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The validation process for planets discovered by the Kepler space telescope, which began just a few months ago, is giving excellent results. The latest, published in the Astrophysical Journal and the Monthly Notices of the Royal Astronomical Society, describe the confirmation of 26 planets in orbit around 11 stars, all at distances less than that of Venus from the Sun.
The sizes of the 26 planets range from 1.5 times that of the Earth to larger than Jupiter, with 15 having dimensions intermediate between those of the Earth and Neptune. The orbital periods are between 6 and 143 days. It doesn't seem very likely that any of the new planets could be habitable.
All the new systems contain between 2 and 5 planets which transit the disks of their stars in very close orbits. The closeness of the orbits to each other causes reciprocal gravitational forces between the planets, and these cause small perturbations in the transit timings, so-called Transit Timing Variations (TTV). These interactions provide a wealth of information concerning the orbits and masses of the planets, without having to wait for follow-up observations with large ground-based telescopes.
The proximity of many of the planets results in their location in various resonances: 5 systems host pairs of planets where the innermost body completes exactly 2 orbits while the other completes just one (2:1 resonance); while another 4 systems host pairs of planets where the ratio is 3:2 instead.
Of these 11 systems, the most populous is Kepler-33, containing 5 planets with dimensions between 1.5 and 5 times that of the Earth. The illustration above shows all the multiple planet systems so far validated. The process of validation is actually only 2.5% complete!
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by Michele Ferrara & Marcel
Clemens |
credit: NASA Ames/Dan Fabrycky, UC Santa Cruz |
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