J/A+A/644/A84 GUAPOS. identified transitions of C2H4O2 (Mininni+, 2020)
The GUAPOS project: G31.41+0.31 Unbiased ALMA sPectral Observational Survey.
I. Isomers of C2H4O2.
Mininni C., Beltran M.T., Rivilla V.M., Sanchez-Monge A., Fontani F.,
Moeller T., Cesaroni R., Schilke P., Viti S., Jimenez-Serra I., Colzi L.,
Lorenzani A., Testi L.
<Astron. Astrophys. 644, A84 (2020)>
=2020A&A...644A..84M 2020A&A...644A..84M (SIMBAD/NED BibCode)
ADC_Keywords: Star Forming Region ; Radio lines
Keywords: astrochemistry - ISM: molecules - stars: formation -
ISM: individual objects: G31.41+0.31
Abstract:
We present an unbiased spectral survey of one of the most chemically
rich hot molecular cores located outside the Galactic Center, in the
high-mass star-forming region G31.41+0.31. In this first paper, we
discuss the detection and relative abundances of the three isomers of
C2H4O2: methyl formate, glycolaldehyde, and acetic acid.
Observations were carried out with the ALMA interferometer, covering
all of band 3 (∼32GHz bandwidth) with an angular resolution of
1.2"x1.2" (∼4400aux4400au) and a spectral resolution of ∼0.488MHz.
The transitions of the three molecules have been analyzed with the
software XCLASS to determine the physical parameters of the emitted
gas. The comparison with chemical models in literature suggests the
necessity of grain-surface routes for the formation of methyl formate
in G31, while for glycolaldehyde both grain-surface reactions and
gas-phase chemistry could be able to explain the observations.
Description:
Tables of identified transitions of the 3 isomers of C2H4O2 in
the GUAPOS survey towards G31.41+0.31. In the 3 tables the
frequencies, Einstein coefficients, Energies of the upper level,
degeneracies of the upper level, quantum numbers of the upper and
lower levels and the optical depths of the lines calculated using the
column density and the excitation temperature of the best fit are
given. The first column is a flag indicating the most unblended
transitions used for the fit.
Objects:
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RA (2000) DE Designation(s)
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8 47 34.49 -01 12 40.3 G31.41+0.31 = GAL 031.4+00.3
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
acetic.dat 82 84 Identified transitions of acetic acid
glycol.dat 79 23 Identified transitions of glycolaldehyde
methyl.dat 82 255 Identified transitions of methyl formate
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Byte-by-byte Description of file: acetic.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1 A1 --- Flag Flag (1)
3- 16 A14 --- State Molecular vibrational state
18- 28 F11.4 MHz Freq Rest frequency
30- 38 E9.4 s-1 AE Einstein coefficient
40- 45 F6.2 K Eu Upper state energy Eu
47- 48 I2 --- gu Degeneracy of the upper state gu
50- 51 I2 --- Ju Upper state quantum number J
53- 54 I2 --- Kau Upper state quantum number Ka
56- 57 I2 --- Kcu Upper state quantum number Kc
59- 60 A2 --- A1/A2/Eu State A1/A2/E
62- 63 I2 --- Jl Lower state quantum number J
65- 66 I2 --- Kal Lower state quantum number Ka
68- 69 I2 --- Kcl Lower state quantum number Kc
71- 72 A2 --- A1/A2/El State A1/A2/E
74- 82 E9.4 --- tau Optical depth at the center of the line
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Note (1): Flag as follows:
0 = default value
1 = transitions selected for the fit presented in Sect. 4.2
2 = transitions selected for the fit including high-energy transitions in
Section 4.4
9 = possible contributions to other identified transitions
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Byte-by-byte Description of file: glycol.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1 A1 --- Flag Flag (1)
3- 17 A15 --- State Molecular vibrational state
19- 29 F11.4 MHz Freq Rest frequency
31- 41 E11.6 s-1 AE Einstein coefficient
43- 48 F6.2 K Eu Upper state energy E_u
50- 51 I2 --- gu Degeneracy of the upper state gu
53- 54 I2 --- Ju Upper state quantum number J
56- 57 I2 --- Kau Upper state quantum number Ka
59- 60 I2 --- Kcu Upper state quantum number Kc
62- 63 I2 --- Jl Lower state quantum number J
65- 66 I2 --- Kal Lower state quantum number Ka
68- 69 I2 --- Kcl Lower state quantum number Kc
71- 79 F9.7 --- Tau Optical depth at the center of the line
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Note (1): Flag as follows:
0 = default value
1 = transitions selected for the fit presented in Sect. 4.3
9 = possible contributions to other identified transitions
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Byte-by-byte Description of file: methyl.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1 A1 --- Flag Flag (1)
3- 16 A14 --- State Molecular vibrational state
18- 28 F11.4 MHz Freq Rest frequency
30- 38 E9.4 s-1 AE Einstein coefficient
40- 46 F7.2 K Eu Upper state energy E_u
48- 50 I3 --- gu Degeneracy of the upper state g_u
52- 53 I2 --- Ju Upper state quantum number J
55- 56 I2 --- Kau Upper state quantum number K_a
58- 59 I2 --- Kcu Upper state quantum number K_c
61 A1 --- A/Eu State A/E
63- 64 I2 --- Jl Lower state quantum number J
66- 67 I2 --- Kal Lower state quantum number K_a
69- 70 I2 --- Kcl Lower state quantum number K_c
72 A1 --- A/El State A/E
74- 82 E9.4 --- tau Optical depth at the center of the line
--------------------------------------------------------------------------------
Note (1): Flag as follows:
0 = default value
1 = transitions selected for the fit presented in Sect. 4.1
2 = transitions selected for the fit including high-energy transitions in
Section 4.4
9 = possible contributions to other identified transitions
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Acknowledgements:
Chiara Mininni, chiara.mininni.astro(at)gmail.com
(End) Patricia Vannier [CDS] 20-Oct-2020