Browsing by Author "Day-Jones, A.C."

Now showing items 1-15 of 15

    • Chromospheric activities and kinematics for solar type dwarfs and subgiants : analysis of the activity distribution and the AVR 

      Jenkins, J.S.; Murgas, F.; Rojo, P.; Jones, H.R.A.; Day-Jones, A.C.; Jones, M.I.; Clarke, J.R.A.; Ruiz, M.; Pinfield, D.J. (2011)
      Aims : In this work we present chromospheric activity indices, kinematics, radial-velocities, and rotational velocities for more than 850 FGK-type dwarfs and subgiant stars in the southern hemisphere and test how best to ...

    • The discovery of a very cool binary system 

      Burningham, B.; Leggett, S.K.; Lucas, P.W.; Pinfield, D.J.; Smart, R.L.; Day-Jones, A.C.; Jones, H.R.A.; Murray, D.N.; Nickson, E.; Tamura, M.; Zhang, Z.; Lodieu, N.; Tinney, C.G.; Zapatero Osorio, M.R. (2010)
      We report the discovery of a very cool d/sdL7+T7.5p common proper motion binary system, SDSS J1416+13AB, found by cross-matching the United Kingdom Infrared Telescope (UKIRT) Infrared Deep Sky Survey (UKIDSS) Large Area ...

    • Discovery of a widely separated ultracool dwarf–white dwarf binary 

      Day-Jones, A.C.; Pinfield, D.J.; Napiwotzki, R.; Burningham, B.; Jenkins, J.S.; Jones, H.R.A.; Folkes, S.; Weights, D.; Clarke, J.R.A. (2008)

    • The discovery of an M4+T8.5 binary system 

      Burningham, B.; Pinfield, D.J.; Leggett, S.K.; Tinney, C.G.; Liu, M.C.; Homeier, D.; West, A.A.; Day-Jones, A.C.; Huelamo, N.; Dupuy, T.J.; Zhang, Z.; Murray, D.N.; Lodieu, N.; Navascues, D.B.Y.; Folkes, S.; Galvez-Ortiz, M.C.; Jones, H.R.A.; Lucas, P.W.; Calderon, M.M.; Tamura, M. (2009)
      We report the discovery of a T8.5 dwarf, which is a companion to the M4 dwarf Wolf 940. [Please see original online abstract for complete version with correct notation]

    • Discovery of the first L dwarf plus giant binary system and eight other ultracool dwarfs in wide binaries 

      Zhang, Z.; Pinfield, D.J.; Day-Jones, A.C.; Burningham, B.; Jones, H.R.A.; Yu, S.; Jenkins, J.S.; Han, Z.; Galvez-Ortiz, M.C.; Gallardo, J.; Garcia Perez, A.E.; Weights, D.; Tinney, C.G.; Pokorny, R.S. (2010)
      We identify 806 ultracool dwarfs (of which 34 are newly discovered L dwarfs) from their Sloan Digital Sky Survey (SDSS) riz photometry and obtain proper motions through cross-matching with the United Kingdom Infrared ...

    • Discovery of the First Very Wide WD LD Binary System 

      Day-Jones, A.C.; Pinfield, D.J.; Jones, H.R.A.; Kendall, T.R.; Napiwotzki, R.; Jenkins, J.S. (Astronomical Society of the Pacific, 2007)
      We report on our large scale search of 2MASS and SuperCOS- MOS in the southern hemisphere for very widely separated white dwarf / L-dwarf binary systems and present our findings, including eight widely separated can- didate ...

    • Fifteen new T dwarfs discovered in the UKIDSS Large Area Survey 

      Pinfield, D.J.; Burningham, B.; Tamura, M.; Leggett, S.K.; Lodieu, N.; Lucas, P.W.; Mortlock, D.J.; Warren, S.J.; Homeier, D.; Ishi, M.; Deacon, Niall; McMahon, R.G.; Hewett, P.C.; Zapatero Osorio, M.R.; Martin, E.L.; Jones, H.R.A.; Venemans, B.P.; Day-Jones, A.C.; Dobbie, P.D.; Folkes, S.; Dye, S.; Allard, F.; Baraffe, I.; Barrado y Navascues, D.; Casewell, S.L.; Chiu, K.; Chabrier, G.; Clarke, F.; Hodgkin, S.T.; Magazzu, A.; McCaughrean, M.J.; Moraux, E.; Nakajima, T.; Pavlenko, Y.; Tinney, C.G. (2008)
      We present the discovery of fifteen new T2.5-T7.5 dwarfs (with estimated distances between 24–93pc), identified in the first three main data releases of the UKIRT Infrared Deep Sky Survey. This brings the total number of ...

    • Finding benchmark brown dwarfs to probe the sub-stellar IMF as a function of time 

      Pinfield, D.J.; Jones, H.R.A.; Lucas, R.A.; Kendall, T.R.; Folkes, S.; Day-Jones, A.C.; Chappelle, R.J.; Steele, I.A. (2006)

    • First results from the Calan–Hertfordshire Extrasolar Planet Search : exoplanets and the discovery of an eccentric brown dwarf in the desert 

      Jenkins, J.S.; Jones, H.R.A.; Gozdziewski, K.; Migaszewski, C.; Barnes, J.R.; Jones, M.I.; Rojo, P.; Pinfield, D.J.; Day-Jones, A.C.; Hoyer, S. (2009)
      We report the discovery of a brown dwarf on an eccentric orbit and with a semimajor axis that places it in the brown dwarf desert region around the star HD 191760. The star has a spectral type of G3IV/V and a metallicity ...

    • Fundamental Properties of Low-Mass Stars and Brown Dwarfs 

      Liu, M.C.; Stassun, K.G.; Allard, F.; Blake, C.H.; Bonnefoy, M.; Cody, A.M.; Day-Jones, A.C.; Dupuy, T.J.; Kraus, A.; Lopez-Morales, M. (2009)
      Precise measurements of the fundamental properties of low-mass stars and brown dwarfs are key to understanding the physics underlying their formation and evolution. While there has been great progress over the last decade ...

    • A metal-biased planet search 

      Jenkins, J.S.; Jones, H.R.A.; Barnes, J.R.; Pavlenko, Y.; Rojo, P.; Jones, M.I.; Day-Jones, A.C.; Pinfield, D.J. (American Institute of Physics (AIP), 2009)
      We have begun a metal-rich planet search project using the HARPS instrument in La Silla, Chile to target planets with a high potential to transit their host star and add to the number of bright benchmark transiting planets. ...

    • NACO-SDI imaging of known companion host stars from the AAPS and Keck planet search surveys 

      Jenkins, J.S.; Jones, H.R.A.; Biller, B.; O'Toole, S.; Pinfield, D.J.; Close, L.; Tinney, C.G.; Butler, R.P.; Wittenmyer, R.; Carter, B.D.; Day-Jones, A.C. (2010)
      Context. Direct imaging of brown dwarfs as companions to solar-type stars can provide a wealth of well-constrained data to “benchmark” the physics of such objects, since quantities like metallicity and age can be determined ...

    • A search for southern ultracool dwarfs in young moving groups 

      Clarke, J.R.A.; Pinfield, D.J.; Galvez-Ortiz, M.C.; Jenkins, J.S.; Burningham, B.; Deacon, Niall; Jones, H.R.A.; Pokorny, R.S.; Barnes, J.R.; Day-Jones, A.C. (2010)
      We associate 132 low-mass ultracool dwarfs in the southern hemisphere as candidate members of five moving groups (MGs) using photometric and astrometric selection techniques. Of these objects, we present high-resolution ...

    • Searching for Brown Dwarf Companions 

      Day-Jones, A.C. (2009-06-03)
      In this thesis I present the search for ultracool dwarf companions to main sequence stars, subgiants and white dwarfs. The ultracool dwarfs identified here are benchmark objects, with known ages and distances. The online ...

    • Spectroscopy and kinematics of low-mass members of young moving groups 

      Galvez-Ortiz, M. C.; Clarke, J.R.A.; Pinfield, D.J.; Jenkins, J. S.; Folkes, S. L.; Garcia Perez, A. E.; Day-Jones, A.C.; Burningham, B.; Jones, H.R.A.; Barnes, J. R.; Pokorny, R.S. (2010)
      We study a target sample of 68 low-mass objects (with spectral types in the range M4.5–L1) previously selected via photometric and astrometric criteria, as possible members of five young moving groups: the Local Association ...