They Might Be Giants: An Efficient Color-Based Selection of Red Giant Stars

Abstract

We present a color-based method for identifying red giants based on Pan-STARRS grz and WISE W1 and W2 photometry. We utilize a subsample of bright stars with precise parallaxes from Gaia DR2 to verify that the color-based selection reliably separates dwarfs from giants. The selection is conservative in the sense that contamination is small (~30%) but not all giants are included (the selection primarily identifies K giants). The color-based selection can be applied to stars brighter than $W1\approx 16$, more than two magnitudes fainter than techniques relying on shallower 2MASS photometry. Many streams and clouds are visible in the resulting sky maps, especially when binned by Gaia DR2 proper motions, including the Sagittarius stream, the Hercules-Aquila Cloud, the Eastern Banded Structure, Monoceros, and the Virgo Overdensity. In addition to the characterization of new and known stellar streams, we expect that this method for selecting red giants will enable detailed analysis of the diffuse stellar halo to distances exceeding 100 kpc.

7 pages, 6 figures, ApJL Accepted

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Cited by in corpus (12)

• The merger that led to the formation of the Milky Way's inner stellar halo and thick disk
• Evidence from the H3 Survey that the Stellar Halo is Entirely Comprised of Substructure
• The CatWISE2020 Catalog
• Mapping the Stellar Halo with the H3 Spectroscopic Survey
• All-Sky Dynamical Response of the Galactic Halo to the Large Magellanic Cloud
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• The Stellar Halo of the Galaxy is Tilted & Doubly Broken
• Discovery of the Magellanic Stellar Stream Out to 100 Kiloparsecs
• Distant Echoes of the Milky Way's Last Major Merger
• HALO7D I: The Line of Sight Velocities of Distant Main Sequence Stars in the Milky Way Halo
• Linking nearby stellar streams to more distant halo overdensities
• Mapping the Distant and Metal-Poor Milky Way with SDSS-V