Radio observations of globulettes in the Carina nebula

Abstract

The Carina nebula hosts a large number of globulettes. The majority are of planetary mass, but there are also those with masses of several tens up to a few hundred Jupiter masses. We carried out radio observations of molecular line emission in 12CO and 13CO (2-1) and (3-2) of 12 larger objects in addition of positions in adjacent shell structures using APEX. All selected objects were detected with radial velocities shifted relative to the emission from related shell structures and background molecular clouds. Globulettes along the western part of an extended dust shell show a small spread in velocity with small velocity shifts relative to the shell. This system of globulettes and shell structures in the foreground of the bright nebulosity surrounding the cluster Trumpler 14 is expanding with a few km/s relative to the cluster. The Carina globulettes are compact and denser than objects of similar mass studied previously in the Rosette nebula. Some globulettes in Tr 14 are located far from any shell structures. These objects move at a similar speed as the globulettes along the shell. The distribution and velocities of the globulettes studied suggest that they have originated from eroding shells and elephant trunks.