- ID:
- ivo://CDS.VizieR/J/ApJS/227/16
- Title:
- Energy levels & transition rates for F-like ions
- Short Name:
- J/ApJS/227/16
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have performed extensive multiconfiguration Dirac-Hartree-Fock calculations and second-order many-body perturbation calculations for F-like ions with Z=24-30. Energy levels and transition rates for electric dipole (E1), electric-quadrupole (E2), electric-octupole (E3), magnetic dipole (M1), and magnetic-quadrupole (M2) transitions, as well as radiative lifetimes, are provided for the lowest 200 levels belonging to the 1s^2^2s^2^2p^5^, 1s^2^2s2p^6^, 1s^2^2s^2^2p^4^3l, 1s^2^2s2p^5^3l, 1s^2^2p^6^3l, and 1s^2^2s^2^2p^4^4l configurations of each ion. The results from the two sets of calculations are in excellent agreement. Extensive comparisons are also made with other theoretical results and observed data from the CHIANTI and NIST databases. The present energies and wavelengths are believed to be accurate enough to aid line identifications involving the n=3 and n=4 configurations, for which observations are largely missing. The calculated wavelengths and transition data will be useful in the modeling and diagnostics of astrophysical and fusion plasmas.
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- ID:
- ivo://CDS.VizieR/J/ApJS/235/27
- Title:
- Energy levels & transition rates for P-like ions
- Short Name:
- J/ApJS/235/27
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The fully relativistic multiconfiguration Dirac-Hartree-Fock method is used to compute excitation energies and lifetimes for the 143 lowest states of the 3s^2^3p^3^, 3s3p^4^, 3s^2^3p^2^3d, 3s3p^3^3d, 3p^5^, 3s^2^3p3d^2^ configurations in P-like ions from Cr X to Zn XVI. Multipole (E1, M1, E2, M2) transition rates, line strengths, oscillator strengths, and branching fractions among these states are also given. Valence-valence and core-valence electron correlation effects are systematically accounted for using large basis function expansions. Computed excitation energies are compared with the NIST ASD and CHIANTI compiled values and previous calculations. The mean average absolute difference, removing obvious outliers, between computed and observed energies for the 41 lowest identified levels in Fe XII, is only 0.057%, implying that the computed energies are accurate enough to aid identification of new emission lines from the Sun and other astrophysical sources. The amount of energy and transition data of high accuracy are significantly increased for several P-like ions of astrophysics interest, where experimental data are still very scarce.
- ID:
- ivo://CDS.VizieR/J/ApJS/218/16
- Title:
- Energy levels & transition rates of Be-like ions
- Short Name:
- J/ApJS/218/16
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report calculations of energy levels and radiative rates for transitions among the lowest 116 fine-structure levels arising from the n<=5 configurations in Be-like ions with Z=10-30. The wavelengths, oscillator strengths, line strengths, and radiative rates for all possible electric dipole, magnetic dipole, electric quadrupole, and magnetic quadrupole transitions among the 116 levels have been calculated using the combined configuration interaction and many-body perturbation method. The accuracy of the results is determined through extensive comparisons with existing laboratory measurements and theoretical results. The present complete set of results should be of great help in line identification and the interpretation of spectra, as well as in the modeling and diagnostics of astrophysical and fusion plasmas.
- ID:
- ivo://CDS.VizieR/J/ApJS/229/37
- Title:
- Energy levels & transition rates of O-like ions
- Short Name:
- J/ApJS/229/37
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Employing two state-of-the-art methods, multiconfiguration Dirac-Hartree-Fock and second-order many-body perturbation theory, the excitation energies and lifetimes for the lowest 200 states of the 2s^2^2p^4^, 2s2p^5^, 2p^6^, 2s^2^2p^3^3s, 2s^2^2p^3^3p, 2s^2^2p^3^3d, 2s2p^4^3s, 2s2p^4^3p, and 2s2p^4^3d configurations, and multipole (electric dipole (E1), magnetic dipole (M1), and electric quadrupole (E2)) transition rates, line strengths, and oscillator strengths among these states are calculated for each O-like ion, from CrXVII to ZnXXIII. Our two data sets are compared with the National Institute of Standards and Technology and CHIANTI compiled values, and previous calculations. The data are accurate enough for identification and deblending of new emission lines from the Sun and other astrophysical sources. The amount of high-accuracy data is significantly increased for the n=3 states of several O-like ions of astrophysical interest, where experimental data are very scarce.
- ID:
- ivo://CDS.VizieR/J/ApJ/416/276
- Title:
- Eq. of State in Magnetic Neutron Stars
- Short Name:
- J/ApJ/416/276
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This catalog is based on the calculated equation of state in cold dense matter. Each table in the catalog lists bulk properties of Fe-56 in a magnetic field ranging from one million to 1000 million Tesla.
- ID:
- ivo://CDS.VizieR/J/A+A/503/545
- Title:
- Equivalent widths of Li, Na, Fe, Ca in NGC 6397
- Short Name:
- J/A+A/503/545
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- To alleviate the discrepancy between the prediction of the primordial lithium abundance in the universe and the abundances observed in Pop II dwarfs and subgiant stars, it has been suggested that the stars observable today have undergone photospheric depletion of lithium. To identify the cause of such depletion, it is important to accurately establish the behaviour of lithium abundance with effective temperature and evolutionary phase. Stars in globular clusters are ideal objects for such abundance analysis, as relative stellar parameters can be precisely determined. We conduct a homogeneous analysis of a very large sample of stars in the metal-poor globular cluster NGC 6397, covering well all evolutionary phases from below the main sequence turn-off to high up the red giant branch. Non-LTE Li abundances or abundance upper limits are obtained for all stars, and for a size-able sub-set of the targets also Na abundances are obtained. The sodium abundances are used to distinguish stars formed out of pristine material from stars formed out of material affected by pollution from a previous generation of more massive stars. The dwarfs, turn-off, and early subgiant stars in our sample form a thin abundance plateau, disrupted in the middle of the subgiant branch by the lithium dilution caused by the first dredge-up. A second steep abundance drop is seen at the luminosity of the red giant branch bump. The turn-off stars are more lithium-poor, by up to 0.1dex, than subgiants that have not yet undergone dredge-up. In addition, hotter dwarfs are slightly more lithium-poor than cooler dwarfs, which may be a signature of the so-called Li dip in the cluster, commonly seen among PopI stars. The feature is however weak. A considerably large spread in Na abundance confirms that NGC6397 has suffered from intra-cluster pollution in its infancy and a limited number of Na-enhanced and Li-deficient stars strongly contribute to form a significant anti-correlation between the abundances of Na and Li. It is nevertheless seen that lithium abundances are unaffected by relatively high degrees of pollution. Lithium abundance trends with effective temperature and stellar luminosity are compared to predictions from stellar structure models including atomic diffusion and ad-hoc turbulence below the convection zone. We confirm previous findings that some turbulence, with strict limits to its efficiency, is necessary to explain the observations.
- ID:
- ivo://CDS.VizieR/J/ApJ/768/81
- Title:
- Ethyl cyanide, CH_3_CH_2_CN, vibrational states
- Short Name:
- J/ApJ/768/81
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Ethyl cyanide, CH_3_CH_2_CN, is an important interstellar molecule with a very dense rotational-vibrational spectrum. On the basis of new laboratory data in the range of 17-605GHz and ab initio calculations, two new vibrational states, {nu}_12_ and {nu}_20_, have been detected in molecular clouds of Orion. Laboratory data consist of Stark spectroscopy (17-110GHz) and frequency-modulated spectrometers (GEM laboratory in Valladolid: 17-170, 270-360GHz; Toyama: 26-200GHz; Emory: 200-240GHz; Ohio State: 258-368GHz; and JPL: 270-318, 395-605GHz). More than 700 distinct lines of each species were measured in J up to 71 and in K_a_ up to 25. The states were fitted with Watson's S-reduction Hamiltonian. The two new states have been identified in the interstellar medium toward the Orion Nebula (Orion KL). The ground state, the isotopologues of CH_3_CH_2_CN, and the vibrationally excited states have been fitted to obtain column densities and to derive vibrational temperatures. All together, ethyl cyanide is responsible for more than 2000 lines in the observed frequency range of 80-280GHz.
- ID:
- ivo://CDS.VizieR/J/ApJ/499/517
- Title:
- Ethylene oxide spectrum
- Short Name:
- J/ApJ/499/517
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The cyclic molecule ethylene oxide (c-C_2_H_4_O) has recently been detected in the interstellar source Sgr B2N. Previous laboratory work on the rotational spectrum of this molecule extends only to a frequency of 123GHz. We report here the extension of the laboratory rotational spectrum of this species through the frequency range 262358GHz using a new fast scan spectrometer (fast scan submillimeter spectroscopic technique, FASSST). The newly measured lines have been combined with previous data at lower frequencies to form a data set consisting of 662 lines that has been assigned and fitted via a standard semirigid asymmetric top analysis. The spectral constants obtained from the fit have allowed us to predict the frequencies of many additional lines.
- ID:
- ivo://CDS.VizieR/J/A+A/610/A44
- Title:
- Ethyl isocyanide submillimeter wave spectroscopy
- Short Name:
- J/A+A/610/A44
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- About 40 cyanide molecules have been detected in the interstellar medium, but only 3 examples of organic isocyanide molecules were observed in this medium. Ethyl isocyanide is one of the best candidates for possible detection. To date, measurements of rotational spectra are limited to 40 GHz. The extrapolation of the prediction in the millimeter wave domain is inaccurate and does not permit an unambiguous detection. The rotational spectra were reinvestigated from 0.15 to 1THz. Using the new prediction, we searched for the compound ethyl isocyanide in Orion KL and Sgr B2. We newly assigned 2906 transitions and fitted these new data with those from previous studies, reaching quantum numbers up to J=103 and Ka=30. The asymmetric top Hamiltonian proposed by Watson in the Ir representation was used for the analysis, and both reductions A and S were tested. The search for CH_3_CH_2_NC in SgrB2 (IRAM 30m) and Orion KL (IRAM 30m, ALMA Science Verification) result in a non-detection; upper limits to the column density were derived.
- ID:
- ivo://CDS.VizieR/J/A+A/639/A129
- Title:
- Ethyl methyl sulfide rotational spectroscopy
- Short Name:
- J/A+A/639/A129
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Sulfur-containing molecules constitute only 8% of the molecules observed in the interstellar medium (ISM) in spite that sulfur has been shown to be an abundant element in the ISM. In order to understand the chemical behaviour of the ISM and specific cases like the missing sulfur reservoir, a detailed chemical molecular composition in the ISM must be mapped out. Our goal is the investigation of the rotational spectrum of ethyl methyl sulfide, CH_3_CH_2_SCH_3_, which seems to be a potential candidate to be observed in the ISM since the simpler analogs, CH_3_SH and CH_3_CH_2_SH, have been already detected. Rotational spectrum of ethyl methyl sulfide has been observed before, but its experimental rotational parameters are not precise enough to allow its detection in the ISM. The rotational spectrum of ethyl methyl sulfide in the frequency range 72-116.5GHz was measured using a broadband millimeter-wave spectrometer based on radio astronomy receivers with fast Fourier transform backends. The spectral searches and identification of the vibrational excited states of ethyl methyl sulfide was supported by high-level ab initio calculations on the harmonic and anharmonic force fields. The rotational spectra for the trans and gauche conformers of ethyl methyl sulfide was analyzed and a total of 172 and 259 rotational transitions were observed for each one, respectively. The observation of A-E internal rotation splittings allowed the experimental determination of the V3 hindered internal rotation barrier height for both trans and gauche species. In addition, the vibrational excited states, resulting from the lowest frequency vibrational mode nu30 were identified for both conformers. The new experimental rotational parameters were employed to search for ethyl methyl sulfide in the cold and warm molecular clouds Orion KL, Sgr B2(N), B1-b and TMC-1, using the spectral surveys captured by IRAM 30m at 3mm and 2mm.
