- UHRA Home
- University of Hertfordshire
- Browsing University of Hertfordshire by Author
Browsing University of Hertfordshire by Author "Christlieb, N."
Now showing items 1-20 of 31
-
Barium lines in high-quality spectra of two metal-poor giants in the Galactic halo
Cescutti, G.; Morossi, C.; Franchini, M.; Marcantonio, P. Di; Chiappini, C.; Steffen, M.; Valentini, M.; François, P.; Christlieb, N.; Cortés, C.; Kobayashi, C.; Depagne, E. (2021-10-01)Context. Theoretical results showed the possibility that neutron capture elements were produced in the early Universe by two different sources: a frequent s-process source hosted by rotating massive stars, and a rare ... -
Binaries discovered by the SPY project IV. Five single-lined DA double white dwarfs
Nelemans, G.; Napiwotzki, R.; Karl, C.; Marsh, T.R.; Voss, B.; Roelofs, G.; Izzard, R.G.; Montgomery, M.; Reerink, T.; Christlieb, N.; Reimers, D. (2005)We present results from our ongoing follow-up observations of double white dwarf binaries detected in the ESO SN Ia Progenitor SurveY (SPY). We discuss our observing strategy and data analysis and present the orbital ... -
Binaries discovered by the SPY project. I. HE 1047-0436: A subdwarf B white dwarf syste
Napiwotzki, R.; Edelmann, H.; Heber, U.; Karl, C.; Drechsel, H.; Pauli, E.M.; Christlieb, N. (2001-10)In the course of our search for double degenerate binaries as potential progenitors of type Ia supernovae with the UVES spectrograph at the ESO VLT (ESO SNIa Progenitor surveY { SPY) we discovered that the sdB star HE1047−0436 ... -
Binaries discovered by the SPY project. II. HE 1414-0848: A double degenerate with a mass close to the Chandrasekhar limit
Napiwotzki, R.; Koester, D.; Nelemans, G.; Yungelson, L.; Christlieb, N.; Renzini, A.; Reimers, D.; Drechsel, H.; Leibundgut, B. (2002-05)In the course of our search for double degenerate (DD) binaries as potential progenitors of type Ia supernovae with the UVES spectrograph at the ESO VLT (ESO SNIa Progenitor surveY { SPY) we discovered that the white dwarf ... -
Binaries discovered by the SPY project. III. HE 2209-1444: A massive, short period double degenerate
Karl, C.; Napiwotzki, R.; Nelemans, G.; Christlieb, N.; Koester, D.; Heber, U.; Reimers, D. (2003-11)In the course of our search for double degenerate (DD) binaries as potential progenitors of type Ia supernovae with the UVES spectrograph at the ESO VLT (ESO SN Ia Progenitor surveY – SPY) we discovered HE2209−1444 to be ... -
Binary White Dwarfs in the Supernova Ia Progenitor Survey
Napiwotzki, R.; Karl, C.; Nelemans, G.; Yungelson, L.; Christlieb, N.; Drechsel, H.; Heber, U.; Homeier, D.; Koester, D.; Leibundgut, B.; Marsh, T.R.; Moehler, S.; Renzini, A.; Reimers, D. (Astronomical Society of the Pacific, 2007)We report results of 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 (WDs) and ... -
Carbon enhanced metal-poor stars I : Chemical compositions of 26 stars
Aoki, W.; Beers, T.C.; Christlieb, N.; Norris, J.E.; Ryan, Sean G.; Tsangarides, S. (2007) -
Close binary EHB stars from SPY
Napiwotzki, R.; Karl, C.; Lisker, T.; Heber, U.; Christlieb, N.; Reimers, D.; Nelemans, G.; Homeier, D. (2004-06) -
DAZ White Dwarfs in the SPY Sample
Koester, D.; Rollenhagen, K.; Napiwotzki, R.; Voss, B.; Christlieb, N.; Homeier, D.; Reimers, D. (Astronomical Society of the Pacific, 2005)We search for faint Ca II lines in the spectra of about 800 apparently single white dwarfs observed at high resolution for the SPY (ESO Supernova Progenitor Survey) survey. Photospheric Ca is detected in 24 DAZ; in 25 ... -
Double Degenerate and Progenitors of Supernovae Type Ia
Napiwotzki, R.; Yungelson, L.; Nelemans, G.; Marsh, T.R.; Leibundgut, B.; Renzini, A.; Homeier, D.; Koester, D.; Moehler, S.; Christlieb, N.; Reimers, D.; Drechsel, H.; Heber, U.; Karl, C.; Pauli, E.M. (Astronomical Society of the Pacific, 2004)We report on systematic radial velocity surveys for white dwarf { white dwarf binaries (double degenerates { DDs) including SPY (ESO Supernovae Ia progenitor survey) recently carried out at the VLT. A large sample of DD ... -
The Hamburg/ESO R-process Enhanced Star survey (HERES). I : Project description and discovery of two stars with strong enhancements of neutron-capture elements
Christlieb, N.; Beers, T.C.; Barklem, P.S.; Bessell, M.S.; Hill, V.; Holmberg, J.; Korn, A.J.; Marsteller, B.; Mashonkina, L.; Qian, Y.Z.; Rossi, S.; Wasserburg, G.J.; Zickgraf, F.J.; Kratz, K.L.; Nordstrom, B.; Pfeiffer, B.; Rhee, J.; Ryan, Sean G. (2004-12) -
HE 0437-5439: an unbound hypervelocity main-sequence B-type star
Edelmann, H.; Napiwotzki, R.; Heber, U.; Christlieb, N.; Reimers, D. (2005) -
High resolution UVES/VLT spectra of white dwarfs observed for the ESO SN Ia Progenitor Survey III. DA white dwarfs
Koester, D.; Voss, B.; Napiwotzki, R.; Christlieb, N.; Homeier, D.; Lisker, T.; Reimers, D.; Heber, U. (2009-10)Context. The ESO Supernova Ia Progenitor Survey (SPY) took high-resolution spectra of more than 1000 white dwarfs and pre-white dwarfs. About two thirds of the stars observed are hydrogen-dominated DA white dwarfs. Here ... -
A high-resolution spectral analysis of three carbon-enhanced metal-poor stars
Goswami, A.; Aoki, W.; Beers, T.C.; Christlieb, N.; Norris, J.E.; Ryan, Sean G.; Tsangarides, S. (2006) -
High-resolution UVES/VLT spectra of white dwarfs observed for the ESO SN Ia progenitor survey (SPY). I
Koester, D.; Napiwotzki, R.; Christlieb, N.; Drechsel, H.; Hagen, H.J.; Heber, U.; Homeier, D.; Karl, C.; Leibundgut, B.; Moehler, S.; Nelemans, G.; Reimers, D.; Pauli, E.M.; Renzini, A.; Yungelson, L. (2001-11) -
Hot subdwarfs from the ESO Supernova Ia Progenitor Survey. I. Atmospheric parameters and cool companions of sdB stars
Lisker, T.; Heber, U.; Napiwotzki, R.; Christlieb, N.; Han, Z.; Homeier, D.; Reimers, D. (2005-01) -
Identification of a DO white dwarf and a PG 1159 star in the ESO SN Ia progenitor survey (SPY)
Werner, K.; Rauch, T.; Napiwotzki, R.; Christlieb, N.; Reimers, D.; Karl, C. (2004-09) -
Identification of a DO White Dwarf and a PG1159 Star in the ESO SN Ia Progenitor Survey (SPY)
Werner, K.; Rauch, T.; Napiwotzki, R.; Christlieb, N.; Reimers, D.; Karl, C. (Astronomical Society of the Pacific, 2005)We present high-resolution VLT spectra of a new DO white dwarf and a new PG1159 star, which we identified in the ESO SPY survey. The PG1159 star is a low-gravity, extremely hot (Te® = 160 000 K, log g = 6) star, having a ... -
Lithium abundances of extremely metal-poor turnoff stars
Aoki, W.; Barklem, P.S.; Beers, T.C.; Christlieb, N.; Inoue, S.; Garcia Perez, A.E.; Norris, J.E.; Carollo, D. (2009)We have determined Li abundances for eleven metal-poor turnoff stars, among which eight have [Fe/H] <–3, based on LTE analyses of high-resolution spectra obtained with the High Dispersion Spectrograph on the Subaru Telescope. ... -
Metal traces in white dwarfs of the SPY (ESO Supernova Ia Progenitor Survey) sample
Koester, D.; Rollenhagen, K.; Napiwotzki, R.; Voss, B.; Christlieb, N.; Homeier, D.; Reimers, D. (2005-03)