Browsing by Author "Yong, David"

Now showing items 1-7 of 7

    • A Critique of the Spite Plateau, and the Astration of Primordial Lithium 

      Norris, J.E.; Yong, David; Frebel, Anna; Ryan, Sean (2023-03-30)
      We investigate the distribution of the lithium abundances, A(Li), of metal-poor dwarf and subgiant stars within the limits 5500 K< eff < 6700 K, –6.0 < [Fe/H] < –1.5, and log >∼3.5 (a superset of parameters first adopted ...

    • Evolution of fluorine in the galaxy with the v-process 

      Kobayashi, Chiaki; Izutani, Natsuko; Karakas, Amanda I.; Yoshida, Takashi; Yong, David; Umeda, Hideyuki (2011-10-01)
      We calculate the evolution of fluorine in the solar neighborhood with the v-process of core-collapse supernovae, the results of which are in good agreement with the observations of field stars. The v-process operating in ...

    • The Most Metal-poor Stars. I : Discovery, Data and Atmospheric Parameters 

      Norris, John; Bessell, Michael; Yong, David; Christlieb, Norbert; Barklem, Paul; Asplund, Martin; Murphy, Michael; Beers, Timothy; Frebel, Anna; Ryan, Sean G. (2013-01)
      We report the discovery of 34 stars in the Hamburg/ESO Survey for metal-poor stars and the Sloan Digital Sky Survey that have [Fe/H] <~ -3.0. Their median and minimum abundances are [Fe/H] = -3.1 and -4.1, respectively, ...

    • The Most Metal-poor Stars. II : Chemical Abundances of 190 Metal-poor Stars Including 10 New Stars with [Fe/H] <= -3.5 

      Yong, David; Norris, John; Bessell, Michael S.; Asplund, Martin; Beers, Timothy C.; Barklem, Paul S.; Frebel, Anna; Ryan, Sean G. (2013-01)
      We present a homogeneous chemical abundance analysis of 16 elements in 190 metal-poor Galactic halo stars (38 program and 152 literature objects). The sample includes 171 stars with [Fe/H] <= -2.5, of which 86 are extremely ...

    • The Most Metal-poor Stars. III : The Metallicity Distribution Function and Carbon-enhanced Metal-poor Fraction 

      Yong, David; Norris, John; Bessell, Michael; Christlieb, Norbert; Asplund, Martin; Beers, Timothy; Barklem, Paul; Frebel, Anna; Ryan, Sean G. (2013)
      We examine the metallicity distribution function (MDF) and fraction of carbon-enhanced metal-poor (CEMP) stars in a sample that includes 86 stars with [Fe/H] <= -3.0, based on high-resolution, high signal-to-noise spectroscopy, ...

    • The Most Metal-Poor Stars. IV : The Two Populations with [Fe/H] <~ -3.0 

      Norris, John; Yong, David; Bessell, Michael; Christlieb, Norbert; Asplund, Martin; Gilmore, G.F.; Wyse, Rosemary F. G.; Beers, Timothy; Barklem, Paul; Frebel, Anna; Ryan, Sean G. (2013-01-01)
      We discuss the carbon-normal and carbon-rich populations of Galactic halo stars having [Fe/H] lsim -3.0, utilizing chemical abundances from high-resolution, high signal-to-noise model-atmosphere analyses. The C-rich ...

    • The remarkable solar twin HIP 56948: : a prime target in the quest for other Earths 

      Melendez, Jorge; Bergemann, Maria; Cohen, Judith G.; Endl, Michael; Karakas, Amanda I.; Ramirez, Ivan; Cochran, William D.; Yong, David; MacQueen, Phillip J.; Kobayashi, Chiaki; Asplund, Martin (2012-07-01)
      We study HIP 56948, the best solar twin known to date, to determine with an unparalleled precision how similar is to the Sun in its physical properties, chemical composition and planet architecture. We explore whether the ...