Diverse protostellar evolutionary states in the young cluster AFGL961

TL;DR

This study uses high-resolution mid-infrared and millimeter observations to reveal a variety of protostellar evolutionary stages within a young stellar cluster, indicating complex and possibly rapid star formation processes.

Contribution

It provides detailed observational evidence of diverse protostellar states in a single cluster, highlighting the complexity of star formation in clustered environments.

Findings

Presence of an early B star in a dense core

Detection of a starless, collapsing core

Observation of an outflow from a protostellar core

Abstract

We present arcsecond resolution mid-infrared and millimeter observations of the center of the young stellar cluster AFGL961 in the Rosette molecular cloud. Within 0.2 pc of each other, we find an early B star embedded in a dense core, a neighboring star of similar luminosity with no millimeter counterpart, a protostar that has cleared out a cavity in the circumcluster envelope, and two massive, dense cores with no infrared counterparts. An outflow emanates from one of these cores, indicating a deeply embedded protostar, but the other is starless, bound, and appears to be collapsing. The diversity of states implies either that protostellar evolution is faster in clusters than in isolation or that clusters form via quasi-static rather than dynamic collapse. The existence of a pre-stellar core at the cluster center shows that that some star formation continues after and in close proximity to massive, ionizing stars.