Planetary scientists agree that a planet's distance from its parent star is of paramount importance for creating conditions where liquid water might spur life. But what about the host star's chemical makeup? A paper in press at The Astrophysical Journal Letters argues that a greater abundance of carbon, sodium, magnesium, and silicon should be a plus for an inner solar system's long-term habitability. That's because the abundance of these elements make the star cooler and cause it to evolve more slowly, thereby giving planets in its habitable zone more time to develop life as we know it. The stellar abundance of oxygen, in particular, seems crucial in determining how long newly formed planets stay in the habitable zone around their host star, the researchers report. If our own sun had a lower abundance of oxygen, for example, Earth would have left the habitable zone a billion years ago, well before complex organisms evolved.
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