Radio observations of globulettes in the Carina nebula

Abstract

Context. The Carina nebula hosts a large number of globulettes. An optical study of these tiny molecular clouds shows that the majority are of planetary mass, but there are also those with masses of several tens up to a few hundred Jupiter masses. Aims. We seek to search for, and hopefully detect, molecular line emission from some of the more massive objects; in case of successful detection we aim to map their motion in the Carina nebula complex and derive certain physical properties. Methods. We carried out radio observations of molecular line emission in 12 CO and 13 CO (2-1) and (3-2) of 12 globulettes in addition to positions in adjacent shell structures using APEX. Results. 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 −1 relative to the cluster. A couple of isolated globulettes in the area move at similar speed. Compared to similar studies of the molecular line emission from globulettes in the Rosette nebula, we find that the integrated line intensity ratios and line widths are very different. The results show that the Carina objects have a different density/temperature structure than those in the Rosette nebula. In comparison the apparent size of the Carina globulettes is smaller, owing to the larger distance, and the corresponding beam filling factors are small. For this reason we were unable to carry out a more detailed modelling of the structure of the Carina objects in the way as performed for the Rosette objects. Conclusions. The Carina globulettes observed are compact and denser than objects of similar mass in the Rosette nebula. The distribution and velocities of these globulettes suggest that they have originated from eroding shells and elephant trunks. Some globulettes in the Trumpler 14 region are quite isolated and located far from any shell structures. These objects move at a similar speed as the globulettes along the shell, suggesting that they once formed from cloud fragments related to the same foreground shell.

Modelling massive star feedback with Monte Carlo radiation hydrodynamics: photoionization and radiation pressure in a turbulent cloud

“…From 0.4 Myr onwards there are several clumps with bright-rimmed envelopes and tails pointing radially away from the massive star. These characteristics are shared with the proplyds, elephant trunks, and cometary knots seen in well-known H ii regions spanning multiple size scales, such as the Orion Nebula, NGC 7293 (the Helix, a planetary nebula; O'Dell 2000), the Carina nebula (Haikala et al 2017), the Eagle nebula, and the Rosette cloud (Tremblin et al 2013). We save a full characterisation of masses and sizes for a future study, but values are of the order 1 to 30 M and 0.1 to 1 pc 2 .…”

“…As a representative example of the range of original surface brightnesses, at 0. (Haikala et al 2017), the Eagle nebula, and the Rosette cloud (Tremblin et al 2013). We save a full characterisation of masses and sizes for a future study, but values are of the order 1 to 30 M and 0.1 to 1 pc 2 .…”

Illuminating the Tadpole's metamorphosis I: MUSE observations of a small globule in a sea of ionizing photons

“…This is two orders of magnitude higher than the ∼ 14 M Jupiter (or 0.01 M ) estimated by Grenman & Gahm (2014) and regarded as a lower limit due to superimposed bright nebulosity. Indeed, subsequent single-dish observations of some of the Carina globulettes (not including the Tadpole) found systematically higher masses than those estimated from the extinction (Haikala et al 2017).…”

ALMA detection of the dusty object silhouetted against the S0 galaxy NGC 3269 in the Antlia cluster

“…Mäkelä et al 2014), as they are seen as silhouettes against the bright nebular background emission. Despite their small sizes (4 to 20 ), the globulettes in the Rosette and Carina nebulae were well detected in 12 CO and 13 CO (3-2) and (2-1) lines at Atacama pathfinder experiment (APEX) (Gahm et al 2013;Haikala et al 2017). It has been suggested (Lawrence 2001) that some of the common unidentified faint sub-millimetre sources found in recent surveys are small cold (7 K) clouds of dust and gas with masses of ∼10 −4 − 10 −2 M (0.1 -10 Jupiter masses) residing in our neighbourhood, r < 100 pc.…”