J/ApJ/853/175 12CO and 13CO cores & clumps in LHA 120-N 55 (Naslim+, 2018)
ALMA reveals molecular cloud N55 in the Large Magellanic Cloud as a site of
massive star formation.
Naslim N., Tokuda K., Onishi T., Kemper F., Wong T., Morata O., Takada S.,
Harada R., Kawamura A., Saigo K., Indebetouw R., Madden S.C., Hony S.,
Meixner M.
<Astrophys. J., 853, 175-175 (2018)>
=2018ApJ...853..175N 2018ApJ...853..175N (SIMBAD/NED BibCode)
ADC_Keywords: Magellanic Clouds; Molecular clouds; Interstellar medium;
Carbon monoxide; Millimetric/submm sources; Velocity dispersion;
YSOs
Keywords: galaxies: ISM; ISM: molecules; Magellanic Clouds; stars: formation
stars: massive; stars: protostars
Abstract:
We present the molecular cloud properties of N55 in the Large
Magellanic Cloud using 12CO(1-0) and 13CO(1-0) observations
obtained with Atacama Large Millimeter Array. We have done a detailed
study of molecular gas properties, to understand how the cloud
properties of N55 differ from Galactic clouds. Most CO emission
appears clumpy in N55, and molecular cores that have young stellar
objects (YSOs) show larger linewidths and masses. The massive clumps
are associated with high and intermediate mass YSOs. The clump masses
are determined by local thermodynamic equilibrium and virial analysis
of the 12CO and 13CO emissions. These mass estimates lead to the
conclusion that (a) the clumps are in self-gravitational virial
equilibrium, and (b) the 12CO(1-0)-to-H2 conversion factor, XCO,
is 6.5x1020cm-2 (K.km/s)-1. This CO-to-H2 conversion factor
for N55 clumps is measured at a spatial scale of ∼0.67pc, which is
about two times higher than the XCO value of the Orion cloud at a
similar spatial scale. The core mass function of N55 clearly show a
turnover below 200M☉, separating the low-mass end from the
high-mass end. The low-mass end of the 12CO mass spectrum is fitted
with a power law of index 0.5±0.1, while for 13CO it is fitted
with a power law index 0.6±0.2. In the high-mass end, the core mass
spectrum is fitted with a power index of 2.0±0.3 for 12CO, and
with 2.5±0.4 for 13CO. This power law behavior of the core mass
function in N55 is consistent with many Galactic clouds.
Description:
N55 was observed with ALMA in cycle 1 and 2 (2013.1.00214.S and
2012.1.00335.S), using band 3 receivers in spectral windows centered
at 115.27, 110.20, and 109.67GHz, with 70.557kHz (0.2km/s) spectral
resolution.
Objects:
----------------------------------------------------------
RA (ICRS) DE Designation(s)
----------------------------------------------------------
05 32 32.89 -66 24 20.0 N55 = LHA 120-N 55
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 44 18 Positions of identified YSOs and associated clumps
table3.dat 73 57 12CO(1-0) clump (dendrogram trunks) properties
table4.dat 87 43 13CO(1-0) clump (dendrogram trunks) properties
table5.dat 56 64 13CO(1-0) core (dendrogram leaves) properties
table6.dat 47 121 12CO(1-0) core (dendrogram leaves) properties
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See also:
VIII/39 : Composite CO Survey of the Milky Way (Dame+ 1987)
J/ApJS/110/21 : Molecular clouds in Cepheus and Cassiopeia (Yonekura+ 1997)
J/ApJ/551/852 : FCRAO CO survey of the outer Galaxy (Heyer+, 2001)
J/ApJ/639/259 : Sub-mm clumps in Orion B South MoC (Johnstone+, 2006)
J/AJ/132/2268 : SAGE calibration stars (Meixner+, 2006)
J/ApJ/665/1194 : Dense cores in the Orion A cloud survey (Ikeda+, 2007)
J/ApJS/178/56 : CO observations of LMC Giant Molecular clouds (Fukui+, 2008)
J/ApJ/686/948 : CO in extragalactic giant molecular clouds (Bolatto+, 2008)
J/ApJ/691/1560 : Dense core survey in the Orion B cloud (Ikeda+, 2009)
J/ApJ/695/511 : Young massive stars in LHA 120-N 44 (Chen+, 2009)
J/ApJ/699/1092 : Giant molecular clouds (SRBY) (Heyer+, 2009)
J/ApJS/184/172 : High- and intermediate-mass YSOs in the LMC (Gruendl+, 2009)
J/ApJS/197/16 : CO observations of LMC molecular clouds (MAGMA). (Wong+, 2011)
J/ApJS/202/4 : Planck cold clumps survey in the Orion complex (Liu+, 2012)
J/ApJ/774/73 : ALMA CO observations of 30 Dor (Indebetouw+, 2013)
J/ApJ/784/3 : The PAWS catalogs of GMCs and islands in M51 (Colombo+, 2014)
J/AJ/148/124 : Herschel key program Heritage (Seale+, 2014)
Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 2 I2 --- Seq [1/15]? Running sequence number
4 A1 --- f_Seq Flag on Seq (1)
6- 12 F7.4 deg RAYdeg ? YSO right ascension (J2000)
14- 21 F8.4 deg DEYdeg ? YSO declination (J2000)
23- 29 F7.4 deg RAdeg Associated clump right ascension (J2000)
31- 38 F8.4 deg DEdeg Associated clump declination (J2000)
40- 42 I3 --- Clump [2/125]? 13CO clump number ID from Table 5
44 A1 --- f_Clump [*] *: Clump identified in 12CO emission but
not in 13CO
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Note (1): Flag as follows:
a = Spitzer YSOs from Gruendl & Chu (2009, J/ApJS/184/172).
b = Herschel YSOs from Seale et al. (2014, J/AJ/148/124).
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Byte-by-byte Description of file: table[34].dat
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Bytes Format Units Label Explanations
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1- 2 I2 --- Seq [1/57] Running sequence number
4- 10 F7.4 deg RAdeg [82.9/83.2] Right ascension (J2000)
12- 19 F8.4 deg DEdeg [-66.5/-66.3] Declination (J2000)
21- 24 F4.2 pc Rad [0.5/4.3] Radius
26- 29 F4.2 pc e_Rad [0.1/0.6] Rad uncertainty
31- 35 F5.3 km/s Sigv [0.2/2.4] Velocity dispersion, σV
37- 40 F4.2 km/s e_Sigv [0.1/0.6] Sigv uncertainty
42- 46 F5.1 km/s Vel [276/294] Velocity
48- 53 F6.1 K.km/s/pc2 LCO [0.9/2958] CO luminosity
55- 57 F3.1 K.km/s/pc2 e_LCO [0.1/9] LCO uncertainty
59- 63 F5.2 K Tpk [0.9/40] Temperature
65- 69 I5 Msun Mvir [46/21824] Virial mass
71- 73 I3 Msun e_Mvir [30/550] Mvir uncertainty
75- 78 F4.1 10+21cm-2 NH2 [1/27]? H2 column density (only for Table 4)
80- 84 I5 Msun MLTE [66/28278]? LTE mass (only for Table 4)
86- 87 I2 Msun e_MLTE [15/78]? MLTE uncertainty
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Byte-by-byte Description of file: table[56].dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 I3 --- Seq [1/121] Running sequence number
5- 11 F7.4 deg RAdeg [82.9/83.2] Right ascension (J2000)
13- 20 F8.4 deg DEdeg [-66.5/-66.3] Declination (J2000)
22- 25 F4.2 pc Rad [0.4/2] Radius
27- 30 F4.2 km/s SigV [0.1/2] Velocity dispersion, σV
32- 36 F5.1 km/s Vel [275/294] Velocity
38- 42 F5.1 K.km/s/pc2 LCO [0.2/124] CO luminosity
44- 47 I4 Msun Mvir [6/6775] Virial mass
49- 51 F3.1 K Tpk [0.7/6.6]? Temperature (only for Table 5)
53- 56 I4 Msun MLTE [33/1482]? LTE mass (only for Table 5)
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History:
From electronic version of the journal
(End) Emmanuelle Perret [CDS] 06-Oct-2023