Astrobites authors Caroline Morley, Lauren Weiss, and I have spent the week at NASA Ames Research Center for the First Kepler Science Conference. For today’s astrobite, I’ll summarize a few of the excellent talks from the meeting. Please note that this is only a small sample of the many wonderful talks at the conference and that the summary below doesn’t include any of the fantastic posters. If you’d like to learn more about the results presented at the conference, I encourage you to watch the talks on the conference website. The first three days have focused on exoplanets, but the remaining two days of the conference will be devoted to the amazing stellar astrophysics results that have come out of the Kepler mission so far. Even though Kepler is often viewed as an exoplanet mission, it’s worth remembering that the majority of the papers related to the Kepler mission have been related to stellar astrophysics and that Kepler even studies extragalactic objects like AGN.
NASA Ames Center Director Dr. Pete Worden kicked of the Kepler Science Conference on Monday morning by describing the Kepler mission with two words, “Way cool.” Next, Greg Laughlin gave an invited talk about the Kepler mission and exoplanet statistics. One of the interesting points Greg made during his talk was that the mass ratios of Super-Earths and their host stars resembles the mass ratios of the moons of the Jovian and Saturnian systems to Jupiter and Saturn. This might be an interesting coincidence, or perhaps we can apply lessons from satellite formation to exoplanet formation.
After a nice update on the European Space Agency’s planet-finding mission CoRoT from Claire Moutou, Kepler Principle Investigator Bill Borucki announced the discovery of Kepler-22b, a 2.4 Earth radius planet in the habitable zone of a Sun-like star. For more information about Kepler-22b, check out Ellie’s astrobite or read the paper.
Next, Natalie Batalha discussed the progress that Kepler is making toward finding smaller planets in the habitable zone. She mentioned that Kepler has already discovered small rocky planets orbiting relatively close to their parent stars (e.g., Kepler-10b) and larger planets orbiting within the habitable zone (e.g., Kepler-22b), so the mission is getting closer to the goal of detecting small rocky planets in the habitable zone of Sun-like stars. Natalie also highlighted the large increase (204%) in the number of 1-2 Earth radius candidates in the new candidate list compared to the February 2011 list and mentioned that 48 of those candidates have estimated equilibrium temperatures between 185 and 303 Kelvin. Additionally, 10 of those candidates have radii less than twice the radius of the Earth.
After the Monday morning coffee break, Jon Jenkins discussed the data reduction pipeline and the amazing work that the team has done to transform the raw Kepler data into gorgeous light curves. Jon also cracked up the room by playing a recording of the frequencies of one of the light curves that sounded suspiciously like Lieutenant Uhura hailing Captain Kirk. He followed the Star Trek clip with an actual sonification of a Kepler target star. Check out the Kepler Star Sounds website if you’d like to hear the music of the spheres yourself.
In the afternoon, Andrew Howard presented revised estimates of the planet occurrence rate using the updated Kepler candidate list and Christophe Lovis discussed results from the HARPS radial velocity planet survey. Next, Leslie Rogers and Eric Lopez presented interesting talks about modeling rocky exoplanets. The last talk of the day was a presentation by Jill Tarter about using the Allen Telescope Array to search for signals from the Kepler candidates. Jill explained that the SETI Institute had decided to survey all of the candidates in the field (not just the ones in the habitable zone) to avoid biasing the search for life based on our Earth-centric views of habitability. In a laugh-inspiring Contact reference, Jill said that SETI was getting out the push-pins just like Jodie Foster.
Kevin Schlaufman kicked off the day on Tuesday by announcing that low-mass planets are more frequent around low-mass stars with high metallicity, but that the metallicity dependence disappears for higher host star masses. Next, Jerome Orosz presented some of the interesting work the Kepler team is doing to model circumbinary planet candidates and Sarah Ballard discussed using the Spitzer space telescope to validate Super Earth candidates in the habitable zone. As explained in a previous astrobite, the transit of a planet should have the same depth in the optical and infrared, but a false positive eclipsing binary will have a wavelength-dependent transit depth.
After coffee, Megan Schwamb presented exoplanets found by the Citizen Science group Planet Hunters in the Kepler data and George Ricker provided an introduction to the Transiting Exoplanet Survey Satellite (TESS), which will perform an all-sky survey to find Earths and Super Earths around F5-M5 stars if it is selected for funding. Later in the day, Jack Lissauer argued that candidates in multiple planet systems are very likely to be real planets given the low chance of finding both a planet and a false positive for the same star. Dan Fabrycky gave an excellent talk about modeling the dynamics of planetary systems and amused us all by showing off a photo of the Kepler-11 corn maze.
On Wednesday afternoon, Sara Seager gave an invited tak about Kepler’s giant planet discoveries. Sarah pointed out that Jupiters are out-numbered by planets Neptune-size or smaller, but we that we still don’t know how exo-Neptunes form. She predicted that determining the origin of exo-Neptunes will likely be one of the major contributions of Kepler. She also touched on a few other results from Kepler, such as the lack of massive solid planets and the (relatively) bright albedo of Kepler-7b. She concluded her talk by advising young researchers to “think of something new to do [with the Kepler data] and use the data wisely.”
Jonathan Fortney discussed the heavy element abundances of giant planets and argued that giant planets are probably enriched in heavy elements in their atmospheres instead of simply being heavy element cores surrounded by solar composition envelopes. Next, Brice-Olivier Demory presented results that giant planets typically appear dark in the Kepler bandpass and Mark Marley educated all of us on the differences between geometric albedo and Bond albedo. For reference, bond albedo varies depending on the illumination, while geometric albedo is an intrinsic property of a planet.
In the final session of the day, Gyula Szabo and Jason Barnes discussed the gravity darkening and spin-orbit alignment of KOI-13. Gravity darkening means that the equator of the planet appears dark relative to the poles. Gravity darkening is caused by the fast rotation rate of the star, which causes the star to become oblate and have less surface gravity at the equator than at the poles. In addition, Josh Carter presented an analysis of the true obliquity of HAT-P-7b (Kepler 2b) and argued that the spin axis of the star is most likely pointed toward Earth and that HAT-P-7b is therefore in a polar orbit.