S. T. Bryson

Publications (24)63.48 Total impact

• Article: Kepler-62: A five-planet system with planets of 1.4 and 1.6 Earth radii in the Habitable Zone

  W. J. Borucki, E. Agol, F. Fressin, L. Kaltenegger, J. Rowe, H. Isaacson, D. Fischer, N. Batalha, J. J. Lissauer, G. W. Marcy, [......], S. Seader, A. Shporer, J. H. Steffen, M. Still, P. Tenenbaum, S. E. Thompson, G. Torres, J. D. Twicken, W. F. Welsh, J. N. Winn
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  ABSTRACT: We present the detection of five planets -- Kepler-62b, c, d, e, and f -- of size 1.31, 0.54, 1.95, 1.61 and 1.41 Earth radii, orbiting a K2V star at periods of 5.7, 12.4, 18.2, 122.4 and 267.3 days, respectively. The outermost planets (Kepler-62e & -62f) are super-Earth-size (1.25 < planet radius/earth radius < 2.0) planets in the habitable zone (HZ) of their host star, receiving 1.2 +- 0.2 and 0.41 +- 0.05 times the solar flux at Earth's orbit. Theoretical models of Kepler-62e and -62f for a stellar age of ~7 Gyr suggest that both planets could be solid: either with a rocky composition or composed of mostly solid water in their bulk.
  04/2013;
• Source

  Available from: L. Gizon

  Article: Asteroseismology of the Solar Analogs 16 Cyg A and B from Kepler Observations

  T. S. Metcalfe, W. J. Chaplin, T. Appourchaux, R. A. García, S. Basu, I. Brandão, O. L. Creevey, S. Deheuvels, G. Doğan, P. Eggenberger, [......], B. Mosser, S. T. Bryson, M. D. Still, J. Christensen-Dalsgaard, R. L. Gilliland, S. D. Kawaler, H. Kjeldsen, K. A. Ibrahim, T. C. Klaus, and J. Li
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  ABSTRACT: The evolved solar-type stars 16 Cyg A and B have long been studied as solar analogs, yielding a glimpse into the future of our own Sun. The orbital period of the binary system is too long to provide meaningful dynamical constraints on the stellar properties, but asteroseismology can help because the stars are among the brightest in the Kepler field. We present an analysis of three months of nearly uninterrupted photometry of 16 Cyg A and B from the Kepler space telescope. We extract a total of 46 and 41 oscillation frequencies for the two components, respectively, including a clear detection of octupole (l = 3) modes in both stars. We derive the properties of each star independently using the Asteroseismic Modeling Portal, fitting the individual oscillation frequencies and other observational constraints simultaneously. We evaluate the systematic uncertainties from an ensemble of results generated by a variety of stellar evolution codes and fitting methods. The optimal models derived by fitting each component individually yield a common age (t = 6.8 ± 0.4 Gyr) and initial composition (Z i = 0.024 ± 0.002, Y i = 0.25 ± 0.01) within the uncertainties, as expected for the components of a binary system, bolstering our confidence in the reliability of asteroseismic techniques. The longer data sets that will ultimately become available will allow future studies of differential rotation, convection zone depths, and long-term changes due to stellar activity cycles.
  The Astrophysical Journal Letters 02/2012; 748(1):L10. · 5.53 Impact Factor
• Article: KEPLER-21b: A 1.6 R-Earth PLANET TRANSITING THE BRIGHT OSCILLATING F SUBGIANT STAR HD 179070

  S B Howell, J F Rowe, S T Bryson, S N Quinn, G W Marcy, H Isaacson, D R Ciardi, W J Chaplin, T S Metcalfe, Mjpfg Monteiro, [......], J L Christiansen, C K Middour, M R Haas, J R Hall, J M Jenkins, S McCaulif, M N Fanelli, C Kulesa, D McCarthy, C E Henze
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  ABSTRACT: We present Kepler observations of the bright (V = 8.3), oscillating star HD 179070. The observations show transit-like events which reveal that the star is orbited every 2.8 days by a small, 1.6 R-Earth object. Seismic studies of HD 179070 using short cadence Kepler observations show that HD 179070 has a frequency-power spectrum consistent with solar-like oscillations that are acoustic p-modes. Asteroseismic analysis provides robust values for the mass and radius of HD 179070, 1.34 +/- 0.06 M-circle dot and 1.86 +/- 0.04 R-circle dot, respectively, as well as yielding an age of 2.84 +/- 0.34 Gyr for this F5 subgiant. Together with ground-based follow-up observations, analysis of the Kepler light curves and image data, and blend scenario models, we conservatively show at the >99.7% confidence level (3 sigma) that the transit event is caused by a 1.64 +/- 0.04 R-Earth exoplanet in a 2.785755 +/- 0.000032 day orbit. The exoplanet is only 0.04 AU away from the star and our spectroscopic observations provide an upper limit to its mass of similar to 10 M-Earth (2 sigma). HD 179070 is the brightest exoplanet host star yet discovered by Kepler.
  The Astrophysical Journal 02/2012; 746:123 (18pp). · 6.02 Impact Factor
• Source

  Available from: ArXiv

  Article: Observational Constraints, Stellar Models, and Kepler Data for theta Cyg, the Brightest Star Observable by Kepler

  J. A. Guzik, G. Houdek, W. J. Chaplin, D. Kurtz, R. L. Gilliland, F. Mullally, J. F. Rowe, M. R. Haas, S. T. Bryson, M. D. Still, T. Boyajian
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  ABSTRACT: The V=4.48 F4 main-sequence star theta Cyg is the brightest star observable in the Kepler spacecraft field-of-view. Short-cadence (58.8 s) photometric data were obtained by Kepler during 2010 June-September. Preliminary analysis shows solar-like oscillations in the frequency range 1200- 2500 microHz. To interpret these data and to motivate further observations, we use observational constraints from the literature to construct stellar evolution and pulsation models for this star. We compare the observed large frequency separation of the solar-like oscillations with the model predictions, and discuss the prospects for gamma Doradus-like g-mode pulsations, given the observational constraints. We discuss the value of angular diameter measurements from optical interferometry for constraining stellar properties and the implications for asteroseismology.
  10/2011;
• Source

  Available from: Avi Shporer

  Article: The architecture of the hierarchical triple star KOI 928 from eclipse timing variations seen in Kepler photometry

  J. H. Steffen, S. N. Quinn, W. J. Borucki, E. Brugamyer, S. T. Bryson, L. A. Buchhave, W. D. Cochran, M. Endl, D. C. Fabrycky, E. B. Ford, [......], J. F. Rowe, D. T. Sanderfer, S. E. Seader, D. Short, A. Shporer, S. E. Thompson, G. Torres, J. D. Twicken, W. F. Welsh, G. Windmiller
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  ABSTRACT: We present a hierarchical triple star system (KIC 9140402) where a low mass eclipsing binary orbits a more massive third star. The orbital period of the binary (4.98829 Days) is determined by the eclipse times seen in photometry from NASA's Kepler spacecraft. The periodically changing tidal field, due to the eccentric orbit of the binary about the tertiary, causes a change in the orbital period of the binary. The resulting eclipse timing variations provide insight into the dynamics and architecture of this system and allow the inference of the total mass of the binary ($0.424 \pm 0.017 \text{M}_\odot$) and the orbital parameters of the binary about the central star.
  06/2011;
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  Available from: H. Lehmann

  Article: Cepheid investigations using the Kepler space telescope

  R. Szabó, L. Szabados, C.-C. Ngeow, R. Smolec, A. Derekas, P. Moskalik, J. Nuspl, H. Lehmann, G. Fűrész, J. Molenda-Żakowicz, [......], A. Sliski, G. Handler, L. L. Kiss, Z. Kolláth, J. Kovács, J. Christensen-Dalsgaard, H. Kjeldsen, C. Allen, S. E. Thompson, J. Van Cleve
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  ABSTRACT: We report results of initial work done on selected candidate Cepheids to be observed with the Kepler space telescope. Prior to the launch, 40 candidates were selected from previous surveys and data bases. The analysis of the first 322 d of Kepler photometry, and recent ground-based follow-up multicolour photometry and spectroscopy allowed us to confirm that one of these stars, V1154 Cyg (KIC 7548061), is indeed a 4.9-d Cepheid. Using the phase lag method, we show that this star pulsates in the fundamental mode. New radial velocity data are consistent with previous measurements, suggesting that a long-period binary component is unlikely. No evidence is seen in the ultraprecise, nearly uninterrupted Kepler photometry for non-radial or stochastically excited modes at the micromagnitude level. The other candidates are not Cepheids, but an interesting mix of possible spotted stars, eclipsing systems and flare stars.
  Monthly Notices of the Royal Astronomical Society 05/2011; 413(4):2709 - 2720. · 4.90 Impact Factor
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  Available from: H. Lehmann

  Article: HD 181068: a red giant in a triply eclipsing compact hierarchical triple system.

  A Derekas, L L Kiss, T Borkovits, D Huber, H Lehmann, J Southworth, T R Bedding, D Balam, M Hartmann, M Hrudkova, [......], J Sturmann, L Sturmann, N Turner, P G Tuthill, J Christensen-Dalsgaard, R L Gilliland, H Kjeldsen, E V Quintana, P Tenenbaum, J D Twicken
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  ABSTRACT: Hierarchical triple systems comprise a close binary and a more distant component. They are important for testing theories of star formation and of stellar evolution in the presence of nearby companions. We obtained 218 days of Kepler photometry of HD 181068 (magnitude of 7.1), supplemented by ground-based spectroscopy and interferometry, which show it to be a hierarchical triple with two types of mutual eclipses. The primary is a red giant that is in a 45-day orbit with a pair of red dwarfs in a close 0.9-day orbit. The red giant shows evidence for tidally induced oscillations that are driven by the orbital motion of the close pair. HD 181068 is an ideal target for studies of dynamical evolution and testing tidal friction theories in hierarchical triple systems.
  Science 04/2011; 332(6026):216-8. · 31.20 Impact Factor
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  Available from: S. Hekker

  Article: Predicting the detectability of oscillations in solar-type starsobserved by Kepler

  W. J. Chaplin, H. Kjeldsen, T. R. Bedding, J. Christensen-Dalsgaard, R. L. Gilliland, S. D. Kawaler, T. Appourchaux, Y. Elsworth, R. A. Garcia, G. Houdek, [......], B. Mosser, R. New, M. H. Pinsonneault, D. Pricopi, P. -O. Quirion, C. Regulo, I. W. Roxburgh, D. Salabert, D. Stello, M. D. Suran
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  ABSTRACT: Asteroseismology of solar-type stars has an important part to play in the exoplanet program of the NASA Kepler Mission. Precise and accurate inferences on the stellar properties that are made possible by the seismic data allow very tight constraints to be placed on the exoplanetary systems. Here, we outline how to make an estimate of the detectability of solar-like oscillations in any given Kepler target, using rough estimates of the temperature and radius, and the Kepler apparent magnitude.
  The Astrophysical Journal 03/2011; 732:54. · 6.02 Impact Factor
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  Available from: L. A. Balona

  Article: Kepler observations of rapidly oscillating Ap, δ Scuti and γ Doradus pulsations in Ap stars

  L. A. Balona, M. S. Cunha, D. W. Kurtz, I. M. Brandão, M. Gruberbauer, H. Saio, R. Østensen, V. G. Elkin, W. J. Borucki, J. Christensen-Dalsgaard, H. Kjeldsen, D. G. Koch, S. T. Bryson
  [show abstract] [hide abstract]
  ABSTRACT: Observations of the A5p star KIC 8677585 obtained during the Kepler 10-d commissioning run with 1-min time resolution show that it is a rapidly oscillating Ap (roAp) star with several frequencies with periods near 10 min. In addition, a low frequency at 3.142 d−1 is also clearly present. Multiperiodic γ Doradus (γ Dor) and δ Scuti (δ Sct) pulsations, never before seen in any Ap star, are present in Kepler observations of at least three other Ap stars. Since γ Dor pulsations are seen in Ap stars, it is likely that the low frequency in KIC 8677585 is also a γ Dor pulsation. The simultaneous presence of both γ Dor and roAp pulsations and the unexpected detection of δ Sct and γ Dor pulsations in Ap stars present new opportunities and challenges for the interpretation of these stars. Since it is easy to confuse Am and Ap stars at classification dispersions, the nature of these Ap stars in the Kepler field needs to be confirmed.
  Monthly Notices of the Royal Astronomical Society 12/2010; 410(1):517 - 524. · 4.90 Impact Factor
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  Available from: J. M. Nemec

  Article: Does Kepler unveil the mystery of the Blazhko effect? First detection of period doubling in Kepler Blazhko RR Lyrae stars

  R. Szabó, Z. Kolláth, L. Molnár, K. Kolenberg, D. W. Kurtz, S. T. Bryson, J. M. Benko, J. Christensen-Dalsgaard, H. Kjeldsen, W. J. Borucki, D. Koch, J. D. Twicken, M. Chadid, M. Di Criscienzo, Y. -B. Jeon, P. Moskalik, J. M. Nemec, J. Nuspl
  [show abstract] [hide abstract]
  ABSTRACT: The first detection of the period doubling phenomenon is reported in the Kepler RR Lyrae stars RR Lyr, V808 Cyg and V355 Lyr. Interestingly, all these pulsating stars show Blazhko modulation. The period doubling manifests itself as alternating maxima and minima of the pulsational cycles in the light curve, as well as through the appearance of half-integer frequencies located halfway between the main pulsation period and its harmonics in the frequency spectrum. The effect was found to be stronger during certain phases of the modulation cycle. We were able to reproduce the period doubling bifurcation in our nonlinear RR Lyrae models computed by the Florida-Budapest hydrocode. This enabled us to trace the origin of this instability in RR Lyrae stars to a resonance, namely a 9:2 resonance between the fundamental mode and a high-order (9th) radial overtone showing strange-mode characteristics. We discuss the connection of this new type of variation to the mysterious Blazhko effect and argue that it may give us fresh insights to solve this century-old enigma. Comment: 10 pages, 12 figures and 1 table, accepted for publication in MNRAS
  Monthly Notices of the Royal Astronomical Society 07/2010; · 4.90 Impact Factor
• Article: Selection and Prioritization of Targets for the Kepler Mission

  Natalie M. Batalha, W. J. Borucki, T. M. Brown, S. T. Bryson, D. A. Caldwell, M. E. Everett, J. M. Jenkins, D. G. Koch, D. W. Latham
  [show abstract] [hide abstract]
  ABSTRACT: The Kepler mission is designed to detect and characterize Earth-size planets in the habitable zone of their parent stars. This will be possible for the brightest late-type Main Sequence stars (e.g. 12th magnitude for sun-like stars, 15-16th magnitude for M-type stars). There are nearly a half million stars brighter than 16th magnitude in the Kepler field of view, most of which are too large or too faint for detection of an Earth-like planet. The Kepler Stellar Classification Program (SCP) is a pre-launch effort to characterize every star in the field (with reasonable completeness down to m=20) using ground-based multi-color photometry to determine the surface gravity and effective temperature. The SCP products will allow us to pre-select and prioritize targets based on the predicted SNR of an Earth-like transit. The methodology is designed to maximize the science yield of the mission by quantifying, for every potential target, the minimum detectable planet radius as a function of semi-major axis. The metric considers issues of crowding by quantifying the amount of contamination from background stars that works to dilute the transit signal. We describe the selection/prioritization methodology and present the magnitude and spectral type distribution for a target list generated from a preliminary release of the Kepler Input Catalog. Support for this work came from NASA's Discovery Program.
  11/2007; 39:974.
• Conference Proceeding: Detecting Multiple Transiting Planets with the Kepler Mission

  J ~M Jenkins, H Chandrasekaran, D ~A Caldwell, C Allen, S ~T Bryson, N ~M Batalha, W ~J Borucki
  American Astronomical Society Meeting Abstracts #210;
• Conference Proceeding: A framework for propagation of uncertainties in the Kepler data analysis pipeline

  B ~D Clarke, C Allen, S ~T Bryson, D ~A Caldwell, H Chandrasekaran, M ~T Cote, F Girouard, J ~M Jenkins, T ~C Klaus, J Li, C Middour, S McCauliff, E ~V Quintana, P Tenenbaum, J ~D Twicken, B Wohler, H Wu
  Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series;
• Source

  Available from: nasa.gov

  Conference Proceeding: Selecting pixels for Kepler downlink

  S ~T Bryson, J ~M Jenkins, T ~C Klaus, M ~T Cote, E ~V Quintana, J ~R Hall, K Ibrahim, H Chandrasekaran, D ~A Caldwell, J ~E Cleve, M ~R Haas
  Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series;
• Source

  Available from: nasa.gov

  Conference Proceeding: Semi-weekly monitoring of the performance and attitude of Kepler using a sparse set of targets

  H Chandrasekaran, J ~M Jenkins, J Li, F ~R Girouard, J ~D Twicken, D ~A Caldwell, C Allen, S ~T Bryson, T ~C Klaus, M ~T Cote, B ~A Stroozas, J ~R Hall, K Ibrahim
  Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series;
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  Available from: nasa.gov

  Conference Proceeding: The Kepler end-to-end model: creating high-fidelity simulations to test Kepler ground processing

  S ~T Bryson, J ~M Jenkins, D ~J Peters, P ~P Tenenbaum, T ~C Klaus, J ~P Gunter, M ~T Cote, D ~A Caldwell
  Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series;
• Source

  Available from: Douglas A Caldwell

  Conference Proceeding: Pixel-level calibration in the Kepler Science Operations Center pipeline

  E ~V Quintana, J ~M Jenkins, B ~D Clarke, H Chandrasekaran, J ~D Twicken, S ~D McCauliff, M ~T Cote, T ~C Klaus, C Allen, D ~A Caldwell, S ~T Bryson
  Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series;
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  Available from: Douglas A Caldwell

  Conference Proceeding: Photometer performance assessment in Kepler science data processing

  J Li, C Allen, S ~T Bryson, D ~A Caldwell, H Chandrasekaran, B ~D Clarke, J ~P Gunter, J ~M Jenkins, T ~C Klaus, E ~V Quintana, P Tenenbaum, J ~D Twicken, B Wohler, H Wu
  Society of Photo-Optical Instrumentation Engineers (SPIE) Conference Series;
• Article: A closely packed system of low-mass, low-density planets transiting Kepler-11

  J ~J Lissauer, D ~C Fabrycky, E ~B Ford, W ~J Borucki, F Fressin, G ~W Marcy, J ~A Orosz, J ~F Rowe, G Torres, W ~F Welsh, [......], D ~W Latham, E Lopez, S McCauliff, N Miller, R ~C Morehead, E ~V Quintana, D Ragozzine, D Sasselov, D ~R Short, J ~H Steffen
  nat. 470:53-58.
• Article: Kepler Planet-Detection Mission: Introduction and First Results

  W ~J Borucki, D Koch, G Basri, N Batalha, T Brown, D Caldwell, J Caldwell, J Christensen-Dalsgaard, W ~D Cochran, E DeVore, [......], E ~V Quintana, B ~D Clarke, C Allen, J Li, H Wu, P Tenenbaum, E Verner, F Bruhweiler, J Barnes, A Prsa
  Science. 327:977-.