- ID:
- ivo://CDS.VizieR/J/A+A/503/541
- Title:
- Neutral Li in late-type stars non-LTE calculations
- Short Name:
- J/A+A/503/541
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We perform non-LTE calculations of lithium in late-type stars for a wide range of stellar parameters, including quantum mechanical cross-sections for collisions with neutral hydrogen and the negative hydrogen ion. Non-LTE abundance corrections for the lithium resonance line at 670.7nm and the subordinate line at 610.3nm, are calculated using 1D MARCS model atmospheres spanning a large grid in effective temperature, surface gravity, and metallicity, and lithium abundance. The competing effects of ultraviolet over-ionization and photon losses in the resonance line govern the behaviour of the non-LTE effects with stellar parameters and lithium abundance. The size and sign of the non-LTE abundance corrections vary significantly over the grid for the 670.7nm line, but are typically positive and below 0.15dex for the 610.3nm line. The new collisional data play a significant role in determining the abundance corrections.
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- ID:
- ivo://CDS.VizieR/J/ApJ/686/448
- Title:
- Neutrino cross sections for SNe
- Short Name:
- J/ApJ/686/448
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The neutrino-nucleus reaction cross sections of ^4^He and ^12^C are evaluated using new shell model Hamiltonians. Branching ratios of various decay channels are calculated to evaluate the yields of Li, Be, and B produced through the {nu}-process in supernova explosions. The new cross sections enhance the yields of ^7^Li and ^11^B produced during the supernova explosion of a 16.2M_{sun}_ star model compared to the case using the conventional cross sections by about 10%. On the other hand, the yield of ^10^B decreases by a factor of 2. The yields of ^6^Li, ^9^Be, and the radioactive nucleus ^10^Be are found at a level of ~10^-11^M_{sun}_. The temperature of {nu}_{mu},{tau}_ - and {nu}{bar}_{mu},{tau}_ - neutrinos inferred from the supernova contribution of ^11^B in Galactic chemical evolution models is constrained to the 4.3-6.5MeV range. The increase in the ^7^Li and ^11^B yields due to neutrino oscillations is demonstrated with the new cross sections.
- ID:
- ivo://CDS.VizieR/J/A+A/513/A61
- Title:
- Neutron-induced astrophysical reaction rates
- Short Name:
- J/A+A/513/A61
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Neutron-induced reaction rates, including fission, are calculated in the temperature range 10^8^<=T(K)<=10^10^ within the framework of the statistical model for targets with atomic number 84<=Z<=118 (from Po to Uuo) from the neutron to the proton drip-line. Four sets of rates have been calculated, utilizing - where possible - consistent nuclear data for neutron separation energies and fission barriers from Thomas-Fermi (TF), Extended Thomas-Fermi plus Strutinsky Integral (ETFSI), Finite-Range Droplet Model (FRDM) and Hartree-Fock-Bogolyubov (HFB) predictions. Tables of calculated values as well as analytic seven parameter fits in the standard REACLIB format are supplied. We also discuss the sensitivity of the rates to the input, aiming at a better understanding of the uncertainties introduced by the nuclear input.
- ID:
- ivo://CDS.VizieR/J/A+A/543/A135
- Title:
- New analysis of ^13^C-CH_3_CH_2_CN up to 1THz
- Short Name:
- J/A+A/543/A135
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Millimeter- and submillimeter-wave spectra of regions such as the Orion molecular cloud show many rotational-torsional lines that are caused by the emission of complex organic molecules (COM). Previous laboratory investigations have been conducted for three isotopologues of ethyl cyanide up to 360GHz, and subsequently, several hundred lines of the three isotopologues have been detected in Orion IRc2 using the IRAM 30m radiotelescope. In this survey we present the analysis based on a Watson Hamiltonian for an asymmetric one-top rotor of the ^13^C-substituted ethyl cyanide ^13^CH_3_CH_2_CN, CH_3_^13^CH_2_CN and CH_3_CH_2_^13^CN in the frequency range 480-650GHz and 780-990GHz.The rotational spectra of the three species were measured with a submillimeter spectrometer (50-990GHz) using solid-state sources. A new set of spectroscopic parameters was determined from a least-squares fit procedure for each isotopologue. These parameters permit a new accurate prediction of rotational lines suitable for an astrophysical detection in the submillimeter wave range.
- ID:
- ivo://CDS.VizieR/J/A+A/520/A57
- Title:
- New FeII energy levels from stellar spectra
- Short Name:
- J/A+A/520/A57
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The spectra of B-type and early A-type stars show numerous unidentified lines in the whole optical range, especially in the 5100-5400{AA} interval. Because FeII transitions to high energy levels should be observed in this region, we used semiempirical predicted wavelengths and gf-values of FeII to identify unknown lines. Semiempirical line data for FeII computed by Kurucz are used to synthesize the spectrum of the slow-rotating, Fe - overabundant CP star HR6000.
- ID:
- ivo://CDS.VizieR/J/ApJS/216/1
- Title:
- New FeI level energies from stellar spectra
- Short Name:
- J/ApJS/216/1
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The spectrum of the Fe I atom is critical to many areas of astrophysics and beyond. Measurements of the energies of its high-lying levels remain woefully incomplete, however, despite extensive laboratory and solar analysis. In this work, we use high-resolution archival absorption-line ultraviolet and optical spectra of stars whose warm temperatures favor moderate Fe I excitation. We derive the energy for a particular upper level in Kurucz's semiempirical calculations by adopting a trial value that yields the same wavelength for a given line predicted to be about as strong as that of a strong unidentified spectral line observed in the stellar spectra, then checking the new wavelengths of other strong predicted transitions that share the same upper level for coincidence with other strong observed unidentified lines. To date, this analysis has provided the upper energies of 66 Fe I levels. Many new energy levels are higher than those accessible to laboratory experiments; several exceed the Fe I ionization energy. These levels provide new identifications for over 2000 potentially detectable lines. Almost all of the new levels of odd parity include UV lines that were detected but unclassified in laboratory Fe I absorption spectra, providing an external check on the energy values. We motivate and present the procedure, provide the resulting new energy levels and their uncertainties, list all the potentially detectable UV and optical new Fe I line identifications and their gf values, point out new lines of astrophysical interest, and discuss the prospects for additional Fe I energy level determinations.
- ID:
- ivo://CDS.VizieR/J/ApJS/229/23
- Title:
- New FeI level energies from stellar spectra. II.
- Short Name:
- J/ApJS/229/23
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Fe I spectrum is critical to many areas of astrophysics, yet many of the high-lying levels remain uncharacterized. To remedy this deficiency, Peterson & Kurucz (2015, J/ApJS/216/1) identified Fe I lines in archival ultraviolet and optical spectra of metal-poor stars, whose warm temperatures favor moderate Fe I excitation. Sixty-five new levels were recovered, with 1500 detectable lines, including several bound levels in the ionization continuum of Fe I. Here, we extend the previous work by identifying 59 additional levels, with 1400 detectable lines, by incorporating new high-resolution UV spectra of warm metal-poor stars recently obtained by the Hubble Space Telescope Imaging Spectrograph. We provide gf values for these transitions, both computed as well as adjusted to fit the stellar spectra. We also expand our spectral calculations to the infrared, confirming three levels by matching high-quality spectra of the Sun and two cool stars in the H-band. The predicted gf values suggest that an additional 3700 Fe I lines should be detectable in existing solar infrared spectra. Extending the empirical line identification work to the infrared would help confirm additional Fe I levels, as would new high-resolution UV spectra of metal-poor turnoff stars below 1900{AA}.
- ID:
- ivo://CDS.VizieR/J/ApJS/184/133
- Title:
- New ground-state measurements of ethyl cyanide
- Short Name:
- J/ApJS/184/133
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The spectrum of ethyl cyanide, or propionitrile (CH_3_CH_2_CN), has been repeatedly observed in the interstellar medium with large column densities and surprisingly high temperatures in hot core sources. The construction of new, more sensitive, observatories accessing higher frequencies such as Herschel, ALMA, and SOFIA have made it important to extend the laboratory data for ethyl cyanide to coincide with the capabilities of the new instruments. We report extensions of the laboratory measurements of the rotational spectrum of ethyl cyanide in its ground vibrational state to 1.6THz. A global analysis of the ground state, which includes all of the previous data and 3356 newly assigned transitions, has been fitted to within experimental error to J=132, K=36, using both Watson A-reduced and Watson S-reduced Hamiltonians.
- ID:
- ivo://CDS.VizieR/J/ApJS/224/35
- Title:
- New lifetimes and log(gf) for vanadium (V I)
- Short Name:
- J/ApJS/224/35
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report a new study of the V I atom using a combination of time-resolved laser-induced fluorescence and Fourier transform spectroscopy that contains newly measured radiative lifetimes for 25 levels between 24648/cm and 37518/cm and oscillator strengths for 208 lines between 3040 and 20000{AA} from 39 upper energy levels. Thirteen of these oscillator strengths have not been reported previously. This work was conducted independently of the recent studies of neutral vanadium lifetimes and oscillator strengths carried out by Den Hartog et al. (2014ApJS..215....7D) and Lawler et al. (2014, J/ApJS/215/20), and thus serves as a means to verify those measurements. Where our data overlap with their data, we generally find extremely good agreement in both level lifetimes and oscillator strengths. However, we also find evidence that Lawler et al. have systematically underestimated oscillator strengths for lines in the region of 9000+/-100{AA}. We suggest a correction of 0.18+/-0.03dex for these values to bring them into agreement with our results and those of Whaling et al. (1985A&A...153..109W). We also report new measurements of hyperfine structure splitting factors for three odd levels of V I lying between 24700 and 28400/cm.
- ID:
- ivo://CDS.VizieR/J/ApJS/164/297
- Title:
- New relativistic atomic data for Fe IX
- Short Name:
- J/ApJS/164/297
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A large-scale configuration interaction (CI) calculation using Program CIV3 of Hibbert is performed for the lowest 87 fine-structure levels of argon-like iron ions. We have calculated energy levels, oscillator strengths, and transition probabilities for all electric-dipole-allowed and intercombination transitions between the levels of 3s^2^3p^6^, 3s^2^3p^5^3d, 3s3p^6^3d, 3s^2^3p^5^4s, 3s^2^3p^5^4p, 3s^2^3p^5^4d, 3s3p^6^4s, 3s^2^3p^5^4f, 3s3p^6^4p, 3s^2^3p^5^5s, 3s^2^3p^5^5p, and 3s^2^3p^5^5d states of Fe ix in the LSJ coupling scheme. Lifetimes of the 3d levels are also determined. The calculations include the major correlation effects.
