In All the Right Places
The exoplanet discoveries just keep on rolling in as astronomers use some of the most sophisticated instruments and techniques available to look for them. The latest focus of attention is a small planet only about twice the size of Earth that is rushing like mad around its star. The planet, called Gliese 581 e is one of four planets found so far orbiting the star Gliese 581. It turns out, according to team leader and Geneva Observatory astronomer Michel Mayor, that it’s also the lightest exoplanet found so far.
This extraordinary find was announced today at the JENAM conference during the European Week of Astronomy & Space Science, which is taking place at the University of Hertfordshire, U.K. If you’re a professional astronomer and want to read the paper where these results are discussed, you will be able to find it in a future edition of the research journal Astronomy & Astrophysics (“The HARPS search for southern extra-solar planets: XVIII. An Earth-mass planet in the GJ 581 planetary system”, by Mayor et al., 2009), so keep your eyes peeled for that one.
The main goal of the work done by Mayor and other exoplanet searchers is to find an Earth-like planet orbiting in the so-called “habitable zone” around its star. That zone is the place where conditions are not too hot, not too cold and safe enough for life to originate and evolve.
The newly found planet “e” around Gliese 581 is not in the habitable zone. However, there’s another planet in the system that is and it could have water. New observations of the system made by Mayor’s European team let them take a closer spectral look at that planet — called 581 d. It’s the most distant planet from the star, and orbits in 66.8 days. According to team member Stephane Udry, “Gliese 581 d is probably too massive to be made only of rocky material, but we can speculate that it is an icy planet that has migrated closer to the star.”
If true, it has migrated right into the habitable zone for that star, and Udry says that the planet could even be covered by a large and deep ocean. That would be very exciting and if this is confirmed, 581 d could be the first serious ‘water world’ candidate around another star. There’s more info and some very cool images and video about this project over at the European Southern Observatory’s website. Check it out!