A metallicity of -0.33 means this star has roughly 47% the metal content of the Sun. This is fairly standard for a population I disk star (the Sun is actually abnormally metal rich). Population II stars have metallicities from roughly -1 (10% the Sun’s metals) to less than -2 (less than 1% the Sun’s metals).

So far no planets have been found via any method around population 2 stars and several photometric studies of clusters using Hubble had the potential to find something. Many planetary theorists predict that the population II systems formed out of clouds with too few heavy elements to form planets. This is more than pop II stars not having life – pop II stars don’t even have planets!

I can’t find anything that indicates how old Gliese 581 may be. Determining stellar ages is a tricky business. In our own system we use radio-active dating. Unfortunately, we can’t go grab a rock from the Gliese 581 sample and see how many half-lifes have past.

I hope this helps!

Cheers,
Pamela

Just how old (young) is Gliese 581?

Would you class it as a Population I or II star?

The obvious reason for these questions are if Gleise 581 is a Population I star, formed relatively recently, 5 to 7 billion years, and from material containing elements similar to what was available for our sun to form, i.e heavier metals, then there is a good chance of “life” being possible on a planet occupying the “habitable” zone of Gleise 581.

I seldom see this information in press releases for exosolar planets discovered, especially “earth-like” discoveries. Are we wrong to expect lifeless worlds surrounding Population II stars even though they may reside in the “habitable” zone?

Your comments please. Thank you.

I found your comment on planet age between Earth and the new planet most intriguing. The fact that Earth is in its relative golden years is probably something that most people don’t realize. On the other hand, one billion years is a long time and surely we’ll have figured out a way to colonize in space by then.

This point is driven home even more after my recent trip to the Museum of Natural History in New York City. In the dinosaur wing, there’s a clock-like display showing the age of the earth relative to the existence of life on our planet. The fact that humans on our planet didn’t show up until after 10:00 or 10:30 is quite humbling.

By the way, I’m a regular listener to AstronomyCast and a super-amateur star gazer. I’m excited that you’ll be blogging regularly so I can get my daily(?) fix of how it all works and comes together in regard to astronomy. Keep it up!