- ID:
- ivo://CDS.VizieR/VI/136
- Title:
- Dielectronic Recombination Lines of C+ - SS1
- Short Name:
- VI/136
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A computed list of transition lines for the atomic ion C^+^ is generated using R-matrix [1], Autostructure [2] and Emissivity [3] codes. These lines are produced by dielectronic recombination and subsequent cascade decays of the low-lying autoionizing states above the threshold of C^2+1^S^e^ with a principal quantum number n<5 for the captured electron. The line list contains 6187 optically-allowed transitions which include many C II lines observed in the astronomical spectra [4]. Beside the transition lines, the data also include level energies for the bound and resonance states, radiative transition probabilities, recombination rate coefficients, and oscillator strengths. A 26-term C^2+^ atomic target was used within an intermediate coupling scheme in the production of these data. The theoretical results for energy and fine structure splitting agree very well with the available experimental data for both resonances and bound states. The data were also validated by comparison to theoretical data previously reported in the literature which include radiative transition probabilities, effective dielectronic recombination rate coefficients and autoionization probabilities.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/558/A112
- Title:
- Dimethyl ether-13C lab spectra up to 1.5THz
- Short Name:
- J/A+A/558/A112
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The interpretation of astronomical observations depends on the knowledge of accurate rest frequencies and intensities. The objective of this work is to provide spectroscopic data for the two ^13^C-isotopologues of dimethyl ether in the vibrational ground state. High-resolution rotational-torsional spectra of dimethyl ether-^13^C1 and dimethyl ether-^13^C2 have been measured in the laboratory covering frequencies up to 1.5THz. The analysis is based on an effective rotational Hamiltonian for molecules with two large amplitude motions.
- ID:
- ivo://CDS.VizieR/J/A+A/504/635
- Title:
- Dimethyl ether laboratory spectra up to 2.1THz
- Short Name:
- J/A+A/504/635
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Dimethyl ether (CH_3_OCH_3_) is one of the largest organic molecules detected in the interstellar medium. As an asymmetric top molecule with two methyl groups which undergo large amplitude motions and a dipole moment of mu_b_=1.3D it conveys a dense spectrum throughout the terahertz region and contributes to the spectral line confusion in astronomical observations at these frequencies. Rotational spectra of dimethyl ether in its ground vibrational states are presented in this paper, which have been measured in the laboratory and analyzed covering frequencies up to 2.1THz. The analysis is based on an effective Hamiltonian for a symmetric two-top rotor and includes experimental data published so far. Frequency predictions are presented up to 2.5THz for astronomical applications with accuracies better than 1MHz.
- ID:
- ivo://CDS.VizieR/J/ApJ/500/1059
- Title:
- Dimethyl ether transitions frequencies
- Short Name:
- J/ApJ/500/1059
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Dimethyl ether (CH_3_OCH_3_) is a well-known interstellar molecule with a large abundance in hot core regions. We have measured many rotational-torsional transition lines of this molecule in the 100-550GHz frequency range using two experimental techniques: a klystron-based traditional millimeter-wave spectrometer and a new fast scan spectrometer (designated "FASSST") with a voltage-tunable backward wave oscillator. The lines arising from the ground vibrational state have been combined with previous data, mainly at lower frequencies, to form a global data set consisting of over 1600 lines that have been assigned and fitted by an effective Hamiltonian method. The spectral constants obtained from the fit allow us to predict the frequencies of almost 6000 additional lines of dimethyl ether through 600GHz.
- ID:
- ivo://CDS.VizieR/J/ApJ/806/L3
- Title:
- Disilicon carbide (SiCSi) discovery in CW Leo
- Short Name:
- J/ApJ/806/L3
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the discovery in space of a disilicon species, SiCSi, from observations between 80 and 350GHz with the IRAM 30m radio telescope. Owing to the close coordination between laboratory experiments and astrophysics, 112 lines have now been detected in the carbon-rich star CW Leo. The derived frequencies yield improved rotational and centrifugal distortion constants up to sixth order. From the line profiles and interferometric maps with the Submillimeter Array, the bulk of the SiCSi emission arises from a region of 6" in radius. The derived abundance is comparable to that of SiC_2_. As expected from chemical equilibrium calculations, SiCSi and SiC_2_ are the most abundant species harboring a Si-C bond in the dust formation zone and certainly both play a key role in the formation of SiC dust grains.
- ID:
- ivo://CDS.VizieR/J/ApJ/733/L31
- Title:
- Distribution of ^26^Al in the solar system
- Short Name:
- J/ApJ/733/L31
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- It is believed that ^26^Al, a short-lived (t_1/2_=0.73Ma) and now extinct radionuclide, was uniformly distributed in the nascent solar system (SS) with the initial ^26^Al/^27^Al ratio of ~5.2x10^-5^, suggesting an external, stellar origin rather than local, solar source. However, the stellar source of ^26^Al and the manner in which it was injected into the SS remain controversial: the ^26^Al could have been produced by an asymptotic giant branch star, a supernova, or a Wolf-Rayet star and injected either into the protosolar molecular cloud, protosolar cloud core, or protoplanetary disk. Corundum (Al_2_O_3_) is predicted to be the first condensate from a cooling gas of solar composition. Here we show that micron-sized corundum condensates from ^16^O-rich ({Delta}^17^O~-25%) gas of solar composition recorded heterogeneous distribution of ^26^Al at the birth of the SS: the inferred initial ^26^Al/^27^Al ratio ranges from ~6.5x10^-5^ to <2x10^-6^; 52% of corundum grains measured are ^26^Al-poor. Abundant ^26^Al-poor, ^16^O-rich refractory objects include grossite- and hibonite-rich calcium-aluminum-rich inclusions (CAIs) in CH (high metal abundance and high iron concentration) chondrites, platy hibonite crystals in CM (Mighei-like) chondrites, and CAIs with fractionation and unidentified nuclear effects CAIs chondrites. Considering the apparently early and short duration (<0.3Ma) of condensation of refractory ^16^O-rich solids in the SS, we infer that ^26^Al was injected into the collapsing protosolar molecular cloud and later homogenized in the protoplanetary disk. The apparent lack of correlation between ^26^Al abundance and O-isotope composition of corundum grains constrains the stellar source of ^26^Al in the SS.
- ID:
- ivo://CDS.VizieR/J/A+A/590/A93
- Title:
- Doubly ^13^C-substituted ethyl cyanide
- Short Name:
- J/A+A/590/A93
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have performed a spectral line survey called Exploring Molecular Complexity with ALMA (EMoCA) toward Sagittarius B2(N) between 84.1 and 114.4GHz with the Atacama Large Millimeter/submillimeter Array (ALMA) in its Cycles 0 and 1. Line intensities of the main isotopic species of ethyl cyanide and its singly ^13^C-substituted isotopomers observed toward the hot molecular core Sagittarius B2(N2) suggest that the doubly ^13^C-substituted isotopomers should also be detectable. We want to determine the spectroscopic parameters of all three doubly ^13^C-substituted isotopologues of ethyl cyanide to search for them in our ALMA data. We investigated the laboratory rotational spectra of the three species between 150GHz and 990GHz. We searched for emission lines produced by these species in the ALMA spectrum of Sagittarius B2(N2). We modeled their emission and the emission of the ^12^C and singly ^13^C-substituted isotopologues assuming local thermodynamic equilibrium.
- ID:
- ivo://CDS.VizieR/J/A+A/493/697
- Title:
- Effective collision strength of Mg IX
- Short Name:
- J/A+A/493/697
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Electron impact excitation collision strengths are required for analysing and interpreting stellar observations. This calculation aims to provide fine-structure effective collision strengths for the Mg IX ion using a method that includes contributions from resonances. A 26-state Breit-Pauli R-matrix calculation has been performed.
- ID:
- ivo://CDS.VizieR/J/A+A/494/729
- Title:
- Effective collision strength of Mg V
- Short Name:
- J/A+A/494/729
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Electron-impact excitation collision strengths are required for the analysis and interpretation of stellar observations. This calculation aims to provide effective collision strengths for the MgV ion for a larger number of transitions and for a greater temperature range than previously available, using collision strength data that include contributions from resonances.
- ID:
- ivo://CDS.VizieR/J/A+A/537/A12
- Title:
- Effective collision strength of Ni XVII
- Short Name:
- J/A+A/537/A12
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Electron-impact excitation collision strengths are required for the analysis and interpretation of stellar observations. This calculation aims to provide effective collision strengths for the Ni XVII ion using collision strength data which include contributions from resonances.
