J/A+A/620/A158 High-mass IR-dark clumps MALT90 molecular content (Saral+, 2018)
MALT90 molecular content on high-mass IR-dark clumps.
Saral G., Audard M., Wang Y.
<Astron. Astrophys. 620, A158 (2018)>
=2018A&A...620A.158S 2018A&A...620A.158S (SIMBAD/NED BibCode)
ADC_Keywords: Molecular clouds ; Interstellar medium
Keywords: stars: formation - stars: massive - ISM: lines and bands -
ISM: abundance - ISM: molecules - submillimeter: ISM
Abstract:
High mass stars form in groups or clusters in dense molecular clumps
with sizes of 1pc and masses of 200M☉. Infrared-dark clumps
and the individual cores within them with sizes <0.1pc and masses
<100M☉ are important laboratories for high-mass star
formation in order to study the initial conditions.
We investigate the physical and chemical properties of high-mass
clumps in order to better understand the early evolutionary stages and
find targets which show star formation signs such as infall motions or
outflows.
We selected the high-mass clumps from ATLASGAL survey that were
identified as dark at 8/24um wavelengths. We use MALT90 Survey data
which provides a molecular line set (HCO+, HNC, HCN, N13CH+,
H13CO+, HN13C (1-0), SiO) to investigate the physical and
chemical conditions in early stages of star formation.
Results.
(1) Eleven sources have significant SiO detection (over 3σ)
which usually indicates outflow activity.
(2) Thirteen sources are found with blue profiles in both/either HCO+
and/or HNC lines and clump mass infall rates are estimated to be in
the range of 0.2x10-3M☉/yr-1.8x10-2M☉/yr.
(3) The excitation temperature is obtained as <24K for all sources.
(4) The column densities for optically thin lines of H13CO+ and
HN13C (1-0) are in the range of 0.4-8.8(x1012)cm-2, and
0.9-11.9(x1012)cm-2, respectively, while it is in the range of
0.1-7.5(x1014)cm-2 for HCO+ and HNC lines. The column densities
for N13CH+ were ranging between 4.4-275.7(x1012)cm-2 as
expected from cold dense regions.
(5) Large line widths of N13CH+ might indicate turbulence and large
line widths of HCO+, HNC, and SiO indicate outflow activities.
(6) Mean optical depths are 20.32, and 23.19 for optically thick
HCO+ and HCN lines, and 0.39 and 0.45 for their optically thin
isotopologues H13CO+ and HN13C (1-0), respectively.
This study reveals the physical and chemical properties of 30
high-mass IR-dark clumps and the interesting targets among them based
on their emission line morphology and kinematics.
Description:
The data are taken from Millimetre Astronomy Legacy Team 90GHz
(MALT90) survey (https://atoa.atnf.csiro.au/MALT90). MALT90 data cubes
of 30 High-Mass Clumps are presented here. Data cubes includes
processed (l,b,v) cubes. hcop stands for HCO+ (1-0), htco for
H13CO+, hnc for HNC, hntc for HN13C (1-0), n2hp for
N2H+ (1-0), sio for SiO, and hcn for HCN.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
clumps.dat 41 30 List of studied clusters
list.dat 117 210 List of fits datacubes
fits/* . 210 Individual fits datacubes
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See also:
J/A+A/549/A45 : ATLASGAL Compact Source Catalog: 330<l<21 (Contreras+, 2013)
J/A+A/568/A41 : ATLASGAL Compact Source Catalog: 280<l<60 (Urquhart+, 2014)
Byte-by-byte Description of file: clumps.dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- ID Identification number of the clump
6- 20 A15 --- Name Name of the clump (GLLL.lll+BB.bbb)
22- 41 A20 --- SName Simbad name (AGAL GLLL.lll+BB.bbb)
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Byte-by-byte Description of file: list.dat
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Bytes Format Units Label Explanations
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1 A1 --- --- [G]
2- 10 F9.5 deg GLON Galactic longitude of center (J2000)
11- 19 F9.5 deg GLAT Galactic latitude of center (J2000)
21- 22 I2 --- Nx Number of pixels along X-axis
24- 25 I2 --- Ny Number of pixels along Y-axis
27- 30 I4 --- Nz Number of slices
32- 40 F9.1 m/s bVlsr Lower value of LSR velocity interval
42- 47 I6 m/s BVlsr Upper value of LSR velocity interval
49- 55 F7.3 m/s dVlsr LSR velocity resolution
57- 61 I5 Kibyte size Size of FITS file
63- 75 A13 --- FileName Name of FITS file, in subdirectory fits
77-117 A41 --- Title Title of the FITS file
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Acknowledgements:
Gozde Saral, saralgozde(at)gmail.com
(End) Gozde Saral [Geneva Univ., Switzerland] Patricia Vannier [CDS] 25-Oct-2018