- ID:
- ivo://CDS.VizieR/J/A+A/376/1113
- Title:
- Line ratios for helium-like ions
- Short Name:
- J/A+A/376/1113
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The tables include data concerning six He-like ions: wavelengths, transition probabilities, wavelengths at which the radiation temperatures should be determined. Line ratios (G and R, see definition in table 1 below) for six He-like ions from Tables 3 to 69 for various parameters: density (n_e_), temperature (T_e_), dilution factor (W), radiation temperature (T_rad_), and spectral resolution. Atomic data (appendix A) concerning the unresolved satellite lines are displayed (from Tables A1 to A6).
Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/VI/16
- Title:
- Line Spectra of the Elements
- Short Name:
- VI/16
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This catalog contains wavelength information for 99 different atomic species. The wavelengths for about 46,610 spectral lines of neutral through quadruply ionized atoms are tabulated. The information is presented in a general table of headers and references for each element and for each element a table of relative intensities, wavelengths ordered numerically, chemical elements, and stages of ionization indicated for each line in the wavelength range 40 to 40,000 Angstroms. Listed in the 99 data files are lines that appear in emission from the vacuum ultraviolet to the far infrared. For most atoms these lines are chosen from much larger lists so as to include the stronger observed lines in each spectral region. Below 2000 Angstroms the wavelengths are in vacuum; above 2000 Angstroms the wavelengths are in air. Wavelengths given to three decimal places are suitable for spectrograph calibration purpose such as Ne, Ar, Kr, Fe in the air region and C, N, O, Si, and Cu in the vacuum region. The intensity estimates are useful only as a rough indication of the appearance of a spectrum. The literature references as they appear the the the Handbook of Chemistry and Physics are given in a separate file.
- ID:
- ivo://CDS.VizieR/J/A+AS/103/293
- Title:
- Lines unaffected by polarization
- Short Name:
- J/A+AS/103/293
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- (no description available)
- ID:
- ivo://CDS.VizieR/J/A+A/541/A158
- Title:
- ^7^Li(p,{alpha})^4^He reaction rate
- Short Name:
- J/A+A/541/A158
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The charged-particle induced reactions on lithium have been studied by several works. In particular, several direct measurements of the ^7^Li(p,{alpha})^4^He reaction have been performed to extrapolate its low-energy astrophysical S(E)-factor and evaluate the electron screening potential, Ue. In view of recent direct measurements, we discuss our estimate of the bare-nucleus S(E)-factor and an evaluation of the corresponding reaction rate. Moreover, we present the extracted electron screening potential.
- ID:
- ivo://CDS.VizieR/J/A+A/657/A66
- Title:
- List of FeI and FeII used for SteParSyn
- Short Name:
- J/A+A/657/A66
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- SteParSyn is an automatic code written in Python 3.X designed to infer the stellar atmospheric parameters Teff, log(g), and [Fe/H] of FGKM-type stars following the spectral synthesis method. We present a description of the SteParSyn code and test its performance against a sample of late-type stars that were observed with the HERMES spectrograph mounted at the 1.2-m Mercator Telescope. This sample contains 35 late-type targets with well-known stellar parameters determined independently from spectroscopy. The code is available to the astronomical community in a GitHub repository. SteParSyn uses a Markov chain Monte Carlo (MCMC) sampler to explore the parameter space by comparing synthetic model spectra generated on the fly to the observations. The synthetic spectra are generated with an spectral emulator. Results: We computed Teff, log(g), and [Fe/H] for our sample stars and discussed the performance of the code. We calculated an internal scatter for these targets of -12+/-117K in Teff, 0.04+/-0.14dex in log(g), and 0.05+/-0.09dex in [Fe/H]. In addition, we find that the log(g) values obtained with SteParSyn are consistent with the trigonometric surface gravities to the 0.1dex level. Finally, SteParSyn can compute stellar parameters that are accurate down to 50K, 0.1dex, and 0.05dex for Teff, log(g), and [Fe/H] for stars with vsini<=30km/s.
- ID:
- ivo://CDS.VizieR/J/A+A/535/A117
- Title:
- Low-charge ions charge transfer rate coeff.
- Short Name:
- J/A+A/535/A117
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present total and final-state resolved charge transfer (CT) rate coefficients for low-charge Ge, Se, Br, Kr, Rb, and Xe ions reacting with neutral hydrogen over the temperature range 102-106K. Each of these elements has been detected in ionized astrophysical nebulae, particularly planetary nebulae. CT rate coefficients are a key ingredient for the ionization equilibrium solutions needed to determine total elemental abundances from those of the observed ions. A multi-channel Landau Zener approach was used to compute rate coefficients for projectile ions with charges q=2-5, and for singly-charged ions the Demkov approximation was utilized.
- ID:
- ivo://CDS.VizieR/J/A+A/494/403
- Title:
- Low temperature Rosseland opacities
- Short Name:
- J/A+A/494/403
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We provide low temperature opacity data that incorporate varied abundances of the elements carbon and nitrogen. In the temperature range that we focus at, molecules are the dominant opacity source. Our dataset spans a large metallicity range and shall deliver the necessary input data for stellar evolution models as well as other applications. We conduct chemical equilibrium calculations in order to evaluate the partial pressures of neutral atoms, ions and molecules. Based on a large dataset containing atomic line and continuum data, and, most importantly, a plethora of molecular lines, we subsequently calculate Rosseland mean opacity coefficients. This is done not only for a number of different metallicities, but also for varied abundances of the isotopes ^12^C and ^14^N at each metallicity. The molecular data comprise the main opacity sources at either an oxygen-rich or carbon-rich chemistry. We tabulate the opacity coefficients as a function of temperature and, basically, density. Already within a certain chemistry regime an alteration in the carbon abundance causes, due to the special role of the CO molecule, considerable changes in the Rosseland opacity. The transition from a scaled solar (i.e. oxygen-rich) mixture to the carbon-rich regime results in opacities that can, at low temperatures, be orders of magnitude different compared to the initial situation. The reason is that different molecular absorbers make up the mean opacity in either case. A varying abundance of nitrogen has less pronounced effects but, nevertheless, cannot be neglected.
- ID:
- ivo://CDS.VizieR/J/A+AS/145/491
- Title:
- Ly{alpha} dipolar emission
- Short Name:
- J/A+AS/145/491
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Computer simulation techniques have been used to calculate the Stark broadening profiles of the hydrogen dipolar Lyman-{alpha} transition and of two-photon absorption, dispersion and polarization profiles in the 1S->2S transition. The calculations have considered electron densities in the range between 4.64*10^19^(m^-3^) and 1*10^23^(m^-3^), and temperatures in the range between 2000 and 100000K. The fine structure of level n=2 has been taken into account in the calculations. Four different sets of tables are given. The two first sets are the tables of the autocorrelation function for the dipolar moment of the emitter and for the operator that gives the transition amplitude for a two-photon absorption between the 1S and the 2S levels. This tables have the names rXXnYYYY.c1p and rXXnYYYY.c2p. The .c1p and .c2p extensions stands for 1 photon dipolar moment and for two-photon absorption transition amplitude. XX is 100*{rho}, {rho} being the quotient between the mean distance between particles and the Debye radius for the conditions of the plasma for which the profiles where calculated. YYYY is 100*Log(Ne), Ne being the electron density (m^-3^) of the plasma considered. The last two sets of tables correspond to the 1 photon Lyman-{alpha} profiles (rXXnYYYY.d1p) and to two-photon polarization profiles (rXXnYYYY.p2p). In each file the results obtained considering perturbers of different reduced masses ({mu}) are tabulated in different columns. The caption of each file contains the conditions of electron density and plasma temperature for which the calculation was made.
- ID:
- ivo://CDS.VizieR/J/MNRAS/403/1541
- Title:
- Lyman and Werner molecular hydrogen transitions
- Short Name:
- J/MNRAS/403/1541
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Molecular transitions recently discovered at redshift z_abs_=2.059 towards the bright background quasar J2123-0050 are analysed to limit cosmological variation in the proton-to-electron mass ratio, {mu}=mp/me. Observed with the Keck telescope, the optical echelle spectrum has the highest resolving power and largest number (86) of H_2_ transitions in such analyses so far. Also, (seven) HD transitions are used for the first time to constrain {mu}-variation.
- ID:
- ivo://CDS.VizieR/J/A+A/630/A143
- Title:
- Magnesium and silicon K-edges cross sections
- Short Name:
- J/A+A/630/A143
- Date:
- 07 Mar 2022 07:15:48
- Publisher:
- CDS
- Description:
- Studying absorption and scattering of X-ray radiation by interstellar dust grains allows us to access the physical and chemical properties of cosmic grains even in the densest regions of the Galaxy. We aim at characterising the dust silicate population which presents clear absorption features in the energy band covered by the Chandra X-ray Observatory. Through these absorption features, in principle, it is possible to infer the size distribution, composition, and structure of silicate in the interstellar medium. In particular, in this work we investigate magnesium and silicon K-edges. We built X-ray extinction models for 15 dust candidates using newly acquired synchrotron measurements. These models were adapted for astrophysical analysis and implemented in the Spex spectral fitting program. We used the models to reproduce the dust absorption features observed in the spectrum of the bright low mass X-ray binary GX 3+1, which is used as a background source. With the simultaneous analysis of the two edges we test two different size distributions of dust: one corresponding to the standard Mathis-Rumpl-Nordsieck model and one considering larger grains (n(a){prop.to}a_i_^-3.5^ with 0.005{mu}m<a_1_<0.25{mu}m and 0.05{mu}m<a_2_<0.5{mu}m, respectively, with a the grain size). These distributions may be representative of the complex Galactic region towards this source. We find that up to 70% of dust is constituted by amorphous olivine. We discuss the crystallinity of the cosmic dust found along this line of sight. Both magnesium and silicon are highly depleted into dust ({delta}_Z_=0.89 and 0.94, respectively), while their total abundance does not depart from solar values.
