J/ApJ/912/156 Core kinematics in the Dragon IRDC from ALMA (Kong+, 2021)
Evidence of core growth in the Dragon infrared dark cloud: a path for massive
star formation.
Kong S., Arce H.G., Shirley Y., Glasgow C.
<Astrophys. J., 912, 156 (2021)>
=2021ApJ...912..156K 2021ApJ...912..156K
ADC_Keywords: Molecular clouds; Velocity dispersion; YSOs;
Spectra, millimetric/submm
Keywords: Star formation ; Infrared dark clouds ; Stellar jets ;
Young stellar objects ; Protostars ; Observational astronomy ;
Millimeter astronomy ; Nonparametric hypothesis tests ;
Astrostatistics strategies ; Young massive clusters ;
Massive stars ; Interstellar filaments
Abstract:
A sample of 1.3mm continuum cores in the Dragon infrared dark cloud
(also known as G28.37+0.07 or G28.34+0.06) is analyzed statistically.
Based on their association with molecular outflows, the sample is
divided into protostellar and starless cores. Statistical tests
suggest that the protostellar cores are more massive than the starless
cores, even after temperature and opacity biases are accounted for. We
suggest that the mass difference indicates core mass growth since
their formation. The mass growth implies that massive star formation
may not have to start with massive prestellar cores, depending on the
core mass growth rate. Its impact on the relation between core mass
function and stellar initial mass function is to be further explored.
Description:
The statistical sample consists of two parts:
The first is a sample of cores defined by Kong (2019ApJ...873...31K 2019ApJ...873...31K)
which studied the core mass function (CMF) in the Dragon IRDC based on
an Atacama Large Millimeter/submillimeter Array (ALMA) 1.3mm continuum
mosaic of the cloud.
And the second is an outflow sample defined by
Kong+ (2019ApJ...874..104K 2019ApJ...874..104K) which identified 62 astrograph cores with
CO and/or SiO outflows.
To estimate the core virial status, we utilize the molecular line data
from ALMA projects 2013.1.00183.S and 2015.1.00183.S. In particular,
we use the C18O(3-2), DCO+(3-2), N2D+(3-2), and DCN(3-2) line
cubes to derive the kinematic information for the cores. See Appendix.
Objects:
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RA (ICRS) DE Designation(s)
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18 42 50.6 -04 03 30 G28.37+0.07 = NAME Dragon Nebula
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1.dat 107 280 Core kinematics
img_avg/* . 280 Individual ALMA spectra figures in PDF format
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See also:
J/A+A/291/943 : Protostellar cores (Ossenkopf+, 1994)
J/MNRAS/450/1926 : Infall motions in massive star-forming regions (He+, 2015)
J/ApJ/867/94 : ALMA 1.3mm flux measurements of C1-S core (Kong+, 2018)
Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- Core [1/280] Core number
5- 13 F9.5 deg RAdeg [280.68/280.74] Right Ascension (J2000)
15- 22 F8.5 deg DEdeg [-4.08/-4.01] Declination (J2000)
24- 36 A13 --- Det Detection (1)
38- 41 A4 --- Line Adopted fitting line
43- 45 A3 --- o_Line Number of components to check in Line (2)
47- 51 F5.2 km/s Vc [75.6/83.1]? Averaged LSR velocity of
projected core
53- 56 F4.2 km/s e_Vc [0.02/0.4]? Uncertainty in Vc
58- 61 F4.2 km/s sigmac [0.16/1.31]? Average dispersion of projected
core
63- 66 F4.2 km/s e_sigmac [0.02/0.4]? Uncertainty in sigmac
68- 72 F5.2 km/s Vb [75.7/83.1]? Average LSR velocity within the
beam
74- 77 F4.2 km/s e_Vb [0.02/0.3]? Uncertainty in Vb
79- 82 F4.2 km/s sigmab [0.1/1.2]? Average dispersion within the beam
84- 87 F4.2 km/s e_sigmab [0.02/0.3]? Uncertainty in sigmab
89- 92 F4.2 km/s sigma [0.2/1.4]? Total velocity dispersion (3)
94- 97 F4.2 km/s e_sigma [0.02/0.4]? Uncertainty in sigma
99- 102 F4.2 km/s sigmaNH3 [0.44/1.17] Total velocity dispersion from
NH3 dispersion
104- 107 F4.2 km/s e_sigmaNH3 [0/0.03] Uncertainty in sigmaNH3
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Note (1): The number of components detected in each line (C18O, N2D+,
DCO+, DCN, CH3OH). A dash sign right of the number indicates a
tentative detection (i.e., a low signal-to-noise component).
Note (2): The number of components to check in the integrated intensity maps.
Note (3): Where the line thermal component is subtracted, and the sound speed
is added back (using the gas temperature from W18
(Wang+ 2018RNAAS...2...52W 2018RNAAS...2...52W) and assuming a mean molecular weight per
free particle of 2.37).
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History:
From electronic version of the journal for Table A1
Spectra figures (PDF) downloaded at: http://doi:10.7910/DVN/OLRED4
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 03-Nov-2022