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- ID:
- ivo://CDS.VizieR/J/AZh/79/932
- Title:
- On the atomic constants of TaI
- Short Name:
- J/AZh/79/932
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Cross sections for the excitation of transitions in the tantalum atom (Z=73) not related to the ground state have been measured using extended crossed beams and optical spectroscopy. The total excitation cross sections for 23 energy levels of TaI have been determined.
- ID:
- ivo://CDS.VizieR/J/A+A/328/617
- Title:
- 16O18O isotopomer collision rate
- Short Name:
- J/A+A/328/617
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this paper, a chemical model of interstellar clouds including ^18^O and ^13^C isotopic reactions with a non-LTE calculations of ^16^O^18^O rotational population has been used to predict the intensity of the three ^16^O^18^O lines observable from the ground, namely 234, 298 and 402GHz.
- ID:
- ivo://CDS.VizieR/J/A+A/648/A76
- Title:
- O(3P) + H2(v, j)-->OH + H:OH reactions
- Short Name:
- J/A+A/648/A76
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The reaction between atomic oxygen and molecular hydrogen is an important one in astrochemistry as it regulates the abundance of the hydroxyl radical and serves to open the chemistry of oxygen in diverse astronomical environments. However, the existence of a high activation barrier in the reaction with ground state oxygen atoms limits its efficiency in cold gas. In this study we calculate the dependence of the reaction rate coefficient on the rotational and vibrational state of H_2_ and evaluate the impact on the abundance of OH in interstellar regions strongly irradiated by far-UV photons, where H_2_ can be efficiently pumped to excited vibrational states. We use a recently calculated potential energy surface and carry out time-independent quantum mechanical scattering calculations to compute rate coefficients for the reaction O(^3^P)+H_2_(v,j)-->OH+H, with H_2_ in vibrational states v=0-7 and rotational states j=0-10. We find that the reaction becomes significantly faster with increasing vibrational quantum number of H_2_, although even for high vibrational states of H_2_ (v=4-5) for which the reaction is barrierless, the rate coefficient does not strictly attain the collision limit and still maintains a positive dependence with temperature. We implemented the calculated state-specific rate coefficients in the Meudon PDR code to model the Orion Bar PDR and evaluate the impact on the abundance of the OH radical. We find the fractional abundance of OH is enhanced by up to one order of magnitude in regions of the cloud corresponding to AV=1.3-2.3, compared to the use of a thermal rate coefficient for O+H_2_, although the impact on the column density of OH is modest, of about 60%. The calculated rate coefficients will be useful to model and interpret JWST observations of OH in strongly UV-illuminated environments.
- ID:
- ivo://CDS.VizieR/J/A+A/356/1010
- Title:
- Ortho:para-H2 ratio in C and J shocks
- Short Name:
- J/A+A/356/1010
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Tables 2a-f and 4a-f contain an extensive set of parameters derived from our grid of C-type (tables 2a-f) and J-type (tables 4a-f) planar stationary shock models. Models of C-type shocks were calculated for * initial density, nH = 10^3^, 10^4^, 10^5^, 10^6^ cm-3 * shock speed, Vs = 10, 20, 30, 40 km/s (except for nH=10^6^ cm-3, where Vs = 10, 15, 20, 25, 30 km/s) * initial ortho:para-H2 ratio, o/p=0.01, 1, 2, 3 Models of J-type shocks were calculated for * initial density, nH = 10^3^, 10^4^, 10^5^, 10^6^ cm-3 * shock speed, Vs = 5, 10, 15, 20, 25 km/s * initial ortho:para-H2 ratio, o/p=0.01, 1, 2, 3 Tables 2a and 4a list for each model some selected physical parameters (width, duration, temperature, ortho:para ratios ...), tables 2b and 4b contain H2-line fluxes in 0-0 S (0)...S(11), 1-0 S(0)...S(11), and 2-0 S(1) lines, and total H2 luminosity. Tables 2c-f and 4c-f list column densities in each energy level of H2 (each table corresponds to one initial density nH=10^3^, 10^4^, 10^5^ or 10^6^ cm-3).
- ID:
- ivo://CDS.VizieR/J/A+A/548/A27
- Title:
- Oscillator and collision strengths for MgVI
- Short Name:
- J/A+A/548/A27
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Electron impact excitation collision strengths and oscillator strengths for the astrophysically important lines in MgVI are reported. Thermally averaged collision strengths are presented as a function of electron temperature for application to solar and other astrophysical plasmas.
- ID:
- ivo://CDS.VizieR/J/A+A/541/A61
- Title:
- Oscillator and collision strengths for SiVIII
- Short Name:
- J/A+A/541/A61
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Oscillator strengths and electron impact excitation collision strengths for transitions between the 68 fine-structure levels of the 2s^2^2p^3^, 2s2p^4^, 2p^5^, 2s^2^2p^2^3s, 2s^2^2p^2^3p, 2s^2^2p^2^3d and 2s2p^3^3s configurations in SiVIII are calculated. Thermally averaged collision strengths are presented as a function of electron temperature for application to solar and other astrophysical plasmas.
- ID:
- ivo://CDS.VizieR/J/ApJS/163/207
- Title:
- Oscillator and collision strengths in NI
- Short Name:
- J/ApJS/163/207
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The nonorthogonal orbitals technique in a multiconfiguration Hartree-Fock approach is used to calculate oscillator strengths and transition probabilities of NI lines.
- ID:
- ivo://CDS.VizieR/J/ApJS/121/265
- Title:
- Oscillator Strengths and Radiative Rates for FeXV
- Short Name:
- J/ApJS/121/265
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report oscillator strengths and radiative decay rates for 1108 optically allowed and intercombination transitions among the lowest 87 fine-structure energy levels of Fe XV. Two independent calculations are carried out using the CIV3 (Configuration Interaction version 3) atomic structure code of Hibbert and the GRASP (General Relativistic Atomic Structure Program) code of Dyall et al. (1989) The results from the two calculations agree well for almost all the strong transitions. However, there are notable disagreements between the two calculations for a few relatively weaker transitions involving some levels belonging to the 3p4d and 3p4f configurations.
- ID:
- ivo://CDS.VizieR/J/A+A/426/717
- Title:
- Oscillator strengths for ClII lines
- Short Name:
- J/A+A/426/717
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Non-orthogonal orbitals technique in the multiconfiguration Hartree-Fock approach is used to calculate oscillator strengths and transition probabilities for allowed and intercombination lines in Cl II. The relativistic corrections are included through the Breit-Pauli Hamiltonian. The Cl II wave functions show strong term dependence. The non-orthogonal orbitals are used to describe the term dependence of radial functions. Large sets of spectroscopic and correlation functions are chosen to describe adequately strong interactions in the 3s^2^ 3p^3^nl ^3^P^o^, ^1^P^o^ and ^3^D^o^ Rydberg series and to properly account for the important correlation and relaxation effects. The length and velocity forms of oscillator strength show good agreement for most transitions.
