306 new planets

Kepler released most of the first little bit of data today.

306 new candidate exoplanets, with 5 multiple transiting systems – ie stars with more than one planet transiting them.

The really interesting systems though are the 400 objects that the Kepler team got permission to withhold, and the data on which will be released later.
Statistically 100+ of those ought to be real planets, and probably the most interesting of all the exoplanets they found.

There is a story there.
More later.

Characteristics of Kepler Planetary Candidates Based on the First Data Set: The Majority are Found to be Neptune-Size and Smaller

William J. Borucki, for the Kepler Team

In the spring of 2009 the Kepler Mission conducted high precision photometry on nearly 156,000 stars to detect the frequency and characteristics of small exoplanets. On 15 June 2010 the Kepler Mission released data on all but 400 of the ~156,000 planetary target stars to the public. At the time of this publication, 706 targets from this first data set have viable exoplanet candidates with sizes as small as that of the Earth to larger than that of Jupiter. Here we give the identity and characteristics of 306 of the 706 targets. The released targets include 5 candidate multi-planet systems. Data for the remaining 400 targets with planetary candidates will be released in February 2011. The Kepler results based on the candidates in the released list imply that most candidate planets have radii less than half that of Jupiter.

Five Kepler target stars that show multiple transiting exoplanet candidates – Steffen et al

We present and discuss five candidate exoplanetary systems identified with the Kepler spacecraft. These five systems show transits from multiple exoplanet candidates. Should these objects prove to be planetary in nature, then these five systems open new opportunities for the field of exoplanets and provide new insights into the formation and dynamical evolution of planetary systems. We discuss the methods used to identify multiple transiting objects from the Kepler photometry as well as the false-positive rejection methods that have been applied to these data. One system shows transits from three distinct objects while the remaining four systems show transits from two objects. Three systems have planet candidates that are near mean motion commensurabilities – two near 2:1 and one just outside 5:2. We discuss the implications that multitransiting systems have on the distribution of orbital inclinations in planetary systems, and hence their dynamical histories; as well as their likely masses and chemical compositions. A Monte Carlo study indicates that, with additional data, most of these systems should exhibit detectable transit timing variations (TTV) due to gravitational interactions – though none are apparent in these data. We also discuss new challenges that arise in TTV analyses due to the presence of more than two planets in a system.


  1. #1 feedayeen
    June 15, 2010

    The UFO guys are going to go nuts when they find out that the Kepler team is withholding information on potential planets that ET could be living on.

  2. #2 andy
    June 15, 2010

    Interestingly enough, none of the planets in these candidate multi-planet systems are Jupiter-size. Hot Jupiters don’t appear to like company.

  3. #3 Helmut
    June 15, 2010

    The UFO guys go nuts every time the sun comes up, NASA doesn’t particularly care what they think. If the orbits are something like earth’s periodicity, they’d need to wait a bit longer to see a second transit anyway.

  4. #4 andy
    June 15, 2010

    Aargh got my eyes crossed, both 191 and 209 have possibly Jupiter-size planets, although both are in longer-period orbits than the typical hot Jupiters.

  5. #5 Steinn Sigurdsson
    June 15, 2010

    We know fro RV obs that hot Jovians have outer companions
    I think what we’re seeing is that hot Jove companions rend to be significantly non-coplanar due to scattering during migration

  6. #6 Helmut
    June 15, 2010

    Neat stuff so far, two sets of data: one for 9.7 days and the second for 33.5 days. This is the unvetted data, so the stuff coming out in February should be higher quality and have more earth-like sizes. So even though the data is biased towards larger planets, it looks like a 1/(planet radius in earth radii)^2 is a decent fit for how common the planets show up for periods less than 30 days. Very different than the previous hot jupiter stuff.

  7. #7 Torbjörn Larsson, OM
    June 16, 2010

    Though I gather from another thread that this (after eliminating the expected ~ 50 % false positives) is the bulk of the expected stars due to the selection effect of transits. (I.e. short period, easier to see.)

    So, good news, the 1/r^2 likely means many Earth sized planets, bad news, planets are overall scarcer than the previous skewed data let us believe – it roughly plays out as “good enough”?!

  8. #8 Helmut
    June 16, 2010

    ^ Do you have a link?

    This set is mostly only good for the 30 days and faster period, with the 1/r^2 applying to those alone. Who knows what the distribution of planets with longer periods or smaller sizes is at this point, that data has been withheld for follow-up observation. And on top of that, the bigger the orbit, the fewer the chances are that we’ll ever catch it on the elliptical at all. So even though this is probably the bulk of the planets that Kepler expects to observe, it’s observing a statistically large enough sample to imply a lot more planets are out there than what it’s going to observe.

  9. #9 Torbjörn Larsson, OM
    June 17, 2010

    Helmut, as you seem to respond to me, and with interesting facts so thanks:


  10. #10 Torbjörn Larsson, OM
    June 18, 2010

    I gave a link yesterday but I think it is stuck in moderation. Helmut, you can go over to Universe Today and the Kepler discussion.

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