Browsing University of Hertfordshire by Author "Christlieb, N."

Now showing items 21-31 of 31

    • The new record holder for the most iron-poor star: HE 1327−2326, a dwarf or subgiant with [Fe/H] = −5.4 

      Frebel, A.; Aoki, W.; Christlieb, N.; Ando, H.; Asplund, M.; Barklem, P.S.; Beers, T.C.; Eriksson, K.; Fechner, C.; Fujimoto, M.Y.; Honda, S.; Kajino, T.; Minezaki, T.; Nomoto, K.; Norris, J.E.; Ryan, Sean G.; Takada-Hidai, M.; Tsangarides, S.; Yoshii, Y. (2005)
      We describe the discovery of HE 1327−2326, a dwarf or subgiant with [Fe/H] = −5.4. The star was found in a sample of bright metal-poor stars selected from the Hamburg/ESO survey. Its abundance pattern is characterized by ...

    • New Results from the Supernova Ia Progenitor Survey 

      Napiwotzki, R.; Karl, C.; Nelemans, G.; Yungelson, L.; Christlieb, N.; Drechsel, H.; Heber, U.; Homeier, D.; Koester, D.; Kruk, J.; Leibundgut, B.; Marsh, T.R.; Moehler, S.; Renzini, A.; Reimers, D. (Astronomical Society of the Pacific, 2005)
      We report on a systematic radial velocity survey for double degenerate (DD) binaries as potential progenitors of type Ia supernovae: SPY (ESO Supernovae Ia Progenitor surveY). More than 1000 white dwarfs and pre-white ...

    • A new sample of extremely/ultra metal-poor stars 

      Perez, A. E. Garcia; Christlieb, N.; Ryan, Sean G.; Beers, T.C.; Aoki, W.; Asplund, M.; Barklem, P.S.; Bessell, M.S.; Eriksson, K.; Frebel, A.; Gustafsson, B.; Korn, A.J.; Nordstrom, B.; Norris, J.E. (2008-12)
      A sample of 30 very metal-poor stars from the Hamburg-European Southern Observatory (ESO) objective-prism survey have been observed at high spectral resolution at the Very Large Telescope (VLT) using the Ultraviolet and ...

    • Nucleosynthetic signatures of the first stars 

      Frebel, A.; Aoki, W.; Christlieb, N.; Ando, H.; Asplund, M.; Barklem, P.S.; Beers, T.C.; Eriksson, K.; Fechner, C.; Fujimoto, M.Y.; Honda, S.; Kajino, T.; Minezaki, T.; Nomoto, K.; Norris, J.E.; Ryan, Sean G.; Takada-Hidai, M.; Tsangarides, S.; Yoshii, Y. (2005-04)

    • Oxygen Overabundance in the Extremely Iron-poor Star CS 29498-043 

      Aoki, W.; Norris, J.E.; Ryan, Sean G.; Beers, T.C.; Christlieb, N.; Tsangarides, S.; Ando, H. (2004-06)

    • Search for progenitors of supernovae type Ia with SPY 

      Napiwotzki, R.; Christlieb, N.; Drechsel, H.; Hagen, H.J.; Heber, U.; Homeier, D.; Karl, C.; Koester, D.; Leibundgut, B.; Marsh, T.R.; Moehler, S.; Nelemans, G.; Pauli, E.M.; Reimers, D.; Renzini, A.; Yungelson, L. (2001)

    • Spectral Analysis of sdB Stars from the Hamburg ESO Survey 

      Edelmann, H.; Heber, U.; Napiwotzki, R.; Lemke, M.; Christlieb, N. (2001)

    • Spectral analysis of sdB Stars from the Hamburg ESO Survey 

      Edelmann, H.; Heber, U.; Napiwotzki, R.; Lemke, M.; Christlieb, N. (Astronomical Society of the Pacific, 2001)
      We aim at the compilation of a statistically complete sample of sdB stars in the southern hemisphere. Candidates are selected from the database of digitized spectra of the Hamburg/ESO objective prism survey. First simulations ...

    • Spectroscopic analysis of sdB stars from the ESO Supernova Ia Progenitor Survey 

      Lisker, T.; Heber, U.; Napiwotzki, R.; Christlieb, N.; Han, Z.; Homeier, D.; Reimers, D. (2004)

    • SPY - the ESO Supernovae type Ia Progenitor survey 

      Napiwotzki, R.; Christlieb, N.; Drechsel, H.; Hagen, H.J.; Heber, U.; Homeier, D.; Karl, C.; Koester, D.; Leibundgut, B.; Marsh, T.R.; Moehler, S.; Nelemans, G.; Pauli, E.M.; Reimers, D.; Renzini, A.; Yungelson, L. (2003)
      Supernovae (SNe) mark the violent termination of a star’s life in an explosion. They are classified according to their light curve as type I or II, with the type I SNe producing very similar light curves, while the SNe ...

    • Subdwarf B Stars from the ESO Supernova Ia Progenitor Survey -- Observation versus Theory 

      Lisker, T.; Heber, U.; Napiwotzki, R.; Christlieb, N.; Han, Z.; Homeier, D.; Reimers, D. (Astronomical Society of the Pacific, 2005)
      We present the analysis of a high-quality sample of optical spectra for 76 sdB stars from the ESO Supernova Ia Progenitor Survey. Effective temperature, surface gravity, and photospheric helium abundance were derived from ...