Friday, November 26, 2010
A densely packed planetary system at HD 10180
C. Lovis and colleagues at the European Southern Observatory in Chile used the 3.6m telescope there to discover 5 or more planets orbiting the star HD 10180. The five certain planets are all Neptune-class, having masses of 12-25 times that of Earth. Also, all orbit rather close to the star, at distances of 0.06-1.4 AU. There is also tentative evidence for an Earth-mass planet orbiting at r=0.02 AU, and a possible 3-Neptune-mass planet orbiting at r=3.4 AU. Ellipses in the above figure show the planets current orbits, while the colored regions indicate their range of motions over time that are due to their mutual gravities. As the figure shows, this system is quite dense with planets, which is actually rather typical for multi-planets extra-solar planetary systems. See the preprint for more details.