Stars supporting life as we know it
Delta pav (shown here in the yellow circle) is identified by Margaret Turnbull as a candidate for having a habitable stellar system. "That particular star", Turnbull said, "is an older star, and it's very much like the sun, just about exactly the same brightness, same luminosity as the sun. It's about six parsecs away, which is about 25 light light-years. And that's about a 3.6 magnitude, and it's fairly metal-rich too, so I would expect that there's a lot of good material around that star to form planets out of." (NASA)
DB: This is Earth & Sky, with astrobiologist Margaret Turnbull of the Carnegie Institution of Washington.
JB: Turnbull and colleague Jill Tarter of the SETI Institute took a catalog of over 100,000 stars, and tried to determine how many are relatively nearby and capable of supporting life as we know it.
Margaret Turnbull: The fact that we have water on this planet is what makes it possible for all life that we know of to exist.
DB: Turnbull told Earth & Sky that in order to have liquid water on a planet’s surface, the planet needs to be in what’s called the habitable zone of a star. That’s not too far from the star, or the water would freeze, and not too close, or it would boil away. She and Tarter selected stars with properties that didn’t interfere with each star’s habitable zone.
Margaret Turnbull: So now, we have stars that orbit peacefully within the disc of the galaxy like our sun. They’re not overly active, or variable. They don’t have companions that are interfering with the habitable zone and they are not extremely young. And so they’ve had enough time to give rise to—we hope—an intelligent civilization.
JB: From a catalog of over 100,000 stars, Turnbull and Tarter found about 17,000 that are relatively nearby and capable of supporting life as we know it.
DB: That’s our show. Earth & Sky is celebrating its 15th anniversary and its 5000th radio broadcast. Visit us on the web at earthsky.org. We’re Block and Byrd for Earth & Sky.
Our thanks to:
Margaret Turnbull
Carnegie Institution of Washington
NASA Post doctoral fellow
NASA Astrobiology Institute
