Rotational spectra of HCCCN in some excited vibrational states

Yamada, Kōichi; Creswell, R. A.

doi:10.1016/0022-2852(86)90135-9

Cited by 47 publications

(44 citation statements)

References 11 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: 93%

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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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: 93%

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). The 3 = 1 and 2 = 1 entries are based on Sanz et al (2005).…”

Section: Cyanoacetylene Hc 3 Nmentioning

confidence: 99%

“…The 13 C entries, including the doubly substituted ones, are based on Thorwirth et al (2001), and those of HC 3 15 N on Fayt et al (2004). Additional measurements in the range of our survey were taken from Creswell et al (1977) for the ground vibrational states of the main as well as singly substituted 13 C and 15 N entries, from Yamada et al (1995) for = 0 of the main species, Yamada & Creswell (1986) and Mbosei et al (2000) for several excited states of the main isotopologue, and Thorwirth et al (2001) for the HC 3 15 N entries.…”

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)

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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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“…The v 7 = 1 and v 6 = 1 states are doublets, with single states labeled e and f , depending on the parity of the wave function (Yamada & Creswell 1986). The v 7 = 1e and v 6 = 1 f lines are only ∼10 MHz apart and are often blended.…”

Section: Hc 3 Nmentioning

confidence: 99%

High-resolution mm and cm study of the obscured LIRG NGC 4418

Costagliola

Aalto

Sakamoto

et al. 2013

A&A

119

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Context. Understanding the nature of the power-source in luminous infrared galaxies (LIRG) is difficult due to their extreme obscuration. Observations at radio and mm wavelengths can penetrate large columns of dust and gas and provide unique insights into the properties of the compact obscured nuclei of LIRGs. Aims. The aim of this study is to constrain the dynamics, structure, and feeding of the compact nucleus of NGC 4418, and to reveal the nature of the main hidden power-source: starburst or active galactic nucleus (AGN). Methods. We obtained high spatial resolution observations of NGC 4418 at 1.4 and 5 GHz with MERLIN, and at 230 and 270 GHz with the SMA in very extended configuration. We used the continuum morphology and flux density to estimate the size of the emitting region, the star formation rate, and the dust temperature. Emission lines were used to study kinematics through position-velocity diagrams. Molecular emission was studied with population diagrams and by fitting a local thermal equilibrium (LTE) synthetic spectrum. Results. We detect bright 1-mm-line emission from CO, HC 3 N, HNC, and C 34 S and 1.4 GHz absorption from HI. The CO 2-1 emission and HI absorption can be fit by two velocity components at 2090 and 2180 km s −1 . We detect vibrationally excited HC 3 N and HNC, with T vib ∼ 300 K. Molecular excitation is consistent with a layered temperature structure, with three main components at 80, 160, and 300 K. For the hot component we estimate a source size of less than 5 pc. The nuclear molecular gas surface density of 10 4 M pc −2 is extremely high and similar to that found in the ultra-luminous infrared galaxy (ULIRG) Arp220. Conclusions. Our observations confirm the presence of a molecular and atomic in-flow, previously suggested by Herschel observations, which is feeding the activity in the center of NGC 4418. Molecular excitation confirms the presence of a very compact, hot dusty core. If a starburst is responsible for the observed IR flux, this has to be at least as extreme as the one in the ULIRG Arp 220, with an age of 3-10 Myr and a star formation rate >10 M yr −1 . If an AGN is present, it must be extremely Compton-thick.

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Rotational spectra of HCCCN in some excited vibrational states

Cited by 47 publications

References 11 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)

High-resolution mm and cm study of the obscured LIRG NGC 4418

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