SpS5 - I. Obscured and distant clusters

Abstract

Abstract. This first part of Special Session 5 explored the current status of infrared-based observations of obscured and distant stellar clusters in the Milky Way galaxy. Recent infrared surveys, either serendipitously or using targeted searches, have uncovered a rich population of young and massive clusters. However, cluster characterization is more challenging as it must be obtained often entirely in the infrared due to high line-of-sight extinction. Despite this, much is to be gained through the identification and careful analysis of these clusters, as they allow for the early evolution of massive stars to be better constrained. Further, they act as beacons delineating the Milky Way's structure and as nearby, resolved analogues to the distant unresolved massive clusters studied in distant galaxies.

High-mass stars in Milky Way clusters

“…Indeed, in Westerlund 1, we can see examples of many binary systems that represent different stages along these paths (Clark et al 2014b) Unfortunately, young massive clusters (YMCs) are rare, and this means that we generally find them at large distances and behind heavy extinction. If we follow Hanson et al (2015) in defining a YMC as a cluster with M cl > ∼ 10 4 M , we know less than twenty YMCs in the Milky Way. Moreover, some of the most massive clusters in the Galaxy, such as NGC 3063 or the Arches cluster, are too young to display any effects of stellar evolution.…”