Related papers: HE1327-2326, an unevolved star with [Fe/H]<-5.0. I…

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 very high C and N…

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 effects to provide an abundance pattern that supersedes…

We present a new iron abundance analysis of the hyper metal-poor star HE$~$1327-2326, based on Fe II lines detected in its UV spectral range for the first time. In a Cosmic Origins Spectrograph (COS) spectrum, five new Fe II lines could be…

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/Fe]_OH = 3.7 (subgiant case) and [O/Fe]_OH = 3.4 (dwarf…

We present the analysis of four new extremely metal poor turn-off stars thanks to high-resolution spectra obtained with the Subaru/HDS spectrograph. We determined the abundances and upper limits of Li, C, Mg, Ca, Sr, and Ba. Metallicities…

We give an update on our 0Z Survey to find more extremely metal poor (EMP) stars with [Fe/H] < -3 dex through mining the database of the Hamburg/ESO Survey. We present the most extreme such stars we have found from ~1550 moderate resolution…

We present a Magellan/MIKE high-resolution (R ~ 35,000) spectrum of the ancient star SD 1313-0019 which has an iron abundance of [Fe/H] = -5.0, paired with a carbon enhancement of [C/Fe] ~ 3.0. The star was initially identified by Allende…

Based on spectroscopic constraints derived from NLTE line formation, we explore the likely range of stellar parameters (T_eff and log g) for the hyper-metal-poor (HMP) star HE 1327-2326. Combining the constraints from Balmer line profiles…

We present elemental abundances for eight unevolved extremely metal-poor stars with $T_{\rm eff}>5500\,\mathrm{K}$, among which seven have $[\mathrm{Fe/H}]<-3.5$. The sample is selected from the Sloan Digital Sky Survey / Sloan Extension…

We report the discovery of SMSS J160540.18-144323.1, a new ultra-metal poor halo star discovered with the SkyMapper telescope. We measure [Fe/H] = -6.2 +- 0.2 (1D LTE), the lowest ever detected abundance of iron in a star. The star is…

We report the discovery and high-resolution, high S/N, spectroscopic analysis of the ultra-metal-poor red giant HE 0557-4840, which is the third most heavy-element deficient star currently known. Its atmospheric parameters are T_eff = 4900…

We present an analysis of the UVES high-resolution spectroscopic observations at the 8.2m VLT of J0023+0307, a main-sequence extremely iron-poor dwarf star. We are unable to detect iron lines in the spectrum but derive [Fe/H]<-6.1 from the…

We show that the "puzzling" chemical composition observed in the extremely metal poor star HE0107-5240 may be naturally explained by the concurrent pollution of at least two supernovae. In the simplest possible model a supernova of quite…

We report the discovery of SDSS J131326.89-001941.4, an ultra iron-poor red giant star ([Fe/H] ~ -4.3) with a very high carbon abundance ([C/Fe]~ +2.5). This object is the fifth star in this rare class, and the combination of a fairly low…

The vast majority of the most iron-poor stars in the Galaxy exhibit a strong carbon enhancement, with C/H ratios only about two orders of magnitude below solar. This unusual chemical composition likely reflects the properties of the gas…

Spectra of unevolved metal-poor halo stars uniquely reflect the elemental abundances incorporated during the earliest Galactic epoch. Their heavy-element content is well understood as the products of neutron capture on iron-peak elements.…

Context: Star HE 1327-2326 is a unique object, with the lowest measured iron abundance ([Fe/H] ~ -6) and a peculiar chemical composition that includes large overabundances of C, N, and O with respect to iron. One important question is…

We present an elemental abundance analysis for four newly discovered ultra metal-poor stars from the Hamburg/ESO survey, with $\mathrm{[Fe/H]}\leq-4$. Based on high-resolution, high signal-to-noise spectra, we derive abundances for 17…

We have derived elemental abundances of a remarkable star, HD 179821, with unusual composition (e.g. [Na/Fe]=1.0$\pm$0.2 dex) and extra-ordinary spectral characteristics. Its metallicity at [Fe/H]=0.4 dex places it among the most metal-rich…

We present an abundance analysis for the extremely metal poor star HE1424-0241 based on high dispersion spectra from HIRES at Keck. This star is a giant on the lower red giant branch with [Fe/H] ~ -4.0 dex. Relative to Fe, HE1424-0241 has…