White Dwarf, 12 Billion Years Old, Found Only 100LY Away

Dotini

What a wonderful coincidence to find such an old star so close by!

http://phys.org/news/2012-04-astrono...arf-stars.html

Respectfully submitted,
Steve

Chronos

Here is the arxiv version http://arxiv.org/abs/1204.2570

Drakkith

Nice! Thanks guys!

Radrook

Close by? Strange!

Dotini

Why strange? Is that because the galaxy is ~100,000 LY in diameter, and 100 seems strangely small? As I understand it, our galaxy is peppered with white dwarfs.

Amusingly, NASA is thinking that a newly discovered galactic structure of 50,000 LY, the FERMI bubble, has arisen in only a few million years. http://www.nasa.gov/mission_pages/GL...structure.html

Does that seem odd, too?

Respectfully submitted,
Steve

DaveC426913

Take that, fundamentalists!

DaveC426913

"Your planet Earth is soooo fat (how fat is it?) - it causes a wiggle in SDSS J110217, 48+411315.4's motion! BOOyah!"

[ EDIT ] That is really sloppy journalism.

It sounds like they were saying "Earth's movement caused a wobble in the star's path". Well, that actually is what they said.

What they surely meant was "Earth's movement (around the sun) causes a parallax, by which we can observe how far away the star is". Which is a completely different thing.

Chronos

Journalists are victimized by scientists who feed them just enough information to overload their simple, disordered neural networks.

TheTechNoir

Journalist: Scientists are overloading journalists with high levels of entropy! Or something like that.

TheTechNoir

Journalist: Scientists are overloading journalists with high levels of entropy! Or something like that. Physics makes it very difficult for us to reverse this and provide the world with low entropy articles about cosmology.

Kaldanis

Obvious, stupid question time!

The article says the white dwarf was probably formed from a star similar to our sun. Our sun is about 4.6 billion years old and is expected to become a white dwarf too in another 5 billion years. So let's say it takes ~10 billion years to become a white dwarf. How can the white dwarf be 12 billion years old if the universe is only estimated to be 13.8 billion years old?

Unless... it means the star has existed for 12 billion years over its entire life?

Drakkith

From the paper:
J1102 only burned Hydrogen in it's core for about 2 billion years thanks to it's greater mass compared to the Sun (2x more). It formed a white dwarf soon after Hydrogen fusion ceased and has been cooling ever since.

WD0346 was even more massive, at around 3 solar masses, and burned through its hydrogen in about 250 million years, formed a white dwarf, and has been cooling since.

Kaldanis

Thank you Drakkith :)

Ken G

"We found its distance by measuring a tiny wiggle in its path caused by the Earth's motion... "

Although the statement is sure to confuse readers, there isn't necessarily anything wrong with saying the Earth's motion "caused" a wiggle in the star's motion, as long as one recognizes that all motion is relative, so any "wiggle" is relative also. It's merely an issue of what it is relative to. We might take the Copernican stance that motion of a star relative to a galaxy is "more absolute", in some sense, than motion relative to Earth, but the most empirically demonstrable stance is simply that motion itself requires the identification of an observer to say that the motion is there in the first place, and in that sense is "caused" by that relationship (true causality has no really solid foundation in physics). That would seem the most closely adhering to general relativity, but this article is never going to be used to teach general relativity, so readers will indeed get the wrong impression from that statement.

DaveC426913

My concern was more the implication that there was a gravitational effect. When I read it, is sounds like they're saying that Earth's mass actually made the star move.

We know it's preposterous, but many readers won't.

Ken G

But in a sense, it is a "gravitational" affect in the larger sense of general relativity, where fictitious forces are treated on a similar footing as "real" forces which stem from the stress-energy tensor. But I know what you mean, it's not an effect related to the Earth's mass or anything like that, and the words are likely to be interpreted as if the Earth had some kind of special connection to the star, which can lead to pseudoscientific thinking about 2012 and who knows what else. I was just pointing out how slippery the word "cause" can be in physics, it tends to be tied to interpretations of theories moreso than to demonstrable truths, and this is sometimes a trap. In the final analysis, "causes" are always sociological constructs, albeit important ones, but physics tends to be quite uneasy about the whole concept.

DaveC426913

Explain this one again?

The Earth revolving around the sun causes parallax of the nearby star against the backdrop of the galaxy, meaning we can measure its distance.

How exactly is that a gravitational effect? Even 'in a sense'?