Discussion: KOI-42.01 (Kepler-410Ab) is a Neptune-sized exoplanet orbiting one star (Kepler-410A) of a binary star system (see Van Eylen reference below). This webpage summarizes its transit timing variation and several potential further implications of the observed sinusoidal variation of the TTV residuals. After a sinusoidal curve-fit of the (O-C) vs. Time data showed (Figure 1. below) a periodicity (P_ttv) of 965.34 ± 16.07 days (981.12 days was observed in the Lomb-Scargle Periodogram (LSP) of the same data), a plot (Figure 2.) of the Residuals also gave a good sinusoidal curve-fit with a periodicity of 283.52 ± 7.18 days (LSP: 284.70 days). The added combination of these two sinusoidal curves is arrayed in Figure 3. and reasonably reproduces a complex overall curvature consistent with the initial data. While the sinusoidal character of the residuals could very well be due to KOI-42.01's known eccentric orbit (see reference), it is also possible that (a) 1 or 2 additional unseen (non-transiting) planets are present in the system or (b) 1 additional such planet and the second star (Kepler-410B) are jointly responsible for the observed (O-C) results.
TTVs are derived from Short-Cadence Kepler data for one-third of Q1 and all of Q3-Q17; no data was recorded for two-thirds of Q1 nor for all of Q2. X-axes: “Observed Tc” (Mid-Transit Time): EXOFAST’s best-fits from Normalized PDCSAP_FLUX Kepler light flux vs. time (BJD_tdb - 2454900) short-cadence data. Y-axes: “(O – C)”: difference between Observed Tc and the Calculated Tc from the graphically obtained linear ephemeris.
References: • Van Eylen, V., Lund, M. N., Aguirre, V. S., et al., arXiv: 1312.4938, 17 Dec 2013. • Numerous other literature and major Tc#, Tc, and TTV tabulation references can be found on my "Summary" webpage following the table.
17 Nov 2014
Kepler KOI-42.01 (Kepler-410Ab; KIC-8866102 2-(or more?)-Planet System