Description of source "G8.67-0.36" from Gomez et al. (2010)


The UC HII region G8.67−0.36, at a distance of 4.8 kpc (Fish et al. 2003), was classified by Wood & Churchwell (1989) as having a core-halo morphology; i.e., a single compact peak surrounded by an extended, low-surface-brightness halo.

As in NGC 6334F, the relatively large number of masers detected in this field (12) indicates an unusually high level of maser activity. We identify two regions of maser activity in the field (see Fig. 2): one to the north and the other to the south of the UC HII region. No velocity trend with respect to position is seen. The strongest two masers in this field lie at the edge of an Extended Green Object (EGO; Cyganowski et al. 2008), consistent with the idea that EGOs trace molecular outflows from MYSOs and that class I methanol masers arise from the interaction of outflows with dense clumps of gas (Plambeck & Menten 1990). Cyganowski et al. (2008) did not catalog the G8.67−0.36 region because it lies outside their survey area (10◦ < l < 65◦ and 295◦ < l < 350◦, b = ±1◦). Although eight of the twelve masers lie at the edge of some infrared feature, four of the masers appear relatively isolated

from the infrared emission; hence our data do not suggest a unique correlation of these masers with a particular set of gas conditions.

KHV04 report maser emission at from 33 to 37 kms−1, which is in close agreement with the velocity of HCO+ and H13CO+ emission (34.8 kms−1; Purcell et al. 2006). We detect maser emission in a velocity range of 33.6–39.9 kms−1.

The average projected distance from the masers to the geometric center of the UC HII region is 0.29 pc.