Cats and Dogs, Hair and a Hero: A Quintet of New Milky Way Companions

2006/08/21 by V. Belokurov, Vasily Belokurov, D. B. Zucker +48 · 24 citations
Physics and Astronomy · #Galaxies: Formation, Evolution, Phenomena #Gamma-ray bursts and supernovae #Stellar, planetary, and galactic studies #astro-ph

paper · pdf · doi:10.1086/509718

published as Astrophys.J.654:897-906,2007 · 10 pages, 8 figures, submitted to the Astrophysical Journal

arxiv created 2006/08/21 · openalex publication_date 2007/01/10 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/01

Abstract

We present five new satellites of the Milky Way discovered in Sloan Digital Sky Survey (SDSS) imaging data, four of which were followed up with either the Subaru or the Isaac Newton Telescopes. They include four probable new dwarf galaxies—one each in the constellations of Coma Berenices, Canes Venatici, Leo, and Hercules—together with one unusually extended globular cluster, Segue 1. We provide distances, absolute magnitudes, half-light radii, and color-magnitude diagrams for all five satellites. The morphological features of the color-magnitude diagrams are generally well described by the ridge line of the old, metal-poor globular cluster M92. In the past two years, a total of 10 new Milky Way satellites with effective surface brightness μ v ≳ 28 mag arcsec -2 have been discovered in SDSS data. They are less luminous, more irregular, and apparently more metal-poor than the previously known nine Milky Way dwarf spheroidals. The relationship between these objects and other populations is discussed. We note that there is a paucity of objects with half-light radii between ~40 and ~100 pc. We conjecture that this may represent the division between star clusters and dwarf galaxies.

Citations

• The Field of Streams: Sagittarius and Its Siblings

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