Discovery of a Faint Old Stellar System at 150 kpc
نویسندگان
چکیده
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 +1.4 −1.0 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 (a) a faint and small dwarf galaxy or (b) 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 discriminate these possibilities.
منابع مشابه
Comments on a faint old stellar system at 150 kpc
Context. Recent study of SDSS J1257+3419 has revealed that this stellar system is either a faint and small dwarf galaxy or a faint and widely extended globular cluster. Aims. In this short note, the author suggests that this system is one of the smallest dwarf spheroidals (dSphs) in the Milky Way. Methods. We re-examine some observational quantities of this object and check whether it can be bo...
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