Related papers: The r-Process and Chronometers

The oldest stars in the Milky Way are metal-poor with [Fe/H] < -- 1.0, displaying peculiar elemental abundances compared to solar values. The relative variations in the chemical compositions among stars is also increasing with decreasing…

New high resolution, very high signal-to-noise spectra of ultra-metal-poor (UMP) giant stars HD 115444 and HD 122563 have been gathered with the High-Resolution Echelle Spectrometer of the McDonald Observatory 2.7m Telescope. With these…

We present a comprehensive analysis of the detailed chemical abundances for a sample of 11 metal-poor, very metal-poor and extremely metal-poor stars ([Fe/H] = -1.65 to [Fe/H] = -3.0) as part of the HESP-GOMPA (Galactic survey Of Metal Poor…

We report the first detection of the Pb II line at 2203.534 Angstroms in three metal-poor stars, using ultraviolet spectra obtained with the Space Telescope Imaging Spectrograph on board the Hubble Space Telescope. We perform a standard…

Using the Hubble Space Telescope, we detail the first abundance analysis enabled by far-ultraviolet spectroscopy of a low-mass (~0.19 Msun) white dwarf (WD), GALEX J1717+6757, which is in a 5.9-hr binary with a fainter, more-massive…

This work describes a study of elemental abundances for 30 metal-poor stars whose chemical abundances provide excellent information for setting constraints on models of neutron-capture processes. Based on the abundances of main r- and weak…

We report on a new spectroscopic analysis of the very metal deficient star G 64-12 ([Fe/H]=-3.3), aimed at determining, for the first time, its Be content. The spectra were observed during the Science Verification of UVES, the ESO VLT…

We have determined lead (Pb) abundances for twelve red giants having [Fe/H] between -2.1 and -1.3, and its upper-limits for two lower metallicity objects, as well as the abundances of lanthanum (La) and europium (Eu). The averages of…

We present a detailed abundance analysis, including spectral syntheses, of a very metal-poor ([Fe/H]= -2.7), peculiar main sequence star, HE0024-2523 detected during the course of the Keck Pilot Program. Radial velocities of this star were…

The recent detection of a binary neutron star merger and the clear evidence for the decay of radioactive material observed in this event have, after sixty years of effort, provided an astrophysical site for the rapid neutron-capture ($r$-)…

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 objective-prism spectra, the data were recoverable and…

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 present a detailed chemical analysis study of 16 candidate metal-poor stars, previously identified with 2dF + AAOmega, using X-Shooter spectra and the Korg 1D local thermodynamic equilibrium spectral synthesis code. We confirm the…

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.…

Sagittarius (Sgr) is a massive disrupted dwarf spheroidal galaxy in the Milky Way halo that has undergone several stripping events. Previous chemical studies were restricted mainly to a few, metal- rich ([Fe/H]~ -1) stars that suggested a…

We present radial velocities, stellar parameters, and detailed abundances of 39 elements derived from high-resolution spectroscopic observations of red giant stars in the luminous, metal-poor globular cluster NGC 5824. We observe 26 stars…

Extensive progress has been recently made into our understanding of heavy element production via the $r$-process in the Universe, specifically with the first observed neutron star binary merger (NSBM) event associated with the gravitational…

We have gathered high resolution echelle spectra for more than two dozen high-velocity metal-poor field stars, including BD+80 245, a star previously known to have extremely low [alpha/Fe] abundances, as well as G4-36, a new low-alpha star…

The chemical abundances of metal-poor stars are an excellent test bed by which to set new constraints on models of neutron-capture processes at low metallicity. Some r-process-rich (hereafter r-rich) metal-poor stars, such as HD221170, show…

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…