Related papers: An Update on the 0Z Project
We report high-resolution, high-signal-to-noise, observations of the extremely metal-poor double-lined spectroscopic binary CS 22876-032. The system has a long period : P = 424.7 $\pm$ 0.6 days. It comprises two main sequence stars having…
Extremely metal-poor (EMP) stars preserve a fossil record of the composition of the ISM when the Galaxy formed. It is crucial, however, to verify whether internal mixing has modified their surface. We aim to understand the CNO abundance…
We elaborate the binary scenario for the origin of HE0107-5240, the most metal-poor star yet observed ([Fe/H] = -5.3), using current knowledge of the evolution of extremely metal-poor stars. From the observed C/N value, we estimate the…
Extremely Metal-Poor (EMP) stars provide a valuable probe of early chemical enrichment in the Milky Way. Here we leverage a large sample of $\sim600,000$ high-resolution stellar spectra from the GALAH survey plus a machine learning…
We present the analysis of an extensive set of new and literature high quality data concerning Fe, C, N, O, Na, and Mg, exploiting the Teff scale determined in Gratton et al. (1996), and the non-LTE abundance corrections computed in Gratton…
We present our chemical abundance investigation of the metal-poor ([Fe/H]=-1.60 dex), r-process-enriched ([Eu/Fe]=0.73 dex) halo star HD 20 using novel and archival high-resolution spectra at outstanding signal-to-noise ratios. By combining…
We have performed a differential, line-by-line, chemical abundance analysis, ultimately relative to the Sun, of nine very metal-poor main sequence halo stars, near [Fe/H]=$-$2 dex. Our abundances range from…
Metal-poor solar-type stars display a significant reduction in metal-line blanketing at short wavelengths, leading to an excess of near-ultraviolet (NUV) flux compared to their metal-rich counterparts. We utilize GALEX NUV and $\it{Gaia}$…
In this PhD thesis we investigate stellar evolution and nucleosynthesis in the low- and extremely-low metallicity regime - including models of stars with a pure Big Bang composition (i.e. $\rm{Z} = 0$). The metallicity range of the…
Elemental abundance measurements have been obtained for a sample of 18 very metal-poor stars using spectra obtained with the Subaru Telescope High Dispersion Spectrograph. Seventeen stars, among which 16 are newly analyzed in the present…
Early phases of the chemical evolution and formation history of extremely metal poor (EMP) stars are investigated using hierarchical galaxy formation models. We build a merger tree of the Galaxy according to the extended Press-Schechter…
We analyze a high-resolution, high signal-to-noise spectrum of the carbon-rich, extremely metal-poor star CS29498-043, obtained with the Subaru Telescope High Dispersion Spectrograph. We find its iron abundance is extremely low ([Fe/H] =…
Context: Studies of extremely metal-poor stars indicate that chemical abundance ratios [X/Fe] have an rms scatter as low as 0.05 dex (12 \%). It remains unclear whether this reflects observational uncertainties or intrinsic astrophysical…
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.…
We investigate hydrodynamical and nucleosynthetic properties of the jet-induced explosion of a population III $40M_\odot$ star and compare the abundance patterns of the yields with those of the metal-poor stars. We conclude that (1) the…
We report on a dedicated effort to identify and study metal-poor stars strongly enhanced in r-process elements ([r/Fe] > 1 dex; hereafter r-II stars), the Hamburg/ESO R-process Enhanced Star survey (HERES). Moderate-resolution (~2A)…
We present the chemical analysis of a new set of stars known to harbor low mass companions, namely HD 1237, HD 52265, HD 82943, HD 83443, HD 169830, and HD 202206. In addition, we have also analyzed HD 13445 and HD 7528}, already studied…
We report on an investigation into stellar evolution and nucleosynthesis in the low and extremely low metallicity regime, including models of stars with a pure Big Bang composition (i.e. Z=0). The metallicity range of the extremely metal…
We present homogeneous abundance analysis of over 20 elements for 385 very metal-poor (VMP) stars based on the LAMOST survey and follow-up observations with the Subaru Telescope. It is the largest high-resolution VMP sample (including 363…
We present the measurement of 26 elemental abundances of SMSS J022423.27$-$573705.1 (SMSS 0224$-$5737), an extremely metal-poor (EMP) star with a weak $r$-process signature. We report the measurements of N, O, V, Zn, and Ba, and the upper…