Distribution of HNCO 505−404 in massive star-forming regions
1 Shanghai Astronomical Observatory, Chinese Academy of Sciences, 80 Nandan Road, 200030 Shanghai, PR China
2 Key Laboratory of Radio Astronomy, Chinese Academy of Sciences, 210008 Nanjing, PR China
3 School of Astronomy & Space Science, Nanjing University, 22 Hankou RD, 210093 Nanjing, PR China
4 Key Laboratory of Modern Astronomy and Astrophysics (Nanjing University), Ministry of Education, 210093 Nanjing, PR China
Received: 18 December 2012
Accepted: 6 May 2013
Aims. The goal of this paper is to study the spatial distribution of HNCO in massive star-forming region and to investigate both its spatial association with infrared sources and physical conditions in region of HNCO emission.
Methods. We mapped nine massive star-forming regions in HNCO 505–404 with the Purple Mountain Observatory 13.7 m telescope. The C18O maps of these sources were obtained simultaneously.
Results. The HNCO emission shows compact distribution, with the emission peak centered on water masers. Nearly all the HNCO clumps show signs of embedded mid-infrared or far-infrared sources. The FWHM sizes of HNCO clumps are significantly smaller than C18O clumps but rather similar to HC3N clumps. We find a good correlation between the integrated intensities, linewidths, and LSR velocities of HNCO and HC3N emission, implying similar excitation mechanisms for these two species. As such, collisional excitation is likely to be the dominant excitation mechanism for HNCO 505 − 404 emission in galactic massive star-forming regions.
Key words: ISM: clouds / ISM: molecules / radio lines: ISM
© ESO, 2013