Ammonia mapping observations of the Galactic infrared bubble N49: Three NH3 clumps along the molecular filament

Abstract

Abstract We have carried out the NH3(J, K) = (1, 1), (2, 2), and (3, 3) mapping observations toward the Galactic infrared bubble N49 (G28.83−0.25) using the Nobeyama 45 m telescope. Three NH3 clumps (A, B, and C) were discovered along the molecular filament with the radial velocities of ∼96, 87, and 89 km s−1, respectively. The kinetic temperature derived from the NH3(2, 2)/NH3(1, 1) shows Tkin = 27.0 ± 0.6 K enhanced at Clump B in the eastern edge of the bubble, where position coincides with massive young stellar objects (MYSOs) associated with the 6.7 GHz class II methanol maser source. This result shows the dense clump is locally heated by stellar feedback from the embedded MYSOs. The NH3 Clump B also exists at the 88 km s−1 and 95 km s−1 molecular filament intersection. We therefore suggest that the NH3 dense gas formation in Clump B can be explained by a filament–filament interaction scenario. On the other hand, NH3 Clumps A and C at the northern and southern sides of the molecular filament might be the sites of spontaneous star formation because these clumps are located ∼ 5–10 pc away from the edge of the bubble.