Description of source "NGC 6334F" from Gomez et al. (2010)


NGC 6334F is a well-known UC HII region, lying within the NGC 6334 cloud complex, at a distance of 1.7 kpc (Neckel 1978). It is also known as NGC 6334I, where "I" is a roman numeral "one", originating from far-infrared studies (e.g., Gezari 1982). We adopt the convention of Rodriguez et al. (1982), in which the letter "F" refers to the UC HII region.

The eight 44 GHz class I masers detected within the one arcminute VLA primary beam indicate a higher level of maser activity than the majority of the sources in the KHV04 survey, which has a median of four maser features per field. Figure 1 shows the three-color Spitzer/GLIMPSE image of NGC 6434F and the location of the maser components. The eight masers are distributed over an area ~0.25 pc × 0.25 pc. As is typical for class I masers, these eight components do not appear to be associated with the UC HII region, other masers, or the IR emission. Nor do they coincide with thermal ammonia peaks or ammonia masers as reported by Beuther et al. (2005, 2007) or with the millimeter peaks reported by Hunter et al. (2006). The average projected distance from the masers to the geometric center of the UC HII region is 0.12 pc.

Neglecting the two northern-most masers, there is a southwest to northeast positional orientation of the remaining six masers. This orientation corresponds to the blue-shifted (southwest) and red-shifted (northeast) high velocity outflow mapped with the APEX 12 m telescope by Leurini et al. (2006). There is a weak tendency in the maser velocity structure in accordance with this pattern: the average velocity of the southwestern masers is −9.5 kms−1 while the average for the northeastern masers is −6.3 kms−1. We suggest that these six masers are related to the bipolar outflow reported by Leurini et al. (2006). We caution, however, that the trends in both position and velocity are not particularly strong.

The velocity range of emission that we detected (−10.9 to −4.6 kms−1) is slightly shifted from that reported by KHV04 (−9.0 to −2.5 kms−1) and also differs from the single-dish observations of Slysh et al. (1994) (−8.4 to −4.8 kms−1).