First Chemical Analysis of Stars in The Triangulum-Andromeda Star Cloud

Abstract

We undertake the first high resolution spectroscopic study of the Triangulum-Andromeda (TriAnd) star cloud --- an extended, mid-latitude Milky Way halo substructure about 20 kpc away in the second Galactic quadrant --- through six M giant star candidates selected to be both spatially and dynamically associated with this system. The abundance patterns of [Ti/Fe], [Y/Fe] and [La/Fe] as a function of [Fe/H] for these stars support TriAnd as having an origin in a dwarf galaxy with a chemical enrichment history somewhat similar to that of the Sagittarius dwarf spheroidal (dSph) galaxy. We also investigate the previously proposed hypothesis that TriAnd is an outlying, dynamically older piece of the Monoceros Stream (also known as the Galactic Anticenter Stellar Structure, "GASS") under the assumption that both features come from the tidal disruption of the same accreted Milky Way satellite and find that net differences in the above abundance patterns between the TriAnd and GASS stars studied suggest that these two systems are independent and unrelated.

Accepted for publication in ApJ Letters

References in corpus (8)

• Outer structure of the Galactic warp and flare: explaining the Canis Major over-density
• The exotic chemical composition of the Sagittarius dwarf Spheroidal galaxy
• The ACS Survey of Galactic Globular Clusters: M54 and Young Populations in the Sagittarius Dwarf Spheroidal Galaxy
• A 2MASS All-Sky View of the Sagittarius Dwarf Galaxy: Variation of the Metallicity Distribution Function Along the Sagittarius Stream
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• No Excess of RR Lyrae Stars in the Canis Major Overdensity
• The Chemical Evolution of the Monoceros Ring/Galactic Anticenter Stellar Structure

Cited by in corpus (17)

• Target Selection for the SDSS-IV APOGEE-2 Survey
• Rings and Radial Waves in the Disk of the Milky Way
• LAMOST Spectroscopic Survey of the Galactic Anti-centre (LSS-GAC): target selection and the first release of value-added catalogues
• Stellar Streams and Clouds in the Galactic Halo
• A re-interpretation of the Triangulum-Andromeda stellar clouds: a population of halo stars kicked out of the Galactic disk
• Final Targeting Strategy for the SDSS-IV APOGEE-2N Survey
• A Cold Milky Way Stellar Stream in the Direction of Triangulum
• Identifying Contributions to the Stellar Halo from Accreted, Kicked-Out, and In Situ Populations
• Exploring Halo Substructure with Giant Stars: The Nature of the Triangulum-Andromeda Stellar Features
• Mapping the Monoceros Ring in 3D with Pan-STARRS1
• The fall of the Northern Unicorn: Tangential motions in the Galactic Anti-centre with SDSS and Gaia
• Exploring Halo Substructure with Giant Stars. XV. Discovery of a Connection between the Monoceros Ring and the Triangulum-Andromeda Overdensity?
• Disk-Like Chemistry of the Triangulum-Andromeda Overdensity as Seen by APOGEE
• Probing the Halo From the Solar Vicinity to the Outer Galaxy: Connecting Stars in Local Velocity Structures to Large-Scale Clouds
• Cartography of Triangulum-Andromeda using SDSS stars
• Triangulum-Andromeda overdensity: a region with a complex stellar population
• The Chemodynamical Nature of the Triangulum-Andromeda Overdensity