Thursday, February 3, 2011

Kepler -11, Kepler Bags A Very Strange Solar System

Left Panel: The Kepler-11 solar system, 6 confirmed planets orbiting around a sun-like star, all within what would be the orbit of Venus. Right Panel: Kepler-11c transit as seen from Kepler-11d, with 11B about to transit next. Kepler-11 system visualized in Celestia (click to embiggen).

The Kepler spacecraft has been really busy. Hot on the heels of the magma world Kepler-10b comes a very different solar system, Kepler-11. Kepler 11 is a multi-planet solar system, with 6 confirmed planets it ties with HD 10180 the biggest solar system known to date ( HD may have a 7th planet, but it is currently unconfirmed, Gliese 581 may have 6 planets, but two of the planets are currently unconfirmed).

However, this solar system is unlike that of ours. Kepler-11 is a Sun-like G class star, around the same size and luminosity as our Sun. However, its stable of detected planets all huddle well inside the equivalent of the orbit of Venus. They zip around their central star in a handful of days, and the two innermost are quite close to each other. Of the 6, 4 are Neptune-like and two, b and f, are most likely water worlds (boiling water in the case of b).

Multi-planet systems are rather rare, of the 521 planetary systems found by transit and radial velocity measurements, only 59 are multiple planetary systems. This is most likely an artifact of how we discover exoplanets; small planets are hard to find against a background of big planets, as are planets with long orbital periods. Also, with transiting planets the system has to be in the right orientation to have the outer planets observably transit.

Of course, you can visualize this system in Celestia. First you need to create a file in the extras folder that has the star Kepler-11 in it (see the Kepler-10b post), I've already created one, and you can download here, then copy into the Celestia extras folder. Then you need the file the sets out the exoplanets (Kepler11abcdef.ssc, download it here and copy into the extras folder), and Robert is your avuncular relative.

So download the files and have a play. (I'll post about the 1200 planets Kepler has found, and the Earth-like ones, tomorrow).


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