S316p.13 — Comparing ALMA, VLT, and HST data for Massive, Young Clusters in Grand-Design Spirals

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Aug 10th at 6:00 PM until 7:30 PM




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Author(s): Preben Grosboel1, Horacio Dottori2

Institution(s): 1. European Southern Observatory, 2. UFRGS

A population of young, massive stellar cluster complexes with near-infrared (NIR) colors indicating high extinction (i.e. Av ~ 7mag) was identified on HAWK-I/VLT images of several nearby, grand-design spiral galaxies (Grosboel & Dottori 2012, A&A 542, A39). Models suggest that they are very young cluster complexes still embedded in a dust/gas envelope which will be expelled after the first supernovae explosions (Grosboel & Dottori 2013, A&A 551, L13). Optical studies of nearby disk galaxies using HST data (see e.g. Larsen & Richtler 1999 A&A 345, 49, and Bastian et al. 2012, MNRAS 419, 2606) do not find a similar population of clusters. This may be due to several reasons such as a) lower spatial resolution of the NIR data (Bastian et al. 2014, MNRAS 444, 3829), b) high attenuation by dust limiting detection at optical wavelengths, or c) such populations only exist in grand-design spirals due to the strong perturbations in their arm regions. The current paper presents a detailed comparison of HST and HAWK-I images to better understand the discrepancy between the optical and NIR detection of stellar clusters in nearby galaxies. Further, the ALMA CO-map of NGC 4321 is compared with the VLT NIR images to analyze the possible correlation between giant molecular clouds and formation of massive clusters.