First Planet Candidates Discovered by Planet Hunters
We are very, very happy to announce that the first Planet Hunters paper has been submitted to the journal Monthly Notices of the Royal Astronomical Society, or MNRAS.*
The title page of the paper shows:
If you take a close look at the affiliations, you will see that #16 is called “Planet Hunter.” That’s because this paper reports the discovery of two planet candidates discovered by our volunteers – and naturally, we included those those who were the first people to identify possible transits in the the 9 stars discussed in the paper. We also include a link to the full list of all Planet Hunters; you can find it here.
So what does the paper actually say? As it’s the first (of hopefully many) papers, we give a brief overview of the Kepler data and the Planet Hunters interface. How did we display the data? What questions did we ask? What did you guys actually do to identify transits?
We then used some of the first data from the site, and took the “top ten” stars (though 9 are discussed in the paper) with transits flagged by you guys and vetted them to determine, for example, whether they are masquerading eclipsing binaries. For our top three candidates, we looked for a companion star very close to the star by taking high-resolution images with the Keck telescopes (we will have a guest blog by Justin Crepp coming up very soon explaining how these images were taken). The images of the two final planet candidate stars (KIC 10905646 and KIC 6185331) and one of our candidates (KIC 8242434) that appears to be a background eclipsing binary system are here (regular 2MASS image left, Keck AO giving the all-clear right):
For KIC 8242434 it appears there may be a source in the south east very close to the star, and with help from our friends in the Kepler team, we were able to find evidence to suggest that this particular star is either a binary or, more likely, contaminated by a background eclipsing binary system. We then analyzed the properties of those remaining planet candidates. For those who are curious, you can take a look at the light curves here:
The properties of the planet candidates around these two stars are reported in Table 4 of the paper:
As you can see, both planets are fairly close to their stars with periods (“years”) of ~10 and 50 days respectively. One of the two planets has a fairly small radius of just over 2 Earth-radii and the other is just a little smaller than Jupiter with a radius of 8 Earth-radii. Models for planet formation, predict that likely both produced planetary cores that would would amass a large puffy atmosphere like the giant planets in our solar system.
Congratulations on this great find and for the new record we’ve set as the fastest Zooniverse project to go from launch to submitted publication! This paper is a real milestone for us in many ways. It shows that teaming up with citizen scientists to discover exo-planets works. It also shows that there’s lots to discover! Just in the top ten candidates of the first look at the first quarter data, we found two new planet candidates! Planet Hunters is already producing fantastic results, and we have no doubt that with each new round of data, there will be more discoveries to come. Imagine what you can find as more and more Kepler data goes public!
Want to read the paper for yourself? The full text PDF including all figures and tables is available at the arXiv.
PS. Here’s the part of the paper crediting the Planet Hunters will identified all our our top ten candidates. The first person for each one of these curves was added as an author to the paper– well done all!