One question that I have about this research is whether it is possible that the star could have picked up heavier elements in unexpected ways. Sure, the amount of heavy elements is 10x higher than cosmic radiation could explain. But is it 10x higher than could be explained if somewhere in its 13+ billion years it went through a stellar nursery full of metal-rich elements?
Actually I believe that the amount of heavy elements in that star was lower than expected. They used the ratio of heavy elements (uranium and thorium) to date the star, not the quantity. This star, I believe, is what is called a Population II (low metallicity) star. Older stars have lower amounts of heavy elements, and the yet-to-be-observed Population III stars are posited to have no heavy elements whatsoever.
Not so important for it's age, but for what it tells us about when both first and second generation stars likely formed. Which helps in determining how well current models hold up.
i think you're misunderstanding slightly why this is important.
it's not surprising for small stars to live a long time (they burn quite slowly). what's surprising is that we don't see any older than about 14 billion years old.
so that suggests that the universe is only that old.
and really, to astronomers, that's not surprising either, since the universe is known to be that old from other measurements.
what's actually surprising is that this star matches the universe's age so closely when it contains some elements other than hydrogen or helium. since that implies that it wasn't one of the first stars made (which would be pure hydrogen and helium), but a star made from remnants of other stars. so it is at least "second generation". so there must have been some stars of short lifetime before it. and it's actually tricky to fit that in, given how we think stars are created and how the universe evolved (the real problem is that the hydrogen starts out fairly evenly spread out and needs time to clump, under gravitation, to form the first stars - the density fluctuations that describe this are constrained by observations of the microwave background, which is quite smooth).
[some more background to make this consistent: the universe "started" as hydrogen; large stars, which live a short time, can make other elements than helium from hydrogen; small stars, which live a long time, make only helium from hydrogen.]
It's not embarrassing. I learned it only a few years ago and I was very surprised. And looking for more information, today I learned that the Milky Way is a barred spiral galaxy.
When I was young the Big Bang only produced Hydrogen and the Milky Way had no bars :) . http://xkcd.com/1053/
It's still a population II star, we have yet to find a genuine pop III (formed entirely of hydrogen and helium). Surely there would have been some small pop I stars from that early on. Or is it that stars may have been 'polluted' with heavier elements after formation?
I just don't get why its close to us. I mean I understand that if stars were evenly distributed there would be one nearby, but they clump into galaxies, and our galaxy isn't one of the 'first' ones so why is it here?
That would be a misconception on your part. Excepting galaxies created due to collisions between other galaxies, all galaxies are believed to have been formed around the same time, and then got separated by the expansion of the universe. So yes, we are one of the first galaxies..just like every other galaxy. Thus we had stars created at all points of time, and some have survived.
That said, there is a more interesting question underlying "why its close to us" that deserves comment. It turns out that the Sun has a tendency to oscillate up and down through the galactic halo. This is good for the Earth, because it limits our time spent in neighborhoods where there is a lot of other stuff we can run into. However early star formation took place in the galactic plane, so most old stars are very near the galactic plane, and therefore the Sun is usually not close to them.
I believe that the period of the oscillation is somewhere in the neighborhood of 64 million years, so we punch through the plane about every 32 million years or so. We last passed through an estimated 3 million years ago, and are currently about a hundred light years away from the plane, so we are still near objects in the plane, including old stars like this one. But in another 10 million years, we shouldn't be!
I'm not sure, because I'm not an expert, but let's guess: Probably there are a lot of stars of this type wandering. That star just was in the place where the Milky Way was formed or it was captured later by the Milky Way. The star is not very bright because bright stars die soon. So we only can see it because it's near us.
All galaxies are descended from big clumps of gas that formed during the Big Bang. These gas clouds eventually formed into galaxies. So yeah, our galaxy can be traced back to the very beginning just like every other one. There are lots of stages of galactic evolution. Its probable that the modern galaxy was cobbled together from many smaller ones (satellites, etc) over the eons.
So with all the mixing and matching that has gone on over time, we've picked up many stars from many different stages of galactic evolution. Its not unusual at all to find such an old star.
Actually, according to the article HD 140283 is only 190 light years away. That's practically right next door to us. So no, the star could quite possibly still be alive and well in its old age.
The expansion of the universe is visible in the very very very big scale. The galaxies are generally spreading away from one another. But it is only the general direction. The gravity makes them move in complex trajectories so some of then are aproaching or even colide.
The Milky Way ~100,000 light-years in diameter, so this star is inside it. Inside a galaxy the movements of the individual stars are even more complex, so they get closer or more distant.
Technically if we see anything, we are seeing something that was, not is. The sun could have disappeared a handful of minutes ago but we wouldn't know; the earth would even continue orbiting the spot where it used to be (until information of the disappearance reached it.) Since no information, not even gravitation, is going that fast, it makes the most intuitive sense to speak as though things happen when we can observe them happening.
Anything that we can measure shows the star still there, even if stellar evolution allows us to accurately predict that it wouldn't be if we could travel there faster than light.
Generic reply to every other comment on this thread.
Its 190 light years away. That's close.
That means that its light has only taken a bit less than 200 years to reach us, compared to the millions and billions of years we see when looking at distant galaxies.
The star has been around for 13 some odd billion years. Its very unlikely that it finally exploded in the last 190 years.
As for comments about universal expansion, no simultaneous events happening, yada yada, none of that applies nor has anything to do with an old-ass star that's literally on our doorstep.
I'm not going to get into a physics debate right now, but suffice it to say that if you were here and I was there (somewhere around the star), the light from both stars would be 190 years old to each of us. You and I would comfortably be existing in the universe at the same moment as long as we weren't travelling at relativistic speeds.
For a closer-to-home example, imagine that I am sitting at my desk in my office. (I am.) And you are currently reading this in the car or on MUNI moving at 30-60 mph. Are you going to say that I, or you, don't currently exist at the same moment on the same planet or even the same city (San Francisco) because you're going slightly faster than I am?
