High-resolution AMI large array imaging of spinning dust sources: Spatially correlated 8 μm emission and evidence of a stellar wind in L675

Abstract

We present 25 arcsec resolution radio images of five Lynds Dark Nebulae (L675, L944, L1103, L1111 and 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 μm emission seen with Submillimetre Common-User Bolometer Array (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 μm emission seen with Spitzer. Since the mid-infrared emission is present only in Spitzer band 4 we suggest that it arises from a population of polycyclic aromatic hydrocarbon molecules, which also give rise to the cm-wave emission through spinning dust emission. © 2010 The Authors. Journal compilation © 2010 RAS.