- ID:
- ivo://CDS.VizieR/J/A+A/653/A129
- Title:
- GUAPOS II. Identified transitions of molecules
- Short Name:
- J/A+A/653/A129
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- We present an unbiased spectral survey of one of the most chemically rich hot molecular cores located outside the Galactic Center, in the high-mass star-forming region G31.41+0.31. In this second paper, we discuss the detection and relative abundances of the peptide-like bond molecules: HNCO, HC(O)NH2, CH_3_NCO, CH_3_C(O)NH_2_, CH_3_NHCHO, CH_3_CH_2_NCO, NH_2_C(O)NH_2_, NH_2_C(O)CN, and HOCH_2_C(O)NH_2_. Observations were carried out with the ALMA interferometer, covering all of band 3 (about 32GHz bandwidth) with an angular resolution of 1.2"x1.2" (about 4400aux4400au) and a spectral resolution of about 0.488MHz. The transitions of the nine molecules have been analyzed with the software MADCUBA to determine the physical parameters of the emitted gas. The results suggest that all these species are formed on grain surfaces in early evolutionary stages of molecular clouds, and that they are subsequently released back to the gas-phase through thermal desorption or shock-triggered desorption.
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- ID:
- ivo://CDS.VizieR/J/A+A/657/A24
- Title:
- HCCCHCN laboratory observations
- Short Name:
- J/A+A/657/A24
- Date:
- 21 Mar 2022 09:22:16
- Publisher:
- CDS
- Description:
- The reaction between carbon atoms and vinyl cyanide, CH_2_CHCN, is a possible formation route for interstellar 3-cyano propargyl radical, CH_2_C_3_N. 1-Cyano propargyl radical (HC_3_HCN), an isomer of CH_2_C_3_N, is predicted to be produced in the same reaction at least twice more efficiently than CH_2_C_3_N. Hence, HC_3_HCN is a plausible candidate to be observed in space as well. We aim to generate HC_3_HCN radical in the gas phase in order to investigate its rotational spectrum. The derived spectroscopic parameters for this species will be use to obtain reliable frequency predictions to support its detection in the space. Rotational spectrum of HC_3_HCN radical was produce by electric discharges and characterized using a Balle-Flygare narrowband type Fourier-transform microwave (FTMW) spectrometer operating in the frequency region of 4-40GHz. The spectral analysis was supported by high-level ab initio calculations. A total of 193 hyperfine components originated from twelve rotational transitions, a- and b-type, were measured for HC_3_HCN radical. The analysis allowed us to accurately determine twenty-two molecular constants, including rotational and centrifugal distortion constants as well as the fine and hyperfine constants. Transition frequency predictions were used to search for HC_3_HCN radical in TMC-1 using the QUIJOTE survey between 30.1-50.4GHz. We can not confirm the presence of HC_3_HCN in TMC-1 and obtain an upper limit to the column density of HC_3_HCN in TMC-1 of 6.0*10^11^cm^-2^.
293. H13CN/HN13C linelist
- ID:
- ivo://CDS.VizieR/VI/131
- Title:
- H13CN/HN13C linelist
- Short Name:
- VI/131
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A linelist of vibration-rotation transitions for ^13^C substituted HCN is presented. The line list is constructed using known experimental levels where available, calculated levels and ab initio line intensities originally calculated for the major isotopologue. Synthetic spectra are generated and compared with observations for cool carbon star WZ Cas. It is suggested that high resolution HCN spectra recorded near 14um should be particularly sensitive to the ^13^C-^12^C ratio.
- ID:
- ivo://CDS.VizieR/J/A+A/425/767
- Title:
- HC_5_N vibrationally excited states
- Short Name:
- J/A+A/425/767
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The rotational spectrum of the semistable HC_5_N molecule has been investigated in the millimeter-wave region for eight excited bending states which lie below 500cm^-1^, namely v_11_=1, 2, 3, and 4, v_10_=1, v_9_=1, (v_10_=1, v_11_=1), and (v_10_=1, v_11_=2). Transitions up to J=101-100 were measured, reaching a frequency as high as 270GHz. The set of spectroscopic constants determined in the present work makes it possible to predict much improved rest frequencies of millimeter-wave lines produced by vibrationally excited HC_5_N in hot core molecular sources and circumstellar shells. The Tables list the measured frequencies and the corresponding residuals of the least-squares analyses of J+1<--J transitions, with J in the range 8-100, which occur in the centimeter- and millimeter-wave regions.
- ID:
- ivo://CDS.VizieR/J/ApJ/779/119
- Title:
- HCOOCH_2_D detection in Orion KL
- Short Name:
- J/ApJ/779/119
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Based on new measurements carried out in the laboratory from 0.77 to 1.2THz and on a line-frequency analysis of these new data, along with previously published data, we build a line list for HCOOCH_2_D that leads to its first detection in the Orion KL nebula. The observed lines, both in space and in the laboratory, involve the cis D-in-plane and trans D-out-of-plane conformations of HCOOCH_2_D and the two tunneling states arising from the large-amplitude motion connecting the two trans configurations. The model used in the line position calculation accounts for both cis and trans conformations, as well as the large-amplitude motion.
- ID:
- ivo://CDS.VizieR/J/A+A/568/A58
- Title:
- HCOO^13^CH_3_ rotational spectrum
- Short Name:
- J/A+A/568/A58
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- An astronomical survey of interstellar molecular clouds needs a previous analysis of the spectra in the microwave and sub-mm energy range of organic molecules to be able to identify them. We obtained very accurate spectroscopic constants in a comprehensive laboratory analysis of rotational spectra. These constants can be used to predict the transitions frequencies very precisely that were not measured in the laboratory. We present the experimental study and its theoretical analysis for two ^13^C-methyl formate isotopologues to detect these two isotopologues for the first time in their excited torsional states, which lie at 130/cm (200K) in Orion-KL. New spectra of HCO-O-^13^CH_3_ (^13^C_2_) methyl formate were recorded with the mm- and submm-wave spectrometer in Lille from 50 to 940GHz. A global fit for v_t_=0 and 1 was accomplished with the BELGI program to reproduce the experimental spectra with greater accuracy. We analysed 5728 and 2881 new lines for v_t_=0 and 1 for HCOO^13^CH_3_. These new lines were globally fitted with 846 previously published lines for v_t_=0. In consequence, 52 parameters of the RAM Hamiltonian were accurately determined and the value of the barrier height (V_3_=369.93168(395)/cm) was improved. We report the detection of the first excited torsional states (v_t_=1) in Orion-KL for the ^13^C_2_ and ^13^C_1_ methyl formate based on the present analysis and previously published data. We provide column densities, isotopic abundances, and vibrational temperatures for these species. Following this work, accurate prediction can be provided. This permits detecting 135 features of the first excited torsional states of ^13^C-methyl formate isotopologues in Orion-KL in the 80-280GHz frequency range, without missing lines.
- ID:
- ivo://CDS.VizieR/J/ApJS/232/19
- Title:
- H_2_, D_2_, and HD c^3^{Pi}_u_^-^(v,N) levels
- Short Name:
- J/ApJS/232/19
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The c^3^{Pi}_u_ state of the hydrogen molecule has the second largest triplet-state excitation cross-section, and plays an important role in the heating of the upper thermospheres of outer planets by electron excitation. Precise energies of the H_2_, D_2_, and HD c^3^{Pi}_u_^-^(v,N) levels are calculated from highly accurate ab initio potential energy curves that include relativistic, radiative, and empirical non-adiabatic corrections. The emission yields are determined from predissociation rates and refined radiative transition probabilities. The excitation function and excitation cross-section of the c^3^{Pi}_u_ state are extracted from previous theoretical calculations and experimental measurements. The emission cross-section is determined from the calculated emission yield and the extracted excitation cross-section. The kinetic energy (Ek) distributions of H atoms produced via the predissociation of the c^3^{Pi}_u_ state, the c^3^{Pi}_u_^-^-b^3^{Sigma}_u_^+^ dissociative emission by the magnetic dipole and electric quadrupole, and the c^3^{Pi}_u_-a^3^{Sigma}_g_^+^-b^3^{Sigma}_u_^+^ cascade dissociative emission by the electric dipole are obtained. The predissociation of the c^3^{Pi}_u_^+^ and c^3^{Pi}_u_^-^ states both produce H(1s) atoms with an average Ek of ~4.1eV/atom, while the c^3^{Pi}_u_^-^-b^3^{Sigma}_u_^+^ dissociative emissions by the magnetic dipole and electric quadrupole give an average Ek of ~1.0 and ~0.8eV/atom, respectively. The c^3^{Pi}_u_-a^3^{Sigma}_g_^+^-b^3^{Sigma}_u_^+^ cascade and dissociative emission gives an average Ek of ~1.3 eV/atom. On average, each H_2_ excited to the c^3^{Pi}_u_ state in an H_2_-dominated atmosphere deposits ~7.1eV into the atmosphere while each H_2_ directly excited to the a^3^{Sigma}_g_^+^ and d^3^{Pi}_u_ states contribute ~2.3 and ~3.3eV, respectively, to the atmosphere. The spectral distribution of the calculated continuum emission arising from the X^1^{Sigma}_g_^+^-c^3^{Pi}_u_ excitation is significantly different from that of direct a^3^{Sigma}_g_^+^ or d^3^{Pi}_u_ excitations.
- ID:
- ivo://CDS.VizieR/J/A+A/646/L1
- Title:
- HDCCN discovery in space and in laboratory
- Short Name:
- J/A+A/646/L1
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Observations of TMC-1 with the Yebes 40m radio telescope in the 31.0-50.3GHz range allowed the detection of a group of unidentified lines, showing a complex line pattern indicative of an open-shell species. The observed frequencies of these lines and the similarity of the spectral pattern with that of the 2_02_-1_01_ rotational transition of H_2_CCN point to that the lines arise from the deuterated cyanomethyl radical, HDCCN. Using Fourier transform microwave spectroscopy experiments combined with electric discharges we have succeeded in producing the radical HDCCN in the laboratory and observed its 1_01_-0_00_ and 2_02_-1_01_ rotational transitions. From our observations and assuming a rotational temperature of 5K, we derive an abundance ratio H_2_CCN/HDCCN=20. The high abundance of the deuterated form of H_2_CCN is well accounted for by a standard gas-phase model where deuteration is driven by deuteron transfer from the H_2_D+ molecular ion.
- ID:
- ivo://CDS.VizieR/J/A+A/503/945
- Title:
- HD 145788, 21 Peg and pi Cet chemical analysis
- Short Name:
- J/A+A/503/945
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Modern spectroscopy of early-type stars often aims at studying complex physical phenomena such as stellar pulsation, the peculiarity of the composition of the photosphere, chemical stratification, the presence of a magnetic field, and its interplay with the stellar atmosphere and the circumstellar environment. Comparatively less attention is paid to identifying and studying the "normal" A- and B-type stars and testing how the basic atomic parameters and standard spectral analysis allow one to fit the observations. By contrast, this kind of study is paramount for eventually allowing one to correctly quantify the impact of the various physical processes that occur inside the atmospheres of A- and B-type stars. We wish to establish whether the chemical composition of the solar photosphere can be regarded as a reference for early A- and late B-type stars.
- ID:
- ivo://CDS.VizieR/J/ApJ/818/120
- Title:
- H_2_ d^3^{Pi}_u_ excitation by electron impact
- Short Name:
- J/ApJ/818/120
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Electron-impact excitation of H_2_ triplet states plays an important role in the heating of outer planet upper thermospheres. The d^3^{Pi}_u_ state is the third ungerade triplet state, and the d^3^{Pi}_u_-a^3^{Sigma}_g_^+^ emission is the largest cascade channel for the a^3^{Sigma}_g_^+^ state. Accurate energies of the d^3^{Pi}_u_^-^(v, J) levels are calculated from an ab initio potential energy curve. Radiative lifetimes of the d^3^{Pi}_u_(v,J) levels are obtained by an accurate evaluation of the d^3^{Pi}_u_-a^3^{Sigma}_g_^+^ transition probabilities. The emission yields are determined from experimental lifetimes and calculated radiative lifetimes and are further verified by comparing experimental and synthetic d^3^{Pi}_u_-a^3^{Sigma}_g_^+^ spectra at 20eV impact energy. Spectral analysis revealed that multipolar components beyond the dipolar term are required to model the X^1^{Sigma}_g_^+^-d^3^{Pi}_u_ excitation, and significant cascade excitation occurs at the d^3^{Pi}_u_ (v=0,1) levels. Kinetic energy (E_k_) distributions of H atoms produced via predissociation of the ^3^{Pi}_u_ state and the d^3^{Pi}_u_-a^3^{Sigma}_g_^+^-b^3^{Sigma}_u_^+^ cascade dissociative emission are obtained. Predissociation of the d^3^{Pi}_u_ state produces H atoms with an average E_k_ of 2.3+/-0.4 eV/atom, while the E_k_distribution of the d^3^{Pi}_u_-a^3^{Sigma}_g_^+^-b^3^{Sigma}_u_^+^ channel is similar to that of the X^1^{Sigma}_g_^+^-a^3^{Sigma}_g_^+^-b^3^{Sigma}_u_^+^ channel and produces H(1s) atoms with an average E_k_ of 1.15+/-0.05eV/atom. On average, each H_2_ excited to the d^3^{Pi}_u_ state in an H_2_-dominated atmosphere deposits 3.3+/-0.4eV into the atmosphere, while each H_2_directly excited to the a^3^{Sigma}_g_^+^ state gives 2.2-2.3eV to the atmosphere. The spectral distribution of the calculated a^3^{Sigma}_g_^+^-b^3^{Sigma}_u_^+^ continuum emission due to the X^1^{Sigma}_g_^+^-d^3^{Pi}_u_ excitation is significantly different from that of direct a^3^{Sigma}_g_^+^ excitation.
