Alpha Centauri and the complexity of the ‘habitable zone’

There has been a lot of exciting news for exoplanet enthusiasts already this year. My Friday Links posts (here and here and here) have included some of my favorite new discoveries. But when i saw a post at Well-Bred Insolence about some research he had done about Alpha Centauri, I knew I had to highlight it as something special.

If you are new to my blog, you may have missed some of my earlier posts. I don’t expect you to go back through the archives of RFC and read everything, but if you are a romantic space fan like me you will probably enjoy my post that explains the name of my blog. SPOILER ALERT: the blog name has to do with the idea that humans may someday settle undiscovered worlds in the Alpha Centauri system and I picked the banner image because I imagine it as the view from the surface of a small moon near Alpha Centauri A – although perhaps the red shining of Proxima Centauri is a bit too bright. Or is it? Well, that’s kind of the point of Duncan’s research.

Duncan (a postdoctoral fellow at the University of Edinburgh) ran some climate models for a theoretical planet orbiting Alpha Centauri B, taking into account the changing affects of Alpha Centauri A’s sunlight over the 70 years that the two stars orbit each other. He found that the habitable surface area of such a planet could change by several percent (and probably more) on a 70 year cycle. The open question is how much would the gravity of Alpha Centauri A or even the tiny amount of sunlight from Proxima Centauri – more than 1/8th of a light year away – also affect the planet’s climate.

These are very relevant questions given the context of recent discoveries such as a planet in the habitable zone of the triple star system GJ 667. There was also a recent study presented at the AAS meeting about the effects of tidal heating on a planet’s habitability. With all of these factors in play, the typical diagram of a shaded donut showing a star’s habitable zone may soon become an outdated model. It’s so simplistic as to be misleading.

Image Credit: NASA/Ames/JPL-Caltech

This is an exciting time to be in the related fields of astronomy, planetary science, astrobiology, and climate research. Every time I read about these kinds of unanswered questions, I want to go get a PhD in astronomy and study stars and planets. It’s questions like this that make it obvious to me how asking questions about what’s “out there” can help us solve problems down here. Exoplanet research can help develop our climate models to better understand global warming and climate change here at home.

Even more than the practicality of it all, I love the fantasy. Duncan’s speculation about Alphan birds migrating every 35 or 70 years made me think of this artwork by Dan Durda. I would love to explore the jungles of some alien world like an interstellar Indiana Jones or David Attenborough.

Jungle Canyon by Dan Durda (via Bad Astronomy)

I just had a thought. Using humans flying the moon to inspire kids to study STEM is so last century. What we need to be doing is putting cutting edge and up to date information about the study of alien worlds into all of our science curriculum. This is the kind of thing that can excite and inspire just as much as human spaceflight. Who wouldn’t want to be the first biologist of Alphan ecosystems? Count me in.

February 12, 2012 1:34 pm

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