J/ApJ/845/116 Mapping spectral line survey toward W51 in 3mm (Watanabe+, 2017)
Molecular-cloud-scale chemical composition.
I. A mapping spectral line survey toward W51 in the 3mm band.
Watanabe Y., Nishimura Y., Harada N., Sakai N., Shimonishi T., Aikawa Y.,
Kawamura A., Yamamoto S.
<Astrophys. J., 845, 116 (2017)>
=2017ApJ...845..116W 2017ApJ...845..116W
ADC_Keywords: Molecular clouds ; Spectra, millimetric/submm ; Line Profiles
Interstellar medium
Keywords: ISM: clouds ; ISM: individual objects (W51) ; ISM: molecules
Abstract:
We have conducted a mapping spectral line survey toward the Galactic
giant molecular cloud W51 in the 3mm band with the Mopra 22m telescope
in order to study an averaged chemical composition of the gas extended
over a molecular-cloud scale in our Galaxy. We have observed the area
of 25'x30', which corresponds to 39pcx47pc. The frequency ranges of
the observation are 85.1-101.1GHz and 107.0-114.9GHz. In the spectrum
spatially averaged over the observed area, spectral lines of 12
molecular species and 4 additional isotopologues are identified. An
intensity pattern of the spatially averaged spectrum is found to be
similar to that of the spiral arm in the external galaxy M51,
indicating that these two sources have similar chemical compositions.
The observed area has been classified into five subregions according
to the integrated intensity of 13CO(J=1-0) (I13CO), and
contributions of the fluxes of 11 molecular lines from each subregion
to the averaged spectrum have been evaluated. For most of the
molecular species, 50% or more of the flux comes from the subregions
with I13CO from 25 to 100K.km.s-1, which does not involve active
star-forming regions. Therefore, the molecular-cloud-scale spectrum
observed in the 3mm band hardly represents the chemical composition of
star-forming cores, but mainly represents the chemical composition of
an extended quiescent molecular gas. The present result constitutes a
sound base for interpreting the spectra of external galaxies at a
resolution of a molecular-cloud scale (∼10pc) or larger.
Description:
Observations were carried out with the Mopra 22m telescope in 2013
October and 2014 August and September. An on-the-fly (OTF) mapping
method was employed to cover the 25'x30' area of W51 centered at
(l,b)=(49.4902°,-0.2622°) in the Galactic coordinate. The area
corresponds to 39pcx47pc at the distance of W51. Three frequency
settings were observed to cover the frequency ranges of 85.2-101.1GHz
and 107.0-114.9GHz.
Objects:
----------------------------------------------------------
RA (ICRS) DE Designation(s)
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19 23 50 +14 06.0 W51 = W 51
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table8.dat 93 321 Line parameters of W51 e1/e2
fig2.dat 29 70647 Spectra averaged over all the observed area in W51
and W51 e1/e2 (hot cores)
fig5.dat 26 111552 Averaged spectra in the sub-regions A, B, C, D,
and E
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See also:
J/AJ/127/2031 : Catalog of neighboring galaxies (Karachentsev+, 2004)
J/A+A/455/971 : Organic molecules in the Gal. Center (Requena-Torres+, 2006)
J/ApJS/178/56 : CO observations of LMC Giant Molecular clouds (Fukui+, 2008)
J/ApJS/191/232 : CO survey of W51 molecular cloud (Bieging+, 2010)
J/ApJ/709/424 : HII regions identified with WMAPS and GLIMPSE (Murray+, 2010)
J/ApJ/720/1055 : VBLA observations of W51 Main/South (Sato+, 2010)
J/AJ/147/131 : Abundances of nearby late-type galaxies. I. (Pilyugin+, 2014)
J/A+A/579/A101 : 3mm molecular line survey of 8 AGN (Aladro+, 2015)
J/A+A/582/A91 : NGC 4418 ALMA mm-wave spectral scan (Costagliola+, 2015)
J/A+A/582/A64 : W51/e2 and G34.3+0.2 IRAM spectra (Lykke+, 2015)
J/A+A/595/A27 : JVLA images of W51A (Ginsburg+, 2016)
Byte-by-byte Description of file: table8.dat
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Bytes Format Units Label Explanations
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1- 11 A11 --- Line Line identifier (1)
13- 15 A3 --- f_Line Flag(s) on Line (2)
17- 26 F10.6 GHz Freq [85.2/114.1] Frequency
28- 58 A31 --- Trans Transition
60- 65 F6.1 K Eu [4/1490.1]? Upper state energy
67- 72 F6.2 D2 Smu2 [0.01/386.3]? Dipole moment line strength
74- 78 F5.2 K Tmb [0.06/20.3]? Peak main beam temperature
80- 83 F4.2 K e_Tmb [0.04/0.2]? The 3σ uncertainty in Tmb
85- 89 F5.1 K.km/s Int [0.2/250]? Integrated intensity
91- 93 F3.1 K.km/s e_Int [0.2/2]? The 3σ uncertainty in Int
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Note (1): The position is (l,b)=(49.4898 degrees, -0.3874 degrees), which
corresponds to (RA (J2000), DEC (J2000))=(19:23:43.9,+14:30:35.0).
Note (2): Flag as follows:
c = The line is blended with other transition lines.
d = The upper state energy is calculated from an energy state of 1-1 E.
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Byte-by-byte Description of file: fig2.dat
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Bytes Format Units Label Explanations
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1- 4 A4 --- Reg Region identifier (1)
6- 16 F11.7 GHz Freq [85/115] Rest frequency (2)
18- 29 E12.5 K Tmb [-0.5/20.3] Main beam temperature
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Note (1): Region as follows:
All = This spectrum is prepared by averaging over the all observed area
in W51. The observed area is 25 arcmin x 30 arcmin centered
at (l,b)=(49.4902 degree, -0.2622 degree).
Core = Observation position of W51 e1/e2 is at
RA(J2000):19:23:43.9, DE(J2000):+14:30:35.0.
Note (2): At the LSR velocity of 55km/s which is assumed as
the system velocity.
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Byte-by-byte Description of file: fig5.dat
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Bytes Format Units Label Explanations
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1 A1 --- Reg [A-E] Region identifier (1)
3- 13 F11.7 GHz Freq [85/115] Rest frequency at the LSR velocity
of 55km/s
15- 26 E12.5 K Tmb [-0.3/14.7] Main beam temperature
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Note (1): Region as follows:
A = I13CO>200K.km/s. rms: 20-70mK.
B = 200K.km/s>I13CO>100K.km/s. rms: 10-40mK.
C = 100K.km/s>I13CO>50K.km/s. rms: 8-30mK.
D = 50K.km/s>I13CO>25K.km/s. rms: 5-30mK.
E = 25K.km/s>I13CO. rms: 5-20mK.
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History:
From electronic version of the journal
References:
Nishimura et al. Paper II. 2017ApJ...848...17N 2017ApJ...848...17N
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 05-Apr-2018