J/ApJ/962/13 Cont. & H2CS ALMA obs. of IRAS massive protoclusters (Chen+, 2024)
ALMA high-resolution spectral survey of thioformaldehyde (H2CS) toward
massive protoclusters.
Chen Li, Qin S.-L., Liu T., Liu H.-L., Liu S.-Y., Liu M., Shi H., Li C.,
Tang M., Zhang T., Tatematsu K., Li X., Xu F., Wu Y., Yang D.
<Astrophys. J., 962, 13 (2024)>
=2024ApJ...962...13C 2024ApJ...962...13C
ADC_Keywords: Radio continuum; Radio lines; Interstellar medium; Molecular data;
Millimetric/submm sources; Space velocities; Star Forming Region
Keywords: Astrochemistry ; Spectral line identification ; Chemical abundances
Abstract:
Investigating the temperature and density structures of gas in massive
protoclusters is crucial for understanding the chemical properties
therein. In this study, we present observations of the continuum and
thioformaldehyde (H2CS) lines at 345GHz of 11 massive protoclusters
using the Atacama Large Millimeter/submillimeter Array telescope. High
spatial resolution and sensitivity observations have detected 145
continuum cores from the 11 sources. H2CS line transitions are
observed in 72 out of 145 cores, including line-rich cores, warm
cores, and cold cores. The H2 column densities of the 72 cores are
estimated from the continuum emission, which are larger than the
density threshold value for star formation, suggesting that H2CS can
be widely distributed in star-forming cores with different physical
environments. The rotation temperature and column density of H2CS are
derived using the XCLASS software. The results show that the H2CS
abundances increase as temperature rises and higher gas temperatures
are usually associated with higher H2CS column densities. The
abundances of H2CS are positively correlated with its column density,
suggesting that the H2CS abundances are enhanced from cold cores, warm
cores, and line-rich cores in star-forming regions.
Description:
The targeted 11 IRAS sources are a subsample of the ATOMS survey
toward 146 massive protoclusters by Liu+ (2016ApJ...829...59L 2016ApJ...829...59L).
We observed 11 massive protocluster clumps with ALMA cycle 5 band 7
from 2018 May 18-20 (UTC) using 43 12m antennas in the C43-1
configuration (Project ID: 2017.1.00545.S; PI: Tie Liu). The
observations covered four spectral windows (SPWs 31, 29, 27, and 25)
with increasing spectral frequency ranges: (i) 342.36-344.24GHz, (ii)
344.25-346.09GHz, (iii) 354.27-354.74GHz, and (iv) 356.60-357.07GHz.
The integrated on-source time was ∼3.7 minutes per source.
With a spatial resolution of ∼0.8"-1.2", and a high sensitivity of
∼1.2mJy/beam for continuum and ∼4.7mJy per channel for lines, we could
easily observe molecular emission lines.
See Section 2.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 71 11 Physics parameters of the targets in the observations
table2.dat 89 80 Parameters of fitted H2CS molecules among detected
cores
tablea1.dat 84 145 2D Gaussian fit results
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See also:
J/A+A/291/943 : Protostellar cores (Ossenkopf+, 1994)
J/A+AS/115/81 : A CS(2-1) survey of UC HII regions (Bronfman+, 1996)
J/A+A/426/97 : SIMBA survey. 1.2-mm/IRAS sources (Faundez+, 2004)
J/A+A/487/993 : MAMBO Mapping of c2d Clouds and Cores (Kauffmann+, 2008)
J/A+A/604/A6 : SgrB2 ALMA continuum & spectral index (Sanchez-Monge+, 2017)
J/A+A/598/A30 : Massive star forming molecular clumps Tkin (Tang+, 2017)
J/MNRAS/473/1059 : Complete sample of Gal. clump properties (Urquhart+, 2018)
J/A+A/625/A147 : 80-116GHz spectrum of L483 (Agundez+, 2019)
J/A+A/621/A143 : Isotopic H2CS laboratory sp. study (Mueller+, 2019)
J/A+A/632/A83 : NGC 6334 filament with ALMA (Shimajiri+, 2019)
J/MNRAS/496/2790 : ATOMS I Description & first look at G9.62+0.19 (Liu+, 2020)
J/A+A/633/A7 : IRAS 16293-2422 spectral cubes (van't Hoff+, 2020)
J/A+A/648/A66 : CORE high-mass star-forming regions (Gieser+, 2021)
J/MNRAS/505/2801 : ATOMS Paper III, massive star-forming regions (Liu+, 2021)
J/A+A/651/A9 : HIFI molecular line survey of SgrB2 (M) (Moeller+, 2021)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 2 I2 --- Seq [1/11] Running sequence number
4- 14 A11 --- IRAS IRAS name (IHHMMm+DDMM; B1950) (1)
16- 17 I2 h RAh Hour of right ascension (J2000)
19- 20 I2 min RAm Minute of right ascension (J2000)
22- 26 F5.2 s RAs Second of right ascension (J2000)
28 A1 --- DE- Sign of declination (J2000)
29- 30 I2 deg DEd Degree of declination (J2000)
32- 33 I2 arcmin DEm Arcminute of declination (J2000)
35- 38 F4.1 arcsec DEs Arcsecond of declination (J2000)
40- 44 F5.1 km/s Vlsr [-93.7/-18.2] Local Standard of Rest
velocity (2)
46- 49 F4.1 kpc Dist [2.7/10.1] Distance (3)
51- 53 F3.1 kpc RGC [1.3/6.4] Galactocentric distance, RGC (3)
55- 58 F4.2 pc Rad [0.6/2.41] Radius calculated using effective
angular radii and the distances
60- 63 F4.1 K Tdust [23.1/32.2] Averaged dust temperature
from SED fits
65- 67 F3.1 [Lsun] logLbol [4.2/5.8] Log of bolometric luminosity
from SED fits
69- 71 F3.1 [Msun] logMcl [2.9/4.3] Log of clump mass estimated using
the Hildebrand (1983QJRAS..24..267H 1983QJRAS..24..267H) method
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Note (1): IRAS sources are listed in the table with detailed physical
parameters (Urquhart+ 2018, J/MNRAS/473/1059; Liu+ 2020, J/MNRAS/496/2790).
Note (2): The system velocities of the sources are measured from molecular line
observations (e.g., CO, NH3, CS, etc.).
Note (3): The distances to all of the sources are determined using a
combination HI analysis, maser parallax, and spectroscopic measurements.
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 2 I2 --- ID [1/72] Running index source number (1)
4 A1 --- f_ID [d] d: cores with two velocity
components (1)
6- 16 A11 --- IRAS IRAS source identifier (as in Table 1)
18- 19 I2 --- Core [1/21] Extracted core identifier
21- 24 F4.2 arcsec theta [0.59/3.04] Deconvolved source size
26- 28 I3 K TH2CS [23/121] Fitted H2CS rotational
temperature
30- 31 I2 K e_TH2CS [1/18] Uncertainty in TH2CS
33- 38 E6.1 cm-2 NH2CS [41000000000000/3.6e+16] Fitted H2CS
column density
40- 45 E6.1 cm-2 e_NH2CS [2000000000000/1.2e+16] Uncertainty in
NH2CS
47- 49 F3.1 km/s FWHM [0.7/8.7] Fitted H2CS line full-width
at half-maximum
51- 55 F5.1 km/s Voff [-97.4/-16.9] Fitted H2CS velocity
offset
57 A1 --- Type Core type (2)
59- 61 I3 K TCH3OCHO [70/170]? Li+ 2023, ApJ subm. fitted
CH3OCHO rotational temperature
63- 64 I2 K e_TCH3OCHO [2/39]? Uncertainty in TCH3OCHO
66- 69 F4.1 10+23/cm2 NH2 [0.1/15.7]? Peak H2 column density
71- 73 F3.1 10+23/cm2 e_NH2 [0.0/2.1]? Uncertainty in NH2
75- 81 E7.1 --- fH2CS [2.1e-10/1.6e-07]? H2CS abundance
relative to H2
83- 89 E7.1 --- e_fH2CS [6e-11/3e-08]? Uncertainty in fH2CS
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Note (1): For the 8 cores with two velocity components, the parameters are
listed over two lines.
Note (2): Core type as follows:
G = neither H2CS nor CH3OCHO is detected;
H = H2CS is detected but CH3OCHO is not detected;
C = both H2CS and CH3OCHO are detected.
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Byte-by-byte Description of file: tablea1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 I3 --- ID [1/145] Running index source number
5- 15 A11 --- IRAS IRAS source identifier (as in Table 1) (1)
17- 18 I2 --- Core [1/27] Extracted core identifier
20- 21 I2 h RAh [14/17] Hour of Right Ascension (J2000)
23- 24 I2 min RAm Minute of Right Ascension (J2000)
26- 29 F4.1 s RAs Second of Right Ascension (J2000)
31- 31 A1 --- DE- Sign of the Declination (J2000)
32- 33 I2 deg DEd [36/60] Degree of Declination (J2000)
35- 36 I2 arcmin DEm Arcminute of Declination (J2000)
38- 41 F4.1 arcsec DEs Arcsecond of Declination (J2000)
43- 45 F3.1 arcsec MajAxis [0.7/4.1] Semi-major axis
47- 49 F3.1 arcsec MinAxis [0.3/2.5] Semi-minor axis
51- 53 I3 deg PA [0/180] Position angle
55- 59 F5.1 Msun Mass [0.3/263.1] Source mass
61- 64 F4.1 Msun e_Mass [0.1/25.7] Uncertainty in Mass
66- 69 I4 mJy IFlux [10/6990] Integrated flux density
71- 73 I3 mJy e_IFlux [1/880] Uncertainty in IFlux
75- 78 I4 mJy/beam PInt [2/1530] Peak intensity
80- 82 I3 mJy/beam e_PInt [1/160] Uncertainty in PInt
84- 84 A1 --- Note [*] Note (2)
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Note (1): I14498-5859 was very likely a misprint for I14498-5856;
corrected at CDS
Note (2): Note as follows:
* = these molecular cloud cores are recognized as line-rich cores.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 13-Apr-2026