Examinando por Autor "Jones, H.R.A."
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Ítem Discovery of a brown dwarf companion to the A3V star β Circini(Oxford University Press, 2015-12) Smith, L.C.; Lucas, P.W.; Contreras Peña, C.; Kurtev, R.; Marocco, F.; Jones, H.R.A.; Beamin, J.C.; Napiwotzki, R.; Borissova, J.; Burningham, B.; Faherty, J.; Pinfield, D.J.; Gromadzki, M.; Ivanov, V.D.; Minniti, D.; Stimson, W.; Villanueva, V.We report the discovery of an L dwarf companion to the A3V star β Circini. VVV J151721.49−585131.5, or β Cir B, was identified in a proper motion and parallax catalogue of the VISTA Variables in the Vía Láctea survey as having near-infrared luminosity and colour indicative of an early L dwarf, and a proper motion and parallax consistent with that of β Cir. The projected separation of ∼3.6 arcmin corresponds to 6656 au, which is unusually wide. The most recent published estimate of the age of the primary combined with our own estimate based on newer isochrones yields an age of 370–500 Myr. The system therefore serves as a useful benchmark at an age greater than that of the Pleiades brown dwarfs and most other young L dwarf benchmarks. We have obtained a medium resolution echelle spectrum of the companion which indicates a spectral type of L1.0 ± 0.5 and lacks the typical signatures of low-surface gravity seen in younger brown dwarfs. This suggests that signs of low-surface gravity disappear from the spectra of early L dwarfs by an age of ∼370–500 Myr, as expected from theoretical isochrones. The mass of β Cir B is estimated from the BHAC15 isochrones as 0.056 ± 0.007 M⊙.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 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.Ítem VIRAC: The VVV Infrared Astrometric Catalogue(Oxford University Press, 2018) Smith, L.C.; Lucas, P.W.; Kurtev, R.; Smart, R.; Minniti, D.; Borissova, J.; Jones, H.R.A.; Zhang, Z.H.; Marocco, F.; Contreras Peña, C.; Gromadzki, M.; Kuhn, M.A.; Drew, J.E.; Pinfield, D.J.; Bedin, L.R.We present VIRAC version 1, a near-infrared proper motion and parallax catalogue of the VISTA Variables in the Via Lactea (VVV) survey for 312 587 642 unique sources averaged across all overlapping pawprint and tile images covering 560 deg2 of the bulge of the MilkyWay and southern disc. The catalogue includes 119 million high-quality proper motion measurements, of which 47 million have statistical uncertainties below 1 mas yr-1. In the 11 < Ks < 14 magnitude range, the high-quality motions have a median uncertainty of 0.67 mas yr-1. The catalogue also includes 6935 sources with quality-controlled 5s parallaxes with a median uncertainty of 1.1 mas. The parallaxes show reasonable agreement with the Tycho- Gaia Astrometric Solution, though caution is advised for data with modest significance. The SQL data base housing the data is made available via the web. We give example applications for studies of Galactic structure, nearby objects (low-mass stars and brown dwarfs, subdwarfs, white dwarfs) and kinematic distance measurements of young stellar objects. Nearby objects discovered include LTT 7251 B, an L7 benchmark companion to a G dwarf with over 20 published elemental abundances, a bright L subdwarf, VVV 1256-6202, with extremely blue colours and nine new members of the 25 pc sample. We also demonstrate why this catalogue remains useful in the era of Gaia. Future versions will be based on profile fitting photometry, use the Gaia absolute reference frame and incorporate the longer time baseline of the VVV extended survey.Ítem VVV high proper motion stars – I. The catalogue of bright KS ≤ 13.5 stars(OXFORD UNIV PRESS, 2016-09) Kurtev, R.; Gromadzki, M.; Beamín, J.C.; Folkes, S.L.; Pena Ramirez, K.; Ivanov, V.D.; Borissova, J.; Villanueva, V.; Minniti, D.; Mendez, R.; Lucas, P.W.; Smith, L.C.; Pinfield, D.J.; Kuhn, M.A.; Jones, H.R.A.; Antonova, A.; Yip, A.K.P.Knowledge of the stellar content near the Sun is important for a broad range of topics ranging from the search for planets to the study of Milky Way (MW) structure. The most powerful method for identifying potentially nearby stars is proper motion (PM) surveys. All old optical surveys avoid, or are at least substantially incomplete, near the Galactic plane. The depth and breadth of the 'VISTA Variables in Vía Láctea' (VVV) near-IR survey significantly improves this situation. Taking advantage of the VVV survey data base, we have measured PMs in the densest regions of the MW bulge and southern plane in order to complete the census of nearby objects. We have developed a custom PM pipeline based on VVV catalogues from the Cambridge Astronomy Survey Unit, by comparing the first epoch of JHKS with the multiepoch KS bands acquired later. Taking advantage of the large time baseline between the Two Micron All Sky Survey (2MASS) and the VVV observations, we also obtained 2MASS-VVV PMs.We present a near-IR PMcatalogue for the whole area of theVVVsurvey, which includes 3003 moving stellar sources. All of these have been visually inspected and are real PM objects. Our catalogue is in very good agreement with the PM data supplied in IR catalogues outside the densest zone of the MW. The majority of the PM objects in our catalogue are nearby M-dwarfs, as expected. This new data base allows us to identify 57 common PM binary candidates, among which are two new systems within 30 pc of the Sun.