$S^5$: The destruction of a bright dwarf galaxy as revealed by the chemistry of the Indus stellar stream

Abstract

The recently discovered Indus stellar stream exhibits a diverse chemical signature compared to what is found for most other streams due to the abundances of two outlier stars, Indus$\_$0 and Indus$\_$13. Indus$\_$13, exhibits an extreme enhancement in rapid neutron-capture ($r$-)process elements with $[Eu/Fe]=+1.81$. It thus provides direct evidence of the accreted nature of $r$-process enhanced stars. In this paper we present a detailed chemical analysis of the neutron-capture elements in Indus$\_$13, revealing the star to be slightly actinide poor. The other outlier, Indus$\_0$, displays a globular cluster-like signature with high N, Na, and Al abundances, while the rest of the Indus stars show abundances compatible with a dwarf galaxy origin. Hence, Indus$\_0$ provides the first chemical evidence of a fully disrupted dwarf containing a globular cluster. We use the chemical signature of the Indus stars to discuss the nature of the stream progenitor which was likely a chemically evolved system, with a mass somewhere in the range from Ursa Minor to Fornax.

14 pages, 4 figures, and 5 tables, accepted for publication in ApJ

References in corpus (43)

• The NumPy array: a structure for efficient numerical computation
• The Gaia mission
• The Dartmouth Stellar Evolution Database
• Light Curves of the Neutron Star Merger GW170817/SSS17a: Implications for R-Process Nucleosynthesis
• Magnetorotationally driven Supernovae as the origin of early galaxy $r$-process elements?
• Beasts of the Southern Wild: Discovery of nine Ultra Faint satellites in the vicinity of the Magellanic Clouds
• CH in stellar atmospheres: an extensive linelist
• What is a globular cluster? An observational perspective
• Near-UV Observations of HD221170: New Insights into the Nature of r-Process-Rich Stars
• A high resolution VLT/FLAMES study of individual stars in the centre of the Fornax dwarf spheroidal galaxy
• The Chemical Evolution of the Draco Dwarf Spheroidal Galaxy
• New Rare Earth Element Abundance Distributions for the Sun and Five r-Process-Rich Very Metal-Poor Stars
• Multi-Element Abundance Measurements from Medium-Resolution Spectra. IV. Alpha Element Distributions in Milky Way Dwarf Satellite Galaxies
• Improved Laboratory Transition Probabilities for Ce II, Application to the Cerium Abundances of the Sun and Five r-process Rich, Metal-Poor Stars, and Rare Earth Lab Data
• Dynamical Relics of the Ancient Galactic Halo
• VLT/UVES Spectroscopy of Individual Stars in Three Globular Clusters in the Fornax Dwarf Spheroidal Galaxy
• Non-LTE aluminium abundances in late-type stars
• An R-process enhanced star in the dwarf galaxy Tucana III
• The $R$-Process Alliance: Fourth Data Release from the Search for $r$-Process-Enhanced Stars in the Galactic Halo
• Improved Laboratory Transition Probabilities for Er II and Applications to the Erbium Abundances of the Sun and Five r-Process Rich, Metal-Poor Stars
• Multiple populations in globular clusters and their parent galaxies
• VLT/FLAMES spectroscopy of red giant branch stars in the Fornax dwarf spheroidal galaxy
• The R-process Alliance: First Magellan/MIKE Release from the Southern Search for R-Process-enhanced Stars
• The Southern Stellar Stream Spectroscopic Survey (S5): Chemical Abundances of Seven Stellar Streams
• Elevated r-process enrichment in Gaia Sausage and Sequoia
• Nitrogen abundances and multiple stellar populations in the globular clusters of the Fornax dSph
• The Hamburg/ESO R-process Enhanced Star survey (HERES) X. HE 2252-4225, one more r-process enhanced and actinide-boost halo star
• Detailed Abundances of Two Very Metal-Poor Stars in Dwarf Galaxies
• Dynamically Tagged Groups of Very Metal-poor Halo Stars from the HK and Hamburg/ESO Surveys
• An old, metal-poor globular cluster in Sextans A and the metallicity floor of globular cluster systems
• The R-Process Alliance: Chemo-Dynamically Tagged Groups of Halo $r$-Process-Enhanced Stars Reveal a Shared Chemical-Evolution History
• The Populations of Carina. II. Chemical Enrichment
• The role of cluster mass in the multiple populations of Galactic and extragalactic globular clusters
• The Milky Way's stellar streams and globular clusters do not align in a Vast Polar Structure
• Chemical Analysis of the Ultra-Faint Dwarf Galaxy Grus~II. Signature of high-mass stellar nucleosynthesis
• R-process-rich stellar streams in the Milky Way
• Search for globular clusters associated with the Milky Way dwarf galaxies using Gaia DR2
• The GALAH Survey: Chemically tagging the Fimbulthul stream to the globular cluster $\omega$ Centauri
• Rediscovery of the Sixth Star Cluster in the Fornax Dwarf Spheroidal Galaxy
• A chemo-dynamical link between the Gjöll stream and NGC 3201
• Extreme r-process enhanced stars at high metallicity in Fornax
• Detection of Pb II in the Ultraviolet Spectra of Three Metal-Poor Stars
• An investigation of C, N and Na abundances in red giant stars of the Sculptor dwarf spheroidal galaxy

Cited by in corpus (8)

• Origin of highly $r$-process-enhanced stars in a cosmological zoom-in simulation of a Milky Way-like galaxy
• Extending the Chemical Reach of the H3 Survey: Detailed Abundances of the Dwarf-galaxy Stellar Stream Wukong/LMS-1
• Potential Black Hole Seeding of the Spiral Galaxy NGC 4424 via an Infalling Star Cluster
• Finding $r$-II sibling stars in the Milky Way with the Greedy Optimistic Clustering algorithm
• Chemical Abundances of the Typhon Stellar Stream
• Discovery of a pair of very metal-poor stars enriched in neutron-capture elements: The proto-disk r-II star BPS CS 29529-0089 and the Gaia-Sausage-Enceladus r-I star TYC 9219-2422-1
• Detection of the actinide Th in an r-process-enhanced star with accretion origin
• Epicyclic Density Variations in the Indus Stellar Stream