Ionized filaments and ongoing physical processes in massive-star-forming sites around l = 345.°5

Abstract

Numerous research studies on dust and molecular filaments in star-forming sites have been conducted, but only a limited number have focused on ionized filaments. To observationally study this aspect, we present an analysis of multiwavelength data from an area of ∼74.6 arcmin × 55 arcmin around l = 345∘.5. Using the 843-MHz continuum map, two distinct ionized filaments, namely IF-A (extent ∼8.5 arcmin) and IF-B (extent ∼22.65 arcmin), hosting ionized clumps powered by massive OB stars are identified. Using the 13CO(2–1) and C18O(2–1) line data, the parent molecular clouds of IF-A and IF-B are studied in the velocity range [−21, −10] km s−1, and found to have filamentary appearances. At least two cloud components around −18 and −15 km s−1 towards the parent clouds of IF-A and IF-B are investigated and are found to be connected in velocity space. These filamentary clouds also overlap spatially along the major axis, supporting the filamentary twisting/coupling nature. Noticeable Class I protostars and massive stars appear to be observed towards the common zones of the cloud components. These findings support the collision of two filamentary clouds about 1.2 Myr ago. The existence of the ionized filaments seems to be explained by the combined feedback of massive stars. The molecular filaments associated with IF-A and IF-B favour the outcomes of the most recent model concerning the escape and the trapping of the ionizing radiation from an O star formed in a filament.