Thread: Oldest possible Population 1 (high metallicity) stars

From what I have been able to gather from Google, NGC 188 contains Population 1 stars and is about 5-6 billion years old. Considering that Population 1 stars are the only ones likely to have stable Earth-like planets, does that mean that there are likely no life that originated on planets older than, say, 7 billions years?

Maybe 7 billion years is the cut off. My guess is 13 billion years, but terrestrial planets were likely very rare between 13 and 7 billion years ago. Stars possibly began forming shortly before the universe changed from opaque to transparent. Many of the earliest stars were class O = very massive, so they went super nova a few million years after their birth. This produced metals to build terrestrial planets perhaps as early as 13 billion years ago. Also the Universe was smaller 13 billion years ago, so the little metal there was, was not as widely scattered. Even before that, there was a small amount of lithium = a metal that forms compounds with hydrogen. So perhaps a very few mostly lithium planets formed very early. Neil