Study of ammonia emission in the NGC 6334 region

Abstract

The region centered in the NGC 6334 I(N) radio continuum source was surveyed in an extension of 6 arcmin in right ascension and 12 arcmin in declination, in the NH3(J,K) = (1,1) transition, using the Itapetinga radio telescope. The spectra show non-LTE behavior, and gradients of velocity and line-width were detected along the region. A detailed analysis of the spectra showed that the surveyed region is composed of at least three overlapped sources related to regions that are in different stages of star formation: NGC 6334 I, associated with an already known molecular bipolar outflow, NGC 6334 I(N)w, the brightest ammonia source, coincidental with the continuum source NGC 6334 I(N), and NGC 6334 I(N)e, weaker, more extended and probably less evolved than the others. The physical parameters of the last two sources were calculated in non-LTE conditions, assuming that their spectra are the superposition of the narrow line spectra produced by small dense clumps. The H2 density, NH3 column density, kinetic temperature, diameter and mass of the clumps were found to be very similar in the two regions, but the density of clumps is lower in the probably less evolved source NGC 6334 I(N)e. Differences between the physical parameters derived assuming LTE and non-LTE conditions are also discussed in this work.