J/ApJS/243/13 Massive star-forming clump from MALT90 (Li+, 2019) ================================================================================ Spatial variation of the chemical properties of massive star-forming clumps. Li M., Zhou J., Esimbek J., Quan D., He Y., Li Q., Zhu C. =2019ApJS..243...13L ================================================================================ ADC_Keywords: Molecular clouds; Star Forming Region; Interstellar medium; Radio lines Keywords: ISM: kinematics and dynamics ; ISM: molecules ; radio lines: ISM ; stars: formation Abstract: We selected 90 massive star-forming clumps with strong N2H+(1-0), HCO+(1-0), HCN(1-0), and HNC(1-0) emission from the Millimetre Astronomy Legacy Team 90 GHz survey. We obtained Herschel data for all 90 sources and NRAO VLA Sky Survey data for 51 of them. We convolved and regridded all images to the same resolution and pixel size and derived the temperature, H2 column density, molecules' abundances and abundance, and ratios of each pixel. Our analysis yields three main conclusions. First, the abundances of N2H+, HCO+, HCN, and HNC increase when the column density decreases and the temperature increases, with spatial variations in their abundances dominated by changes in the H2 column density. Second, the abundance ratios between N2H+, HCO+, HCN, and HNC also display systemic variations as a function of the column density due to the chemical properties of these molecules. Third, the sources associated with the 20cm continuum emission can be classified into four types based on the behavior of the abundances of the four molecules considered here as a function of this emission. The variations of the first three types could also be attributed to the variation of the H2 column density. Description: The Millimetre Astronomy Legacy Team 90 GHz (MALT90) survey is a large international project that exploited the fast-mapping capability of the Australia Telescope National Facility Mopra 22m telescope and obtained 16 molecular line maps near 90GHz in order to characterize the physical and chemical conditions of high-mass star formation regions over a wide range of evolutionary states (from prestellar cores to protostellar cores and to HII regions). The sample of this survey is a subsample of the ATLASGAL catalog. The angular and spectral resolution of this survey are about 36" and 0.11km/s (Jackson+ 2013PASA...30...57J). The MALT90 data has been obtained from the online archive. The NRAO VLA Sky Survey (NVSS) is a continuum survey, which covers the entire sky north of 40{deg} decl. at 1.4GHz. The angular resolution is about 45", and the noise level in the images is about 0.5mJy/beam. A detailed description of the survey can be found in Condon+ (1998, VIII/65). In this paper, we use images provided by the home page of NVSS. The Herschel Infrared Galactic (Hi-GAL) Plane Survey is an Open Time Key Project on board the Herschel Space Observatory, which mapped the inner Galaxy at 70 and 160um with Photoconductor Array Camera and Spectrometer (PACS) and at 250, 350, and 500um with the Spectral and Photometric Imaging Receiver (SPIRE). The spatial resolution of the images are 6", 12", 18", 24", and 35" for the five wavelength bands (Molinari+ 2010A&A...518L.100M), respectively. File Summary: -------------------------------------------------------------------------------- FileName Lrecl Records Explanations -------------------------------------------------------------------------------- ReadMe 80 . This file table1.dat 30 51 *51 massive star-forming clumps selected from Zhang+ (2016, J/other/ApSS/361.191) table2.dat 30 39 39 massive star-forming clumps selected from Zhang+ (2016, J/other/ApSS/361.191) -------------------------------------------------------------------------------- Note on table1.dat: Here are 51 sources that have more than 10 pixels that overlapped with the 20cm continuum emission (see details in Section 4.5). -------------------------------------------------------------------------------- See also: VIII/65 : 1.4GHz NRAO VLA Sky Survey (NVSS) (Condon+ 1998) J/A+A/291/943 : Protostellar cores (Ossenkopf+, 1994) J/A+AS/124/205 : W3 star-forming region 345 GHz survey (Helmich+ 1997) J/A+A/527/A88 : Chemistry in infrared dark clouds (Vasyunina+, 2011) J/ApJ/756/60 : A 3mm line survey in 37 IR dark clouds (Sanhueza+, 2012) J/ApJ/777/157 : 90GHz obs. of high-mass star-forming regions (Hoq+, 2013) J/A+A/563/A97 : IRAM 30m reduced spectra of 59 sources (Gerner+, 2014) J/A+A/568/A41 : ATLASGAL Compact Source Catalog: 280