This was alluded to in the article, but was presented as a fact rather than an open question (a really common problem in science reporting). The article said that this star is impossible under the current accepted theory: that you need lots of metals to get the gas cloud to cool. I think it's more accurate to say that this is one theory, and there is some debate.

The issue is one of gas cloud fragmentation: stars form in large clouds of gas that mass many hundreds or thousands of Solar masses. Stars like the Sun formed along with many siblings because that gas cloud fractured down into hundreds of lighter stars; to do so, one school of thought says you need cooling through metals (they will allow more efficient radiation and so faster cooling). If that's the case, such an old star (only 700 million years after the Big Bang), is impossible. The gas cloud could not fracture and you should get one giant star that burns out quickly (a "Population 3" star. We're Pop 1, the previous "generation" of stars that seeded our mother nebula with metals was Pop 2). So, if that theory is true, we'd see evidence of a very old generation of stars that were enormous, short lived, and with low metalicities. The problem is we don't: right now there is no clear evidence for such stars, but this is a prediction of the theory that the article takes as correct (in fairness, most of the work done on cooling processes does come to this conclusion, so there's that).

The alternative theory is that you don't need metals to fracture the gas cloud. Maybe you can get away with radiative cooling from deuterium, or maybe something else we haven't figured out yet. So the Pop 3 stars (the giant ones) don't occur, and we go straight to Pop 2: low metalicity stars, some large, some small. This would do better at explaining the observation here: the star in question is very light (as could occur if fracturing doesn't need metals), very long lived, and would destroy all the primordial lithium because, as I said, lithium is fragile and doesn't last in high temperatures. It doesn't explain the calcium though; so this isn't ironclad. Maybe the calcium was a pollutant from the original nebula that was seeded by a much shorter lived Pop 2 star, or maybe that is impossible, and we need to come up with a better theory to fit the facts.

So, this star is fascinating. It will give us a new way to test some really interesting theories about star formation, maybe revealing (or condemning) a generation of stars that was only predicted till now. It may tell us more about the primordial Li abundance, which will be interesting to guys like me who don't care much about stars (you know, professionally. I'm a big fan of Sol's work on a personal level).

What it won't do is reveal ancient aliens. That hypothesis is pretty much untestable, because you can always come up with a just-so story that allows life early on who decide to do stupid things like build stars with no metals, but let me talk about two problems with it. First, there isn't enough time. This star was born 700 million years after the Big Bang. There are few heavy elements around then (necessary for interesting chemistry), any planets that formed would either be mostly gas, or, if made of the few scare metals, still rock-meltingly hot. So our proposed super-intelligent aliens have to be very, very lucky to even be around (also, note it took billions of years of evolution on Earth to just get to multicellular life. These guys have less than 1 billion to get to the phenomenal cosmic power stage). In my opinion, the Gaurdians of Oa are somewhat unlikely (Nibbolians are, of course, well known to be real).

Second, as was pointed out, this is a terrible, low-bandwidth way to communicate. You get 1 bit, and you picked the worst channel to communicate in. As I said, Li abundance is tricky, and anyone smart enough to build this star (which is a massive, nearly impossible undertaking) is smart enough to realize that distant observers would be more likely to attribute it to unusual stellar processes than intelligent intervention. You want to communicate and you can build stars? Dope a star with heavy elements (like iron and uranium heavy) in particular ratios that will be impossible to mistake for anything other than intelligence (maybe get elements with prime atomic numbers and give them relative abundances that spell out your message). Anything is possible, you have a magic-star moving machine, after all. (on preview, dgoddathunda got here first, which is a nice illustration that even us puny Earthlings can reliably come up with a better communication channel on short notice).

Saying that aliens are unlikely to have done this then isn't arrogance, it's just a statement that 1) all evidence indicates no one could have physically been around to do it and 2) if they were, there were better ways for them to get a message across.

Anyway, the most exciting phrase in science isn't "Eureka," but "hmm... that's odd." So this is great stuff, but there's a reason scientists rarely jump to "aliens" as an legit explanation. If we always assumed aliens when we found something new (in this context, might as well say "magic" rather than aliens), we'd be still sitting in caves scared of fire.
posted by physicsmatt at 10:19 AM on September 4, 2011 [29 favorites]


Also, as BigCalm alluded to, there is always the "Anna Karinina" problem of every unhappy star being unhappy in its own way. Maybe this star is evidence of some new process, or maybe it was just very unlikely. In a Universe this big, unlikely things aren't as uncommon as you'd like (if you're trying to draw strong conclusions, that is).
posted by physicsmatt at 10:39 AM on September 4, 2011


Fuckin' low-helium impossible stars, how do they work?
posted by Pirate-Bartender-Zombie-Monkey at 11:28 AM on September 4, 2011 [2 favorites]


symbioid: "Fortunately for humanity"

Fortunately for humanity, I was describing a work of fiction.
posted by Conrad Cornelius o'Donald o'Dell at 11:32 AM on September 4, 2011


I agree with most of what physicsmatt says, but the fact that elements beyond Lithium are seen in this star directly implies that there was a "population 3" before this star. The observed elements must have been formed in stars (and dispersed in supernovae) - elements like Calcium can't form in the Big Bang (as the Universe expanded and cooled down too fast for fusion to get past the point of forming Lithium and unstable isotopes of Beryllium).

Basically, population III stars are those which contain only the elements that formed in the Big Bang. To collapse and form a star, a gas cloud's gravity needs to be strong enough to overcome the thermal motion of its gas: when the gas is hot, this can only happen to a relatively large, massive cloud. With just hot H, He, and a tiny amount of lithium, there aren't many ways gas can radiate off energy, so we expect only very massive stars could form (quite possibly more massive than any seen today).

In contrast, once the amount of 'metals' (as astronomers call any element beyond He) becomes significant, a whole menu of atomic and molecular transitions that can cool gas become available, so gas clouds can lose energy and shrink, reaching higher densities at which smaller stars can form. There are predictions from simulations that this transition to being able to form low-mass stars should occur at about one-three-thousandth of the metal content of the Sun.

The puzzle this star poses is that it's below that predicted transition amount of metals, but still low in mass. Of course, if it had been as massive as Pop III stars should be, it would have used up its fuel for fusion in only a few million years, and wouldn't still be around for us to see it. So perhaps we're just seeing a fluke, the last living remnant of early Pop II stars; but I'd certainly believe the predictions for the transition amount of metals could be off by a factor of 10 given our current limited understanding of star formation.

Because (based on current theories) population III stars were extremely massive (perhaps 100 times as massive as the Sun or more), and hence extremely short-lived, no one expects to find them in the local neighborhood. There are some hopes that observations with the in-construction James Webb Space Telescope could find signs of these stars (presuming that Congress doesn't kill it, previously), but that is still uncertain. Any Pop III stars are so far away (almost to the limit of the observable universe) that we probably can't spot them individually (we might be able to see them dying explosively), and so short-lived and so efficient at polluting their local neighborhoods with metals that we are unlikely to find galaxies full of them (which we could identify from their combined light).

Like physicsmatt, I'm not too worked up about the lack of lithium. Lithium is extremely easy to fuse into other things - 'fragile', as physicsmatt put it. This is why even brown dwarfs are able to fuse lithium, though not hydrogen. Lithium fusion is even easier in a star, but a minor contribution to energy generation, whereas in brown dwarfs it's the full extent of the action.

The reason we see any lithium at the surfaces of stars is that, for some types of stars, material at the core of the star (which is where the fusion happens) does not mix well with what's at the surface. If (for whatever reason, e.g. if it spent some time using convection for energy transport throughout - I'm not up-to-date on what the interiors of low-mass, low-metallicity stars are like) this star has kept well-mixed, it should be lacking in Lithium for that reason.
posted by janewman at 11:41 AM on September 4, 2011 [11 favorites]


That's no moon star...
posted by bowmaniac at 11:53 AM on September 4, 2011


What if a pop 3 star didn't clear the entire gas cloud it was formed in and this star was just 'what was left over'.
posted by empath at 12:12 PM on September 4, 2011


So I don't think this has been mentioned yet, but we've known for years that the sun is highly depleted in lithium, by something like a factor of 70. So when we talk about "predictions of big bang nucleosynthesis", the dirty secret is that we have to pick which lithium abundance we want to believe. I think the one that's commonly used right now are the measurements from carbonaceous condrites, but I'm not sure I'm remembering that right. All of the star formation people I talk to seem to think that this lithium gets burned during the initial contraction of the star, and this process was kind of ignored by older models, models created by people who sort of ignored star formation as a complicated process and treated it more as a given.
posted by kiltedtaco at 12:23 PM on September 4, 2011 [1 favorite]


I wonder if this star could have formed out of a polar jet from a supermassive black hole.

You might expect such a jet to be enriched in hydrogen and helium because they emerge at something like the escape velocity of near the event horizon, and for a plasma of a given temperature, hydrogen and helium will be moving faster than lithium.

Being part of a jet conditioned by magnetic fields might also make particles have lower relative velocities than otherwise expected, and that could make condensing into a star easier.
posted by jamjam at 12:59 PM on September 4, 2011


try not to head off into OMG aliens la-la land, people

Yeah, because that would be crazy. /stares in mirror

It's arrogant to think puny lifeforms could have an effect on something the size of a star.

No, what's arrogant is to suggest that there are normal fluctuations in the distribution of elements throughout the universe, that the basic rules are still the same everywhere… EXCEPT oh yeah not consciousness, no no, that's PURELY an Earth-bound phenomenon, utterly unique to the whole of creation.

We now return you to your regularly scheduled shadows cast upon a wall in a cave.
posted by Civil_Disobedient at 1:24 PM on September 4, 2011 [1 favorite]


physicsmatt: The early Universe created stable elements up to Li (two isotopes, 6Li and 7Li) in a process called Big Bang Nucleosynthesis (BBN). My work actually cares a great deal about Li abundances, since additional energy injection (say, from annihilating dark matter) would change the Li created during BBN: creating more 6Li and destroying 7Li. The experimental problem is that Li is a very fragile element; it likes to fall apart (into 2 He nuclei, I'm guessing) in the presence of too much energy, like in a star. So measuring the initial abundance is really hard, and I really would like to know how stars process elements in the early Universe, in order to get a better picture of what happened in BBN....

Blah..blah...blah...etc...etc.....etc....Zzzzzzzzzz


Look, Mr. Astrophysicist Smartypants, goddamned aliens sucked the Lithium out of that star to make contact with earthlings and this planet needs to wake up and get it's interspace military corps up and running so we can attack them.
posted by Skygazer at 1:37 PM on September 4, 2011


Kevin Street: "Maybe this star formed in in another, metal poor galaxy, and was then captured by ours?"

It must suck to live in a metal poor galaxy. Let's help them out and beam them some Slayer.
posted by brundlefly at 3:00 PM on September 4, 2011 [4 favorites]


>> Dope a star with heavy elements (like iron and uranium heavy) in particular ratios that will be impossible to mistake for anything other than intelligence

Like this one?
posted by BigCalm at 3:15 PM on September 4, 2011


Thanks janewman, stuff like this is why I'm always eager to read the comments on science FPPs. *cough* SIDEBAR *cough*
posted by chaff at 4:03 PM on September 4, 2011


It's even more arrogant to think all lifeforms are as puny as us.

They've certainly got to be better than us at detecting satire.
posted by obiwanwasabi at 7:46 PM on September 4, 2011


Surely it is our mission as the nexus of humanity to go forth and civilize this primitive star.
posted by dhartung at 10:42 PM on September 4, 2011 [2 favorites]


Surely it is our mission as the nexus of humanity to go forth and civilize this primitive star.

The White Man's Burden! Now in outer space!
posted by flapjax at midnite at 11:37 PM on September 4, 2011 [1 favorite]


Someone raised the question of the distance to SDSS "NoWayGetOutHoser"; a COSMOS article reports it as "found hovering about 3,500 light-years above the disc of the Milky Way." Which suggests that it's within about 30K parsecs.

IN the comments to this article, with regard to lithium getting mixed down to the core, one respondant raises the question:
If I remember correctly, lithium fuses easily so Pop I stars should burn it off in a pre-Main Sequence “lithium flash”. I also understand that low-mass Pop I stars tend to be fully convective. However, with low opacity this star would presumably have less convection. How then would stellar envelope lithium get mixed down into the stellar core to get burned away? The missing lithium is indeed a puzzle.
One possibility that seems missing from MeFi discussion: this could be evidence of Star Lifting. Several occurences in fiction are noted there.
posted by Twang at 2:07 AM on September 5, 2011


Thank you physicsmatt and janewman. Amid all the sillyness, I appreciate someone actually talking about the real implications of this discovery. I actually find real astronomy more interesting than babble about aliens.
posted by happyroach at 9:49 AM on September 5, 2011


I think it's banter, not babble. But perhaps both banter and babble are in the eye of the beholder.
posted by stebulus at 12:39 PM on September 5, 2011


Nice find, Twang. Although low-metallicity stars are less convective, it looks like this isn't a huge effect (in one paper I found, the inner radius of the convective zone changed by only about 10% from high-metal to low-metal stars). The reason for this is that in the interior of a star, H and He are completely ionized and dominate the opacity; the metals are significantly less important. They play a much bigger role when H and He are not completely ionized, e.g. near the 'surface' of a star.
posted by janewman at 1:01 PM on September 5, 2011


Astronomy Picture of the Day has linked to this thread.
posted by neuron at 10:32 PM on September 23, 2011


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