2008AJ....136.1415R

We present a study of the individual super star clusters (SSCs) in the low-metallicity galaxy SBS 0335-052 using new near-infrared (near-IR) and archival optical Hubble Space Telescope observations. The physical properties of the SSCs are derived from fitting model spectral energy distributions (SEDs) to the optical photometry, as well as from the Hα and Paα nebular emission lines. Among the clusters, we find a significant age spread that is correlated with position in the galaxy, suggesting that successive cluster formation occurred in SBS 0335-052 triggered by a large-scale disturbance traveling through the galaxy at a speed of ∼35 km/s. The SSCs exhibit I-band (∼0.8 µm) and near-IR (∼1.6-2.1 µm) excesses with respect to model SEDs that are fit to the optical data. We hypothesize that the I-band excess is dominated by a photoluminescent process known as Extended Red Emission; however, this mechanism cannot account for the excesses observed at longer near-IR wavelengths. From the cluster SEDs and colors, we find that the primary origin of the near-IR excess observed in the youngest SSCs (≲3 Myr) is hot dust emission, while evolved red supergiants dominate the near-IR light in the older (≳7 Myr) clusters. We also find evidence for a porous and clumpy interstellar medium surrounding the youngest, embedded SSCs: the ionized gas emission underpredicts the expected ionizing luminosities from the optical stellar continuum, suggesting that ionizing photons leak out of the immediate vicinity of the clusters before ionizing hydrogen. The corrected, intrinsic ionizing luminosities of the two SSCs younger than ∼3 Myr are each ∼5x10⁵²/s, which is equivalent to each cluster hosting ∼5000 O7.5 V stars. The inferred masses of these SSCs are ∼10⁶ M_☉.