Letter to the Editor

The high velocity outflow in NGC 6334 I

Max-Planck-Institut für Radioastronomie, Auf Dem Hügel 69, 53121 Bonn, Germany e-mail: [sleurini;schilke;bparise;wyrowski;rguesten;sphilipp]@mpifr-bonn.mpg.de

Received: 31 March 2006
Accepted: 27 April 2006

Abstract

Aims.We observed the high velocity outflow originating from NGC 6334 I in several CO transitions with the APEX telescope, with the goal of deriving the physical parameters of the gas.

Methods.Using an LVG analysis, we studied line ratios between the CO(3–2), CO(4–3), and CO(7–6) data as a function of the density and of the kinetic temperature of the gas. An upper limit on the CO column density is derived by comparison with ¹³CO data.

Results.We constrained the temperature to be higher than 50 K and the H₂ density to values higher than  cm^-3 towards the peak position in the red lobe, while  K and  cm^-3 are derived towards the peak position in the blue lobe. The physical parameters of the outflow, its mass and its energetics, have been computed using the temperatures derived from this analysis.

Conclusions.We conclude that high kinetic temperatures are present in the outflow and traced by high excitation CO lines. Observations of high-J CO lines are thus needed to infer reliable values of the kinetic temperatures and of the other physical parameters in outflows.