- ID:
- ivo://CDS.VizieR/J/A+A/559/A70
- Title:
- Blue wing of the 2p-1s He_2_ line
- Short Name:
- J/A+A/559/A70
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The shape and broadening of He lines affects radiative transport in dense, He-rich, stellar atmospheres. At wavelengths inaccessible for direct observation, we rely on theoretical calculations of self-broadening to support stellar structure and spectral modeling. In this work, we examine lines of He due to 1s-2p and 2p-3s transitions. The line profiles are analyzed in terms of a unified theory of spectral line broadening using ab initio potential energies that have been recently determined. For temperatures up to 20000K, the linear dependence of width and shift on gas density and the non-linear dependence on temperature of the Lorentzian core of the resonance line are described. Beyond the conventional symmetrical Lorentzian core, we show that they are asymmetrical and have significant additional contributions on the short wavelength side. This blue asymmetry is a consequence of maxima in the corresponding He2 potential energy difference curves at short and intermediate internuclear distance. Over a limited range of density and temperature, laboratory measurements in the visible and near infrared can be used to validate the potentials that underlie the spectral line profile theory, which is useful for modeling spectra over the extreme ranges of temperature and density encountered in stellar and planetary atmospheres.
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/559/A100
- Title:
- Boron isoelectronic sequence data
- Short Name:
- J/A+A/559/A100
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Relativistic configuration interaction (RCI) calculations are performed for 291 states belonging to the configurations 1s^2^2s^2^2p, 1s^2^2s2p^2^, 1s^2^2p^3^, 1s^2^2s^2^3l, 1s^2^2s2p3l, 1s^2^2p^2^3l, 1s^2^2s^2^4l', 1s^2^2s2p4l', and 1s^2^2p^2^4l' (l=0, 1, 2 and l'=0, 1, 2, 3) in boronlike ions Si X and Ti XVIII to Cu XXV. Electron correlation effects are represented in the wave functions by large configuration state function (CSF) expansions. States are transformed from j j-coupling to LS -coupling, and the LS -percentage compositions are used for labeling the levels. Radiative electric dipole transition rates are given for all ions, leading to massive data sets. Calculated energy levels are compared with other theoretical predictions and crosschecked against the Chianti database, NIST recommended values, and other observations. The accuracy of the calculations are high enough to facilitate the identification of observed spectral lines.
- ID:
- ivo://CDS.VizieR/J/A+A/455/1157
- Title:
- Boron-like Fe XXII transition probabilities
- Short Name:
- J/A+A/455/1157
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Energy levels and the corresponding transition probabilities as well as oscillator strengths and line strengths for allowed (E1) and forbidden (E2, M1) transitions among the lowest 407 levels of boron-like Fe XXII are presented. Calculations were performed using the multiconfigurational Dirac-Fock GRASP code.
- ID:
- ivo://CDS.VizieR/J/ApJS/188/32
- Title:
- Breit-Pauli transition probabilities for SII
- Short Name:
- J/ApJS/188/32
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- New improved calculations are reported for transition probabilities and electron impact excitation collision strengths for the astrophysically important lines in SII. The collision strengths have been calculated in the close-coupling approximation using the B-spline Breit-Pauli R-matrix method. The multiconfiguration Hartree-Fock method with term-dependent non-orthogonal orbitals is employed for an accurate representation of the target wave functions. The close-coupling expansion includes 70 bound levels of SII covering all possible terms of the ground 3s^2^3p^3^ and singly excited 3s3p^4^, 3s^2^3p^2^3d, 3s^2^3p^2^4s, and 3s^2^3p^2^4p configurations. The present calculations are more extensive than previous ones, leading to a total 2415 transitions between fine-structure levels. The effective collision strengths are obtained by averaging the electron collision strengths over a Maxwellian distribution of velocities and these are tabulated for all fine-structure transitions at electron temperatures in the range from 5000 to 100000K. The present results are compared with a variety of other close-coupling calculations and available experimental data. There is an overall good agreement with the recent 18-state calculations by Ramsbottom, Bell, & Stafford and with the 19-state calculations by Tayal for the most part, but some significant differences are also noted for some transitions.
- ID:
- ivo://CDS.VizieR/J/A+A/435/373
- Title:
- Broadening of Fe II lines by H collisions
- Short Name:
- J/A+A/435/373
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Data for the broadening of 24188 Fe II lines by collisions with neutral hydrogen atoms have been computed using the theory of Anstee & O'Mara (1991MNRAS.253..549A, 1995MNRAS.276..859A) as extended to singly ionised species and higher orbital angular momentum states by Barklem & O'Mara (1998MNRAS.300..863B). Data have been computed for all Fe II lines between observed energy levels in the line lists of Kurucz with loggf>-5 for which the theory is applicable. The variable energy debt parameter Ep used in computing the second order perturbation theory potential is chosen to be consistent with the long range dispersion interaction constant C_6_ computed using the f-values from Kurucz.
- ID:
- ivo://CDS.VizieR/J/A+AS/142/467
- Title:
- Broadening of metallic lines by H collisions
- Short Name:
- J/A+AS/142/467
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- File table1 is a list of theoretical data for the broadening of metallic lines by collisions with neutral hydrogen atoms. The list contains data for 4891 spectral lines between 2300 and 13000 Angstroms of elements from Li to Ni.
- ID:
- ivo://CDS.VizieR/J/A+A/441/1195
- Title:
- Brussels nuclear reaction rate library
- Short Name:
- J/A+A/441/1195
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The present data is part of the Brussels nuclear reaction rate library (BRUSLIB) for astrophysics applications and concerns nuclear reaction rate predictions calculated within the statistical Hauser-Feshbach approximation and making use of global and coherent microscopic nuclear models for the quantities (nuclear masses, nuclear structure properties, nuclear level densities, gamma-ray strength functions, optical potentials) entering the rate calculations.
- ID:
- ivo://CDS.VizieR/J/A+A/635/A84
- Title:
- BSk26 functionals
- Short Name:
- J/A+A/635/A84
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In the cooling process of a non-accreting neutron star, the composition and properties of the crust are thought to be fixed at the finite temperature where nuclear reactions fall out of equilibrium. A lower estimation for this temperature is given by the crystallization temperature, which can be as high as ~7x10^9^K in the inner crust, potentially leading to sizeable differences with respect to the simplifying cold-catalyzed matter hypothesis. We extend a recent work (Fatina et al., 2020, Cat. J/A+A/633/A149) on the outer crust, to the study of the crystallization of the inner crust and the associated composition in the one-component plasma approximation. The finite temperature variational equations for non-uniform matter in both the liquid and the solid phases are solved using a compressible liquid-drop approach with parameters optimized on four different microscopic models which cover the present uncertainties in nuclear modeling. We consider separately the effect of the different nuclear ingredients with their associated uncertainties, namely the nuclear equation of state, the surface properties in the presence of a uniform gas of dripped neutrons, and the proton shell effects arising from the ion single-particle structure. Our results suggest that the highest source of model dependence comes from the smooth part of the nuclear functional. We show that shell effects play an important role at the lowest densities close to the outer crust, but the most important physical ingredient to be settled for a quantitative prediction of the inner crust properties is the surface tension at extreme isospin values.
- ID:
- ivo://CDS.VizieR/J/A+A/526/A71
- Title:
- C abundances in G and K nearby stars
- Short Name:
- J/A+A/526/A71
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a determination of photospheric parameters and carbon abundances for a sample of 172 G and K dwarf, subgiant, and giant stars with and without detected planets in the solar neighbourhood. The analysis was based on high signal-to-noise ratio and high resolution spectra observed with the ELODIE spectrograph (Haute Provence Observatory, France) and for which the observational data were publicly available. We intend to contribute precise and homogeneous C abundances in studies that compare the behaviour of light elements in stars with and without planets. This will bring new arguments to the discussion of possible anomalies that have been suggested and will contribute to a better understanding of different planetary formation process.
- ID:
- ivo://CDS.VizieR/J/MNRAS/357/471
- Title:
- Calculated spectra for HeH^+^
- Short Name:
- J/MNRAS/357/471
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The wavelength and Einstein A coefficient are calculated for all rotation-vibration transitions of ^4^HeH^+^, ^3^HeH^+^, ^4^He^2^H^+^ and ^3^He^2^H^+^, giving a complete line list and the partition function for ^4^HeH^+^ and its isotopologues. This opacity is included in the calculation of the total opacity of low-metallicity stars and its effect is analysed for different conditions of temperature, density and hydrogen number fraction. For a low helium number fraction (as in the Sun), it is found that HeH^+^ has a visible but small effect for very low densities ({rho}<=10^-10^g/cm^3^), at temperatures around 3500K. However, for high helium number fraction, the effect of HeH^+^ becomes important for higher densities ({rho}<=10^-6^g/cm^3^), its effect being most important for a temperature around 3500K. Synthetic spectra for a variety of different conditions are presented.
