2011AJ....142...42F

Stephan's Quintet (SQ; also known as Hickson Compact Group 92) is a compact group of galaxies that exhibits numerous signs of interactions between its members. Using high-resolution (0".04 per pixel) images of SQ in B₄₃₈, V₆₀₆, and I₈₁₄ bands from the Early Release Science project obtained with the Wide Field Camera 3 on the Hubble Space Telescope, we identify 496 star cluster candidates (SCCs), located throughout the galaxies themselves as well as in intergalactic regions. Our photometry goes ∼2 mag deeper and covers an additional three regions, the Old Tail, NGC 7317, and the southern debris region (SDR), compared to previous work. Through comparison of the B₄₃₈ - V₆₀₆ and V₆₀₆- I₈₁₄colors of the SCCs with simple stellar population synthesis models, we are able to constrain cluster ages. In particular, the most massive galaxy of SQ, NGC 7319, exhibits continuous star formation throughout its history, although at a lower rate over the past few tens of Myr. NGC 7318 A/B and the northern star burst region both show ongoing active star formation; there are a number of star clusters that are younger than 10 Myr. NGC 7318 A/B also features a peculiar gap in the color distribution of the star clusters that can be used to date the onset of the recent burst. The majority of the SCCs detected in the Young Tail were formed 150-200 Myr ago, whereas the tight distribution of star cluster colors in the Old Tail allows us to constrain its age of formation to ∼400 Myr ago. The star clusters in the SDR are seemingly divided into two groups with ages of 50 and ∼500 Myr, and virtually all of the SCCs detected in NGC 7317 are over 2 Gyr old. Based on these ages, we estimate time intervals for the interactions between SQ members that triggered the massive star cluster formation.