On the origin of dynamically cold rings around the milky way

Joshua D. Younger, Gurtina Besla, T. J. Cox, Lars Hernquist, Brant Robertson, Beth Willman

Research output: Contribution to journalArticlepeer-review

47 Scopus citations


We present a scenario for the production of dynamically cold rings around the Milky Way via a high-eccentricity, flyby encounter. These initial conditions are more cosmologically motivated than those considered in previous works. We find that the encounters we examine genetically produce a series of nearly dynamically cold ringlike features on low-eccentricity orbits that persist over timescales of ∼2-4 Gyr via the tidal response of the primary galaxy to the close passage of the satellite. Moreover, they are both qualitatively and quantitatively similar to the distribution, kinematics, and stellar population of the Monoceros Ring. Therefore, we find that a higheccentricity flyby by a satellite galaxy represents a cosmologically appealing scenario for forming kinematically distinct ringlike features around the Milky Way.

Original languageEnglish (US)
Pages (from-to)L21-L24
JournalAstrophysical Journal
Issue number1 PART 2
StatePublished - 2008


  • Galaxies: Interactions
  • Galaxies: Structure
  • Galaxy: Kinematics and dynamics
  • Galaxy: Structure
  • Methods: N-body simulations

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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