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Observing the r-Process Signature in the Oldest Stars
Anna Frebel
The abundance patterns of metal-poor stars provide us a wealth of chemical information about various stages of the chemical evolution of the Galaxy. In particular, these stars allo…
The minimum stellar metallicity observable in the Galaxy
Anna Frebel, Jarrett L. Johnson, Volker Bromm
The first stars fundamentally transformed the early Universe through their production of energetic radiation and the first heavy chemical elements. The impact on cosmic evolution s…
The stellar content of the Hamburg/ESO survey. V. The metallicity distribution function of the Galactic halo
T. Schoerck, N. Christlieb, J. G. Cohen +22
We determine the metallicity distribution function (MDF) of the Galactic halo by means of a sample of 1638 metal-poor stars selected from the Hamburg/ESO objective-prism survey (HE…
HE 1327-2326, an unevolved star with [Fe/H]<-5.0. II. New 3D-1D corrected abundances from a VLT/UVES spectrum
Anna Frebel, Kjell Eriksson, Remo Collet +2
We present a new abundance analysis of HE 1327-2326, the currently most iron-poor star, based on observational data obtained with VLT/UVES. We correct the 1D LTE abundances for 3D…
The stellar content of the Hamburg/ESO survey. IV. Selection of candidate metal-poor stars
N. Christlieb, T. Schoerck, A. Frebel +3
We present the quantitative methods used for selecting candidate metal-poor stars in the Hamburg/ESO objective-prism survey (HES). The selection is based on the strength of the Ca…
The Hobby-Eberly Telescope "Chemical Abundances of Stars in the Halo" (CASH) Project. I. The Lithium-, s-, and r-Enhanced Metal-Poor Giant HKII 17435-00532
Ian U. Roederer, Anna Frebel, Matthew D. Shetrone +7
We present the first detailed abundance analysis of the metal-poor giant HKII 17435-00532. This star was observed as part of the University of Texas long-term project "Chemical Abu…
Metal-Poor Stars
Anna Frebel
The abundance patterns of metal-poor stars provide us a wealth of chemical information about various stages of the chemical evolution of the Galaxy. In particular, these stars allo…
Discovery of HE 1523-0901, a Strongly r-Process Enhanced Metal-Poor Star with Detected Uranium
Anna Frebel, Norbert Christlieb, John E. Norris +3
We present age estimates for the newly discovered very r-process enhanced metal-poor star HE 1523-0901 ([Fe/H]=-2.95) based on the radioactive decay of Th and U. The bright (V=11.1…
Probing the Formation of the First Low-Mass Stars with Stellar Archaeology
Anna Frebel, Jarrett L. Johnson, Volker Bromm
We investigate the conditions under which the first low-mass stars formed in the universe by confronting theoretical predictions governing the transition from massive Population II…
Chemical Abundance Analysis of the Extremely Metal-Poor Star HE 1300+0157
Anna Frebel, John E. Norris, Wako Aoki +5
We present a detailed chemical abundance analysis of HE 1300+0157, a subgiant with [Fe/H]=-3.9. From a high-resolution, high-S/N Subaru/HDS spectrum we find the star to be enriched…
Broadband UBVRI Photometry of Horizontal-Branch and Metal-Poor Candidates from the HK and Hamburg/ESO Surveys. I
Timothy C. Beers, Chris Flynn, Silvia Rossi +17
We report broadband UBV and/or BVRI CCD photometry for a total of 1857 stars in the thick-disk and halo populations of the Galaxy. The majority of our targets were selected as cand…
Bright Metal-Poor Stars from the Hamburg/ESO Survey. I. Selection and Follow-up Observations from 329 Fields
A. Frebel, N. Christlieb, J. E. Norris +9
We present a sample of 1777 bright (9<B<14) metal-poor candidates selected from the Hamburg/ESO Survey (HES). Despite saturation effects present in the red portion of the HES objec…
The Oxygen Abundance of HE 1327-2326
Anna Frebel, Norbert Christlieb, John E. Norris +2
From a newly obtained VLT/UVES spectrum we have determined the oxygen abundance of HE 1327-2326, the most iron-poor star known to date. UV-OH lines yield a 1D LTE abundance of [O/F…
The new record holder for the most iron-poor star: HE 1327-2326, a dwarf or subgiant with [Fe/H]=-5.4
A. Frebel, W. Aoki, N. Christlieb +16
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. It…
HE1327-2326, an unevolved star with [Fe/H]<-5.0. I. A Comprehensive Abundance Analysis
W. Aoki, A. Frebel, N. Christlieb +17
We present the elemental abundances of HE1327-2326, the most iron-deficient star known, determined from a comprehensive analysis of spectra obtained with the Subaru Telescope High…
Nucleosynthetic signatures of the first stars
Anna Frebel, Wako Aoki, Norbert Christlieb +16
The chemically most primitive stars provide constraints on the nature of the first stellar objects that formed in the Universe; elements other than hydrogen, helium and traces of l…