J/ApJS/215/25 Methyl formate (HCOOCH3) observations (Favre+, 2014)
13C-Methyl formate: observations of a sample of high-mass star-forming regions
including Orion-KL and spectroscopic characterization.
Favre C., Carvajal M., Field D., Jorgensen J.K., Bisschop S.E.,
Brouillet N., Despois D., Baudry A., Kleiner I., Bergin E.A.,
Crockett N.R., Neill J.L., Margules L., Huet T.R., Demaison J.
<Astrophys. J. Suppl. Ser., 215, 25 (2014)>
=2014ApJS..215...25F 2014ApJS..215...25F
ADC_Keywords: Atomic physics ; Radio lines ; Interstellar medium
Keywords: astrochemistry; ISM: abundances; line: identification;
methods: data analysis; methods: laboratory: molecular;
techniques: spectroscopic
Abstract:
We have surveyed a sample of massive star-forming regions located over
a range of distances from the Galactic center for methyl formate,
HCOOCH3, and its isotopologues H13COOCH3 and HCOO13CH3. The
observations were carried out with the APEX telescope in the frequency
range 283.4-287.4GHz. Based on the APEX observations, we report
tentative detections of the 13C-methyl formate isotopologue
HCOO13CH3toward the following four massive star-forming regions:
Sgr B2(N-LMH), NGC 6334 IRS 1, W51 e2, and G19.61-0.23. In addition,
we have used the 1mm ALMA science verification observations of
Orion-KL and confirm the detection of the 13C-methyl formate species
in Orion-KL and image its spatial distribution. Our analysis shows
that the 12C/13C isotope ratio in methyl formate toward the
Orion-KL Compact Ridge and Hot Core-SW components (68.4±10.1 and
71.4±7.8, respectively) are, for both the 13C-methyl formate
isotopologues, commensurate with the average 12C/13C ratio of CO
derived toward Orion-KL. Likewise, regarding the other sources, our
results are consistent with the 12C/13C in CO. We also report the
spectroscopic characterization, which includes a complete partition
function, of the complex H13COOCH3 and HCOO13CH3species. New
spectroscopic data for both isotopomers H13COOCH3and
HCOO13CH3, presented in this study, have made it possible to
measure this fundamentally important isotope ratio in a large organic
molecule for the first time.
Description:
Orion-KL was observed with 16 antennas (each 12m in diameter) on 2012
January 20 as part of the ALMA Science Verification (ALMA-SV) program.
The observations cover the frequency range 213.7GHz to 246.6GHz in
band 6. The phase-tracking center was RAJ2000=05:35:14.35,
DEJ2000=-05:22:35.00. We used the public release calibrated data that
are available through the ALMA Science Verification Portal.
Observations of seven high-mass star-forming regions (including
Orion-KL) were performed with the APEX telescope on Llano de
Chajnantor, Northern Chile, between 2012 March and August. The Swedish
Heterodyne Facility Instrument (SHeFi) APEX-2 receiver, which operates
with an IF range of 4-8GHz, was used in single sideband mode in
connection with the eXtended bandwidth Fast Fourier Transform
Spectrometer (XFFTS) backend in the frequency range 283.4GHz-287.4GHz.
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
table12.dat 68 867 Transitions of 12C and 13C-methyl formate
observed with the ALMA telescope
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See also:
J/A+A/568/A58 : HCOO13CH3 rotational spectrum (Haykal+, 2014)
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/ApJS/190/315 : Rotational spectrum of H13COOCH3 (Carvajal+, 2010)
J/ApJ/724/994 : Cyano- to methanol and ammonia observations (Braakman+, 2010)
J/ApJ/714/1120 : Rotational spectrum and DCOOCH3 in Orion (Margules+, 2010)
J/A+A/500/1109 : Rotational spectrum of HCOO13CH3 (Carvajal+, 2009)
J/ApJS/169/28 : Rotational transitions of Methyl carbamate (Groner+, 2007)
http://www.astro.uni-koeln.de/cdms : The Cologne database for molecular
spectroscopy
Byte-by-byte Description of file: table12.dat
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Bytes Format Units Label Explanations
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1- 15 A15 --- Mol Molecule (HCOOCH3, HCOO13CH3 or
H13COOCH3) (1)
17- 25 F9.2 MHz Freq [213882/246623.2] Frequency
27 A1 --- f_Freq [*] Flag on Freq (2)
29- 61 A33 --- Trans Transition
63- 65 I3 K Eup [99/504] Upper level energy
67- 68 I2 D2 Smu2 [10/74] Sµ2 coefficient
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Note (1): This Table lists the detected, blended, partially blended and
optically thin lines of HCOOCH3. Transitions that are emitting with
an intensity less or equal to 3 times the noise level and that we
used to constrain our model are also listed.
Note (2):
* = a transition we estimate to be optically thick.
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 09-Feb-2015