Wednesday, July 16, 2008

Prospects of a Habitable Planet Around Proxima Centauri

Hot on the heels of his earlier post about discouraging prospects for habitable planets around α Centauri, Paul Gilster of Centauri Dreams has (as promised) posted a follow-up about the prospects of finding habitable planets around Proxima Centauri. Proxima, it seems, has no chance of planets larger than 2-3 Earth masses in circular orbits out to about 1 AU (which is way farther out than the habitable region around such a wimpy little star as Proxima Centauri), but could have Earth mass or smaller planets in close.

The habitable zone around Proxima is so tight that any planets in it would orbit the star in as little as 3.6 days or as much as 13.8 days. That's a pretty short year. But planets with low-enough mass to be habitable are really, really hard for us to detect, especially if they're in multiple-planet systems. We need more precise results in order to study the radial velocity of stars with sufficient precision to find small planets.

That's where new probes like Kepler (due to launch early next year) come in. And also where software like that being developed for the PlanetQuest not-for-profit group, which is making software to combine the results of multiple observations, come in. So over the next several years our ability to identify smaller and smaller planets will improve dramatically.

And who knows? We may then discover that Proxima Centauri, the closest star to us, has a planet friendly to life.


gilster said...

Matt, a habitable planet around Proxima Centauri would be a fantastic find, wouldn't it? So much study is now going into these small red dwarfs that only a few years ago were considered insignificant in terms of having potentially habitable planets. Another bonus of these stars is the fact that their small size makes them easier to detect, both with radial velocity and also transit methods. I suspect our first terrestrial class world in a habitable zone will be around a red dwarf -- Gliese 581 c, which was once thought to be that planet, has been since shown to be too close to its star.

Matt Metcalf said...

My major concern about these red dwarf stars is their tendency to be unstable and flare up, and when you're that close to them... yikes.