Browsing by Subject "1st 4 months"

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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, Michael
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-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.
Kepler-20: A Sun-Like Star With Three Sub-Neptune Exoplanets And Two Earth-Size Candidates
(2012-04) Gautier, Thomas N., III; Charbonneau, David; Rowe, Jason F.; Marcy, Geoffrey W.; Isaacson, Howard; Torres, Guillermo; Fressin, Francois; Rogers, Leslie A.; Desert, Jean-Michel; Buchhave, Lars A.; Latham, David W.; Quinn, Samuel N.; Ciardi, David R.; Fabrycky, Daniel C.; Ford, Eric B.; Gilliland, Ronald L.; Walkowicz, Lucianne M.; Bryson, Stephen T.; Cochran, William D.; Endl, Michael; Fischer, Debra A.; ; Howell, Steve B.; Horch, Elliott P.; Barclay, Thomas; Batalha, Natalie; Borucki, William J.; Christiansen, Jessie L.; Geary, John C.; Henze, Christopher E.; Holman, Matthew J.; Ibrahim, Khadeejah; Jenkins, Jon M.; Kinemuchi, Karen; Koch, David G.; Lissauer, Jack J.; Sanderfer, Dwight T.; Sasselov, Dimitar D.; Seager, Sara; Silverio, Kathryn; Smith, Jeffrey C.; Still, Martin; Stumpe, Martin C.; Tenenbaum, Peter; Van Cleve, Jeffrey; Cochran, William D.; Endl, Michael
We present the discovery of the Kepler-20 planetary system, which we initially identified through the detection of five distinct periodic transit signals in the Kepler light curve of the host star 2MASS J19104752+4220194. From high-resolution spectroscopy of the star, we find a stellar effective temperature T-eff = 5455 +/- 100 K, a metallicity of [Fe/H] = 0.01 +/- 0.04, and a surface gravity of log g = 4.4 +/- 0.1. We combine these estimates with an estimate of the stellar density derived from the transit light curves to deduce a stellar mass of M-* = 0.912 +/- 0.034M(circle dot) and a stellar radius of R-* = 0.944(-0.095)(+0.060) R-circle dot. For three of the transit signals, we demonstrate that our results strongly disfavor the possibility that these result from astrophysical false positives. We accomplish this by first identifying the subset of stellar blends that reproduce the precise shape of the light curve and then using the constraints on the presence of additional stars from high angular resolution imaging, photometric colors, and the absence of a secondary component in our spectroscopic observations. We conclude that the planetary scenario is more likely than that of an astrophysical false positive by a factor of 2x10(5) (Kepler-20b), 1x10(5) (Kepler-20c), and 1.1x10(3) (Kepler-20d), sufficient to validate these objects as planetary companions. For Kepler-20c and Kepler-20d, the blend scenario is independently disfavored by the achromaticity of the transit: from Spitzer data gathered at 4.5 mu m, we infer a ratio of the planetary to stellar radii of 0.075 +/- 0.015 (Kepler-20c) and 0.065 +/- 0.011 (Kepler-20d), consistent with each of the depths measured in the Kepler optical bandpass. We determine the orbital periods and physical radii of the three confirmed planets to be 3.70 days and 1.91(-0.21)(+0.12) R-circle plus for Kepler-20b, 10.85 days and 3.07(-0.31)(+0.20) R-circle plus for Kepler-20c, and 77.61 days and 2.75(-0.30)(+0.17) R-circle plus for Kepler-20d. From multi-epoch radial velocities, we determine the masses of Kepler-20b and Kepler-20c to be 8.7 +/- 2.2M(circle plus) and 16.1 +/- 3.5M(circle plus), respectively, and we place an upper limit on the mass of Kepler-20d of 20.1M(circle plus) (2 sigma).
Planetary Candidates Observed By Kepler Iv: Planet Sample from Q1-Q8 (22 Months)
(2014-02) Burke, Christopher J.; Bryson, Stephen T.; Mullally, F.; Rowe, Jason F.; Christiansen, Jessie L.; Thompson, Susan E.; Coughlin, Jeffrey L.; Haas, Michael R.; Batalha, Natalie M.; Caldwell, Douglas A.; Jenkins, Jon M.; Still, Martin; Barclay, Thomas; Borucki, William J.; Chaplin, William J.; Ciardi, David R.; Clarke, Bruce D.; Cochran, William D.; Demory, Brice-Olivier; Esquerdo, Gilbert A.; Gautier, Thomas N., III; Gilliland, Ronald L.; Girouard, Forrest R.; Havel, Mathieu; Henze, Christopher E.; Howell, Steve B.; Huber, Daniel; Latham, David W.; Li, Jie; Morehead, Robert C.; Morton, Timothy D.; Pepper, Joshua; Quintana, Elisa; Ragozzine, Darin; Seader, Shawn E.; Shah, Yash; Shporer, Avi; Tenenbaum, Peter; Twicken, Joseph D.; Wolfgang, Angie; Cochran, William D.
We provide updates to the Kepler planet candidate sample based upon nearly two years of high-precision photometry (i.e., Q1-Q8). From an initial list of nearly 13,400 threshold crossing events, 480 new host stars are identified from their flux time series as consistent with hosting transiting planets. Potential transit signals are subjected to further analysis using the pixel-level data, which allows background eclipsing binaries to be identified through small image position shifts during transit. We also re-evaluate Kepler Objects of Interest (KOIs) 1-1609, which were identified early in the mission, using substantially more data to test for background false positives and to find additional multiple systems. Combining the new and previous KOI samples, we provide updated parameters for 2738 Kepler planet candidates distributed across 2017 host stars. From the combined Kepler planet candidates, 472 are new from the Q1-Q8 data examined in this study. The new Kepler planet candidates represent similar to 40% of the sample with R-P similar to 1R(circle plus) and represent similar to 40% of the low equilibrium temperature (T-eq < 300 K) sample. We review the known biases in the current sample of Kepler planet candidates relevant to evaluating planet population statistics with the current Kepler planet candidate sample.
Three Red Giants With Substellar-Mass Companions
(2015-04) Niedzielski, A.; Wolszczan, A.; Nowak, G.; Adamow, M.; Kowalik, K.; Maciejewski, G.; Deka-Szymankiewicz, B.; Adamczyk, M.; Adamow, M.
We present three giant stars from the ongoing Penn State-Torun Planet Search with the Hobby-Eberly Telescope, which exhibit radial velocity ( RV) variations that point to the presence of planetary-mass companions around them. BD + 49 828 is a M 1.52 +/- 0.22 M-circle dot K0 giant with a m sin i = 1.6(-0.2)(+0.4) M-J minimum mass companion in a = 4.2(-0.2)(+0.32) AU (2590(-180)(+300)d), e = 0.35(-0.10)(+0.24) orbit. HD 95127, a logL/L-circle dot = 2.28 +/- 0.38, R = 20 +/- 9 R-circle dot, M = 1.20 +/- 0.22 M-circle dot K0 giant, has a m sin i = 5.01(-0.44)(+0.61) M-J minimum mass companion in a = 1.28(-0.01)(+0.01) AU (482(-5)(+5)d), e = 0.11(-0.06)(+0.15) orbit. Finally, HD 216536 is a M = 1.36 +/- 0.38 M-circle dot K0 giant with a m sin i = 1.47(-0.20)(+0.12) M-J minimum mass companion in a = 0.609(-0.002)(+0.002) AU (148.6(-0.7)(+0.7)d), e = 0.38(-0.10)(+0.12) orbit. Both. HD 95127 b and HD 216536 b in their compact orbits. are very close to the engulfment zone and hence prone to ingestion in the near future. BD+49 828 b is among the longest-period planets detected with the RV technique until now and it will remain unaffected by stellar evolution up to a very late stage of its host. We discuss general properties of planetary systems around evolved stars and planet survivability using existing data on exoplanets in more detail.
Transit Timing Observations From Kepler. II. Confirmation Of Two Multiplanet Systems Via A Non-Parametric Correlation Analysis
(2012-05) Ford, Eric B.; Fabrycky, Daniel C.; Steffen, Jason H.; Carter, Joshua A.; Fressin, Francois; Holman, Matthew J.; Lissauer, Jack J.; Moorhead, Althea V.; Morehead, Robert C.; Ragozzine, Darin; Rowe, Jason F.; Welsh, William F.; Allen, Christopher; Batalha, Natalie M.; Borucki, William J.; Bryson, Stephen T.; Buchhave, Lars A.; Burke, Christopher J.; Caldwell, Douglas A.; Charbonneau, David; Clarke, Bruce D.; Cochran, William D.; Desert, Jean-Michel; Endl, Michael; Everett, Mark E.; Fischer, Debra A.; Gautier, Thomas N, III; Gilliland, Ron L.; Jenkins, Jon M.; Haas, Michael R.; Horch, Elliott; Howell, Steve B.; Ibrahim, Khadeejah A; Isaacson, Howard; Koch, David G; Latham, David W; Li, Jie; Lucas, Philip; MacQueen, Phillip J; Marcy, Geoffrey W; McCauliff, Sean; Mullally, Fergal R; Quinn, Samuel N; Quintana, Elisa; Shporer, Avi; Still, Martin; Tenenbaum, Peter; Thompson, Susan E; Torres, Guillermo; Twicken, Joseph D; Wohler, Bill; Kepler Sci, Team; Cochran, William D.; Endl, Michael; MacQueen, Phillip J.
We present a new method for confirming transiting planets based on the combination of transit timing variations (TTVs) and dynamical stability. Correlated TTVs provide evidence that the pair of bodies is in the same physical system. Orbital stability provides upper limits for the masses of the transiting companions that are in the planetary regime. This paper describes a non-parametric technique for quantifying the statistical significance of TTVs based on the correlation of two TTV data sets. We apply this method to an analysis of the TTVs of two stars with multiple transiting planet candidates identified by Kepler. We confirm four transiting planets in two multiple-planet systems based on their TTVs and the constraints imposed by dynamical stability. An additional three candidates in these same systems are not confirmed as planets, but are likely to be validated as real planets once further observations and analyses are possible. If all were confirmed, these systems would be near 4:6:9 and 2:4:6:9 period commensurabilities. Our results demonstrate that TTVs provide a powerful tool for confirming transiting planets, including low-mass planets and planets around faint stars for which Doppler follow-up is not practical with existing facilities. Continued Kepler observations will dramatically improve the constraints on the planet masses and orbits and provide sensitivity for detecting additional non-transiting planets. If Kepler observations were extended to eight years, then a similar analysis could likely confirm systems with multiple closely spaced, small transiting planets in or near the habitable zone of solar-type stars.
Validation Of Kepler's Multiple Planet Candidates. III. Light Curve Analysis And Announcement Of Hundreds Of New Multi-Planet Systems
(2014-03) Rowe, Jason F.; Bryson, Stephen T.; Marcy, Geoffrey W.; Lissauer, Jack J.; Jontof-Hutter, Daniel; Mullally, Fergal; Gilliland, Ronald L.; Issacson, Howard; Ford, Eric; Howell, Steve B.; Borucki, William J.; Haas, Michael; Huber, Daniel; Steffen, Jason H.; Thompson, Susan E.; Quintana, Elisa; Barclay, Thomas; Still, Martin; Fortney, Jonathan; Gautier, T. N., III; Hunter, Roger; Caldwell, Douglas A.; Ciardi, David R.; Devore, Edna; Cochran, William; Jenkins, Jon; Agol, Eric; Carter, Joshua A.; Geary, John; Cochran, William
The Kepler mission has discovered more than 2500 exoplanet candidates in the first two years of spacecraft data, with approximately 40% of those in candidate multi-planet systems. The high rate of multiplicity combined with the low rate of identified false positives indicates that the multiplanet systems contain very few false positive signals due to other systems not gravitationally bound to the target star. False positives in the multi-planet systems are identified and removed, leaving behind a residual population of candidate multi-planet transiting systems expected to have a false positive rate less than 1%. We present a sample of 340 planetary systems that contain 851 planets that are validated to substantially better than the 99% confidence level; the vast majority of these have not been previously verified as planets. We expect similar to two unidentified false positives making our sample of planet very reliable. We present fundamental planetary properties of our sample based on a comprehensive analysis of Kepler light curves, ground-based spectroscopy, and high-resolution imaging. Since we do not require spectroscopy or high-resolution imaging for validation, some of our derived parameters for a planetary system may be systematically incorrect due to dilution from light due to additional stars in the photometric aperture. Nonetheless, our result nearly doubles the number verified exoplanets.