Comments on: Star found, older than Abe Vigoda

By: Sweet Yummy Reality

Sweet Yummy Reality — Mon, 21 Apr 2008 21:21:57 +0000

[...] important about it. Since Phil Plait over at BadAstronomy has already boiled down the science, I’ll just link to his post. No Comments so far Leave a comment Line and paragraph breaks automatic, e-mail address [...]

By: Brian

Brian — Sun, 13 May 2007 21:35:15 +0000

Lab Lemming,

Thank you again.

By: Lab Lemming

Lab Lemming — Sun, 13 May 2007 21:12:13 +0000

Brian:
Evidently one of the biggest problems is that the best U peak overlaps the C-N peak. So you need either very low C,N stars, or hot stars (to break the molecular bond). But of course, hot stars have shorter life expectancy. As a result, I think the two stars that they looked at are giant branch stars- they are not main sequence red dwarves.

By: Brian

Brian — Sun, 13 May 2007 18:20:27 +0000

Lab Lemming,

Thanx. A lot of that was in accord with my suppositions. I had not considered the possibility of her using more than 1 model, although it now seems obviously proper technique to consider several. I had wondered why no one mentioned the lead.

It must be quite difficult to find suitable candidates for this sort of analysis.

By: Lab Lemming

Lab Lemming — Sun, 13 May 2007 04:40:40 +0000

Found the paper at arxiv, I’ll blog it once my conference talk is done.

Basically-
1. assume initial Eu, Ir, Os, Th, U ratios at production (she uses 4 or 5 different models)
2. Assume star forms immediatly after heavy elements are produced (this is what happened in our system- why not extrapolate to the universe)
3. Assume the difference between measured and expected U and Th is due to radioactive decay
4. use decay constants to determine age.

She does all this, and ends up with an answer of 13.2 +/- 2.5 Ga.

Most of the error seems to be from the initial composition assumptions adn disagreement between the stable Os, Ir, or Eu, and not the analysis.

The decay product of Th and U, Pb, cannot be measured, as there is a spectral interference.

By: Brian

Brian — Sun, 13 May 2007 04:07:07 +0000

OK, one more try.
http://www.nature.com/news/2007/070508/pf/070508-13_pf.html

By: Brian

Brian — Sun, 13 May 2007 03:59:22 +0000

I see the computer printed news@nature.com as an email address, but to access the article, go to http://www.nature.com/news/2007/070508. There is more to the address, but that should get you somewhat close.