HD140283

[Ronnie67]

I have a question about one of, or should I say, the oldest stars in the universe, It is believed to be about 13.82 billion years give or take a few hundred million years but it is also noted to be even older, Billions of years older, if this is true then the star would be in actual fact older than our universe. Stars are suppose to be younger than galaxies, galaxy clusters, super clusters and hyper clusters....I am talking about HD140283 which lies about 190lys away. How can this be

[JulianO]

It's a question of how you date such stars. It's usually done by looking at the metallicity of it, and comparing that to calibrated curves and things. It's not terribly precise, and there are other things that can make it metal poor besides being old. The error bars tend to be pretty big too. It's quite likely this is an old star, but you can't saw a star in half and count the rings, or check its sell by date, so its hard to judge dates.

I think the current error bars put it inside the age of the universe on the conservative side.

I know a colleague using similar sorts of tables to date the age of galaxies has found some that are 18 billion years old - which is clearly way outside the realm. Its hard to extrapolate from some of this data.

[Ronnie67]

However if this data was correct then the whole big bang theory would be all wrong or the dates are wrong as to when the big bang occurred. According to what are belied credible dating techniques involving amount of metals ans mass. THe universe is supposed to be 13.82 billion years old, according to the latest CMB analysis by George Efethion. Cosmic coincidences in the universe do not happen

[JulianO]

Yes - if this data did show it was older than the universe, it would cause some issues. The age of the universe has been measured by a number of different techniques, including the CMB (by 3 different satellites and other experiments) + hubble flow and so on.

This star has been dated by one technique I believe, which is trying to fit metalicity to a curve with some big error bars.

As thy say in the paper

Within the errors, the age of HD 140283 [14.46+/- 0.8 Gyr] does not conflict with the age of the Universe, 13.77 +/- 0.06 Gyr, based on the microwave background and Hubble constant, but it must have formed soon after the big bang.

If I had to pick one - I'd go with the age of the universe being right, and this star being wrong if they were in disagreement.

[Ronnie67]

This is whats baffling me, if they can get the age of the universe right, surely they can get the age of a single star right, there is a huge difference in the age of the universe and HD 140283, especially when they can age other stars, maybe between the two, somethings is not just quite right and the answer could throw out all the theories surrounding the universe

[acey]

Same thing used to be said about M13, which appeared to contain stars apparently older than the universe was then believed to be. What it demonstrates is that estimating the age of a star is based on a completely different line of reasoning from estimating the age of the universe, and both are subject to error. You can't cut open a star and count rings like you'd do with a tree, and the estimated age of a star is subject to greater error than the estimated age of the universe. Certainly true that if the star really was proved to be older than the estimated age of the universe then it would upset the theory on which the latter is based. And if the star is shown to be younger than thought, it could be because of improved data, or because of some defect in the reasoning on which the original estimate was based. Looks like a pretty safe bet that the star age will be revised.

[Ronnie67]

Lets hope so, as there are more than one star whith such interesting ages, HD 140283 is considered the oldest as we know it, but one or two others are just as interesting, HD 140283 may be just the tipo f the ice burg, maybe out there in the unknown are many many stars with similar ages or possibly older, and with the shear size of the star is somewhat extraordinary in a sense and in the other hand quite alarming as if and when she blows, that's it for us no more minute earth

[Cath]

In actual fact, we ourselves are just as old, in fact everything we know of is just as old.

The only thing that isn't as old is the current 'form' of an object (including ourselves). 'Form' as in the current arrangement of the atoms that make us who/what we/they currently are. It's the shape/collection of atoms/current form that we seem to like dating, not the raw material itself.

[Treeden]

... It's the shape/collection of atoms/current form that we seem to like dating...

I once said something similar to a lady while we were enjoying a meal in a nice restaurant...

...I still wince at the memory of the sharp stinging pain that was delivered to my shin under the table by the point of her shoe.

[Cath]

I still wince at the memory of the sharp stinging pain that was delivered to my shin under the table by the point of her shoe.

ouch!

Violence is never the best way forward - I find.

[FraserClarke]

This is whats baffling me, if they can get the age of the universe right, surely they can get the age of a single star right, there is a huge difference in the age of the universe and HD 140283

I don't think it follows that because the error on the age of Universe is small, the error on dating a star should also be small. The techniques are completely different, and not really related at all. What you're looking for is some kind of agreement between the two, and that's what we have here. It's important to look at the uncertainties on the measurement, as well as the headline value. The errors (and that is almost certainly a "1-sigma" error level; or 67% confidence) on the ages are 14.5+/-0.8 Gyr and 13.77 +/- 0.06 Gyr. So the measurements give a 67% confidence that the age of the star is between 13.7 and 15.3 Gyr. So there is a 16.5%** (100%-67% / 2) chance the star is younger than 13.7 Gyr. I.e.; there's an ~1/5 chance that the star is actually comfortably younger than the age of the Universe.

Taking all the evidence in context, it's far more likely that this result is pointing towards an error in our theoretical stellar evolution models, or a error in measuring the metalicity of the star, rather than over-throwing a lot of other data on the age of the Universe. Of course, it's great stuff, and exactly the sort of things that we should be checking and questioning. If people started turning up significant numbers of stars with ages of 17Gyr, for example, that would raise some pretty serious questions!

** Assuming the error distribution is equal, which it almost certainly isn't!

[ollypenrice]

This is whats baffling me, if they can get the age of the universe right, surely they can get the age of a single star right, there is a huge difference in the age of the universe and HD 140283, especially when they can age other stars, maybe between the two, somethings is not just quite right and the answer could throw out all the theories surrounding the universe

I agree with Fraser. You have far more information about a universe than you have about a single star. Imagine being asked, 'What does a car weigh?' Hard to say, because they vary considerably. Now ask the question, What does a car carrying six adults and towing two cubic metres of mixed aggreagate up Wry Nose Pass weigh? Here you could make a better estimate because you now know the car is a six seater, therefore at the upper end of the weight rage, and you know what a cubic metre of mixed aggregate weighs, and you know that the car is powerful enough to drag that lot up Wry Nose Pss so it has a big engine, etc etc. The error bars for your second estimate will be narrower than for your first.

On a deeper issue I'd revisit the idea of 'getting it right.' This isn't really what happens in science. What science does is create a 'best possible model' based on careful observation and theory working together. Some disagreement between parts making up the model is healthy and identifies areas where more research would be constructive. Improving the dating of stars, or specifically the metallicity method, looks like a candidate for someone's astronomical carreer.

Cosmologists have disagreed with astrophyscists about the age of stars before. Last time the cosmologists lost. This time they might (well they might!) be on better ground...

Olly

[Knight of Clear Skies]

This is whats baffling me, if they can get the age of the universe right, surely they can get the age of a single star right...

Part of the difficulty is that we have exactly one star whose age can be checked by an independent method: the Sun. Solar system asteroids have been dated to 4.6 billion years, but that's only a single data point to calibrate the models of stellar evolution. Many scientific models are accurate enough to be useful - we can build a pretty good plane, computer or nuclear reactor - but our understanding is never complete.

Myself, I think it's great that we can look at a tiny glimmer of light and make a sensible estimate of a star's age.