J/ApJ/854/154 N159 12CO and 13CO (2-1) clumps (Nayak+, 2018)
Molecular cloud structures and massive star formation in N159.
Nayak O., Meixner M., Fukui Y., Tachihara K., Onishi T., Saigo K.,
Tokuda K., Harada R.
<Astrophys. J., 854, 154 (2018)>
=2018ApJ...854..154N 2018ApJ...854..154N
ADC_Keywords: Magellanic Clouds; Molecular clouds; Carbon monoxide
Keywords: Magellanic Clouds ; stars: formation ; stars: protostars
Abstract:
The N159 star-forming region is one of the most massive giant
molecular clouds (GMCs) in the Large Magellanic Cloud (LMC). We show
the 12CO, 13CO, CS molecular gas lines observed with ALMA in N159
west (N159W) and N159 east (N159E). We relate the structure of the gas
clumps to the properties of 24 massive young stellar objects (YSOs)
that include 10 newly identified YSOs based on our search. We use
dendrogram analysis to identify properties of the molecular clumps,
such as flux, mass, linewidth, size, and virial parameter. We relate
the YSO properties to the molecular gas properties. We find that the
CS gas clumps have a steeper size-linewidth relation than the 12CO
or 13CO gas clumps. This larger slope could potentially occur if the
CS gas is tracing shocks. The virial parameters of the 13CO gas
clumps in N159W and N159E are low (<1). The threshold for massive star
formation in N159W is 501M☉/pc2, and the threshold for massive
star formation in N159E is 794M☉/pc2. We find that 13CO is
more photodissociated in N159E than N159W. The most massive YSO in
N159E has cleared out a molecular gas hole in its vicinity. All the
massive YSO candidates in N159E have a more evolved spectral energy
distribution type in comparison to the YSO candidates in N159W. These
differences lead us to conclude that the giant molecular cloud complex
in N159E is more evolved than the giant molecular cloud complex in
N159W.
Description:
We observe N159W and N159E in ALMA Cycle 1 using the Band 3
(86-116GHz) and Band 6 (211-275GHz) receivers (Project Code:
2012.1.00554.S, PI: Y. Fukui).
Band 6 12m observations of N159W were taken on 2013 November 30.
Band 3 12m observations of N159W were taken on 2013 December 1.
Band 6 12m observations of N159E were taken on 2013 December 2.
Band 3 12m observations of N159E were taken on 2013 December 3.
Objects:
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RA (ICRS) DE Designation(s)
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05 39 46.65 -69 45 39.9 N159 = LHA 120-N 159
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table9.dat 88 364 Mass derived from N159W 12CO (2-1) clumps
table10.dat 83 1085 Column densities and mass derived from N159W 13CO
(2-1) clumps
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See also:
II/288 : IRSF Magellanic Clouds Point Source Catalog (Kato+ 2007)
VII/232 : Nebulae in the Magellanic Clouds (Davies+ 1976)
VI/102 : Geneva stellar evolution tracks and isochrones (Lejeune+, 2001)
VII/233 : The 2MASS Extended sources (IPAC/UMass, 2003-2006)
J/A+A/347/841 : HST Observations of SMC N88A (Heydari-Malayeri+, 1999)
J/A+A/422/129 : JHKs photometry in N159 (LMC) (Meynadier+, 2004)
J/ApJ/638/293 : 1.1mm sources in the Perseus Molecular Cloud (Enoch+, 2006)
J/AJ/132/2268 : SAGE calibration stars (Meixner+, 2006)
J/A+A/453/517 : JKs photometry of N159A (Testor+, 2006)
J/ApJ/686/948 : CO in extragalactic giant molecular clouds (Bolatto+, 2008)
J/ApJS/178/56 : CO observations of LMC Giant Molecular clouds (Fukui+, 2008)
J/AJ/136/18 : LMC SAGE. New candidate YSOs (Whitney+, 2008)
J/ApJS/184/172 : High- and intermediate-mass YSOs in the LMC (Gruendl+, 2009)
J/ApJ/699/1092 : Giant molecular clouds (SRBY) (Heyer+, 2009)
J/ApJS/184/1 : Molecular clouds in the LMC by NANTEN. II. (Kawamura+, 2009)
J/ApJ/699/150 : Spectral classifications of Massive YSOs in LMC (Seale+, 2009)
J/A+A/530/A118 : G29.96-0.02 and G35.20-1.74 1mm and 3mm maps (Pillai+, 2011)
J/ApJS/197/16 : CO observations of LMC molecular clouds (MAGMA). (Wong+, 2011)
J/A+A/544/A146 : ATLASGAL cold high-mass clumps with NH3 (Wienen+, 2012)
J/ApJ/774/73 : ALMA CO observations of 30 Dor (Indebetouw+, 2013)
J/AJ/146/62 : HERschel HERITAGE in Magellanic Clouds (Meixner+, 2013)
J/AJ/148/124 : Herschel key program Heritage (Seale+, 2014)
J/ApJ/811/145 : LMC & SMC evolved stars detected with Herschel (Jones+, 2015)
J/MNRAS/459/342 : Dense cores in Taurus L1495 cloud (Marsh+, 2016)
Byte-by-byte Description of file: table9.dat
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Bytes Format Units Label Explanations
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1- 5 A5 --- Reg Region, N159E or N159W
7- 9 I3 --- Clump [0/237] Clump ID
11- 19 F9.6 deg RAdeg [84.8/85.1] Right Ascension (J2000)
21- 30 F10.6 deg DEdeg [-69.8/-69.7] Declination (J2000)
32- 36 F5.3 pc Rad [0.1/7.3] Effective Radius from the clump area
38- 43 F6.2 K.km/s F12CO [3.9/149] 12CO (2-1) line flux
45- 50 F6.3 K.km/s e_F12CO [0.7/45] Uncertainty in F12CO
52- 58 E7.2 Msun Mtot [6.7/176000] Total H2 Mass (1)
60- 66 E7.2 Msun e_Mtot [0.8/121000] Uncertainty in Mtot
68- 74 E7.2 Msun Mvir [0.05/108000] Virial Mass,
assuming virial param=1
76- 82 E7.2 Msun e_Mvir [0.02/74600] Mvir uncertainty
84- 88 F5.3 km/s LW [0.01/3.6] Measured linewidth
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Note (1): We assumed the typical 12CO(2-1)/12CO(1-0) ratio toward HII
regions of 0.85 (Nishimura+ 2015ApJS..216...18N 2015ApJS..216...18N). We use a XCO
conversion factor of 7x1020cm-2 (Fukui+ 2008, J/ApJS/178/56).
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Byte-by-byte Description of file: table10.dat
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Bytes Format Units Label Explanations
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1- 5 A5 --- Reg Region, N159E or N159W
7- 9 I3 --- Clump [0/889] Clump ID
11- 19 F9.6 deg RAdeg [84.8/85.1] Right Ascension (J2000)
21- 30 F10.6 deg DEdeg [-69.8/-69.7] Declination (J2000)
32- 36 F5.3 pc Rad [0.1/2.7] Effective Radius from the clump area
38- 45 E8.2 cm-2 N13CO [1.3e+15/7.8e+16] 13CO (2-1) number column
density
47- 53 E7.2 Msun Mtot [3.9/43000] Total H2 Mass (1)
55- 61 E7.2 Msun e_Mtot [1.3/22600] Uncertainty in TotMass
63- 69 E7.2 Msun Mvir [0.04/15800] Virial Mass,
assuming virial param=1
71- 77 E7.2 Msun e_Mvir [0.01/8280] Mvir uncertainty
79- 83 F5.3 km/s LW [0.01/2.3] Measured linewidth
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Note (1): The total H2 mass calculated using a 13CO(2-1)/H2 conversion
factor of 3.2*10^-7, Fujii+ (2014ApJ...796..123F 2014ApJ...796..123F).
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 12-Nov-2018