J/ApJ/862/105 Core mass function across Gal. env. II. IRDC clumps (Liu+, 2018)
The core mass function across Galactic environments.
II. Infrared dark cloud clumps.
Liu M., Tan J.C., Cheng Yu, Kong S.
<Astrophys. J., 862, 105 (2018)>
=2018ApJ...862..105L 2018ApJ...862..105L
ADC_Keywords: Interstellar medium; Millimetric/submm sources; Molecular clouds
Keywords: ISM: clouds ; stars: formation
Abstract:
We study the core mass function (CMF) within 32 dense clumps in seven
infrared dark clouds (IRDCs) with the Atacama Large
Millimeter/submillimeter Array via 1.3mm continuum emission at a
resolution of ∼1". We have identified 107 cores with the dendrogram
algorithm, with a median radius of about 0.02pc. Their masses range
from 0.261 to 178M☉. After applying completeness corrections, we
fit the combined IRDC CMF with a power law of the form
dN/d.logM∝M-α and derive an index of
α∼0.86±0.11 for M≥0.79M☉ and α∼0.70±0.13 for
M≥1.26M☉, which is a significantly more top-heavy distribution
than the Salpeter stellar initial mass function index of 1.35. We also
make a direct comparison of these IRDC clump CMF results to those
measured in the more evolved protocluster G286 derived with similar
methods, which have α∼1.29±0.19 and 1.08±0.27 in these mass
ranges, respectively. These results provide a hint that, especially
for the M≥1.26M☉ range where completeness corrections are
modest, the CMF in high pressure, early-stage environments of IRDC
clumps may be top-heavy compared to that in the more evolved, global
environment of the G286 protoclusters. However, larger samples of
cores probing these different environments are needed to better
establish the robustness of this potential CMF variation.
Description:
We use data from ALMA Cycle 2 project 2013.1.00806.S (PI: Tan), which
observed 32 infrared dark cloud (IRDC) clumps on 2015 January 4, 2015
April 10 and 23, using 29 12m antennas in the array. The total
observation time including calibration is 2.4h. The actual on-source
time is ∼2-3min for each pointing (30 pointings in total).
The spectral set-up included a continuum band centered at 231.55GHz
(LSRK frame) with width 1.875GHz from 230.615GHz to 232.490GHz. At
1.3mm, the primary beam of the ALMA 12m antennas is 27" (FWHM).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 77 107 Estimated physical parameters for 1.3mm continuum
cores
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See also:
J/A+A/291/943 : Protostellar cores (Ossenkopf+, 1994)
J/ApJ/428/693 : Rosette Nebula and Maddalena Cloud structures (Williams+ 1994)
J/ApJ/641/389 : Millimetric observations of IRDC cores (Rathborne+, 2006)
J/A+A/462/L17 : Dense cores in interstellar molecular clouds (Alves+, 2007)
J/ApJ/698/324 : Spitzer IRDCs (Ragan+, 2009)
J/ApJS/208/14 : BGPS. IX. Data release 2. (Ginsburg+, 2013)
J/A+A/584/A91 : Cat. of dense cores in Aquila from Herschel (Konyves+, 2015)
J/A+A/606/A133 : IRDC G035.39-00.33 NH3 and CCS data cubes (Sokolov+, 2017)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 4 A4 --- Name Source designation
(<[LTC2018] ANcN> in Simbad)
6- 13 F8.5 deg GLON Galactic longitude
15- 22 F8.5 deg GLAT Galactic latitude
24- 26 F3.1 kpc Dist [2.4/5.7] Distance
28- 33 F6.2 mJy/beam Ipk [1/197] Ipeak flux density at 1.3mm
35- 41 F7.3 mJy Snu [0.5/233] Flux at 1.3mm
43- 49 F7.3 Msun Mass [0.1/178] Raw, uncorrected mass
51- 57 F7.3 Msun Mc [0.2/178] Mass estimate after flux
correction (1)
59- 63 F5.3 0.01pc Rc [0.6/6.6] Core radius (2)
65- 70 F6.3 g/cm2 Sigc [0.2/24] Mass surface density of the core
(Σc=M/A)
72- 77 F6.2 10+6cm-3 nHc [1/130] H nuclei number density in the core (3)
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Note (1): Mc is the mass estimate after flux correction, which equals the raw,
uncorrected mass estimate (Mass) multiplied by the value of
fflux-1 appropriate for Mc. This corrected mass is then used for
the estimates of Sigc and nHc.
Note (2): The radii are evaluated as Rc=(A/π)0.5, where A is the projected
area of the core.
Note (3): nHc=Mc/(µHV), where µH=1.4mH is the mean mass per H
assuming nHe=0.1nH and V=4πRc3/3.
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History:
From electronic version of the journal
References:
Cheng et al. Paper I. 2018ApJ...853..160C 2018ApJ...853..160C
Liu et al. Paper II. 2018ApJ...862..105L 2018ApJ...862..105L This catalog
O'Neill et al. Paper III. 2021ApJ...916...45O 2021ApJ...916...45O Cat. J/ApJ/916/45
(End) Emmanuelle Perret [CDS] 30-Jul-2019