Examinando por Autor "Arriagada, P."
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Ítem GJ 832c: a super-earth in the habitable zone(Institute of Physics Publishing, 2014-08) Wittenmyer, Robert A.; Tuomi, Mikko; Butler, R.P.; Jones, H.R.A.; Anglada-Escudé, Guillem; Horner, Jonathan; Tinney, C.G; Marshall, J.P.; Carter, B.D.; Bailey, J.; Salter, G.S.; O'Toole, S.J.; Wright, D.; Crane, J.D.; Schectman, S.A.; Arriagada, P.; Thompson, I.; Minniti, D.; Jenkins, J.S.; Diaz, M.We report the detection of GJ 832c, a super-Earth orbiting near the inner edge of the habitable zone of GJ 832, an M dwarf previously known to host a Jupiter analog in a nearly circular 9.4 yr orbit. The combination of precise radial velocity measurements from three telescopes reveals the presence of a planet with a period of 35.68 ± 0.03 days and minimum mass (m sin i) of 5.4 ± 1.0 Earth masses. GJ 832c moves on a low-eccentricity orbit (e = 0.18±0.13) toward the inner edge of the habitable zone. However, given the large mass of the planet, it seems likely that it would possess a massive atmosphere, which may well render the planet inhospitable. Indeed, it is perhaps more likely that GJ 832c is a “super-Venus,” featuring significant greenhouse forcing. With an outer giant planet and an interior, potentially rocky planet, the GJ 832 planetary system can be thought of as a miniature version of our own solar system.Ítem 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.Ítem MagAO IMAGING OF LONG-PERIOD OBJECTS (MILO). II. A PUZZLING WHITE DWARF AROUND THE SUN-LIKE STAR HD 11112(IOP PUBLISHING, 2016-11) Rodigas, T.J.; Bergeron, P.; Simon, A.; Arriagada, P.; Faherty, J.K.; Anglada-Escudé, G.; Mamajek, E.E.; Weinberger, A.; Butler, R.P.; Males, J.R.; Morzinski, K.; Close, L.M.; Hinz, P.M.; Bailey, J.; Carter, B.; Jenkins, J.S.; Jones, H.; O'Toole, S.; Tinney, C.G.; Wittenmyer, R.; Debes, J.HD 11112 is an old, Sun-like star that has a long-term radial velocity (RV) trend indicative of a massive companion on a wide orbit. Here we present direct images of the source responsible for the trend using the Magellan Adaptive Optics system. We detect the object (HD 11112B) at a separation of 2 2 (100 au) at multiple wavelengths spanning 0.6-4 mu m. and show that it is most likely a gravitationally bound cool white dwarf. Modeling its spectral energy distribution suggests that its mass is 0.9-1.1M(circle dot), which corresponds to very high eccentricity, near edge-on orbits from a. Markov chain Monte Carlo analysis of the RV and imaging data together. The total age of the white dwarf is > 2 sigma, which is discrepant with that of the primary star under most assumptions. The problem can be resolved if the white dwarf progenitor was initially a double white dwarf binary that then merged into the observed high-mass white dwarf. HD 11112B is a unique and intriguing benchmark object that can be used to calibrate atmospheric and evolutionary models of cool white dwarfs and should thus continue to be monitored by RV and direct imaging over the coming years.Ítem 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.