Planetary Environments for Habitable Kepler Small Planet Candidates


by : 
Justin H.


Zodiacal dust produced mostly by planetesimal collisions is detectable in infrared excess emissions and is also an indication of an existing debris disk. I investigated the effect of Jupiter or small habitable planets within Kepler systems on the detections of zodiacal dust in my project. I probed for IR-excess in the habitable small-planet 47 Kepler Object of Interest (KOI) sample given by Thompson et al. 2018 and a 53 KOI solar-like and jupiter-containing sample that I compiled. I performed photometry on each target’s point spread functions (PSFs) to get accurate W3 (12 µm) and W4 (22 µm) flux values, then used them to generate a spectral energy distribution (SED) fit based on the best-fitting Nextgen or Kurucz model. I also used the significance formula from Sobrinho et al. 2018. to statistically quantify the excess. Next, I interpolated PSF solutions in the UKIRT, Spitzer, and WISE bands (IR space surveys). I used those solutions to subtract flux-contaminating stellar companions and calculate the true flux from the source star. Finally, I refit the new flux SEDs. My research identifies three of 47 (~6%) small-planet-containing KOIs and six of 53 jupiter-containing KOIs (~11%) with IR-excess. Compared with the control sample, the 47 KOI sample has the same proportion while the 53 KOI sample has a higher proportion, indicating that the existence of Jupiter-like planets likely enhances dust formation in some planetary systems. This tells us more about the stellar environment of our early solar system, and the precursors to generating habitable, Earth-like planets.