For this blog I read another article from Scientific American, titled “Do Three Habitable Super-Earths Really Orbit a Nearby Star?”. The article explained that orbiting the star Gliese 667 C were found two planets. One a large rocky “super Earth” was orbiting in the star’s habitable region, and so could have liquid water on its surface.
Modern observations have found between three and five more planes orbiting Gliese 667 C two of them could be super-Earths orbiting in the habitable area. Unlike our system in which smaller rocky planets orbit closer to the star, with gas and ice giants further out, the planets are huddled close to each other very close to the star. Although this seems strange from our perspective, as more and more measurements are taken of other systems these compact orbits seem to be the norm when dealing with sun like stars. This sort of system is referred to as dynamically packed, and now we are also finding them around M dwarfs as well, like Gleise 667 C. This is important because it expands our idea of what a habitable solar system could look like.
It is very hard to detect planets such as these because unlike others, which were detected by looking for transits, these were detected by looking at the wobble of the star as the planets pull it to and fro while they orbit. With a gas giant this can be fairly simple, but when you have multiple, very small planets this because all but impossible. Scientific American describes as “listening for faint music emerging from washes of static on a poorly tuned radio”.
As exciting as this discovery is, doubts do still remain. The team that interpreted the data took shortcuts that made the analysis easier, but less robust. One of the key short cuts used, was that the team assumed the orbits to be fairly circular. While that may seem like a wild assumption, any system that is so packed would be unstable with eccentric orbits. This means that if the planets they thought they detected are actually there, they are likely to be much as the analysis predicted. However, if their data was off, or if the planets are not there, then their analysis will be useless. While that is not very comforting, the prospect of multiple super-Earths is nonetheless intriguing.
This article really excited me, because of the possibility of other Earth like planets on a near by star. I think that it is hard to not be optimistic with findings such as these. Though the predictions may yet be proven wrong, the mere thought that Earth like planets are not as uncommon as previously thought is a nice one. I really hope that the data pans out and we are able to definitively call this, but until then I will remain optimistic.
The article can be found here: http://www.scientificamerican.com/article.cfm?id=habitable-super-earths
