Astronomy and Astrophysics, volume 598A, 76-76 (2017/2-1)
A multiwavelength observation and investigation of six infrared dark clouds.
ZHANG C.-P., YUAN J.-H., LI G.-X., ZHOU J.-J. and WANG J.-J.
Abstract (from CDS):
Context. Infrared dark clouds (IRDCs) are ubiquitous in the Milky Way, yet they play a crucial role in breeding newly-formed stars.
Aims. With the aim of further understanding the dynamics, chemistry, and evolution of IRDCs, we carried out multiwavelength observations on a small sample.
Methods. We performed new observations with the IRAM 30 m and CSO 10.4 m telescopes, with tracers HCO+, HCN, N2H+, C18O, DCO+, SiO, and DCN toward six IRDCs G031.97+00.07, G033.69-00.01, G034.43+00.24, G035.39-00.33, G038.95-00.47, and G053.11+00.05.
Results. We investigated 44 cores including 37 cores reported in previous work and seven newly-identified cores. Toward the dense cores, we detected 6 DCO+, and 5 DCN lines. Using pixel-by-pixel spectral energy distribution (SED) fits of the Herschel 70 to 500 µm, we obtained dust temperature and column density distributions of the IRDCs. We found that N2H+ emission has a strong correlation with the dust temperature and column density distributions, while C18O showed the weakest correlation. It is suggested that N2H+ is indeed a good tracer in very dense conditions, but C18O is an unreliable one, as it has a relatively low critical density and is vulnerable to freezing-out onto the surface of cold dust grains. The dynamics within IRDCs are active, with infall, outflow, and collapse; the spectra are abundant especially in deuterium species.
Conclusions. We observe many blueshifted and redshifted profiles, respectively, with HCO+ and C18O toward the same core. This case can be well explained by model "envelope expansion with core collapse (EECC)".
© ESO, 2017
infrared: stars - stars: formation - ISM: IRDCs - HII regions - radio lines: ISM
VizieR on-line data:
<Available at CDS (J/A+A/598/A76): table2.dat table3.dat table4.dat list.dat fits/*>
Table 2: [ZYL2017] GNN-NN N=44.
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