The central density of R136 in 30 Doradus

European Southern Observatory, Alonso de Cordova 3107 Vitacura Casilla 7630355 Santiago, Chile
e-mail: fselman@eso.org

Received: 18 September 2012
Accepted: 13 February 2013

Abstract

The central density, ρ₀, of a stellar cluster is an important physical parameter for determining its evolutionary and dynamical state. How much mass segregation there is or whether the cluster has undergone core collapse both depend on ρ₀. We reanalyze the results of a previous paper that gives the mass density profile of R136 and combine them with both a conservative upper limit for the core parameter and a more uncertain recent measurement. We thus place a lower limit on ρ₀ under reasonable and defensible assumptions about the IMF, finding ρ₀ ≥ 1.5 × 10⁴ M_⊙/pc³ for the conservative assumption a < 0.4 pc for the cluster core parameter. If we use the lower, but more uncertain value a = 0.025 pc, the central density estimate becomes greater than 10⁷ M_⊙/pc³. A mechanism based on the destruction of a large number of circumstellar disks is posited to explain the hitherto unexplained increase in reddening presented in that same work.