Abundance Analysis of New $r$-Process-Enhanced Stars from the HESP-GOMPA Survey

Abstract

We present a study on the detailed chemical abundances of five new relatively bright $r$-process-enhanced stars that were initially observed as part of the SDSS/MARVELS pre-survey. These stars were selected, on the basis of their metallicities and carbon abundances, among a total of 60 stars, for high-resolution spectroscopic follow-up as part of the HESP-GOMPA survey (Hanle Echelle SPectrograph -- Galactic survey Of Metal Poor stArs). Here we discuss the three new $r$-I and two new $r$-II stars found in this survey. We have carried out a detailed abundance analysis for each of these stars, at a resolving power of $R\sim 30,000$, and compare our results to the existing literature. We could measure three of the first $r$-process-peak elements (Sr, Y and Zr) in all five stars, while Ba, Ce, Nd, Sm, Eu, and Dy could be detected among the second $r$-process-peak elements. Thorium could also be detected in one of the targets, which is found to be an actinide-boost star. We have carried out a comparative study among the sub-populations of the $r$-process-enhanced stars and other stars of the Milky Way halo population to constrain the origin of this class of objects. These bright $r$-process-enhanced stars provide an excellent opportunity to study the nucleosynthesis history of this population in great detail, and shed light on their chemical-enrichment histories.

arXiv comment22 pages, 10 figures, 9 tables, Accepted for publication in The Astrophysical Journal

References in corpus (78)

• First stars V - Abundance patterns from C to Zn and supernova yields in the early Galaxy
• Neutron capture in low mass Asymptotic Giant Branch stars: cross sections and abundance signatures
• Galactic Evolution of Sr, Y, Zr: A Multiplicity of Nucleosynthetic Processes
• VOSA: Virtual Observatory SED Analyzer. An application to the Collinder 69 open cluster
• Neutron-Capture Elements in the Early Galaxy: Insights from a Large Sample of Metal-Poor Giants
• Near-Field Cosmology with Metal-Poor Stars
• The Hamburg/ESO R-process Enhanced Star survey (HERES) II. Spectroscopic analysis of the survey sample
• The Stellar Abundances for Galactic Archeology (SAGA) Database - Compilation of the Characteristics of Known Extremely Metal-Poor Stars
• R-process enrichment from a single event in an ancient dwarf galaxy
• Collapsars as a major source of r-process elements
• The Rise of the s-Process in the Galaxy
• Spectroscopic Studies of Extremly Metal-Poor Stars with Subaru/HDS:II.The r-process Elements, Including Thorium
• Detailed Abundances for 28 Metal-poor Stars: Stellar Relics in the Milky Way
• Neutron star mergers versus core-collapse supernovae as dominant r-process sites in the early Galaxy
• Neutron Star Mergers and Nucleosynthesis of Heavy Elements
• The Most Metal-Poor Stars. II. Chemical Abundances of 190 Metal-Poor Stars Including 10 New Stars With [Fe/H] < -3.5
• Carbon-Enhanced Metal-Poor Star Frequencies in the Galaxy: Corrections for the Effect of Evolutionary Status on Carbon Abundances
• The long-term evolution of neutron star merger remnants - I. The impact of r-process nucleosynthesis
• Abundances of 30 elements in 23 metal-poor stars
• Discovery of HE 1523-0901, a Strongly r-Process Enhanced Metal-Poor Star with Detected Uranium
• Evidence of Multiple r-Process Sites in the Early Galaxy: New Observations of CS 22892-052
• Neutron-capture elements in the very metal-poor star HD122563
• The Origin of r-Process Elements in the Milky Way
• Production of Light Element Primary Process nuclei in neutrino-driven winds
• The Frequency of Carbon-Enhanced Metal-Poor Stars in the Galaxy from the HERES sample
• Normal and Outlying Populations of the Milky Way Stellar Halo at [Fe/H] < -2
• The intermediate neutron-capture process and carbon-enhanced metal-poor stars
• Spectroscopic Studies of Very Metal-Poor Stars with the Subaru High Dispersion Spectrograph. III. Light Neutron-Capture Elements
• Signatures of hypermassive neutron star lifetimes on r-process nucleosynthesis in the disk ejecta from neutron star mergers
• Complete element abundances of nine stars in the r-process galaxy Reticulum II
• From Nuclei to the Cosmos: Tracing Heavy-Element Production with the Oldest Stars
• The Ubiquity of the Rapid Neutron-Capture Process
• The r-process in proto-neutron-star wind revisited
• Explorations of the r-Processes: Comparisons between Calculations and Observations of Low-Metallicity Stars
• Tuning the Clock: Uranium and Thorium Chronometers Applied to CS 31082-001
• Chemical abundances of the Milky Way thick disk and stellar halo II.: sodium, iron-peak and neutron-capture elements
• Neutron Star Mergers as sites of r-process Nucleosynthesis and Short Gamma-Ray Bursts
• The $R$-Process Alliance: First Release from the Southern Search for $r$-Process-Enhanced Stars in the Galactic Halo
• The role of binaries in the enrichment of the early Galactic halo. III. Carbon-enhanced metal-poor stars -- CEMP-s stars
• Detailed Chemical Abundances in the r-Process-Rich Ultra-Faint Dwarf Galaxy Reticulum 2
• An Elemental Assay of Very, Extremely, and Ultra Metal-Poor Stars
• Probing the Neutron-Capture Nucleosynthesis History of Galactic Matter
• The Hamburg/ESO R-process Enhanced Star survey (HERES). I. Project description, and discovery of two stars with strong enhancements of neutron-capture elements
• The R-Process Alliance: First Release from the Northern Search for r-Process Enhanced Metal-Poor Stars in the Galactic Halo
• JINAbase: A database for chemical abundances of metal-poor stars
• NLTE determination of the sodium abundance in a homogeneous sample of extremely metal-poor stars
• NLTE determination of the aluminium abundance in a homogeneous sample of extremely metal-poor stars
• Characterizing the Chemistry of the Milky Way Stellar Halo: Detailed Chemical Analysis of a Metal-Poor Stellar Stream
• High-Resolution Spectroscopic Study of Extremely Metal-Poor Star Candidates from the SkyMapper Survey
• i-process nucleosynthesis and mass retention efficiency in He-shell flash evolution of rapidly accreting white dwarfs
• First stars IV.CS 29497-030: Evidence for operation of the s-process at very low metallicity
• The role of binaries in the enrichment of the early Galactic halo. II. Carbon-Enhanced Metal-Poor Stars - CEMP-no stars
• The Chemical Abundances of Stars in the Halo (CASH) Project. II. A Sample of 16 Extremely Metal-poor Stars
• The Hamburg/ESO R-process Enhanced Star survey (HERES) XI. The highly $r$-process-enhanced star CS 29497-004
• The Hamburg/ESO R-process Enhanced Star survey (HERES) IV. Detailed abundance analysis and age dating of the strongly r-process enhanced stars CS 29491-069 and HE 1219-0312
• Neutron-Capture Nucleosynthesis in the First Stars
• The R-Process Alliance: 2MASS J09544277+5246414, the Most Actinide-Enhanced R-II Star Known
• Kinematics of Highly R-Process-Enhanced Field Stars: Evidence for an Accretion Origin and Detection of Several Groups from Disrupted Satellites
• Actinide Production in Neutron-Rich Ejecta of a Neutron Star Merger
• Spectroscopic analysis of metal-poor stars from LAMOST: early results
• RAVE J203843.2-002333: The first highly r-process-enhanced star identified in the RAVE survey
• Enrichment history of r-process elements shaped by a merger of neutron star pairs
• Metal-Poor Stars Observed with the Magellan Telescope II. Discovery of Four Stars with [Fe/H] < -3.5
• From actinides to zinc: Using the full abundance pattern of the brightest star in Reticulum II to distinguish between different r-process sites
• Chemical Abundance Analysis of Tucana III, the Second $r$-process Enhanced Ultra-Faint Dwarf Galaxy
• NLTE Strontium and Barium in metal poor red giant stars
• Actinide-rich and Actinide-poor $r$-Process Enhanced Metal-Poor Stars do not Require Separate $r$-Process Progenitors
• Kinematic Structure in the Galactic Halo at the North Galactic Pole: RR Lyrae and BHB Stars show different kinematics
• The origins of light and heavy r-process elements identified by chemical tagging of metal-poor stars
• Spectroscopic Validation of Low-Metallicity Stars from RAVE
• Evidence for the accretion origin of halo stars with an extreme r-process enhancement
• The R-Process Alliance: Chemical Abundances for a Trio of R-Process-Enhanced Stars -- One Strong, One Moderate, One Mild
• The low Sr/Ba ratio on some extremely metal-poor stars
• The Hamburg/ESO R-process Enhanced Star survey (HERES) VIII. The r+s star HE 1405 0822
• Spectroscopic Studies of Extremely Metal-Poor Stars with the Subaru High Dispersion Spectrograph. V. The Zn-Enhanced Metal-Poor Star BS 16920-017
• Abundance analysis of SDSS J134338.67+484426.6; an extremely metal-poor star from the MARVELS pre-survey
• Chemical composition of two bright extremely metal-poor stars from the SDSS MARVELS pre-survey
• A high-resolution spectroscopic study of two new Na- and Al-rich field giants -- likely globular cluster escapees in the Galactic halo

Cited by in corpus (7)

• The R-Process Alliance: Chemo-Dynamically Tagged Groups II. An Extended Sample of Halo $r$-Process-Enhanced Stars
• The R-Process Alliance: Fifth Data Release from the Search for R-Process-Enhanced Metal-poor Stars in the Galactic Halo with the GTC
• Decoding the compositions of four bright $r$-process-enhanced stars
• Finding $r$-II sibling stars in the Milky Way with the Greedy Optimistic Clustering algorithm
• Li distribution, kinematics and detailed abundance analysis among very metal-poor stars in the Galactic halo from the HESP-GOMPA survey
• A chemodynamical analysis of bright metal-poor stars from the HESP-GOMPA survey -- Indications of a non-prevailing site for light r-process elements
• Recent Advances in Understanding R-Process Nucleosynthesis in Metal-Poor Stars and Stellar Systems