Examinando por Autor "Shectman, S."

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    MagAO IMAGING OF LONG-PERIOD OBJECTS (MILO). I. A BENCHMARK M DWARF COMPANION EXCITING A MASSIVE PLANET AROUND THE SUN-LIKE STAR HD 7449
    (IOP PUBLISHING, 2016-02) Rodigas, T.J.; Arriagada, P.; Faherty, J.; Anglada-Escudé, G.; Kaib, N.; Butler, R.P.; Shectman, S.; Weinberger, A.; Males, J.R.; Morzinski, K.M.; Close, L.M.; Hinz, P.M.; Crane, J.D.; Thompson, I.; Teske, J.; Diaz, M.; Minniti, D.; Lopez-Morales, M.; Adams, F.C.; Boss, A.P.
    We present high-contrast Magellan adaptive optics images of HD 7449, a Sun-like star with one planet and a long-term radial velocity (RV) trend. We unambiguously detect the source of the long-term trend from 0.6-2.15 mu m. at a separation of similar to 0.'' 54. We use the object's colors and spectral energy distribution to show that it is most likely an M4-M5 dwarf (mass similar to 0.1-0.2 M-circle dot) at the same distance as the primary and is therefore likely bound. We also present new RVs measured with the Magellan/MIKE and Planet Finder Spectrograph spectrometers and compile these with archival data from CORALIE and HARPS. We use a new Markov chain Monte Carlo procedure to constrain both the mass (>0.17 M-circle dot at 99% confidence) and semimajor axis (similar to 18 AU) of the M dwarf companion (HD 7449B). We also refine the parameters of the known massive planet (HD 7449Ab), finding that its minimum mass is 1.09(-0.19)(+0.52) M-J, its semimajor axis is 2.33(-0.02)(+0.01) AU, and its eccentricity is 0.8(-0.06)(+0.08). We use N-body simulations to constrain the eccentricity of HD 7449B to less than or similar to 0.5. The M dwarf may be inducing Kozai oscillations on the planet, explaining its high eccentricity. If this is the case and its orbit was initially circular, the mass of the planet would need to be less than or similar to 1.5 M-J. This demonstrates that strong constraints on known planets can be made using direct observations of otherwise undetectable long-period companions.
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    New planetary systems from the Calan-Hertfordshire Extrasolar planet search
    (Oxford University Press, 2016-11) Jenkins, J.S.; Jones, H.R.A.; Tuomi, M.; Díaz, M.; Cordero, J.P.; Aguayo, A.; Pantoja, B.; Arriagada, P.; Mahu, R.; Brahm, R.; Rojo, P.; Soto, M.G.; Ivanyuk, O.; Becerra Yoma, N.; Day-Jones, A.C.; Ruiz, M.T.; Pavlenko, Y.V.; Barnes, J.R.; Murgas, F.; Pinfield, D.J.; Jones, M.I.; López-Morales, M.; Shectman, S.; Butler, R.P.; Minniti, D.
    We report the discovery of eight new giant planets, and updated orbits for four known planets, orbiting dwarf and subgiant stars using the CORALIE, HARPS, and MIKE instruments as part of the Calan-Hertfordshire Extrasolar Planet Search. The planets have masses in the range 1.1-5.4 MJ's, orbital periods from 40 to 2900 d, and eccentricities from 0.0 to 0.6. They include a double-planet system orbiting the most massive star in our sample (HD147873), two eccentric giant planets (HD128356b and HD154672b), and a rare 14 Herculis analogue (HD224538b). We highlight some population correlations from the sample of radial velocity detected planets orbiting nearby stars, including the mass function exponential distribution, confirmation of the growing body of evidence that low-mass planets tend to be found orbiting more metal-poor stars than giant planets, and a possible period-metallicity correlation for planets with masses > 0.1 MJ, based on a metallicity difference of 0.16 dex between the population of planets with orbital periods less than 100 d and those with orbital periods greater than 100 d.