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Browsing by Author "Aoki, W."
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6Li/7Li estimates for metal-poor stars
Garcia Perez, A.E.; Aoki, W.; Inoue, S.; Ryan, Sean G.; Suzuki, T.K.; Chiba, M. (2009-09)Context. The presence of the lithium-6 isotope in some metal-poor stars is a matter of surprise because of the high values observed. Non-standard models of Big Bang nucleosynthesis and pre-Galactic cosmic ray fusion and ... -
The barium isotopic mixture for the metal-poor subgiant star HD 140283
Gallagher, A.J.; Ryan, Sean G.; Garcia Perez, A.E.; Aoki, W. (2010)Context: Current theory regarding heavy element nucleosynthesis in metal-poor environments states that the r-process would be dominant. The star HD 140283 has been the subject of debate after it appeared in some studies ... -
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) -
Carbon-Enhanced Metal-Poor Stars. III : Main-Sequence Turn-Off Stars from the SDSS/SEGUE Sample
Aoki, W.; Beers, T.C.; Sivarani, T.; Marsteller, B.; Lee, Y.S.; Honda, S.; Norris, J.E.; Ryan, Sean G.; Carollo, D. (2008-05-10)The chemical compositions of seven CEMP turnoff stars are determined from high-resolution spectroscopy. Five are selected from the SDSS SEGUE sample of metal-poor stars. Another star chosen from the SDSS SEGUE sample has ... -
Carbon-enhanced metal-poor stars. Osmium and iridium abundances in the neutron-capture-enhanced subgiants CS31062-050 and LP625-44
Aoki, W.; Bisterzo, S.; Gallino, R.; Beers, T.C.; Norris, J.E.; Ryan, Sean G.; Tsangarides, S. (2006) -
Chemical Composition fo the Carbon-rich, Extremely Metal Poor Star CS 29498-043
Aoki, W.; Norris, J.E.; Ryan, Sean G.; Beers, T.C.; Ando, H. (2002-09) -
The Chemical Composition of Carbon-rich, very Metal Poor Stars : A New Class of Mildly Carbon Rich Objects without Excess of Neutron-Capture Elements
Aoki, W.; Norris, J.E.; Ryan, Sean G.; Beers, T.C.; Ando, H. (2002-03) -
The Detection of Low Eu Abundances in Extremely Metal-poor Stars and the Origin of r-Process Elements
Ishimaru, Y.; Wanajo, S.; Aoki, W.; Ryan, Sean G. (2004-01) -
Europium Isotope Ratios in s-Process Element-enhanced Metal-poor Stars : A New probe of the 151Sm Branching
Aoki, W.; Ryan, Sean G.; Iwamoto, N.; Beers, T.C.; Norris, J.E.; Ando, H.; Kajino, T.; Mathews, G.J.; Fujimoto, M.Y. (2003-08) -
Extremely Metal-poor Stars : IX CS 22949-037 and the Role of Hypernovae
Norris, J.E.; Ryan, Sean G.; Beers, T.C.; Ando, H.; Aoki, W. (2002-04) -
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) -
Lithium 6104 A in Population II stars
Ford, A.; Jeffries, R.D.; Smalley, B.; Ryan, Sean G.; Aoki, W.; Kawanomoto, S.; James, D.J.; Barnes, John R. (2002-10) -
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. ... -
A low upper-limit on the lithium isotope ratio in HD140283
Aoki, W.; Inoue, S.; Kawanomoto, S.; Ryan, Sean G.; Smith, I.M.; Suzuki, T.K.; Takada-Hidai, M. (2004-12) -
Neutron Capture Elements in s-Process-Rich, Very Metal-Poor Stars
Aoki, W.; Ryan, Sean G.; Norris, J.E.; Beers, T.C.; Ando, H.; Iwamoto, N.; Kajino, T.; Mathews, G.J.; Fujimoto, M.Y. (2001-11) -
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 ... -
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) -
s- and r-process elements in two very metal-poor stars
Ryan, Sean G.; Aoki, W.; Blake, L.A.J.; Norris, J.E.; Beers, T.C.; Gallino, R.; Busso, M.; Ando, H. (2001)