J/A+A/594/A117 CO-H2 and complex organic molecules in TMC-1C (Potapov+, 2016)
The CO-H2 van der Waals complex and complex organic molecules in cold
molecular clouds: A TMC-1C survey.
Potapov A., Sanchez-Monge A., Schilke P., Graf U.U., Moeller T.,
Schlemmer S.
<Astron. Astrophys. 594, A117 (2016)>
=2016A&A...594A.117P 2016A&A...594A.117P (SIMBAD/NED BibCode)
ADC_Keywords: Interstellar medium; Molecular clouds; Line Profiles; Radio lines
Keywords: astrochemistry - molecular processes - methods: observational -
techniques: spectroscopic - radio lines: ISM - ISM: molecules
Abstract:
Almost 200 different species have been detected in the interstellar
medium (ISM) during the last decades, revealing not only simple
species but complex molecules with more than 6 atoms. Other exotic
compounds, like the weakly-bound dimer (H2)2, have also been
detected in astronomical sources like Jupiter. We aim at detecting for
the first time the CO-H2 van der Waals complex in the ISM, which if
detected can be a sensitive indicator for low temperatures. We use the
IRAM30m telescope, located in Pico Veleta (Spain), to search for the
CO-H2 complex in a cold, dense core in TMC-1C (with a temperature of
10K). All the brightest CO-H2 transitions in the 3mm (80-110GHz)
band have been observed with a spectral resolution of 0.5-0.7km/s,
reaching a rms noise level of 2mK. The simultaneous observation of a
broad frequency band, 16GHz, has allowed us to conduct a serendipitous
spectral line survey. No lines belonging to the CO-H2 complex have
been detected. We have set up a new, more stringent upper limit for
its abundance to be [CO-H2]/[CO]=5x10-6, while we expect the
abundance of the complex to be in the range 10-8-10-3. The
spectral line survey has allowed us to detect 75 lines associated with
41 different species (including isotopologues). We detect a number of
complex organic species, e.g. methyl cyanide (CH3CN), methanol
(CH3OH), propyne (CH3CCH) and ketene (CH2CO), associated with
cold gas (excitation temperatures about 7K), confirming the presence
of these complex species not only in warm objects but also in cold
regimes.
Description:
Observed spectrum of TMC-1C, with coordinates: RA(J2000)=04:41:16.1
and Dec(J2000)=25:49:43.8. The observations were conducted with the
IRAM30m radiotelescope in the frequency ranges 85.87-93.65GHz and
101.55-109.33GHz.
The ascii-files contain the data in two columns. First column has the
rest frequency in MHz. Second column has the line brightness in K
(main beam temperature units).
Objects:
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RA (2000) DE Designation(s)
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04 41 38.8 +26 00 42 TMC-1C = Barnard 220
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tmc1clsb.dat 27 41482 Spectrum from the LSB range: 85.87-93.65GHz
tmc1cusb.dat 27 41476 Spectrum from the USB range: 101.55-109.33GHz
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Byte-by-byte Description of file: tmc1clsb.dat tmc1cusb.dat
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Bytes Format Units Label Explanations
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1- 12 F12.3 MHz Freq Rest frequency
13- 27 E15.4 K Tmb Main beam line temperature
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Acknowledgements:
Alexey Potapov, alexey.potapov(at)uni-jena.de
Alvaro Sanchez-Monge, sanchez(at)ph1.uni-koeln.de
(End) A. Sanchez-Monge [Cologne, Germany], P. Vannier [CDS] 20-Sep-2016