High resolution AMI Large Array imaging of spinning dust sources: spatially correlated 8 micron emission and evidence of a stellar wind in L675

TL;DR

This study uses high-resolution radio imaging to investigate spinning dust sources in dark nebulae, revealing a potential protostar in L675 and correlating mid-infrared and microwave emissions in L1246, suggesting PAH molecules' role.

Contribution

First high-resolution imaging of these nebulae at 16 GHz, identifying new embedded protostar and linking mid-infrared PAH emission with spinning dust signals.

Findings

Discovery of a compact protostar in L675.

Spatial correlation between 8 micron and microwave emission in L1246.

Evidence supporting PAH molecules as spinning dust emitters.

Abstract

We present 25 arcsecond resolution radio images of five Lynds Dark Nebulae (L675, L944, L1103, L1111 & L1246) at 16 GHz made with the Arcminute Microkelvin Imager (AMI) Large Array. These objects were previously observed with the AMI Small Array to have an excess of emission at microwave frequencies relative to lower frequency radio data. In L675 we find a flat spectrum compact radio counterpart to the 850 micron emission seen with SCUBA and suggest that it is cm-wave emission from a previously unknown deeply embedded young protostar. In the case of L1246 the cm-wave emission is spatially correlated with 8 micron emission seen with Spitzer. Since the MIR emission is present only in Spitzer band 4 we suggest that it arises from a population of PAH molecules, which also give rise to the cm-wave emission through spinning dust emission.