Browsing by Subject "earth gj 1214b"
Now showing 1 - 2 of 2
- Results Per Page
- Sort Options
Item The Kepler-19 System: A Transiting 2.2 R-Circle Plus Planet And A Second Planet Detected Via Transit Timing Variations(2011-12) Ballard, Sarah; Fabrycky, Daniel; Fressin, Francois; Charbonneau, David; Desert, Jean-Michel; Torres, Guillermo; Marcy, Geoffrey; Burke, Christopher J.; Isaacson, Howard; Henze, Christopher; Steffen, Jason H.; Ciardi, David R.; Howell, Steven B.; Cochran, William D.; Endl, Michael; Bryson, Stephen T.; Rowe, Jason F.; Holman, Matthew J.; Lissauer, Jack J.; Jenkins, Jon M.; Still, Martin; Ford, Eric B.; Christiansen, Jessie L.; Middour, Christopher K.; Haas, Michael R.; Li, Jie; Hall, Jennifer R.; McCauliff, Sean; Batalha, Natalie M.; Koch, David G.; Borucki, William J.; Cochran, William D.; Endl, MichaelWe 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-star = 0.936 +/- 0.040 M-circle dot and a stellar radius of R-star = 0.850 +/- 0.018 R-circle dot (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(-110)(+113) 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-circle plus; 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-circle plus, 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 less than or similar to 160 days and mass less than or similar to 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.Item Kepler-445, Kepler-446 And The Occurrence Of Compact Multiples Orbiting Mid-M Dwarf Stars(2015-03) Muirhead, Phillip S.; Mann, Andrew W.; Vanderburg, Andrew; Morton, Timothy D.; Kraus, Adam; Ireland, Michael; Swift, Jonathan J.; Feiden, Gregory A.; Gaidos, Eric; Gazak, J. Zachary; Mann, Andrew W.; Kraus, AdamWe confirm and characterize the exoplanetary systems Kepler-445 and Kepler-446: two mid-M dwarf stars, each with multiple, small, short-period transiting planets. Kepler-445 is a metal-rich ([ Fe/H] = + 0.25 0.10) M4 dwarf with three transiting planets, and Kepler-446 is a metal-poor ([ Fe/H] = -0.30 0.10) M4 dwarf also with three transiting planets. Kepler-445c is similar toGJ 1214b: both in planetary radius and the properties of the host star. The Kepler-446 system is similar to the Kepler-42 system: both are metal-poor with large galactic space velocities and three short-period, likely rocky transiting planets that were initially assigned erroneously large planet-to-star radius ratios. We independently determined stellar parameters from spectroscopy and searched for and fitted the transit light curves for the planets, imposing a strict prior on stellar density in order to remove correlations between the fitted impact parameter and planet-to-star radius ratio for short-duration transits. Combining Kepler-445, Kepler-446, and Kepler-42, and isolating all mid-M dwarf stars observed by Kepler with the precision necessary to detect similar systems, we calculate that 21+ 7 -5 % of mid-M dwarf stars host compact multiples ( multiple planets with periods of less than 10 days) for a wide range of metallicities. We suggest that the inferred planet masses for these systems support highly efficient accretion of protoplanetary disk metals by mid-M dwarf protoplanets.