THE KEPLER-19 SYSTEM: A TRANSITING 2.2R_⊕PLANET AND A SECOND PLANET DETECTED VIA TRANSIT TIMING VARIATIONS

Abstract

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 ± 60 K, a metallicity [Fe/H] = −0.13 ± 0.06, and a surface gravity log(g) = 4.59 ± 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 = 0.936 ± 0.040 M and a stellar radius of R = 0.850 ± 0.018 R (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 μm of 547 +113 −110 ppm, consistent with the depth measured in the Kepler optical bandpass of 567 ± 6 ppm (corrected for stellar limb darkening). We determine a physical radius of the planet Kepler-19b of R p = 2.209 ± 0.048 R ⊕ ; 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 ⊕ , 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 cannot 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 a period 160 days and mass 6 M Jup , confirming its planetary nature as . We place limits on the presence of transits of in the available Kepler data.

Multi-site campaign for transit timing variations of WASP-12 b: possible detection of a long-period signal of planetary origin

“…Ballard et al 2011). To check what planetary configurations may produce timing variations with the postulated periodicity, three-body simulations were performed with the mercury package (Chambers 1999) employing the Bulirsch-Stoer integrator.…”

Multiple planets or exomoons inKeplerhot Jupiter systems with transit timing variations?

“…In multiplanet systems, planets perturb each other, leading to correlated TTVs of them (Holman et al 2010;Lissauer et al 2011). TTVs have also uncovered the presence of further non-transiting planets in planetary systems (Ballard et al 2011;Ford et al 2012a).…”

SPITZERINFRARED OBSERVATIONS AND INDEPENDENT VALIDATION OF THE TRANSITING SUPER-EARTH CoRoT-7 b

“…These tools have already been used to validate small signals for which radial-velocity confirmation is currently out of reach, including possibly rocky planets. Examples include the super-Earth Kepler-9 d , and the Neptune-size planets Kepler-10 c ), Kepler-11 g (Lissauer et al 2011), and Kepler-19 b (Ballard et al 2011).…”

“…To evaluate the BF we make use of the BLENDER technique introduced by Torres et al (2004Torres et al ( , 2011, with further developments as described by Fressin et al (2011). This methodology has been applied successfully to validate a number of shallow transit signals from the Kepler mission including Kepler-9 d, Kepler-10 c, Kepler-11 g, and Kepler-19 b (Torres et al 2011;Fressin et al 2011;Lissauer et al 2011;Ballard et al 2011).…”