2006/10/29 by T. Sakamoto, T. Hasegawa, Takashi Hasegawa · 5 citations
Physics and Astronomy · #Astronomy #Astrophysical Phenomena and Observations #Astrophysics #Dwarf galaxy #Galactic halo #Galaxies: Formation, Evolution, Phenomena #Galaxy #Globular cluster #Halo #Milky Way #Physics #RADIUS #Sky #Stars #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.1086/510332
published as Astrophys.J.653:L29-L32,2006 · 7pages, 3 figures, accepted by Astrophysical Journal Letter
arxiv created 2006/10/29 · openalex publication_date 2006/11/22 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
We report the detection of a faint old stellar system at (α, δ) = (194 29, 34 32) (SDSS J1257+3419), based on the spatial distribution of bright red giant branch stars in the Sloan Digital Sky Survey Data Release 4. SDSS J1257+3419 has a half-light radius of 38 ± 12 pc and an absolute integrated V magnitude of M V = -4.8 mag at a heliocentric distance of 150 ± 15 kpc. A comparison between SDSS J1257+3419 and known Galactic halo objects suggests that SDSS J1257+3419 is either (1) a faint and small dwarf galaxy or (2) a faint and widely extended globular cluster. In the former case, SDSS J1257+3419 could represent an entity of a postulated subhalo of the Milky Way. Further photometric and dynamical study of this stellar system is vital to distinguish these possibilities.