The Millimeter- and Submillimeter-Wave Spectrum of HC3N in the Ground and Vibrationally Excited States

Thorwirth, Sven; Müller, H. S. P.; Winnewisser, G.

doi:10.1006/jmsp.2000.8209

Cited by 64 publications

(52 citation statements)

References 20 publications

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“…All other cyanoacetylene predictions were also taken from the CDMS. The 7 = 1 predictions of the main species are based on Thorwirth et al (2000) with data in the range of our survey from Yamada & Creswell (1986). All predictions of isotopologues containing one or two 13 C are based on Thorwirth et al (2001), and those for HC 15 3 N on Fayt et al (2004).…”

Section: Spectroscopic Predictionsmentioning

confidence: 99%

Exploring molecular complexity with ALMA (EMoCA): Deuterated complex organic molecules in Sagittarius B2(N2)

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Müller

Garrod

et al. 2016

A&A

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Context. Deuteration is a powerful tracer of the history of the cold prestellar phase in star-forming regions. Apart from methanol, little is known about deuterium fractionation of complex organic molecules in the interstellar medium, especially in regions forming high-mass stars. Aims. Our goal is to detect deuterated complex organic molecules toward the high mass star-forming region Sagittarius B2 (Sgr B2) and derive the level of deuteration for these molecules. Methods. We use a complete 3-mm spectral line survey performed with the Atacama Large Millimeter/submillimeter Array (ALMA) to search for deuterated complex organic molecules toward the hot molecular core Sgr B2(N2). We constructed population diagrams and integrated intensity maps to fit rotational temperatures and emission sizes for each molecule. Column densities are derived by modeling the full spectrum under the assumption of local thermodynamic equilibrium. We compare the results to predictions of two astrochemical models that treat the deuteration process. Results. We report the detection of CH 2 DCN toward Sgr B2(N2) with a deuteration level of 0.4%, and tentative detections of CH 2 DOH, CH 2 DCH 2 CN, the chiral molecule CH 3 CHDCN, and DC 3 N with levels in the range 0.05%-0.12%. A stringent deuteration upper limit is obtained for CH 3 OD (<0.07%). Upper limits in the range 0.5-1.8% are derived for the three deuterated isotopologues of vinyl cyanide, the four deuterated species of ethanol, and CH 2 DOCHO. Ethyl cyanide is less deuterated than methyl cyanide by at least a factor five. The [CH 2 DOH]/[CH 3 OD] abundance ratio is higher than 1.8. It may still be consistent with the value obtained in Orion KL. Except for methyl cyanide, the measured deuteration levels lie at least a factor four below the predictions of current astrochemical models. The deuteration levels in Sgr B2(N2) are also lower than in Orion KL by a factor of a few up to a factor ten. Conclusions. The discrepancy between the deuteration levels of Sgr B2(N2) and the predictions of chemical models, and the difference between Sgr B2(N2) and Orion KL may both be due to the higher kinetic temperatures that characterize the Galactic center region compared to nearby clouds. Alternatively, they may result from a lower overall abundance of deuterium itself in the Galactic center region by up to a factor ten.

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Section: Spectroscopic Predictionsmentioning

confidence: 99%

Exploring molecular complexity with ALMA (EMoCA): Deuterated complex organic molecules in Sagittarius B2(N2)

Беллоче

Müller

Garrod

et al. 2016

A&A

200

345

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“…Most entries for the main isotopologue are based on Thorwirth et al (2000a). Entries of the interacting 4 = 1/ 7 = 4/ 5 = 7 = 1/ 6 = 2 states were generated by extension and modification of Yamada & Creswell (1986).…”

Section: Cyanoacetylene Hc 3 Nmentioning

confidence: 99%

Complex organic molecules in the interstellar medium: IRAM 30 m line survey of Sagittarius B2(N) and (M)

Беллоче

Müller

Menten

et al. 2013

A&A

390

523

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Context. The discovery of amino acids in meteorites fallen to Earth and the detection of glycine, the simplest of them, in samples returned from a comet to Earth strongly suggest that the chemistry of the interstellar medium is capable of producing such complex organic molecules and that they may be widespread in our Galaxy. Aims. Our goal is to investigate the degree of chemical complexity that can be reached in the interstellar medium, in particular in dense star-forming regions. Methods. We performed an unbiased, spectral line survey toward Sgr B2(N) and (M), two regions where high-mass stars are formed, with the IRAM 30 m telescope in the 3 mm atmospheric transmission window. Partial surveys at 2 and 1.3 mm were performed in parallel. The spectra were analyzed with a simple radiative transfer model that assumes local thermodynamic equilibrium but takes optical depth effects into account. Results. About 3675 and 945 spectral lines with a peak signal-to-noise ratio higher than 4 are detected at 3 mm toward Sgr B2(N) and (M), i.e. about 102 and 26 lines per GHz, respectively. This represents an increase by about a factor of two over previous surveys of Sgr B2. About 70% and 47% of the lines detected toward Sgr B2(N) and (M) are identified and assigned to 56 and 46 distinct molecules as well as to 66 and 54 less abundant isotopologues of these molecules, respectively. In addition, we report the detection of transitions from 59 and 24 catalog entries corresponding to vibrationally or torsionally excited states of some of these molecules, respectively, up to a vibration energy of 1400 cm −1 (2000 K). Excitation temperatures and column densities were derived for each species but should be used with caution. The rotation temperatures of the detected complex molecules typically range from ∼50 to 200 K. Among the detected molecules, aminoacetonitrile, n-propyl cyanide, and ethyl formate were reported for the first time in space based on this survey, as were five rare isotopologues of vinyl cyanide, cyanoacetylene, and hydrogen cyanide. We also report the detection of transitions from within twelve new vibrationally or torsionally excited states of known molecules. Absorption features produced by diffuse clouds along the line of sight are detected in transitions with low rotation quantum numbers of many simple molecules and are modeled with ∼30-40 velocity components with typical linewidths of ∼3-5 km s −1 . Conclusions. Although the large number of unidentified lines may still allow future identification of new molecules, we expect most of these lines to belong to vibrationally or torsionally excited states or to rare isotopologues of known molecules for which spectroscopic predictions are currently missing. Significant progress in extending the inventory of complex organic molecules in Sgr B2(N) and deriving tighter constraints on their location, origin, and abundance is expected in the near future thanks to an ongoing spectral line survey at 3 mm with ALMA in its cycles 0 and 1. The present single-dish surve...

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“…We have detected several vibrationally excited states of HC 3 N throughout the region and also the three 13 C singly substituted isotopologues, H 13 CCCN, HC 13 CCN, and HCC 13 CN. Spectroscopic data are taken from Thorwirth et al (2000), which is the most recent published measurement for HC 3 N, and from Thorwirth et al (2001) for the 13 C isotopologues. The highest energy vibrationally excited state we can report with confidence is the 6 = 7 = 1 state, at E up ≈ 1170 K and the emission is located near the HC.…”

Section: Vibrationally Excited Hc 3 N and 13 C Singly Substituted Cyamentioning

confidence: 99%

The complexity of Orion: an ALMA view

Pagani

Favre

Goldsmith

et al. 2017

A&A

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Context. We wish to improve our understanding of the Orion central star formation region (Orion-KL) and disentangle its complexity. Aims. We collected data with ALMA during cycle 2 in 16 GHz of total bandwidth spread between 215.1 and 252.0 GHz with a typical sensitivity of 5 mJy/beam (2.3 mJy/beam from 233.4 to 234.4 GHz) and a typical beam size of 1 . 7 × 1 . 0 (average position angle of 89 • ). We produced a continuum map and studied the emission lines in nine remarkable infrared spots in the region including the hot core and the compact ridge, plus the recently discovered ethylene glycol peak. Methods. We present the data, and report the detection of several species not previously seen in Orion, including n-and i-propyl cyanide (C 3 H 7 CN), and the tentative detection of a number of other species including glycolaldehyde (CH 2 (OH)CHO). The first detections of gGg ethylene glycol (gGg (CH 2 OH) 2 ) and of acetic acid (CH 3 COOH) in Orion are presented in a companion paper. We also report the possible detection of several vibrationally excited states of cyanoacetylene (HC 3 N), and of its 13 C isotopologues. We were not able to detect the 16 O 18 O line predicted by our detection of O 2 with Herschel, due to blending with a nearby line of vibrationally excited ethyl cyanide. We do not confirm the tentative detection of hexatriynyl (C 6 H) and cyanohexatriyne (HC 7 N) reported previously, or of hydrogen peroxide (H 2 O 2 ) emission. Results. We report a complex velocity structure only partially revealed before. Components as extreme as −7 and +19 km s −1 are detected inside the hot region. Thanks to different opacities of various velocity components, in some cases we can position these components along the line of sight. We propose that the systematically redshifted and blueshifted wings of several species observed in the northern part of the region are linked to the explosion that occurred ∼500 yr ago. The compact ridge, noticeably farther south displays extremely narrow lines (∼1 km s −1 ) revealing a quiescent region that has not been affected by this explosion. This probably indicates that the compact ridge is either over 10 000 au in front of or behind the rest of the region. Conclusions. Many lines remain unidentified, and only a detailed modeling of all known species, including vibrational states of isotopologues combined with the detailed spatial analysis offered by ALMA enriched with zero-spacing data, will allow new species to be detected.

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The Millimeter- and Submillimeter-Wave Spectrum of HC3N in the Ground and Vibrationally Excited States

Cited by 64 publications

References 20 publications

Exploring molecular complexity with ALMA (EMoCA): Deuterated complex organic molecules in Sagittarius B2(N2)

Exploring molecular complexity with ALMA (EMoCA): Deuterated complex organic molecules in Sagittarius B2(N2)

Complex organic molecules in the interstellar medium: IRAM 30 m line survey of Sagittarius B2(N) and (M)

The complexity of Orion: an ALMA view

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