Observations of some oxygen-containing and sulfur-containing organic molecules in cold dark clouds

Irvine, William M.; Friberg, Per; Kaifu, Norio; Kawaguchi, Kenichi; Kitamura, Yoshihisa; Matthews, H. E.; Minh, Young Chol; Saito, Shuji; Ukita, Nobuharu; Yamamoto, Shun

doi:10.1086/167643

Cited by 75 publications

(49 citation statements)

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“…It is observed in star forming regions and cold dark clouds (e.g. Irvine et al 1989;Minh et al 1991) as well as in translucent clouds (Turner 1996). Tentative extragalactic detections are reported by Heikkilä et al (1999) in the LMC and Martín et al (2006) in NGC253.…”

Section: B20 H 2 Csmentioning

confidence: 89%

Molecules atz= 0.89

Müller

Beelen

Guèlin

et al. 2011

A&A

161

284

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We present the results of a 7 mm spectral survey of molecular absorption lines originating in the disk of a z = 0.89 spiral galaxy located in front of the quasar PKS 1830−211. Our survey was performed with the Australia Telescope Compact Array and covers the frequency interval 30-50 GHz, corresponding to the rest-frame frequency interval 57-94 GHz. A total of 28 different species, plus 8 isotopic variants, were detected toward the south-west absorption region, located about 2 kpc from the center of the z = 0.89 galaxy, which therefore has the largest number of detected molecular species of any extragalactic object so far. The results of our rotation diagram analysis show that the rotation temperatures are close to the cosmic microwave background temperature of 5.14 K that we expect to measure at z = 0.89, whereas the kinetic temperature is one order of magnitude higher, indicating that the gas is subthermally excited. The molecular fractional abundances are found to be in-between those in typical Galactic diffuse and translucent clouds, and clearly deviate from those observed in the dark cloud TMC 1 or in the Galactic center giant molecular cloud Sgr B2. The isotopic ratios of carbon, nitrogen, oxygen, and silicon deviate significantly from the solar values, which can be linked to the young age of the z = 0.89 galaxy and a release of nucleosynthesis products dominated by massive stars. Toward the north-east absorption region, where the extinction and column density of gas is roughly one order of magnitude lower than toward the SW absorption region, only a handful of molecules are detected. Their relative abundances are comparable to those in Galactic diffuse clouds. We also report the discovery of several new absorption components, with velocities spanning between −300 and +170 km s −1 . Finally, the line centroids of several species (e.g., CH 3 OH, NH 3 ) are found to be significantly offset from the average velocity. If caused by a variation in the proton-to-electron mass ratio μ with redshift, these offsets yield an upper limit | Δμ μ | < 4×10 −6 , which takes into account the kinematical noise produced by the velocity dispersion measured from a large number of molecular species.

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Section: B20 H 2 Csmentioning

confidence: 89%

Molecules atz= 0.89

Müller

Beelen

Guèlin

et al. 2011

A&A

161

284

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“…All these species are known to exist in cold dense clouds [7,8,9,10,11]. Thus, their detection in IRC +10216 stress the similarity between the chemistry taking place in cold dense clouds and in the CSEs of C-rich AGB stars.…”

Section: Introductionmentioning

confidence: 87%

Understanding the chemical complexity in Circumstellar Envelopes of C-Rich AGB stars: the case of IRC +10216

Agúndez

Cernicharo

Pardo

et al. 2007

Astrophys Space Sci

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The circumstellar envelopes of carbon-rich AGB stars show a chemical complexity that is exemplified by the prototypical object IRC +10216, in which about 60 different molecules have been detected to date. Most of these species are carbon chains of the type C n H, C n H 2 , C n N, HC n N. We present the detection of new species (CH 2 CHCN, CH 2 CN, H 2 CS, CH 3 CCH and C 3 O) achieved thanks to the systematic observation of the full 3 mm window with the IRAM 30m telescope plus some ARO 12m observations. All these species, known to exist in the interstellar medium, are detected for the first time in a circumstellar envelope around an AGB star. These five molecules are most likely formed in the outer expanding envelope rather than in the stellar photosphere. A pure gas phase chemical model of the circumstellar envelope is reasonably successful in explaining the derived abundances, and additionally allows to elucidate the chemical formation routes and to predict the spatial distribution of the detected species.

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“…This species has been found in the interstellar medium 1,2 and in the coma of the Hale-Bopp comet. 3 It has been suggested that it may be a key compound in the formation of glycine (NH 2 CH 2 COOH) in the interstellar medium.…”

Section: ■ Introductionmentioning

confidence: 89%

Dimers of the Higher-Energy Conformer of Formic Acid: Experimental Observation

et al. 2012

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We report on the first experimental observation of formic acid dimers composed of two molecules of the higher-energy cis conformer. The cis−cis formic acid dimers are prepared in an argon matrix by selective vibrational excitation of the ground state trans conformer (deuterated form HCOOD) combined with thermal annealing of the matrix at about 30 K. Five cis−cis formic acid dimers are predicted by ab initio calculations (interaction energies from −16.9 to −27.2 kJ mol −1 ), and these structures are used for the assignment of the experimental spectra. Selective vibrational excitation of the obtained cis−cis dimers leads to the formation of several trans−cis dimers, which supports the proposed assignments.

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Observations of some oxygen-containing and sulfur-containing organic molecules in cold dark clouds

Cited by 75 publications

References 0 publications

Molecules atz= 0.89

Molecules atz= 0.89

Understanding the chemical complexity in Circumstellar Envelopes of C-Rich AGB stars: the case of IRC +10216

Dimers of the Higher-Energy Conformer of Formic Acid: Experimental Observation

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