- ID:
- ivo://CDS.VizieR/J/A+A/559/A44
- Title:
- Rotational spectrum of MAAN (CH_2_NCH_2_CN)
- Short Name:
- J/A+A/559/A44
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Aminoacetonitrile has been detected in the interstellar medium and the Strecker-type synthesis is considered as one of its possible mechanisms of formation in this medium. Methyleneaminoacetonitrile (CH_2_=N-CH_2_-CN, MAAN) is one of the by-products of the Strecker reaction and a good candidate for astrophysical detection. Rotational spectrum of MAAN has never been studied before. To provide the basis for the detection of MAAN in the interstellar medium we studied its millimeter and submillimeter-wave spectrum. The rotational spectrum of MAAN was measured in the frequency range 120-600GHz. The spectroscopic study was supported by theoretical calculations of the molecular structure and harmonic force field. The ground and two lowest excited vibrational states of the most stable synperiplanar conformation of MAAN were assigned and analyzed. Obtained sets of rotational constants allows us to make accurate predictions of transition frequencies of MAAN in the frequency range up to 900GHz.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/619/A67
- Title:
- Rotational spectrum of methoxyacetaldehyde
- Short Name:
- J/A+A/619/A67
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Methoxyacetaldehyde belongs to a group of structural isomers with the general formula C_3_H_6_O_2_, of which methyl acetate and ethyl formate are known interstellar molecules. Rotational data available for methoxyacetaldehyde are limited to 40GHz, which makes predictions at higher frequencies rather uncertain. The aim of this work is to provide accurate experimental frequencies of methoxyacetaldehyde in the millimeter-wave region to support its detection in the interstellar medium. The rotational spectrum of methoxyacetaldehyde was recorded at room-temperature from 75 to 120GHz and from 170 to 310GHz using the millimeter-wave spectrometer in Valladolid. Additional measurements were also performed at conditions of supersonic expansion from 6 to 18GHz. The assigned rotational transitions were analyzed using the S-reduced semirigid-rotor Hamiltonian. We newly assigned over 1000 lines for the most stable conformer of methoxyacetaldehyde in its ground state and five lowest excited vibrational states, and precise sets of spectroscopic constants were obtained. We searched for spectral features of methoxyacetaldehyde in the high-mass star-forming regions Orion KL and Sagittarius B2, as well as in the cold dark cloud Barnard 1 (B1-b). No lines belonging to methoxyacetaldehyde were detected above the detection limit of our data. We provide upper limits to the methoxyacetaldehyde colum density in these sources.
- ID:
- ivo://CDS.VizieR/J/A+A/609/A24
- Title:
- Rotational spectrum of methoxyamine
- Short Name:
- J/A+A/609/A24
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Methoxyamine is a potential interstellar amine that has been predicted by gas-grain chemical models for the formation of complex molecules. The aim of this work is to provide direct experimental frequencies of its ground-vibrational state in the millimeter and submillimeter-wave regions to achieve its detection in the interstellar medium. Methoxyamine was chemically liberated from its hydrochloride salt, and its rotational spectrum was recorded at room temperature from 75 to 480GHz using the millimeter-wave spectrometer in Valladolid. Many observed transitions revealed A-E splitting caused by the internal rotation of the methyl group, which had to be treated with specific internal rotation codes. Over 400 lines were newly assigned for the most stable conformer of methoxyamine, and a precise set of spectroscopic constants was obtained. Spectral features of methoxyamine were then searched for in the Orion KL, Sgr B2, B1-b, and TMC-1 molecular clouds. Upper limits to the column density of methoxyamine were derived.
- ID:
- ivo://CDS.VizieR/J/A+A/647/A55
- Title:
- Rotational spectrum of propiolamide
- Short Name:
- J/A+A/647/A55
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- For all the amides detected in the interstellar medium (ISM), the corresponding nitriles or isonitriles have also been detected in the ISM, some of which have relatively high abundances. Among the abundant nitriles for which the corresponding amide has not yet been detected is cyanoacetylene (HCCCN), whose amide counterpart is propiolamide (HCCC(O)NH_2_). With the aim of supporting searches for this amide in the ISM, we provide a complete rotational study of propiolamide from 6GHz to 440GHz. Time-domain Fourier transform microwave (FTMW) spectroscopy under supersonic expansion conditions between 6GHz and 18GHz was used to accurately measure and analyze ground-state rotational transitions with resolved hyperfine structure arising from nuclear quadrupole coupling interactions of the 14N nucleus. We combined this technique with the frequency-domain roomtemperature millimeter wave and submillimeter wave spectroscopies from 75GHz to 440GHz in order to record and assign the rotational spectrain the ground state and in the low-lying excited vibrational states. We used the ReMoCA spectral line survey performed with the Atacama Large Millimeter/submillimeter Array toward the star-forming region Sgr B2(N) to search for propiolamide. We identified and measured more than 5500 distinct frequency lines of propiolamide in the laboratory. These lines were fitted using an effective semi-rigid rotor Hamiltonian with nuclear quadrupole coupling interactions taken into consideration. We obtained accurate sets of spectroscopic parameters for the ground state and the three low-lying excited vibrational states. We report the nondetection of propiolamide toward the hot cores Sgr B2(N1S) and Sgr B2(N2). We find that propiolamide is at least 50 and 13 times less abundant than acetamide in Sgr B2(N1S) and Sgr B2(N2), respectively, indicating that the abundance difference between both amides is more pronounced by at least a factor of 8 and 2, respectively, than for their corresponding nitriles. Although propiolamide has yet to be included in astrochemical modeling networks, the observed upper limit to the ratio of propiolamide to acetamide seems consistent with the ratios of related species as determined from past simulations. The comprehensive spectroscopic data presented in this paper will aid future astronomical searches.
- ID:
- ivo://CDS.VizieR/J/ApJS/205/9
- Title:
- Rotational transition frequencies of HCOOCH_3_
- Short Name:
- J/ApJS/205/9
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The cis-methyl formate molecule (HCOOCH_3_) is a well known molecule found in interstellar space. Recently, rotational lines of methyl formate in the first CH_3_ torsional excited state were observed in Orion KL and W51e2. It is quite natural to observe methyl formate in even higher vibrational states considering the temperature estimated in Orion KL and W51e2. Maeda et al. (2008JMoSp.251..293M) reported results on the laboratory spectroscopy of methyl formate including the spectral analysis in its second CH_3_ torsional state. Their assignments were limited to a series of a-type R-branch lines and low K_a_ b-type R-branch transitions, and many assigned lines are excluded in the least-squares analysis. In the present study, we extended the line assignments of both the A- and E-species transitions in the second CH_3_ torsional state especially in the frequency region below the 120GHz region. By combining the present assignments and those made by Maeda et al., 1951 transitions in total for the second CH_3_ torsional state, 1096 A-species transitions up to J=39, and K_a_=15 and 855 E-species transitions up to J=35 and K_a_=13, were least-squares analyzed by using the pseudo-principal-axis-method Hamiltonian with 42 parameters consisting of rotational, centrifugal distortion, and internal rotational constants in the second CH_3_ torsional state. In addition, 1012 transitions out of 1096 A-species transitions could also be least-squares analyzed by using Watson's A-reduced Hamiltonian with 43 parameters, which can serve to calculate the energy levels of the A-species lines of molecules with the CH_3_ internal rotation conveniently.
- ID:
- ivo://CDS.VizieR/J/A+A/644/A3
- Title:
- rotational transitions of cyanoacetamide
- Short Name:
- J/A+A/644/A3
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Cyanoacetamide is a branched chain -CN bearing molecule which is also an amide derivative target molecule in the interstellar medium. The aim of our investigation is to analyze the feasibility of a plausible formation process of protonated cyanoacetamide under interstellar conditions and to provide direct experimental frequencies of the ground vibrational state of the neutral form in the microwave region in order to enable its eventual identification in the interstellar medium. We used high-level theoretical computations to study the formation process of protonated cyanoacetamide. Furthermore, we employed a high resolution laser ablation molecular beam Fourier transform (LA-MB-FTMW) spectroscopic technique to measure the frequencies of the neutral form. We report the first rotational characterization of cyanoacetamide and a precise set of the relevant rotational spectroscopic constants have been determined as a first step to identify the molecule in the interstellar medium. We performed full exploration of the Potential Energy Surface (PES) to study a gas-phase reaction on the formation process of protonated cyanoacetamide. We found an exothermic process with no net activation barrier initiated by the high-energy isomer of protonated hydroxylamine, which leads to protonated cyanoacetamide.
- ID:
- ivo://CDS.VizieR/J/ApJ/897/122
- Title:
- Rotational velocities for PHANGS sample of galaxies
- Short Name:
- J/ApJ/897/122
- Date:
- 11 Mar 2022
- Publisher:
- CDS
- Description:
- We present kinematic orientations and high-resolution (150pc) rotation curves for 67 main-sequence star-forming galaxies surveyed in CO (2-1) emission by PHANGS-ALMA. Our measurements are based on the application of a new fitting method tailored to CO velocity fields. Our approach identifies an optimal global orientation as a way to reduce the impact of nonaxisymmetric (bar and spiral) features and the uneven spatial sampling characteristic of CO emission in the inner regions of nearby galaxies. The method performs especially well when applied to the large number of independent lines of sight contained in the PHANGS CO velocity fields mapped at 1" resolution. The high-resolution rotation curves fitted to these data are sensitive probes of mass distribution in the inner regions of these galaxies. We use the inner slope as well as the amplitude of our fitted rotation curves to demonstrate that CO is a reliable global dynamical mass tracer. From the consistency between photometric orientations from the literature and kinematic orientations determined with our method, we infer that the shapes of stellar disks in the mass range of log(M*(M{odot}))=9.0-10.9 probed by our sample are very close to circular and have uniform thickness.
- ID:
- ivo://CDS.VizieR/J/ApJ/642/868
- Title:
- Rotation measures for 223 pulsars
- Short Name:
- J/ApJ/642/868
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The large-scale magnetic field of our Galaxy can be probed in three dimensions using Faraday rotation of pulsar signals. We report on the determination of 223 rotation measures from polarization observations of relatively distant southern pulsars made using the Parkes radio telescope.
- ID:
- ivo://CDS.VizieR/J/A+A/513/A65
- Title:
- Rotation measures in the fourth Galactic quadrant
- Short Name:
- J/A+A/513/A65
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have re-examined the published rotation measures (RMs) of extragalactic point sources and pulsars with |b|<3{deg} to study the magnetic field in the fourth Galactic quadrant. We reduced the influence of structure in electron density as much as possible by excluding objects for which H{alpha}-data indicate large fluctuations in n_e_ somewhere along the line of sight. We also excluded objects for which the RM may have been significantly "corrupted" by an intervening supernova remnant. We modelled RM(l), the longitude dependence of RM of the unaffected extragalactic sources and pulsars. We assumed several geometries for the large-scale field. All but one of those are based on logarithmic spiral arms (with various pitch angles and widths), while one has circular symmetry. We also made different assumptions about the large-scale n_e_-distribution.
- ID:
- ivo://CDS.VizieR/J/A+A/549/A56
- Title:
- Rotation Measure synthesis of WSRT obs.
- Short Name:
- J/A+A/549/A56
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Rotation Measure synthesis (RM synthesis) of the Westerbork Synthesis Radio Telescope (WSRT) observations at 2m wavelength of the FAN region at l=137deg, b=+7deg shows the morphology of structures in the ionized interstellar medium.