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The Herschel view of massive star formation in G035.39–00.33: dense and cold filament of W48 undergoing a mini-starburst

2011; EDP Sciences; Volume: 535; Linguagem: Inglês

10.1051/0004-6361/201117831

1432-0746

Q. Nguyên Luong, F. Motte, M. Hennemann, T. Hill, K. L. J. Rygl, N. Schneider, S. Bontemps, A. Men’shchikov, Ph. André, N. Peretto, L. D. Anderson, D. Arzoumanian, L. Deharveng, P. Didelon, James Di Francesco, M. J. Griffin, J. M. Kirk, V. Könyves, P. G. Martin, A. Maury, V. Minier, S. Molinari, M. Pestalozzi, S. Pezzuto, Michael A. Reid, H. Roussel, M. Sauvage, F. Schüller, L. Testi, D. Ward‐Thompson, G. J. White, A. Zavagno,

Galaxies: Formation, Evolution, Phenomena

The filament IRDC G035.39--00.33 in the W48 molecular complex is one of the darkest infrared clouds observed by \textit{Spitzer}. It has been observed by the PACS (70 and 160\,$\micron$) and SPIRE (250, 350, and 500\,$\micron$) cameras of the \textit{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 $\sim$$5 \msun$ in G035.39--00.33 and its surroundings. Among them, 13 compact sources are massive dense cores with masses $>$$20 \msun$. The cloud characteristics we derive from the analysis of their spectral energy distributions are masses of $20-50 \msun$, sizes of 0.1--0.2 pc, and average densities of $2-20 \times 10^{5} \cmc$, 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 $\sim$15% and a rate density of $\sim$$40 \msun\,$yr$^{-1}\,$kpc$^{-2}$ within $\sim$8 pc$^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.