- ID:
- ivo://CDS.VizieR/J/A+A/552/A117
- Title:
- Mono-deuterated dimethyl ether
- Short Name:
- J/A+A/552/A117
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Dimethyl ether is one of the most abundant complex organic molecules (COMs) in star-forming regions. Like other COMs, its formation process is not yet clearly established, but the relative abundances of its deuterated isotopomers may provide crucial hints in studying its chemistry and tracing the source history. The mono-deuterated species (CH_2_DOCH_3_) is still a relatively light molecule compared to other COMs. Its spectrum is the most intense in the THz domain in the 100-150K temperature regime, tracing the inner parts of the low-mass star-forming region. Therefore, it is necessary to measure and assign its transitions in this range in order to be able to compute accurate predictions required by astronomical observations, in particular with the telescope operating in the submm range, such as ALMA. We present the analysis of mono-deuterated dimethyl ether in its ground-vibrational state, based on an effective Hamiltonian for an asymmetric rotor molecules with internal rotors, The analysis covers the frequency range 150-990GHz. The laboratory rotational spectrum of this species was measured with a submillimeter spectrometer (50-990GHz) using solid-state sources. For the astronomical detection, we used the IRAM 30m telescope to observe a total range of 27GHz, in 4 frequency bands from 100GHz to 219GHz. New sets of spectroscopic parameters have been determined by a least squares fit with the ERHAM code for both conformers. These parameters have permitted the first identification in space of both mono-deuterated DME isomers via detection of twenty transitions in the solar-type protostar IRAS16293-2422 with the IRAM 30m telescope. The DME deuteration ratio in this source appears as high as observed for methanol and formaldehyde, two species known to play an important role in the COMs formation history.
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- ID:
- ivo://CDS.VizieR/J/ApJS/170/251
- Title:
- Multiplet table for neutral helium
- Short Name:
- J/ApJS/170/251
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This paper combines the precise determination of the energy levels of ^4^HeI from calculations and experiments with theoretical transition probabilities to present multiplet tables and finding lists for the fine structure of the helium atom. The tabulated transition rates and oscillator strengths include corrections for singlet-triplet mixing and spin-orbit coupling, but not the higher order relativistic terms nor the finite nuclear mass, although the latter are tabulated for future use. The results are consistent with laboratory lifetimes and oscillator strengths, but very few measurements are accurate enough to be stringent tests. An Appendix discusses the corrections for finite nuclear mass.
- ID:
- ivo://CDS.VizieR/J/ApJS/167/315
- Title:
- Na IX-X & Mg X-XI recombination rate coefficients
- Short Name:
- J/ApJS/167/315
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Detailed study on the inverse processes of photoionization and electron-ion recombination for NaIX+h{nu}<->NaX+e, NaX+h{nu}<->NaXI+e, MgX+h{nu}<->Mg{nu}+e, and MgXI+h{nu}<->MgXII+e is reported. The unified method for the total electron-ion recombination is used for the self-consistent results of total and level-specific recombination rate coefficients {alpha}_R_ and {alpha}_R_(i) (subsuming both radiative recombination [RR] and dielectronic recombination [DR]), total recombination cross sections {sigma}_RC_, and total and partial level-specific photoionzation cross sections {sigma}_PI_ and {sigma}_PI(g)_. The total recombination spectrum of cross sections and recombination rates versus photoelectron energy are presented for experimental applications. The unified method employs close-coupling approximation in the relativistic Breit-Pauli R-matrix (BPRM) method. The coupled channel wave function expansions for Li-like NaIX and MgX consist of 17 core levels with excitations up to 3d orbital and for He-like NaX and MgXI consist of 16 core levels of excitations up to 4f orbital, respectively. The results are presented for all fine-structure levels of the ions up to n<=10, which correspond to 98 levels with 1/2<=J<=17/2 for Li-like NaIX and MgX, 182 and 185 levels with 0<=J<=10 for He-like NaX and MgXI, respectively. The level specific photoionization cross sections {sigma}_PI_(nSLJ) and recombination rates {alpha}_R_(T; nSLJ) are obtained for the first time for these ions. The single-valued total {alpha}_R_(T) is presented over an extended temperature range for astrophysical and laboratory plasma applications. The total unified R(T) for all ions agrees very well with the available published RR and DR rates. Total recombination rates for H-like NaXI and MgXII are also presented for completeness. The results are expected to be accurate within 10%15% from considerations of important atomic effects such as radiation damping, channel couplings, and interference of DR and RR. The comprehensive data sets are applicable for ionization balance and recombination-cascade models for UV and X-ray lines.
- ID:
- ivo://CDS.VizieR/J/A+A/500/1263
- Title:
- Na-like iso-electronic sequence
- Short Name:
- J/A+A/500/1263
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present our calculated data including energy levels, radiative decay rates and effective collision strengths for all the transitions among the 32 fine-structure levels arising from the 18 lowest LS states of Na-like iso-electronic sequence, i.e. those with configurations: 2p(6)3l (l=s,p,d); 2p(6)4l (l=s,p,d,f); 2p(6)5l (l=s,p,d,f,g); 2p(6)6l (l=s,p,d,f,g,h). The effective collision strengths at 13 temperatures ranging from 2x10^2(q+1)^2 to 2x10^6(q+1)^2 K, where q is the residual charge of ions, i.e. Z-11, have been calculated using the ICFT R-matrix method. The data format adopts ADAS adf04 format, see the file at website http://www.adas.ac.uk/man/appxa-04.pdf
- ID:
- ivo://CDS.VizieR/J/A+A/518/A64
- Title:
- Na-like iso-electronic sequence. II.
- Short Name:
- J/A+A/518/A64
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present our calculated data including energy levels, radiative decay rates and effective collision strengths for all the transitions among the 209 fine-structure levels arising from the 113 lowest LS states of Ne-like iso-electronic sequence, i.e. those with configurations: [1s2]2s2 2p6, 2s2 2p5 {3,4,5}l, 2s 2p6 {3,4,5}l, (l=s, p, d, f and g) 2s2 2p5 {6,7}l' (l'=s, p and d). The effective collision strengths at 13 temperatures ranging from 2x10^2(q+1)^2 to 2x10^6(q+1)^2 K, where q is the residual charge of ions, i.e. Z-10, have been calculated using the ICFT R-matrix method. The data format adopts ADAS adf04 format, see the file at website http://www.adas.ac.uk/man/appxa-04.pdf
- ID:
- ivo://CDS.VizieR/J/ApJS/233/15
- Title:
- ND_2_ rotational spectrum
- Short Name:
- J/ApJS/233/15
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The deuteration mechanism of molecules in the interstellar medium is still being debated. Observations of deuterium-bearing species in several astronomical sources represent a powerful tool to improve our understanding of the interstellar chemistry. The doubly deuterated form of the astrophysically interesting amidogen radical could be a target of detection in space. In this work, the rotational spectrum of the ND_2_ radical in its ground vibrational and electronic X^2^B_1_ state has been investigated between 588 and 1131GHz using a frequency modulation millimeter/submillimeter-wave spectrometer. The ND_2_ molecule has been produced in a free-space glass absorption cell by discharging a mixture of ND_3_ and Ar. Sixty-four new transition frequencies involving J values from 2 to 5 and K_a_ values from 0 to 4 have been measured. A global analysis including all the previous field-free pure rotational data has been performed, allowing for a more precise determination of a very large number of spectroscopic parameters. Accurate predictions of rotational transition frequencies of ND_2_ are now available from a few gigahertz up to several terahertz.
- ID:
- ivo://CDS.VizieR/J/ApJ/852/43
- Title:
- Ne and Na neutrino energy spectra
- Short Name:
- J/ApJ/852/43
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present shell model calculations of nuclear neutrino energy spectra for 70 sd-shell nuclei over the mass number range A=21-35. Our calculations include nuclear excited states as appropriate for the hot and dense conditions characteristic of pre-collapse massive stars. We consider neutrinos produced by charged lepton captures and decays, and for the first time in tabular form, neutral current nuclear deexcitation, providing neutrino energy spectra on the Fuller-Fowler-Newman temperature-density grid for these interaction channels for each nucleus. We use the full sd-shell model space to compute initial nuclear states up to 20 MeV excitation with transitions to final states up to 35-40 MeV, employing a modification of the Brink-Axel hypothesis to handle high-temperature population factors and the nuclear partition functions.
- ID:
- ivo://CDS.VizieR/J/A+A/530/A18
- Title:
- Nebular NII lines effective recombination coeff.
- Short Name:
- J/A+A/530/A18
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In nebular astrophysics, there has been a long-standing dichotomy in plasma diagnostics between abundance determinations using the traditional method based on collisionally excited lines (CELs), on the one, hand and (optical) recombination lines/continuum, on the other. A number of mechanisms have been proposed to explain the dichotomy. Deep spectroscopy and recombination line analysis of emission line nebulae (planetary nebulae and HII regions) in the past decade have pointed to the existence of another previously unknown component of cold, H-deficient material as the culprit. Better constraints are needed on the physical conditions (electron temperature and density), chemical composition, mass, and spatial distribution of the postulated H-deficient inclusions in order to unravel their astrophysical origins. This requires knowledge of the relevant atomic parameters, most importantly the effective recombination coefficients of abundant heavy element ions such as CII, OII, NII, and NeII, appropriate for the physical conditions prevailing in those cold inclusions (e.g. Te<=1000K ).
- ID:
- ivo://CDS.VizieR/VI/144
- Title:
- Nebular [OIII] collision strengths - SS3
- Short Name:
- VI/144
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The list consists of effective collision strengths in the electron excitation (Upsilon) and de-excitation (Downsilon) with a kappa electron energy distribution as a function of the electron temperature and kappa for 10 forbidden transitions between the five lowest energy levels of the astronomically abundant doubly-ionized oxygen ion, O^2+^, in an intermediate coupling scheme using the Breit-Pauli relativistic terms as implemented in an R-matrix atomic scattering code (Berrington et al., 1995). An atomic target for the R-matrix scattering defined by 72 atomic terms is used in these calculations with Gailitis averaging in the region beneath thresholds where the effective quantum number is greater than 10. The raw collision strength data are obtained from a list created previously by the authors (Storey et al., 2014MNRAS.441.3028S, Cat. VI/141). The limits of the effective collision strength data are the same as the limits of the original raw collision strength data, that is the data apply for a temperature range between about 100-25000K with a free electron excitation energy up to about 1.3 Rydberg. These limits are adopted mainly for relevance to planetary nebulae and HII regions.
- ID:
- ivo://CDS.VizieR/VI/141
- Title:
- Nebular [OIII] collision strengths - SSB
- Short Name:
- VI/141
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present electron collision strengths and their thermally averaged values for the nebular forbidden lines of the astronomically abundant doubly ionized oxygen ion, O^2+^, in an intermediate coupling scheme using the Breit-Pauli relativistic terms as implemented in an R-MATRIX atomic scattering code. We use several atomic targets for the R-MATRIX scattering calculations including one with 72 atomic terms. We also compare with new results obtained using the 20 intermediate coupling frame transformation method. We find spectroscopically significant differences against a recent Breit-Pauli calculation for the excitation of the [OIII] {lambda}4363 transition but confirm the results of earlier calculations.
