J/ApJ/871/251 ALMA obs. of ethyl formate toward Orion KL (Peng+, 2019)
ALMA observations of ethyl formate toward Orion KL.
Peng Y., Rivilla V.M., Zhang Li, Ge J.X., Zhou B.
<Astrophys. J., 871, 251 (2019)>
=2019ApJ...871..251P 2019ApJ...871..251P
ADC_Keywords: Interstellar medium; Molecular data; Radio lines
Keywords: ISM: abundances; ISM: individual objects (Orion KL); ISM: molecules;
radio lines: ISM; stars: formation
Abstract:
Orion KL is one of the prime templates of astrochemical and prebiotic
chemical studies. We wish to explore more organic molecules with
increasing complexity in this region. In particular, we have searched
for one of the most complex organic molecules detected in space so
far, ethyl formate (C2H5OCHO). This species is the next step in
chemical complexity after the simplest member of esters (methyl
formate, CH3OCHO). The mechanisms leading to its formation are still
poorly known. We have used high angular resolution (∼1.5") ALMA
observations covering a large bandwidth from 214 to 247GHz. We have
detected 82 unblended lines of C2H5OCHO (49 and 33 of the trans-
and gauche- conformers, respectively). The line images showed that
C2H5OCHO arises mainly from the compact ridge and the hot
core-southwest regions. The derived rotational temperatures and column
densities are 122±34K, (0.9±0.3)x1016cm-2 for the hot core-SW,
and 103±13K, (0.6±0.3)x1016cm-2 for the compact ridge. The
comparison of spatial distribution and abundance ratios with
chemically related molecules (methyl formate, ethanol, and formic
acid) indicates that C2H5OCHO is likely formed on the surface of
dust grains by addition of CH3 to functional-group radicals
(CH2OCHO) derived from methyl formate (CH3OCHO).
Description:
We used data from the ALMA science verification program. The
observations were carried out with 16 antennas of 12m in 2012 January.
The baseline lengths range from 17 to 265m. A total of 20 spectral
windows of 1.875GHz completely cover a frequency range from 214 to
247GHz.
Objects:
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RA (ICRS) DE Designation(s)
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05 35 14.35 -05 22 35.0 Orion-KL = NAME Orion-KL
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 118 80 Selected unblended transitions of the Trans and
Gauche conformers of ethyl formate (C2H5OCHO)
observed with the ALMA
table2.dat 45 470 Selected unblended transitions of methyl formate
(CH3OCHO) observed with the ALMA
table3.dat 56 205 Transitions of the Trans and Gauche conformers
of ethanol (C2H5OH) observed with the ALMA
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See also:
J/ApJS/156/127 : 350µm molecular line survey of Orion KL (Comito+, 2005)
J/ApJS/181/433 : Spectrum of ethyl formate (Medvedev+, 2009)
J/A+A/532/A32 : HCOOCH3 map of Orion-KL (Favre+, 2011)
J/ApJ/770/L13 : Detection of CH3COOCH3 in Orion (Tercero+, 2013)
J/ApJ/779/119 : HCOOCH2D detection in Orion KL (Coudert+, 2013)
J/ApJ/784/L7 : CH3CH2SH detection in Orion KL (Kolesnikova+, 2014)
J/ApJS/215/25 : Methyl formate (HCOOCH3) observations (Favre+, 2014)
J/A+A/581/A71 : Orion-KL substructure at 1.3mm (Feng+, 2015)
J/A+A/581/A48 : 1.3cm line survey toward Orion KL (Gong+, 2015)
J/ApJ/803/97 : Transitions of methyl formate toward Orion KL (Sakai+, 2015)
J/AJ/154/152 : CARMA 1 cm spectral line survey of Orion-KL (Friedel+, 2017)
J/A+A/604/A32 : Orion BN-KL ALMA view (Pagani+, 2017)
J/A+A/598/A59 : G31.41+0.31 SMA spectra (Rivilla+, 2017)
J/A+A/605/A76 : Spectrum of Orion KL between 41.5 and 50GHz (Rizzo+, 2017)
J/A+A/620/A80 : An incipient hot corino in B1b-S (Marcelino+, 2018)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 1 A1 --- C [GT] Corresponding conformer (G=gauche or
T=trans)
3- 13 F11.7 GHz Freq [213.8/246.2] Rest Frequency
15- 33 A19 --- Quant Transition quantum numbers
35- 40 F6.2 D2 Sij [0.3/157.2] Strength, Sijµ2;
in Debye2 units
42- 44 I3 K Eu [152/411] Upper energy
46- 47 A2 --- flag1 Detection flag, hot core-SW (G1)
49- 51 F3.1 km/s vLSR1 [3.8/8.1]? Radial velocity, hot core-SW,
relative to LSR
53- 55 F3.1 km/s e_vLSR1 [0.1/0.4]? Uncertainty in vLSR1
57- 59 F3.1 km/s dV1 [1.5/4.2]? Linewidth, hot core-SW
61- 63 F3.1 km/s e_dV1 [0.1/0.8]? Uncertainty in dV1
65- 68 F4.2 K Ip1 [0.16/1.76]? Line temperature, hot core-SW
70- 73 F4.2 K e_Ip1 [0.03/0.6]? Uncertainty in Ip1
75- 76 A2 --- l_sig1 [≤ ] Limit flag on σ1
77- 78 I2 --- sig1 [3/37]? Detection level, hot core-SW;
in units of σ0
80- 81 A2 --- flag2 Detection flag, compact ridge (G1)
83- 85 F3.1 km/s vLSR2 [6.2/8.2]? Radial velocity, compact ridge,
relative to LSR
87- 89 F3.1 km/s e_vLSR2 [0.1/1.3]? Uncertainty in vLSR2
91- 93 F3.1 km/s dV2 [1.3/2.8]? Linewidth, compact ridge
95- 97 F3.1 km/s e_dV2 [0.1/0.9]? Uncertainty in dV2
99-103 F5.3 K Ip2 [0.128/1.73]? Line temperature, compact ridge
105-109 F5.3 K e_Ip2 [0.006/0.11]? Uncertainty in Ip2
111-112 I2 --- sig2 [4/24]? Detection level, compact ridge;
in units of σ0
114-118 F5.3 K sig0 [0.007/0.09] 1σ spectrum uncertainty
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Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 F9.5 GHz Freq [214.2/246.7] Rest Frequency
11- 30 A20 --- Quant Transition quantum numbers
32- 36 F5.2 D2 Sij [0.02/58.17] Strength, Sijµ2
in Debye2
38- 40 I3 K Eu [23/797] Upper energy, K
42- 43 A2 --- hotcore Detection, hot core-SW (G1)
45- 45 A1 --- ridge Detection, ridge (G1)
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Byte-by-byte Description of file: table3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 1 A1 --- C [GT] Corresponding conformer (G=gauche or T=trans)
3- 11 F9.5 GHz Freq [213.7/246.5] Rest Frequency
13- 41 A29 --- Quant Transition quantum numbers
43- 47 F5.2 D2 Sij [0.32/50.23] Strength, Sijµ2
in Debye2
49- 51 I3 K Eu [24/672] Upper energy
53- 53 A1 --- hotcore Detection, hot core-SW (G1)
55- 56 A2 --- ridge Detection, ridge (G1)
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Global notes:
Note (G1): Detection flags as follows:
Y = Yes, detected
B = Yes, blended;
PB = Yes, partial blend;
ND = Not detected.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 30-Jul-2020