Aarhus University | Stellar Astrophysics Center | 2015 May 14
Orbits of 74 small extrasolar planets are found to be close to circular, in contrast to previous measurements of massive exoplanets.
Researchers based at Aarhus University have measured the orbital eccentricity of 74 small extrasolar planets and found their orbits to be close to circular, similar to the planets in the solar system. But in contrast to previous measurements of more massive exoplanets where highly eccentric orbits are commonly found. These findings have important implications for planet formation theory, as well as planet occurrence rates and habitability. These findings are a major step that will improve understanding of the planet formation mechanisms that lead to high orbital eccentricities. “We want to understand why some exoplanets have extremely eccentric orbits, while in other cases, such as the solar system, planets orbit mostly circularly. This is one of the first times we've reliably measured the eccentricities of small planets, and it's exciting to see they are different from the giant planets, but similar to the solar system.”, says lead author Vincent Van Eylen.
The results are also relevant for the search for life. “None of the planets we studied are in the habitable zone, which means they are not expected to have liquid water required to support life. However, in the future, it will be interesting to see what the eccentricity is of such planets, because we know eccentricity influences the habitability of planets.” In the future, the method used can be extended to habitable planets:“we now know the method works, we just need to wait for sufficient data. The European PLATO satellite, planned for 2024, will likely help with that.”, says prof. Simon Albrecht. ...
Eccentricity from transit photometry: small planets in Kepler multi-planet systems have low eccentricities - Vincent Van Eylen, Simon Albrecht
- arXiv.org > astro-ph > arXiv:1505.02814 > 11 May 2015
Circular Orbits Identified for Small Exoplanets
Massachusetts Institute of Technology | 2015 Jun 01