Browsing by Author "Napiwotzki, Ralf"

Now showing items 1-13 of 13

    • Brown dwarf companions to white dwarfs 

      Burleigh, Matt R.; Steele, Paul R.; Dobbie, Paul D.; Farihi, Jay; Napiwotzki, Ralf; Maxted, Pierre F. L.; Barstow, Martin A.; Jameson, Richard F.; Casewell, Sarah L.; Gaensicke, Boris T.; Marsh, Tom R. (American Institute of Physics (AIP), 2011)
      Brown dwarf companions to white dwarfs are rare, but recent infra-red surveys are slowly revealing examples. We present new observations of the post-common envelope binary WD0137-349, which reveals the effects of irradiation ...

    • The deep OB-star population in Carina from the VST Photometric H-alpha Survey (VPHAS+) 

      Mohr-Smith, M.; Drew, Janet; Napiwotzki, Ralf; Simon-Diaz, S.; Wright, N. J.; Barentsen, Geert; Eisloeffel, J.; Farnhill, Hywel; Greimel, R.; Monguio, Maria; Kalari, V.; Parker, Q. A.; Vink, Jorick S. (2017-02-21)
      Massive OB stars are critical to the ecology of galaxies and yet our knowledge of OB stars in the Milky Way, fainter than V ∼ 12, remains patchy. Data from the VST Photometric Hα Survey (VPHAS+) permit the construction of ...

    • The detection of an older population in the Magellanic Bridge 

      Bagheri, Gemma; Cioni, M-R.L.; Napiwotzki, Ralf (2013-03)
      The Magellanic system comprises the Large Magellanic Cloud (LMC), the Small Magellanic Cloud (SMC), and the less frequently observed Magellanic Bridge and Magellanic Stream. The Bridge is traced by neutral gas and has an ...

    • Discovery of a brown dwarf companion to the A3V star β Circini 

      Smith, Leigh; Lucas, P.W.; Peña, C. Contreras; Kurtev, R.; Marocco, Federico; Jones, H.R.A.; Beamin, J.C.; Napiwotzki, Ralf; Borissova, J.; Burningham, B.; Faherty, J.; Pinfield, D.J.; Gromadzki, M.; Ivanov, V.D.; Minniti, D.; Stimson, W.; Villanueva, V. (2015-12-21)
      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 ...

    • Discovery of a T dwarf + white dwarf binary system 

      Day-Jones, Avril; Pinfield, D.J.; Ruiz, M.; Beaumont, H.; Burningham, B.; Gallardo, J.; Gianninas, A.; Bergeron, P.; Napiwotzki, Ralf; Jenkins, J.S.; Zhang, Z.H.; Murray, D.N.; Catalan, Silvia; Ines Gomes, Joana (2011)
      We present the discovery of the first T dwarf + white dwarf binary system LSPM 1459+0857 AB, confirmed through common proper motion and spectroscopy. The white dwarf is a high proper motion object from the LSPM catalogue ...

    • Discovery of the first white dwarf + T dwarf binary system and the use of white dwarfs as age calibrators 

      Day-Jones, Avril; Pinfield, D.J.; Ruiz, M.; Beaumont, H.; Gallardo, J.; Gianninas, A.; Bergeron, P.; Napiwotzki, Ralf; Jenkins, J.S.; Burningham, B.; Zhang, Z.H.; Jones, H.R.A.; Murray, D.; Catalan, Silvia; Ines Gomes, Joana (American Institute of Physics (AIP), 2010)
      We present the discovery of the first white dwarf + T dwarf binary system. Systems containing a white dwarf and a brown dwarf are rare but can be used to place constraints on the age of the binary, making them valuable ...

    • Ejection velocities of high galactic latitude runaway stars 

      Silva, M.D.V.; Napiwotzki, Ralf (2011)
      We estimate the distribution of ejection velocities for the known population of high Galactic latitude runaway stars. The initial sample is a collection of 174 early-type stars selected from the literature. The stars are ...

    • Evolved solar systems in Praesepe 

      Casewell, Sarah L.; Burleigh, Matt R.; Dobbie, Paul D.; Napiwotzki, Ralf (American Institute of Physics (AIP), 2011)
      We have obtained near-IR photometry for the 11 Praesepe white dwarfs, to search for an excess indicative of a dusty debris disk. All the white dwarfs are in the DAZ temperature regime, however we find no indications of a ...

    • High Galactic latitude runaway stars as tracers of the spiral arms 

      Silva, M.D.V.; Napiwotzki, Ralf (2013-05)
      A direct observation of the spiral structure of the Galaxy is hindered by our position in the middle of the Galactic plane. We propose a method based on the analysis of the birthplaces of high Galactic latitude runaway ...

    • Spectral classification of photometrically selected AGB candidates in NGC 6822 

      Sibbons, L. F.; Ryan, Sean G.; Napiwotzki, Ralf; Thompson, G. P. (2015-02-02)
      Context. The ratio of C- and M-type asymptotic giant branch (AGB) stars is commonly used to estimate the metallicity of extragalactic populations. Sources in the AGB population must therefore be accurately classified as ...

    • Stellar variability on time-scales of minutes: results from the first 5 yr of the Rapid Temporal Survey 

      Barclay, Thomas; Ramsay, Gavin; Hakala, Pasi; Napiwotzki, Ralf; Nelemans, Gijs; Potter, Stephen; Todd, Ian (2011-06)
      The Rapid Temporal Survey (RATS) explores the faint, variable sky. Our observations search a parameter space which, until now, has never been exploited from the ground. Our strategy involves observing the sky close to the ...

    • Substellar companions and the formation of hot subdwarf stars 

      Geier, Stephan; Heber, Ulrich; Tillich, Alfred; Hirsch, Heiko; Kupfer, Thomas; Schaffenroth, Veronika; Classen, Lew; Maxted, Pierre F. L.; Ostensen, Roy H.; Barlow, Brad N.; Marsh, Tom R.; Gaensicke, Boris T.; Napiwotzki, Ralf; O'Toole, Simon J.; Guenther, Eike W. (American Institute of Physics (AIP), 2011)
      We give a brief review over the observational evidence for close substellar companions to hot subdwarf stars. The formation of these core helium-burning objects requires huge mass loss of their red giant progenitors. It ...

    • The VMC survey II : A multi-wavelength study of LMC planetary nebulae and their mimics 

      Miszalski, Brent; Napiwotzki, Ralf; Cioni, M-R.L.; Groenewegen, M.A.T.; Oliveira, J.M.; Udalski, A. (2011)
      The VISTA Magellanic Cloud (VMC) survey is assembling a deep, multi-epoch atlas of Y JKs photometry across the Magellanic Clouds. Prior to the VMC survey only the brightest Magellanic Cloud PNe (MCPNe) were accessible at ...