 date back at least 13.2 billion years.)
The oldest known stars (one seen here in artists impression) date back at least 13.2 billion years.
Image: ESO
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Astronomers have discovered the Methuselah of stars — a denizen of our Solar System's neighborhood that is at least 13.2 billion years old and formed shortly after the Big Bang.
“We believe this star is the oldest known in the universe with a well determined age,” says Howard Bond of Pennsylvania State University in University Park, who announced the finding 10 January at a meeting of the American Astronomical Society in Long Beach, California.
The venerable star, dubbed HD 140283, lies at a comparatively short distance of 186 light years from our Solar System and has been studied by astronomers for more than a century. Researchers have long known that the object consists almost entirely of hydrogen and helium, a hallmark of having formed early in the history of the universe, before successive generations of stars had a chance to forge heavier elements. But no one knew exactly how old it was.
Determining the star’s age required several steps. First, the team made a new and more accurate determination of the star’s distance, using 11 sets of observations recorded between 2003 and 2011 with the Hubble Space Telescope’s fine guidance sensors, which measure the position of target stars relative to reference stars. Having measured the distance and the brightness of the star as it appears on the sky, the astronomers were able to calculate the star’s intrinsic luminosity with unusual precision.
The team then exploited the fact that HD 140283 has advanced to a phase in which it is exhausting the hydrogen at its core. In that phase, the star's slowly dimming luminosity is a highly sensitive indicator of its age, says Bond. His team calculates that the star is 13.9 billion years old, give or take 700 million years. Within the experimental error bars, the age does not conflict with the age of the universe, 13.77 billion years.
The star's age is therefore at least 13.2 billion years — which was the age of another known Methuselah — and possibly somewhat older. Its age is also known with considerably better confidence than in that previous case, Bond says.
The discovery does, however, place constraints on early star formation, says Volker Bromm of the University of Texas in Austin, who was not part of the study. The very first generation of stars coalesced from primordial gas, which did not contain appreciable amounts of elements heavier than helium, he notes. That means that as old as HD 140283 is, its chemical composition — a low but nonzero abundance of heavy elements — shows that the star must have formed after the first stellar generation.
Conditions for making the second generation of stars, then, “must have been in place very early,” says Bromm. In the standard scenario, the very first stars coalesced a few hundred million years after the Big Bang, he notes. Massive and short lived, the first-generation stars died in supernova explosions that heated surrounding gas and seeded it with heavier elements.
But before the second generation of stars could form, that gas had to cool down. The early age of the second-generation star HD 140283 hints that the cooling time, or delay, between the first and second generations might have been extremely short, perhaps only a few tens of million years, Bromm notes.
This article is reproduced with permission from the magazine Nature. The article was first published on January 10, 2013.
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30 Comments
Add Comment"low but nonzero abundance of heavy elements" - could these not have accreted to this star over time as debris from subsequent supernova activity?
Reply | Report Abuse | Link to thisCould this not be a very old (13.2BY+)2nd generation star? Any amount of heavier elements rules out 1st generation, right?
Reply | Report Abuse | Link to thisCAN a star actually live that long, and still be formed of mostly H and He? That means it is STILL a main sequence star...
Reply | Report Abuse | Link to thisNeither this nor the Nature article have any reference to the actual study.
Links, please?
"... In the standard scenario, the very first stars coalesced a few hundred million years after the Big Bang, he notes. Massive and short lived, the first-generation stars died in supernova explosions that heated surrounding gas and seeded it with heavier elements."
Reply | Report Abuse | Link to this"But before the second generation of stars could form, that gas had to cool down. The early age of the second-generation star HD 140283 hints that the cooling time, or delay, between the first and second generations might have been extremely short, perhaps only a few tens of million years, Bromm notes."
As I understand, first gen. stars were (ironically) thought to be extremely massive and short lived. The production of the second gen. might have benefited from the turbulence produced by the supernova of the first gen. and perhaps their remnant black holes - perhaps even supermassive BH's seeding galaxy creation...
The link is at the bottom of the article: http://www.nature.com/news/nearby-star-is-almost-as-old-as-the-universe-1.12196
Reply | Report Abuse | Link to thisIs the quick cooling of phase one a backdoor approach to timing the expansion of the universe, or setting limits on the expansion velocity, from basic gas laws? Or is the expansion rate better known more precisely by other methods, and if so, does this more accurate expansion rate set limits on the advent of phase two start formation era?
Reply | Report Abuse | Link to thisThis certainly puts the phenomenal impact of Inflation in the earliest stages after the Big Bang in perspective, if we can find a 13.2 billion year old star 186 light years away, and through our telescopes observe 13.2 billion year old stars 13 billion light years away.
Reply | Report Abuse | Link to thisHow did this 13.2 billion years old star get to 186 million years close to us baffles me . Does it mean that this one was running towards us faster than the speed of light? We are supposed to keep a respectable distance from older stars , the thumb rule for it being for a star to be "as much away from the spot of the big bang or , wherever it was formed , as our distance from the big bang spot / the spot of the star formation is "; because distance measured in light years means that it takes that much time for the light to reach us from that star ,which means that the star is that much light years away from us and cannot be nearer to us than it's age . There seems to be some contradiction when we say that we have a 13.2 billion year star at a distance of 186 million light years .This completely baffles me ! Can someone clarify this paradox, for me , please ?
Reply | Report Abuse | Link to thisOur own star is 5 billion years old. How far away do you want it to be?
Reply | Report Abuse | Link to thisAcoyauh2: Good point. Is the "low but non-zero" level of heavier elements the result of all those years of fusion? Shouldn't it be a bit higher after all that time?
Reply | Report Abuse | Link to thisa star can be any age at any distance, it can't be YOUNGER than its distance in light years or the light wouldn't have reached us yet. But once it starts shining it goes on shining for billions of years, it doesn't matter when we happen to look up and see the light, it's been there for all that time.
Reply | Report Abuse | Link to thisIt's one of the effects of expansion. This star formed before the Milky Way galaxy and was later caught up in its gravitational field. When the star formed, the universe was smaller and as space expanded, so did the distance between this star and the stars that seeded it with heavier elements.
Reply | Report Abuse | Link to thisSome stars can exist for extremely long times. Red dwarfs under about 0.1 solar masses have the longest lifespan at 10 trillion years or more. These bodies may then further exist as blue dwarfs for a few billion years and then white dwarfs for 10^15 years or longer.
Reply | Report Abuse | Link to thisThere isn't any mention of the mass of the star, if it is a massive or average or even less than a solar mass star.
Reply | Report Abuse | Link to thisThis is important, since when a massive star's hydrogen becomes depleted, or the hydrogen at the core is becoming exhausted, as in HD 140283 and the fusion energy isn't maintaining the outer layer in place, there can be inward collapse of the star outer layers onto the core, setting off a supernova.
Although supernova are probably only thought to be dangerous if less than a hundred light years from earth, having the potential to ionize the ozone layer, I don't know as we have actual historical precedent to say for sure that this star would be harmless to earth if it goes supernova.
The dimming of the star may be a red flag of impending supernova
Even though the article doesn't state the mass of this star, judging by the age, I would guess it was pretty small. Smaller stars live longer and, since it must be small, it couldn't have enough mass to go supernova.
Reply | Report Abuse | Link to thisFollowing apparent contradictions have struck my mind:
Reply | Report Abuse | Link to thisi)Age of star HD 140283 has been estimated at 13.2 billion years +/- 700 million years and it is only 186 light years away from earth. Age of Sun is taken at 4.6 billion years. In astronomical scales, two stars within a range of 186 light years can be treated to be in proximity. How it is possible that two stars located within a distance of only 186 light years can have a large variation in their ages?
ii) Article states that HD 140283 comprises of H and He and its age is also 13.2 billion years which is very much close to the age of universe. How this star has been able to maintain its H and He throughout the age of universe? The contention that small stars burn H and He very slowly also does no appear to hold good. The reasons being in the earlier ages of universe a large amount of un-coalesced gas was present and that too in a small universe ( if concept of expansion is true), therefore, large stars should be formed in earlier universe which can not keep their H and He unburnt for such along period of 13.2 billion years. Even if small stars are formed in early universe, they will coalesce with other small stars to have large stars. In view of this, likelihood of a very old and a small star with unburnt H and He, with the current model and concepts of cosmology, does not appear quite high.
iii) Up to know, age of the oldest globular stars and consequently of MW galaxy was estimated in the range of about 12 billion years. HD 140283 being at distance of only 186 light years should be a part of MW galaxy. Thus age of HD 140283 demands age of MW galaxy to be revised upwards from the present estimate of about 12 billion years.
Has anyone found any genuinely specific information on this star? The article itself and its referenced ones have scant information -- just enough to launch deeper research for foundation.
Reply | Report Abuse | Link to thisHas anyone found any genuinely specific information on this star? The article itself and its referenced ones have scant information -- just enough to launch deeper research for foundation.
Reply | Report Abuse | Link to thisI believe that stars 13 billion light years away are considered 13 billion years old because of their distance not their physical properties. If we had the capabilities of seeing this smaller star (it would have to be smaller to last this long) at a distance of 13 billion light years it would 'appear' to be newly formed.
Reply | Report Abuse | Link to thisheavier elements are created in the later part of a life time. A star's life time varies due to it's size. This star must be very small.
Reply | Report Abuse | Link to thisI have researched everything available for PUBLIC consumption, and there are no scientific details on this study out there. I'm not a reporter, just a dedicated amateur, and since I have insufficient credentials, I cannot approach the author. Does anyone have any information as to where I can find more information on the specific science of this study?
Reply | Report Abuse | Link to thisI have researched all the information and details of this study that is available for PUBLIC consumption. I'm not a reporter, just a dedicated amateur without sufficient credentials to approach the author. I'm just trying to find reliable information on the specifics of the science. Does anyone have any specific information as to specific sources of reliable information?
Reply | Report Abuse | Link to this>Nope. That's the Nature article linked again. No links to the ORIGINAL paper for details.
Reply | Report Abuse | Link to thisI still find it fishy that a star could burn for 13Bn years and still be near-pristine H and He. 13Bn years is a pretty long time, y'know - even if it was mostly He and little H (not specified, either), WHAT has been burning there?
No other references I can find online. Such an old star right next to us would be something to be jumping around about for Astronomy... Is this for real?
Well, it is defined in Astronomy and Astrophysics, (Volume 523, id.A24, 15 pp) as a metal-poor subgiant. So no, it's not particularly small. Strange...
Reply | Report Abuse | Link to thisThis star shouldn't exist. There must be something wrong with the measurements, or our theories.
Reply | Report Abuse | Link to thisThis star shouldn't exist. It should have been extinct eons ago and only its light should be reaching us now. But to say it is very close, at that age, geez, something is wrong with the measurements, or maybe with our conception of cosmology.
Reply | Report Abuse | Link to thisIf you look at a main sequence graph with the mass and age of stars, you'll see that the smaller the star, the longer it burns, getting down to minimal fractions of a solar mass that would ultimately burn for far longer than the present age of the universe. Oh, and at first I thought, how lucky for us this star is so close by... but of course it is, the further we look afield the further back in time it would be. D'oh!
Reply | Report Abuse | Link to thisIf you use the equation for lifespan of a star: t/t(solar) = 1/(M/M(solar))^(3/2)
Reply | Report Abuse | Link to thisa star with a tenth our sun's mass should last more than 3 trillion years... much longer than the age of the universe. To get the maximum mass of the 13.2 billion year old star, we would solve the above equation for M:
M=(10/13.2)^(2/3)=0.831 So the star would have a mass of 8/10 of a solar mass (that is, if it were dying right now). So, the star in question has to be less than 8 tenths of our sun's mass to have lasted this long.
A sub-giant is not necessarily *big*. It can be quite small, it's just brighter than a main-sequence star of the same spectral class. Typically this means it's at the end of its hydrogen-burning phase and has started converting Helium in its core into heavier elements. As the article states, this one seems to be at the end of its lifespan - that's pretty much the same as saying it's a sub-giant or giant. A couple of billions years ago it was a dwarf.
Reply | Report Abuse | Link to thisAll the burning takes place in the core, and so far it's mostly been H to He, so yes, it still consists of mostly H and He, particularly in the outer layers, which are what we observe. Just like Our Sun consists mostly of H, and in the outer layers whatever He and metals were there when the Sun originally formed.
I believe that dadster is confusing age and distance, or age and the almost opposite of age - "time ago". when we look back in time(/far away) we see things as younger, not older.
Reply | Report Abuse | Link to thisTo look at an objekt 1000 light years away is to look at an object and see it as it was 1000 years ago. We can only guess how something that far away looks today. So looking far away also means looking back in time and thus seeing all objects YOUNGER then they are, not older. I.e. we do see them in the age they were when they sent out (or reflected) the light that we receive and see today.
So, looking at an object like the HD 140283 means looking at that star 187 years ago. That is "time ago" and not an age per se - and 187 years ago is not to long ago by the way. :)
So the "age" up for discussion here is NOT the age of the light reaching us (which creates a youngness of the object in view rather than an age) but the age of the actual star.
And that age it is not determined from the distance. It has nothing to do with the distance. Is the properties of the star that has lead the scientists to estimate the age to "something very old".
And - very old object can be found anywhere in the universe, there is no known "mid of the universe", and
stuff far away is not older due to the distance.
We just perceive us as in the middle, and due to the time-problem, we can only see approximatly 13.8 lightyears* away (in all direction, though not well where the milkyway is in the way).
And we can not see further, not because there is not longer distance, but because there is no more time...
But again - we will see everything as younger (not older!) than it is, and more so when we spot something very far away.
Best regard, Ingvar
PS. The 13.8 lightyears is a popular estimate for the age of the universe, but it will go up in the future. And yes - it will go up faster than the time added by entering the future. :)