The increasing chemical complexity of the Taurus dark clouds - Detection of CH3CCH and C4H

Irvine, William M.; Höglund, B.; Friberg, Per; Askne, J.; Elldér, J.

doi:10.1086/183637

Cited by 71 publications

(44 citation statements)

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“…The butadiynyl radical was first reported by Guélin et al (1978) toward IRC+10216 and has been observed toward dark clouds by Irvine et al (1981). It is present in translucent clouds with a quite high abundance of a few 10 −8 relative to H 2 (Turner 2000).…”

Section: B23 C 4 Hmentioning

confidence: 91%

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Molecules atz= 0.89

Müller

Beelen

Guèlin

et al. 2011

A&A

164

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: B23 C 4 Hmentioning

confidence: 91%

“…It is observed in dark clouds (e.g., Irvine et al 1981) and has been detected in the nearby starburst galaxies NGC253, NGC4945 and M82 (e.g. Mauersberger et al 1991;Wang et al 2004).…”

Section: B13 Ch 3 Cchmentioning

confidence: 94%

Molecules atz= 0.89

Müller

Beelen

Guèlin

et al. 2011

A&A

164

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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“…the discussion for ▶ C 3 N). Subsequently, this radical was also detected in interstellar molecular clouds (Irvine et al 1981).…”

Section: See Alsomentioning

confidence: 85%