J/AJ/147/46 Properties of clumps in the NAN complex (Zhang+, 2014)
Molecular clouds in the North American and Pelican Nebulae: structures.
Zhang S., Xu Y., Yang J.
<Astron. J., 147, 46 (2014)>
=2014AJ....147...46Z 2014AJ....147...46Z
ADC_Keywords: Nebulae ; Molecular clouds ; Velocity dispersion
Keywords: ISM: kinematics and dynamics - ISM: molecules - stars: formation
Abstract:
We present observations of a 4.25deg2 area toward the North American
and Pelican Nebulae in the J=1-0 transitions of 12CO, 13CO, and
C18O. Three molecules show different emission areas with their own
distinct structures. These different density tracers reveal several
dense clouds with a surface density of over 500M☉pc-2 and a
mean H2 column density of 5.8, 3.4, and 11.9x1021/cm2 for 12CO,
13CO, and C18O, respectively. We obtain a total mass of
5.4x104M☉(12CO), 2.0x104M☉(13CO), and
6.1x103M☉(C18O) in the complex. The distribution of
excitation temperature shows two phases of gas: cold gas (∼10K)
spreads across the whole cloud; warm gas (>20K) outlines the edge of
the cloud heated by the W80 HII region. The kinetic structure of the
cloud indicates an expanding shell surrounding the ionized gas
produced by the HII region. There are six discernible regions in the
cloud: the Gulf of Mexico, Caribbean Islands and Sea, and Pelican's
Beak, Hat, and Neck. The areas of 13CO emission range within
2-10pc2 with mass of (1-5)x103M☉ and line width of a few
km/s. The different line properties and signs of star-forming activity
indicate they are in different evolutionary stages. Four filamentary
structures with complicated velocity features are detected along the
dark lane in LDN 935. Furthermore, a total of 611 molecular clumps
within the 13CO tracing cloud are identified using the ClumpFind
algorithm. The properties of the clumps suggest that most of the
clumps are gravitationally bound and at an early stage of evolution
with cold and dense molecular gas.
Description:
We observed the North American (NGC 7000) and Pelican (IC 5070)
Nebulae ("NAN complex") in 12CO(1-0), 13CO(1-0), and C18O(1-0)
with the Purple Mountain Observatory Delingha (PMODLH) 13.7m telescope
as one of the scientific demonstration regions for the Milky Way
Imaging Scroll Painting project (http://www.radioast.nsdc.cn/yhhjindex.php)
from 2011 May 27 to June 3.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table4.dat 90 611 Properties of clumps
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See also:
II/196 : Vilnius Photometry in two Nebulae (Straizys et al., 1993)
J/ApJS/193/25 : The NAN complex. II. MIPS observations (Rebull+, 2011)
J/ApJ/697/787 : The NAN complex. I. IRAC observations (Guieu+, 2009)
Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- Seq [1/611] Running sequential clump number (1)
5- 6 I2 h RAh Hour of Right Ascension (J2000)
8- 9 I2 min RAm Minute of Right Ascension (J2000)
11- 14 F4.1 s RAs Secnd of Right Ascension (J2000)
16 A1 --- DE- Sign of the Declination (J2000)
17- 18 I2 deg DEd Degree of Declination (J2000)
20- 21 I2 arcmin DEm Arcminute of Declination (J2000)
23- 26 F4.1 arcsec DEs Arcsecond of Declination (J2000)
28- 32 F5.2 km/s RVel [-7/10] Rest velocity
34- 38 F5.1 arcsec oRA Size in Right Ascension direction (ΔRA)
40- 44 F5.1 arcsec oDE Size in Declination direction (ΔDE)
46- 49 F4.2 pc Rad Clump radius
51- 54 F4.2 km/s sigma One-dimensional velocity dispersion (σ)
56- 60 F5.2 K Tpeak Temperature of 13CO Peak
62- 66 F5.2 K Tex Excitation temperature
68- 72 F5.1 Msun/pc2 Sigma Surface mass density (Σ)
74- 78 F5.1 cm-3 nH2 H2 volume density
80- 84 F5.1 Msun MLTE Local Thermodynamic Equilibrium (LTE) mass
86- 90 F5.2 --- alpha Virial parameter (αvir) (2)
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Note (1): In the North American (NGC 7000) and Pelican (IC 5070) Nebulae
(the "NAN complex").
Note (2): Defined as the ratio of virial mass to LTE mass
(αvir=Mvir/MLTE), where Mvir is the virial mass
(MVir=1164Rσ2vID[M☉], where the clump size R is in pc,
and three-dimensional velocity dispersion σvID is in km/s.
See Section 4.2 for additional details.
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Sylvain Guehenneux [CDS] 08-Sep-2014