Stellar Metallicities from DECam u-band Photometry: A Study of Milky Way Ultra-faint Dwarf Galaxies
Abstract We conducted an in-depth analysis of candidate member stars located in the peripheries of three ultra-faint dwarf (UFD) galaxy satellites of the Milky Way (MW): Boötes I (Boo1), Boötes II (Boo2), and Segue I (Seg1). Studying these peripheral stars has previously been difficult due to contamination from the MW foreground. We used u -band photometry from the Dark Energy Camera (DECam) to derive metallicities to efficiently select UFD candidate member stars. This approach was validated on Boo1, where we identified both previously known and new candidate member stars beyond five half-light radii. We then applied a similar procedure to Boo2 and Seg1. Our findings hinted at evidence for tidal features in Boo1 and Seg1, with Boo1 having an elongation consistent with its proper motion and Seg1 showing some distant candidate stars, a few of which are along its elongation and proper motion. We find two Boo2 stars at large distances consistent with being candidate member stars. Using a foreground contamination rate derived from the Besançon Galaxy model, we ascribed purity estimates to each candidate member star. We recommend further spectroscopic studies on the newly identified high-purity members. Our technique offers promise for future endeavors to detect candidate member stars at large radii in other systems, leveraging metallicity-sensitive filters with the Legacy Survey of Space and Time and the new, narrowband Ca HK filter on DECam.
Authors
- Guilherme Limberg (ORCID: https://orcid.org/0000-0002-9269-8287)
- S. Allam (ORCID: https://orcid.org/0000-0002-7069-7857)
- Ting S. Li (ORCID: https://orcid.org/0000-0002-9110-6163)
- Alexander P. Ji (ORCID: https://orcid.org/0000-0002-4863-8842)
- Anirudh Chiti (ORCID: https://orcid.org/0000-0002-7155-679X)
- A. Drlica-Wagner (ORCID: https://orcid.org/0000-0001-8251-933X)
- D. L. Tucker (ORCID: https://orcid.org/0000-0001-7211-5729)
- Yue Pan (ORCID: https://orcid.org/0000-0002-7922-9726)
Institutions
- Fermi National Accelerator Laboratory (US)
- Electronics for Imaging (United States) (US)
- Astrobiology Center (JP)
- Netherlands Institute for Radio Astronomy (NL)
Publication Details
- Journal
- The Astrophysical Journal
- Published
- 2024-12-26
- DOI
- https://doi.org/10.3847/1538-4357/ad9820
- Citations
- 3
- Primary Topic
- Stellar, planetary, and galactic studies
- Type
- article
- Field-Weighted Citation Impact
- 0.99
Funders
- National Science Foundation
- U.S. Department of Energy
- National Aeronautics and Space Administration
- University of Pennsylvania
- Ohio State University
- University of Chicago
- University of Portsmouth
- European Space Agency
- University College London
- University of Sussex
- Deutsche Forschungsgemeinschaft
- Fundação de Amparo à Pesquisa do Estado de São Paulo
- Ministério da Ciência, Tecnologia e Inovação
- Conselho Nacional de Desenvolvimento Científico e Tecnológico
- Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro
- Financiadora de Estudos e Projetos
- Institut de Física d'Altes Energies
- University of Illinois at Urbana-Champaign
- Office of Science
- Kavli Institute for Cosmological Physics, University of Chicago
- Science and Technology Facilities Council
- High Energy Physics
- Laboratory Directed Research and Development
- Integrated Electronics Engineering Center, Binghamton University
- Argonne National Laboratory
- Fermilab
- Lawrence Berkeley National Laboratory
- SLAC National Accelerator Laboratory