Recently, researchers studied 79 “twins” of our sun, in terms of their temperature, gravity, iron content and content of roughly 30 other elements:
A study of solar twins reveals that the sun’s chemical makeup is surprisingly different from that of its nearby peers, while those stars are almost identical to one another. Since a star and its planets are made from the same materials, that may mean the exoplanets orbiting those stars come in just a few flavors. It also could point to a new way to discover stars with solar systems more like ours.
The team found that the sun’s elements come in subtly different proportions. For example, the sun is missing about four Earth masses worth of rocks and metals — the very elements that the planets are made of. That result could be because of the solar system: The elements are missing from the sun because they’re locked up in the planets, Bedell says. There’s another, less savory possibility: The other stars might contain more rocky elements because they once had planets, and ate them. Lisa Grossman, “Next to its solar twins, the sun stands out” at ScienceNews
Only 7-20% of the “solar twins were like the sun in composition and no exoplanets were found orbiting them.
Although the report does not dwell on this, it implies that the number of truly Earth-like planets in our galaxy may be limited by the absence of sun-like stars.
See also: Rob Sheldon on the sun as an “ordinary star”
The sun is just a typical star
What becomes of science when the evidence does not matter? (fine-tuning)