How Many 2nd Generation Stars Are There In Our Galaxy And How Would One Detect Them ?

Answer 1

every star in our galaxy is a second generation star

Answer 2

There may well be low mass "Population III" stars still existing today. This is a current topic of research (see references).

Now, the earliest stars were almost all very high mass (and consequently were gone in a hundred million years), however these stars could have facilitated lower mass star formation almost immediately w/o necessarily enriching them with metals significantly. If you want to divide Pop III stars into two classes, one the VERY first massive ones and one that included smaller ones that formed a few tens of millions of years later, that might be reasonable. These later stars however will still be dynamically (and heavy element) distinct from the Pop II stars that make up old globular clusters and the galactic bulge.


These guys are tricky to identify and find because at an age of ~12-13 billion years, the most massive primordials left would be fairly dim low mass guys. These fuse faster than higher metallicity stars, so masses of about 0.8 Msun are all that will be left, with luminosities now similar to the sun. Such stars are very hard to detect further than 100 pc and virtually impossible at distances greater than 1 kpc, so there is only a fairly small volume of space in which we can successfully search for these objects.

This is a very young topic of research and the picture is still pretty murky. I bet there will be an early review article in Annual Reviews of Astronomy and Astrophysics summarizing the state of affairs within a few years.

Answer 3

There are no first generation stars left in the Universe, so all stars in our galaxy are second generation. First generation stars would not show any elements heavier than Lithium in their spectrum.

Answer 4

check their age by the amount of glow