EPoS Contribution
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CASCADE: Unveiling the photodissociation chemistry and feedback in DR18
Wonju Kim UzK, Cologne, DE | |
The feedback from the newly born stars, especially O/B associations, significantly contribute to the evolution of molecular clouds, physically and chemically. As the clear evidence of the impact of the massive star formation is the number of globules and pillars throughout of massive cavities around the associations. Understanding such globules and pillars allows us to understand how the molecular clouds evolve and stellar feedback for triggering star formations for lower mass stars. As a sub-project of the Cygnus Allscale Survey of Chemistry and Dynamical Environments (CASCADE) survey which is part of the Max Planck IRAM Observatory Program (MIOP), we have investigated 3.6 mm continuum emission and molecular emission lines toward one of the well-known globule in the Cygnus OB2 association, DR 18. Here, we will present the first report on the complex molecular gas structures in this globule, showing the 2nd and 3rd generations of star formation within it as well as highly fragmented molecular gas cores. In addition, we have found a thin photodissociation region traced by narrow SiO emission that, except for the Orion Bar, is a unique case for the study of SiO chemistry in the photodissociation region. Lastly, we will also present an analysis of deuterated species (i.e., DCN, DNC, and DCO+) in the vicinity region of the PDR. This study of DR18, with its clear geometry, provides important insights on the formation and destruction of SiO (an important tracer of processed gas in many environments), deuterated and other species in the PDR and globules. Together these will constrain the dust-grain chemistry, which plays an central role in formation of ices which, in protoplanetary disks, foster the formation of planets. | |
Caption: (Left) The colour emission shows GLIMPSE 8$\mu$m emission, and the white contours indicate the 6 cm radio continuum emission taken from the GLObal view on STAR formation in the Milky Way (GLOSTAR) survey, which is the combined image of the D-configuration VLA and the Effelsberg 100-m telescope observations. The black contours are the 3.6 mm continuum emission obtained with NOEMA from the CASCADE survey. The blue and magenta contours show N2H+ and SiO moment 0 maps, respectively. (Middle and right) The contours are the same as shown in the left image. The colour maps of the middle and right images show DCN and DNC velocity-integrated emission, respectively. | |
Collaborators: H. Beuther, MPIA, DE F. Wyrowski, MPIfR, DE P. Schilke, UzK, DE K.M. Menten, MPIfR, DE |
Relevant topic(s): Chemistry Feedback Triggered SF |
Relevant Big Question: My work shows that a late-type B star can contribute to the chemistry in the PDR layer as such an example is rare and can explain core fragmentation and triggered SF. |