- ID:
- ivo://CDS.VizieR/VI/148
- Title:
- Collision Strengths for [Co II] Forbidden Lines - SS4
- Short Name:
- VI/148
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The list presents electron collision strengths for the forbidden transitions between the fifteen lowest levels of the singly-ionized cobalt, Co^+^, as a function of the electron energy, in an intermediate coupling scheme using the Breit-Pauli relativistic terms as implemented in an R-matrix atomic scattering code. An atomic target for the R-matrix scattering defined by 26 atomic terms is used in these calculations. The data are particularly useful for analyzing the thermodynamic conditions of supernova ejecta.
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- ID:
- ivo://CDS.VizieR/VI/149
- Title:
- Collision Strengths for [Co III] Forbidden Lines - SS5
- Short Name:
- VI/149
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The list presents electron collision strengths for the forbidden transitions between the fifteen lowest levels of the doubly-ionized cobalt, Co^2+^, as a function of the electron energy, in an intermediate coupling scheme using the Breit-Pauli relativistic terms as implemented in an R-matrix atomic scattering code. An atomic target for the R-matrix scattering defined by 36 atomic terms is used in these calculations. The data are particularly useful for analyzing the thermodynamic conditions of supernova ejecta.
- ID:
- ivo://CDS.VizieR/J/ApJ/788/24
- Title:
- Collision strengths for transitions in Fe VII
- Short Name:
- J/ApJ/788/24
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Extensive calculations have been performed for electron impact excitation collision strengths and oscillator strengths for the Fe VII extreme ultraviolet lines of astrophysical importance. The collision strengths for fine-structure transitions are calculated in the B-spline Breit-Pauli R-matrix approach. The target wavefunctions have been calculated in the multiconfiguration Hartree-Fock method with term-dependent non-orthogonal orbitals. The close-coupling expansion includes 189 fine-structure levels of Fe VII belonging to terms of the ground 3p^6^ 3d^2^ and excited 3p^5^ 3d^3^, 3p^6^ 3d4l, 3p^6^ 3d5s, and 3p^6^ 3d5p configurations. The effective collision strengths are determined from the electron excitation collision strengths by integration over a Maxwellian distribution of electron velocities. The effective collision strengths are provided for 17766 fine-structure transitions at electron temperatures from 10^4^ to 10^7^ K. Our results normally agree with the previous R-matrix frame-transformation calculations by Witthoeft & Badnell (2008A&A...481..543W). However, there are important differences for some transitions with the previous calculations. The corrections to the previous results are mainly due to more extensive expansions for the Fe VII target states.
- ID:
- ivo://CDS.VizieR/J/ApJ/812/174
- Title:
- Collision strengths in FeIX
- Short Name:
- J/ApJ/812/174
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Collision strengths and thermally averaged collision strengths for a large number of extreme-ultraviolet lines of FeIX arising by electron impact have been reported. The thermally averaged collision strengths are calculated at electron temperatures in the range 10^4^-10^7^K for the 122043 forbidden and allowed transitions between the 370 fine-structure levels. The atomic parameters for FeIX play an important role in modeling of various astrophysical plasmas, including especially the solar corona. The B-spline Breit-Pauli R-matrix method has been used in the calculation of collision strengths. The target wave functions and transition probabilities have been determined by combining the multiconfiguration Hartree-Fock method with the B-spline box-based multichannel expansions. We have included 370 fine-structure levels of FeIX in the energy region up to 3s^2^3p^5^5s states. The close-coupling expansion includes levels of the 3s^2^3p^6^, 3s^2^3p^5^3d, 4l, 5s, 3s3p^6^3d, 4s, 4p, 3s^2^3p^4^3d^2^, 3s3p^5^3d^2^ configurations and some low-lying levels of the 3s^2^3p^3^3d^3^ configuration in our collision strengths and transition probabilities calculations. There is a good agreement with the previous R-matrix collision strength calculations by Storey et al. (2002, J/A+A/394/753) and Del Zanna et al. (2014, J/A+A/565/A77) for transitions between the lowest 17 levels of the 3s^2^3p^6^, 3s^2^3p^5^3d and 3s3p^6^3d configurations, especially for electron temperatures logT(K)>=5.0. The transitions between the first 17 levels are dominated by Rydberg series of resonances converging to the levels of the 3s^2^3p^4^3d^2^ configuration. The present results and the calculation of Del Zanna et al. show significant differences for many weaker forbidden and intercombination transitions with thermally averaged collision strengths smaller than 0.01.
- ID:
- ivo://CDS.VizieR/J/ApJ/526/544
- Title:
- Collision strengths in S III
- Short Name:
- J/ApJ/526/544
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Electron collisional excitation strengths for transitions between the 3s^2^3p^2^ ^3^P_0,1,2_, ^1^D_2_, and ^1^S_0_ levels and from these levels to the fine-structure levels of the excited 3s3p^3^, 3s^2^3p3d, 3s^2^3p4s, 3s^2^3p4p, and 3s^2^3p4d configurations of S III are calculated in R-matrix approach. We considered 49 fine-structure levels arising from the 27 LS 3s^2^3p^2^ ^3^P, ^1^D, ^1^S, 3s3p^3^ ^5,3^S_o_, ^1,3^D_o_, ^1,3^P_o_, 3s^2^3p3d ^1,3^P_o_, ^1,3^D_o_, ^1,3^F_o_, 3s^2^3p4s ^1,3^P_o_, 3s^2^3p4p ^1,3^S, ^1,3^P, ^1,3^D, 3s^2^3p4d ^1,3^P_o_, and ^1,3^D_o_ states. These target levels are represented by fairly extensive configuration-interaction wave functions. The collision strengths for transitions between fine-structure levels are calculated by transforming the LS-coupled K-matrices to K-matrices in an intermediate coupling scheme. Complicated resonance structures converging to excited state thresholds are explicitly included in collision strengths. The effective collision strengths are obtained from the total collision strengths by integrating over a Maxwellian velocity distribution. These are tabulated over a wide electron temperature range (0.5 - 10) x 10^4^ K.
- ID:
- ivo://CDS.VizieR/J/ApJS/230/8
- Title:
- Compilation of atomic data for key heavy elements
- Short Name:
- J/ApJS/230/8
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Measurements of element abundances in galaxies from astrophysical spectroscopy depend sensitively on the atomic data used. With the goal of making the latest atomic data accessible to the community, we present a compilation of selected atomic data for resonant absorption lines at wavelengths longward of 911.753{AA} (the HI Lyman limit), for key heavy elements (heavier than atomic number 5) of astrophysical interest. In particular, we focus on the transitions of those ions that have been observed in the Milky Way interstellar medium (ISM), the circumgalactic medium (CGM) of the Milky Way and/or other galaxies, and the intergalactic medium (IGM). We provide wavelengths, oscillator strengths, associated accuracy grades, and references to the oscillator strength determinations. We also attempt to compare and assess the recent oscillator strength determinations. For about 22% of the lines that have updated oscillator strength values, the differences between the former values and the updated ones are >~0.1dex. Our compilation will be a useful resource for absorption line studies of the ISM, as well as studies of the CGM and IGM traced by sight lines to quasars and gamma-ray bursts. Studies (including those enabled by future generations of extremely large telescopes) of absorption by galaxies against the light of background galaxies will also benefit from our compilation.
- ID:
- ivo://CDS.VizieR/J/A+A/634/A34
- Title:
- Complete line list and solar values
- Short Name:
- J/A+A/634/A34
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Open clusters are recognised as excellent tracers of the Galactic thin disc properties. At variance with intermediate-age and old open clusters, for which a conspicuous number of studies is now available, until a few years ago clusters younger than 150Myr had been mostly overlooked in terms of their chemical composition (with few exceptions). On the other hand, previous investigations seem to indicate an anomalous behaviour of young clusters, which include (but is not limited to) slightly sub-solar iron (Fe) abundances and extreme, unexpected barium (Ba) enhancements. In a series of papers, we plan to expand our comprehension of this topic and investigate whether these chemical peculiarities are instead related to abundance analysis techniques. We present here a new determination of the atmospheric parameters for 23 dwarf stars observed by the Gaia-ESO survey in five young open clusters (age less than 150Myr) and one star forming region (NGC 2264). We exploit a new method based on titanium (Ti) lines to derive spectroscopic surface gravity and, most important, microturbulence parameter. A combination of Ti and Fe lines have been used to obtain effective temperatures. We also infer abundances of FeI, FeII, TiI, TiII, NaI, MgI, AlI, SiI, CaI, CrI and NiI. Our findings are in fair agreement with Gaia-ESO iDR5 results for effective temperatures and surface gravities, but suggest that for very young stars the microturbulence parameter is over-estimated when Fe lines are employed. This impacts the derived chemical composition, causing the metal content of very young clusters to be under-estimated. Our clusters display a metallicity [Fe/H] between +0.04 and +0.12; thus they are not more metal-poor than the Sun. Although based on a relatively small sample size, our explorative study suggests that we may not need to call for ad hoc explanations to reconcile the chemical composition of young open clusters with Galactic chemical evolution models.
- ID:
- ivo://CDS.VizieR/J/ApJ/714/476
- Title:
- Complete spectrum of ethyl cyanide
- Short Name:
- J/ApJ/714/476
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- There is a general consensus that many of the unidentified features in astrophysical spectra are due to low lying excited vibrational and torsional states of a few molecules -commonly referred to as the astrophysical weeds. This is a challenging spectroscopic problem not only because there are many such states, but also because these states are often highly perturbed and difficult to analyze. We have previously described an alternative approach based on experimental, intensity-calibrated spectra taken at many temperatures. In this paper, we describe the procedures and results obtained with this approach for ethyl cyanide, strategies for archiving and disseminating these results, and the prospects for using these results to reduce the confusion limit in the powerful new observatories that are coming online.
- ID:
- ivo://CDS.VizieR/J/ApJ/782/75
- Title:
- Complete spectrum of methanol
- Short Name:
- J/ApJ/782/75
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The complete spectrum of methanol (CH_3_OH) has been characterized over a range of astrophysically significant temperatures in the 560.4-654.0GHz spectral region. Absolute intensity calibration and analysis of 166 experimental spectra recorded over a slow 248-398K temperature ramp provide a means for the simulation of the complete spectrum of methanol as a function of temperature. These results include contributions from v_t_=3 and other higher states that are difficult to model via quantum mechanical (QM) techniques. They also contain contributions from the ^13^C isotopologue in terrestrial abundance. In contrast to our earlier work on semi-rigid species, such as ethyl cyanide and vinyl cyanide, significant intensity differences between these experimental values and those calculated by QM methods were found for many of the lines. Analysis of these differences shows the difficulty of the calculation of dipole matrix elements in the context of the internal rotation of the methanol molecule. These results are used to both provide catalogs in the usual line frequency, linestrength, and lower state energy format, as well as in a frequency point-by-point catalog that is particularly well suited for the characterization of blended lines.
- ID:
- ivo://CDS.VizieR/J/ApJ/813/96
- Title:
- CO ro-vibrational transitions
- Short Name:
- J/ApJ/813/96
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present calculated rate coefficients for ro-vibrational transitions of CO in collisions with H atoms for a gas temperature range of 10K<=T<=3000K, based on the recent three-dimensional ab initio H-CO interaction potential of Song et al. (2013JPCA..117.7571S). Rate coefficients for ro-vibrational v=1,j=0-30->v'=0,j' transitions were obtained from scattering cross sections previously computed with the close-coupling (CC) method by Song et al. (2015JChPh.142t4303S). Combining these with the rate coefficients for vibrational v=1-5->v'<v quenching obtained with the infinite-order sudden approximation, we propose a new extrapolation scheme that yields the rate coefficients for ro-vibrational v=2-5,j=0-30->v',j' de-excitation. Cross sections and rate coefficients for ro-vibrational v=2,j=0-30->v'=1,j' transitions calculated with the CC method confirm the effectiveness of this extrapolation scheme. Our calculated and extrapolated rates are very different from those that have been adopted in the modeling of many astrophysical environments. The current work provides the most comprehensive and accurate set of ro-vibrational de-excitation rate coefficients for the astrophysical modeling of the H-CO collision system. The application of the previously available and new data sets in astrophysical slab models shows that the line fluxes typically change by 20%-70% in high temperature environments (800K) with an H/H_2_ ratio of 1; larger changes occur for lower temperatures.
