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.
<Astrophys. J. Suppl. Ser., 243, 13 (2019)>
=2019ApJS..243...13L 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 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° 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 2010A&A...518L.100M), respectively.
File Summary:
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FileName Lrecl Records Explanations
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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)
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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).
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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<l<60 (Urquhart+, 2014)
J/other/ApSS/361.191 : High-mass star forming clumps from MALT90 (Zhang+, 2016)
Byte-by-byte Description of file: table[12].dat
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Bytes Format Units Label Explanations
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1- 2 I2 --- Seq [1/90] Running sequence number
4- 18 A15 --- Name Clump name
from Zhang+ (2016, J/other/ApSS/361.191)
20- 25 A6 --- Type Type (only for Table 1) (1)
27- 28 A2 --- Group Group (2)
30 A1 --- Stage Evolutionary stage
from Zhang+ (2016, J/other/ApSS/361.191)
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Note (1): "first", "second", "third", and "fourth" designate the different
correlation between the 20cm continuum emission and abundances of
N2H+, HCO+, HCN, and HNC; see details in Section 4.5. Type as follows:
First = the abundances of N2H+, HCO+, HCN, and HNC decrease as a
function of an increasing 20cm continuum emission flux;
Second = the abundances of N2H+, HCO+, HCN, and HNC increase as a
function of the increasing 20cm continuum emission flux;
Third = the abundances of N2H+, HCO+, HCN, and HNC increase as a
function of the 20cm continuum emission flux when it is less than
a certain value and decrease as a function of the 20cm continuum
emission flux when it is greater than the same value;
Fourth = no obvious correlation between 20cm continuum emission and molecule
abundances.
Note (2): I and II designate the sources that overlapped with the bubble and
without the bubble, respectively.
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History:
From electronic version of the journal
(End) Emmanuelle Perret [CDS] 12-Dec-2019