Knicole D. Colón — Page 4

arXiv2015

Vetting Kepler Planet Candidates in the Sub-Jovian Desert with Multi-Band Photometry

We present new multi-band transit photometry of three small (R$_{p}$ < 6 R$_{\oplus}$), short-period (P < 6 days) Kepler planet candidates acquired with the Gran Telescopio Canarias. These observations supplement the results presented in Colón & Ford (2011) and Colón et al. (2012), where we used multicolor transit photometry of five Kepler planet candidates to search for wavelength-dependent transit depths and either validate planet candidates or identify eclipsing binary false positives within our sample. In those previous studies, we provided evidence that three targets were false positives and two targets were planets. Here, we present observations that provide evidence supporting a planetary nature for KOI 439.01 and KOI 732.01, and we find that KOI 531.01, a 6 R$_{\oplus}$ planet candidate around an M dwarf, is likely a false positive. We also present a discussion of the purported "sub-Jovian desert" in the orbital period-planet radius plane, which cannot be easily explained by observational bias. Both KOI 439.01 and KOI 732.01 are likely planets located within the so-called desert and should be investigated with further follow-up observations. As only ~30 of the ~3600 currently active Kepler planet candidates are located within the sub-Jovian desert, it will be interesting to see if these candidates also survive the vetting process and fill in the gap in the period-radius plane. Confirming planets in this regime will be important for understanding planetary migration and evolution processes, and we urge additional follow-up observations of these planet candidates to confirm their nature.

astro-ph.EP↗

arXiv2012

Constraining the False Positive Rate for Kepler Planet Candidates with Multi-Color Photometry from the GTC

Using the OSIRIS instrument installed on the 10.4-m Gran Telescopio Canarias (GTC) we acquired multi-color transit photometry of four small (Rp < 5 R_Earth) short-period (P < 6 days) planet candidates recently identified by the Kepler space mission. These observations are part of a program to constrain the false positive rate for small, short-period Kepler planet candidates. Since planetary transits should be largely achromatic when observed at different wavelengths (excluding the small color changes due to stellar limb darkening), we use the observed transit color to identify candidates as either false positives (e.g., a blend with a stellar eclipsing binary either in the background/foreground or bound to the target star) or validated planets. Our results include the identification of KOI 225.01 and KOI 1187.01 as false positives and the tentative validation of KOI 420.01 and KOI 526.01 as planets. The probability of identifying two false positives out of a sample of four targets is less than 1%, assuming an overall false positive rate for Kepler planet candidates of 10% (as estimated by Morton & Johnson 2011). Therefore, these results suggest a higher false positive rate for the small, short-period Kepler planet candidates than has been theoretically predicted by other studies which consider the Kepler planet candidate sample as a whole. Furthermore, our results are consistent with a recent Doppler study of short-period giant Kepler planet candidates (Santerne et al. 2012). We also investigate how the false positive rate for our sample varies with different planetary and stellar properties. Our results suggest that the false positive rate varies significantly with orbital period and is largest at the shortest orbital periods (P < 3 days), where there is a corresponding rise in the number of detached eclipsing binary stars... (truncated)

astro-ph.EP↗