Measuring mass-loss rates from galactic satellites

Kathryn V. Johnston, Steinn Sigurdsson, Lars Hernquist

Research output: Contribution to journalArticlepeer-review

112 Scopus citations


We present the results of a study that uses numerical simulations to interpret observations of tidally disturbed satellites around the Milky Way. When analysing the simulations from the viewpoint of an observer, we find a break in the slope of the star count and velocity dispersion profiles in our models at the location where unbound stars dominate. We conclude that 'extra-tidal' stars and enhanced velocity dispersions observed in the outskirts of Galactic satellites are caused by contamination by stellar debris from the tidal interaction with the Milky Way. However, a significant bound population can exist beyond the break radius and we argue that it should not be identified with the tidal radius of the satellite. We also develop and test a method for determining the mass-loss rate from a Galactic satellite using its extra-tidal population. We apply this method to observations of globular clusters and dwarf spheroidal satellites of the Milky Way, and conclude that a significant fraction of each of these satellite systems is likely to be destroyed within the next Hubble time. Finally, we demonstrate that this mass-loss estimate allows us to place some limits on the initial mass function (IMF) of stars in a cluster from the radial dependence of its present-day mass function (PDMF).

Original languageEnglish (US)
Pages (from-to)771-789
Number of pages19
JournalMonthly Notices of the Royal Astronomical Society
Issue number4
StatePublished - Feb 1 1999

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


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