TheHerschelview of massive star formation in G035.39–00.33: dense and cold filament of W48 undergoing a mini-starburst
Astronomy and Astrophysics
The filament IRDC G035.39--00.33 in the W48 molecular complex is one of the darkest infrared clouds observed by Spitzer. It has been observed by the PACS (70 and 160 ) and SPIRE (250, 350, and 500 ) cameras of the Herschel Space Observatory as part of the W48 molecular cloud complex in the framework of the HOBYS key programme. The observations reveal a sample of 28 compact sources (deconvolved FWHM sizes <0.3 pc) complete down to ∼5 in G035.39--00.33 and its surroundings. Among them, 13 compact
... ng them, 13 compact sources are massive dense cores with masses >20 . The cloud characteristics we derive from the analysis of their spectral energy distributions are masses of 20-50 , sizes of 0.1--0.2 pc, and average densities of 2-20 × 10^5, which make these massive dense cores excellent candidates to form intermediate- to high-mass stars. Most of the massive dense cores are located inside the G035.39--00.33 ridge and host IR-quiet high-mass protostars. The large number of protostars found in this filament suggests that we are witnessing a mini-burst of star formation with an efficiency of ∼15 yr^-1 kpc^-2 within ∼8 pc^2, a large area covering the full ridge. Part of the extended SiO emission observed towards G035.39--00.33 is not associated with obvious protostars and may originate from low-velocity shocks within converging flows, as advocated by previous studies.