Adaptive Optics Follow-up Observations
Today’s blog post come’s from guest blogger Justin Crepp, co-author on our first Planet Hunters paper. Justin is an expert in adaptive optics and fellow planet hunter. He’s going to tell you more about the observations he carried out to help follow up our planet candidates.
Dear Planet Hunters,
Thank you for your diligent work identifying new Kepler planet candidates!
I am a postdoc at Caltech and my job (normally) entails searching for exoplanets using high-contrast imaging, a technique that involves trying to “take a picture” of faint companions in orbit around bright stars. As you can imagine, this is a challenging task: it requires adaptive optics to correct for the blurring effects of Earth’s turbulent atmosphere (as well as other hardware and some advanced data processing). Ironically, the same technology that I use to detect planets directly can also help to find transiting planets. By eliminating false-positives with imaging observations, we can dramatically reduce the likelihood that a nearby object, such as an eclipsing binary star, is mimicking the periodic signal of a transiting planet. In other words, I am often very anxious to see faint points of light next to bright stars, but, in the case of Kepler targets, it is best not to find any sources in the immediate vicinity of the star.
I recently had the pleasure of working with Debra Fischer, Meg Schwamb, and the rest of the Planet Hunters team, to observe the stars that you found to have intriguing light-curves. Armed with the Keck adaptive optics system and the NIRC2 camera, Tim Morton (Caltech grad student) and I were able to record deep images of each target on your list. After some careful analysis, we found that two of the stars you identified were free of contaminants, and therefore almost certainly (>95% confidence) transiting planet hosts.
I am proud to have contributed to such an exciting project, and would like to thank you once again for your dedication examining Kepler’s exquisite data. These are the lowest mass planets for which I have been a co-discoverer; in fact, one of them may be only several times the mass of Earth. I hope we get a chance to work together again sometime soon.
The images of the two final planet candidate stars (KIC 10905746 and KIC 6185331) and one of our candidates (KIC 8242434) that appears to be a background eclipsing binary system are shown below (regular 2MASS image left, Keck AO Justin took right):