2022PASJ...74..545K

We performed NH₃ (J, K) = (1, 1), (2, 2), and (3, 3) mapping observations toward the Galactic massive star-forming region Sh 2-255 and Sh 2-257 using the Nobeyama 45 m telescope as a part of the KAGONMA (KAgoshima Galactic Object survey with the Nobeyama 45 metre telescope by Mapping in Ammonia lines) project. NH₃ (1, 1) has an intensity peak at the cluster S255 N, is distributed over 3 pc x 2 pc, and is located between two H II regions. The kinetic temperature derived from the NH₃ (2, 2)/(1, 1) ratio was ∼35 K near the massive cluster S255 IR. These clusters also show emission with a large line width of ∼3-4 km s^–1. Based on the reported data, we suggest that NH₃ gas in these regions is affected by stellar feedback from embedded youn stellar object (YSO) clusters in S255 IR and S255 N. We also detected NH₃ (1, 1) emission in a region west of the main gas clump at the location of a concentration of Class II YSOs adjacent to the H II regions Sh 2-254. The presence of Class II YSOs implies ∼2 Myr of star formation, younger than Sh 2-254 (∼5 Myr), thus we suggest that star formation in the western region could be influenced by the older H II region Sh 2-254.