Comments on: Dating Stars: HE 1523-0901

By: Hannes

Hannes — Fri, 22 Jun 2007 18:38:56 +0000

Anna Frebel and her team did a wonderful job, measuring all the very difficult parameters involved.
The star is really that old, but also putting stress to the Hubble redshift-age controversion.
I nevertheless think a real progress is made here, and I really want to thank her for this attribution.
What I still find intruiging is the remaining question how long the dust from the star predating HE 1523-0901 whas swirling across the universe before condensing to our measurable star.
How long did the dust take to form our star?
Remember we are only measuring the birth of the supernova preceding our star.
For dutch readers see my comment on: http://www.nwtonline.nl

By: Colin

Colin — Mon, 14 May 2007 13:26:07 +0000

Just to alert you to what spellchecks won’t pick up in case you write any papers; “In what ratio where all the elements …” should be “In what ratio were all the elements…” and “what should have been their originally…” should be “what should have been there originally…” It helps if you know someone pedantic.

By: pamela

pamela — Sun, 13 May 2007 22:53:27 +0000

Hi Gary, I have to admit that I used a definition of population III star’s as stars from the earliest generations (the definition I learned in school), rather than the definition of “something with no metals.” I also kept in mind that there is a general cutoff around [Fe/H]<-2.5 for Population II stars. The reason I used these definitions is simple: Many theorists believe the very first large stars to form lived and exploded as supernova so fast that there are no strict definition Pop III stars around, while the very first (and enhanced by only a couple supernova) G stars and smaller should still exist is mass dependent states of evolution. Thus, the first generation of G stars is out there, and this one appears to be one of them. I have changed my definition above to state it is likely from the first generation of lower mass stars to form.

If you look at the original paper, HE 1523-0901 has an [Fe/H] of -2.95, and is located in the halo. It is thus not a population I star.

This is not the first extremely low metallicity, probably first generation of its mass, star to be found. I would encourage you to read the journal articles before you condemn the science. Thanks to SDSS we are finding statistically significant populations, and some really rich information is being learned.

By: garygech

garygech — Sun, 13 May 2007 19:11:08 +0000

I think this was a good try at explaining an issue but you have to be clear at terminology.

A population III star cannot have any heavy isotopes above Iron (so far none have been found).

Thus, making a claim that you are studying something in science that is an obvious fallacy is scientifically dishonest no matter how hard you work.

The star involved is likely a population I star and the age is overestimated.

One thing about modern science. The skeptic in the null hypothesis has the upper hand, not the scientist. The skeptic for good reason gets to say, “prove it beyond a statistical doubt (usually two standard deviations).

In this case, the claim is that they have found one star. This would be interesting, but with a few billion stars in the galaxy, this would not be noteworthy unless they found a group of stars with exactly the same isotope ratios.

Thus, once again, astronomers of the twenty first century demonstrate that they are good at using new toys but and speculative mathematics but rather bad at real science.

By: Aaron Jackson

Aaron Jackson — Sat, 12 May 2007 05:31:14 +0000

Great post! I have a couple of questions. First, I know there are some that question both the accuracy and consistency of carbon dating. Do similar discrepancies occur in the dating methods you describe? Second, am I understanding correctly that the team used seven separate tests to estimate the age in order to bolster the reliability of the results?