We present the discovery of the Kepler-19 planetary system , which we first identified from a 9.3-day periodic transit signal in the Kepler photometry .
From high-resolution spectroscopy of the star , we find a stellar effective temperature T _ { eff } =5541 \pm 60 K , a metallicity [ Fe/H ] = -0.13 \pm 0.06 , and a surface gravity log ( g ) = 4.59 \pm 0.10 .
We combine the estimate of T _ { eff } and [ Fe/H ] with an estimate of the stellar density derived from the photometric light curve to deduce a stellar mass of M _ { \star } = 0.936 \pm 0.040 M _ { \odot } and a stellar radius of R _ { \star } = 0.850 \pm 0.018 R _ { \odot } ( these errors do not include uncertainties in the stellar models ) .
We rule out the possibility that the transits result from an astrophysical false positive by first identifying the subset of stellar blends that reproduce the precise shape of the light curve .
Using the additional constraints from the measured color of the system , the absence of a secondary source in the high-resolution spectrum , and the absence of a secondary source in the adaptive optics imaging , we conclude that the planetary scenario is more than three orders of magnitude more likely than a blend .
The blend scenario is independently disfavored by the achromaticity of the transit : we measure a transit depth with Spitzer at 4.5 \mu m of 547 ^ { +113 } _ { -110 } ppm , consistent with the depth measured in the Kepler optical bandpass of 567 \pm 6 ppm ( corrected for stellar limb-darkening ) .
We determine a physical radius of the planet Kepler-19b of R _ { p } = 2.209 \pm 0.048 R _ { \oplus } ; the uncertainty is dominated by uncertainty in the stellar parameters .
From radial-velocity observations of the star , we find an upper limit on the planet mass of 20.3 M _ { \oplus } , corresponding to a maximum density of 10.4 g cm ^ { -3 } .
We report a significant sinusoidal deviation of the transit times from a predicted linear ephemeris , which we conclude is due to an additional perturbing body in the system .
We can not uniquely determine the orbital parameters of the perturber , as various dynamical mechanisms match the amplitude , period , and shape of the transit timing signal and satisfy the host star ’ s radial velocity limits .
However , the perturber in these mechanisms has period \lesssim 160 days and mass \lesssim 6 M _ { Jup } , confirming its planetary nature as Kepler-19c .
We place limits on the presence of transits of Kepler-19c in the available Kepler data .