Super star cluster velocity dispersions and virial masses in the M82 nuclear starburst

Nate McCrady, James R. Graham

Research output: Contribution to journalArticlepeer-review

97 Scopus citations


e use high-resolution near-infrared spectroscopy from Keck Observatory to measure the stellar velocity dispersions of 19 super star clusters (SSCs) in the nuclear starburst of M82. The clusters have ages on the order of 10 Myr, which is many times longer than the crossing times implied by their velocity dispersions and radii. We therefore apply the virial theorem to derive the kinematic mass for 15 of the SSCs. The SSCs have masses of 2 × 10 5 to 4 × 106 M, with a total population mass of 1.4 × 107M. Comparison ofthe loci of the young M82 SSCs and old Milky Way globular clusters in a plot of radius versus velocity dispersion suggests that the SSCs are a population of potential globular clusters. We present the mass function for the SSCs and find a power-law fit with an index of γ = -1.91 ± 0.06. This result is nearly identical to the mass function of young SSCs in the Antennae galaxies.

Original languageEnglish
Pages (from-to)844-856
Number of pages13
JournalAstrophysical Journal
Issue number2 I
StatePublished - Jul 10 2007


  • Galaxies: individual (M82)
  • Galaxies: star clusters
  • Galaxies: starburst
  • Infrared: galaxies


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