J/ApJ/770/L13 Detection of CH3COOCH3 in Orion (Tercero+, 2013)
Discovery of methyl acetate and gauche ethyl formate in Orion.
Tercero B., Kleiner I., Cernicharo J., Nguyen H.V.L., Lopez A.,
Munoz Caro G.M.
<Astrophys. J., 770, L13 (2013)>
=2013ApJ...770L..13T 2013ApJ...770L..13T
ADC_Keywords: Atomic physics ; Molecular clouds ; Radio lines
Keywords: ISM: abundances; ISM: individual: Orion KL;
ISM: molecules; line: identification; molecular data
Abstract:
We report on the discovery of methyl acetate, CH3COOCH3, through
the detection of a large number of rotational lines from each one of
the spin states of the molecule: AA species (A1 or A2), EA species
(E1), AE species (E2), and EE species (E3 or E4). We also
report, for the first time in space, the detection of the gauche
conformer of ethyl formate, CH3CH2OCOH, in the same source. The
trans conformer is also detected for the first time outside the
Galactic center source SgrB2. From the derived velocity of the
emission of methyl acetate, we conclude that it arises mainly from the
compact ridge region with a total column density of
(4.2±0.5)x1015/cm2. The derived rotational temperature is 150K.
The column density for each conformer of ethyl formate, trans and
gauche, is (4.5±1.0)x1014/cm2. Their abundance ratio indicates a
kinetic temperature of 135K for the emitting gas and suggests that
gas-phase reactions could participate efficiently in the formation of
both conformers in addition to cold ice mantle reactions on the
surface of dust grains.
Description:
The observations were carried out using the IRAM 30m radiotelescope,
covering the following frequency ranges: 80-115.5GHz, 130-178GHz, and
197-281GHz, during several periods (see Tercero et al.
2010A&A...517A..96T 2010A&A...517A..96T). System temperatures were in the range 200-800K
for the 1.3mm receivers, 200-500K for the 2mm receivers, and 100-350K
for the 3mm receivers, depending on the particular frequency, weather
conditions, and source elevation. The observations were carried out
during September 2004 (3mm and 1.3mm windows), March 2005 (full 2mm
window), April 2005 (completion of 3mm and 1.3mm windows), and January
2007 (maps and pointed observations at particular positions). We
pointed the observations toward IRc2 at RAJ2000=5:35:14.5,
DEJ2000=-5:22:30.0.
Objects:
-------------------------------------------------
RA (ICRS) DE Designation(s)
-------------------------------------------------
05 35 14.5 -05 22 30 IRc2 = NAME KL IRC2
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 129 730 Detected lines of CH3COOCH3 at IRAM (30m)
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See also:
J/A+A/572/A44 : Vibrationally excited vinyl cyanide in Orion-KL (Lopez+, 2014)
J/ApJ/768/81 : Ethyl cyanide, CH3CH2CN, vibrational states (Daly+, 2013)
J/A+A/559/A51 : HC3N in Orion KL (Esplugues+, 2013)
J/A+A/548/A71 : Spectroscopy and ISM detection of formamide (Motiyenko+, 2012)
J/A+A/538/A119 : 18O-methyl formate (HCO18OCH3) spectrum (Tercero+ 2012)
J/A+A/532/A32 : HCOOCH3 map of Orion-KL (Favre+, 2011)
J/ApJ/714/1120 : Rotational spectrum and DCOOCH3 in Orion (Margules+, 2010)
J/A+A/500/1109 : Rotational spectrum of HCOO13CH3 (Carvajal+, 2009)
J/A+A/493/565 : Deuterated and 15N ethyl cyanides (Margules+, 2009)
J/A+A/473/177 : A search for pre-biotic molecules (Wirstrom+, 2007)
J/A+A/466/255 : Isotopic ethyl cyanide (Demyk+, 2007)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 2 I2 --- J [6/30] J quantum number of upper level
4- 6 I3 --- Ka [-17/18] Ka quantum number of upper level
8- 9 I2 --- Kc [0/28] Kc quantum number of upper level
11- 12 I2 --- p [-1/1]? Parity of upper level
14- 15 I2 --- J' [5/30] J' quantum number of lower level
17- 19 I3 --- K'a [-16/17] K'a quantum number of lower level
21- 22 I2 --- K'c [0/29] K'c quantum number of lower level
24- 25 I2 --- p' [-1/1]? Parity of lower level
27- 28 A2 --- State Molecule symmetry state: AA (A1/A2),
EA (E1), AE (E2), E3 or E4
30- 39 F10.3 MHz Flab [82779/277629] Predicted lab frequency
41- 45 F5.3 MHz e_Flab [0.006/3.4] Error in Flab
47- 51 F5.1 K Eu [15.5/217.4] Upper level energy
53- 57 F5.2 D2 Sijmu2 [3.2/71.8] Line strength Sijµ2
59- 66 F8.1 MHz Fobs [82780/277629] Observed frequency assuming
a vLSR of 8km/s
68 A1 --- f_Fobs [d] d = blended with previous line
70- 73 F4.2 K Tmb [0.02/0.7]? Mean beam temperature
75-129 A55 --- Blend Blended line identifier (U=unknown)
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 13-Jan-2015