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

Now showing items 1-14 of 14

    • 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 ...

    • 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 ...