2016MNRAS.458.4222Z

We present investigations of the feedback of a luminous Herbig Be star, IL Cep. We mapped the vicinity of IL Cep in the J=1-0 transitions of ¹²CO, ¹³CO and C¹⁸O molecular lines with the Purple Mountain Observatory 13.7 m telescope. Archival data from Wide-field Infrared Survey Explorer were also employed. A parsec-scale cavity that has probably been excavated by the dominant HBe star, IL Cep, is revealed. An expanding shell-like structure featured by ¹²CO(J=1-0) emission was found surrounding the cavity, which embeds several ¹³CO(J=1-0) molecular clumps. The density and velocity gradients imply strong stellar winds from exciting stars, this is consistent with the morphology of molecular cloud. The ¹²CO(J=1-0) spectra show broad blue wings with a width of about 3.5 km/s. We suggest that the broad blue wings could be emission from the molecular gas shocked by stellar winds, while the main narrow component may originate from pre-shocked gas. Several bright bow-shaped rims have been detected at 12 µm, which serve as the interface of the molecular cloud facing UV dissipation from the exciting stars. The rims all have an orientation facing IL Cep, this may indicate the pre-dominant effects of IL Cep on its surroundings. A very young star candidate (about 10^4.8 yr) was found in the head of one bright rim, but its triggered origin is uncertain. All results achieved in this paper suggest that IL Cep has violent effects on its surroundings.