TTVs are derived from Q1-Q16 Kepler data. x-axes: “Observed Tc” (Mid-Transit Time): EXOFAST’s best-fits from Kepler light flux vs. time data. y-axes: “(O – C)”: difference between Observed Tc and the Calculated Tc from the graphically obtained linear ephemeris. The plots are pictured in the order of orbital periods.
No TTV was found for the first exoplanet, KOI-672.01, in this system. However, via sinusoidal best-fits, not only does KOI-672.02 shows a significant TTV with a P_ttv of ~ 976.40 days, but the residuals of the TTV-xy plot show a second P_ttv of ~ 121.63 days. Correspondingly, the Lomb-Scargle Periodogram of the former shows two credible periodicities of about the same strength at 983.20 and 122.11; the residuals just show one credible periodicity of 121.57 days. This behavior is consistent with the presence of two unseen (non-transiting) exoplanets with greater semi-major axes than 672.02.
1st: KOI-672.01, P = 16.09 days [Plot error bars = ± 4.51 min.]
Linear ephemeris (this work): Tc = 16.08788073(Tc#) + 105.81335225
2nd: KOI-672.02, P = 41.75 days [Plot error bars = ± 3.38 min.]
TTV_minimum: 425.09 ± 101.93 days, Amp_ttv_minimum: -7.62 ± 3.15 min.
TTV_maximum: 913.29 ± 135.36 days, Amp_ttv_maximum: 10.31 ± 3.15 min.
TTV_minimum: 1401.49 ± 179.01 days, Amp_ttv_minimum: -7.62 ± 3.15 min.