Solar twins

Here’s another approach to the problem of finding stars that are much like the sun when your story requires them.  Wikipedia has an article at http://en.wikipedia.org/wiki/Solar_analog that creates a hierarchy of Sol-like stars: solar-type, solar-analogue, and solar-twin, the last category being reserved for the closest matches (temperature with 50 K of Sol’s, metallicity between 89 and 112%, no stellar companion, and age within 1 billion years of Sol’s.)  Unfortunately, the article does not cite who came up with these classifications, but they seem like reasonable ones to me.

The list of solar twins in the article currently comprises nine stars, including one (18 Scorpii) that is also on the Turnbull Top 5 list.  The others are all much farther out, from 84 to 217 light years distant.  But the list includes the stars’ right ascension and declination, so you can figure out how far they are from each other if you want to make them the framework for your interstellar civilization.

One thing to keep in mind is that we’re not at all certain that a G2V star like Sol is the likeliest to have a usable world.  It’s possible that they’re much more likely to form around K stars and that Sol is a statistical outlier.  Which would be good news in a way, since there are a lot more K than G stars, but it means our starfaring descendants would have to get used to living under natural lighting that had a more distinctly orange cast than you and I are used to.

For comparison purposes between solar twins and solar analogues, while the closest twin is 45 light years away, there are five of the more loosely defined analogues within 20 light years: Alpha Centauri A and B, 70 Ophiuchi A, Sigma Draconis, and Eta Cassiopeiae A.