Number of results to display per page
Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/531/A12
- Title:
- Grid of Lya radiation transfer models
- Short Name:
- J/A+A/531/A12
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Ly{alpha} is a key diagnostic for numerous observations of distant star-forming galaxies, but detailed radiation transfer models are required for interpreting them. We provide an extensive grid of 3D radiation transfer models that simulate the Ly{alpha} and UV continuum radiation transfer in the interstellar medium of star-forming galaxies. We have improved our Monte Carlo MCLya code and used it to compute a grid of 6240 radiation transfer models for homogeneous spherical shells containing HI and dust surrounding a central source. The simulations cover a wide range of parameter space. We present the detailed predictions from our models including in particular the Ly{alpha} escape fraction fesc, the continuum attenuation, and detailed Ly{alpha} line profiles. The Ly{alpha} escape fraction is shown to depend strongly on dust content, but also on other parameters (HI column density and radial velocity). The predicted line profiles show a wide diversity of morphologies, ranging from broad absorption lines to emission lines with complex features. The results from our simulations are distributed in electronic format. Our models should be of use for interpreting observations from distant galaxies, for other simulations, and should also serve as an important basis for comparison for future, more refined, radiation transfer models.
- ID:
- ivo://CDS.VizieR/J/ApJ/810/76
- Title:
- Grid of red giant synthetic spectra with 0<[M/H]<=-6
- Short Name:
- J/ApJ/810/76
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate the dependence of the complete system of 22 Lick indices on overall metallicity scaled from solar abundances, [M/H], from the solar value, 0.0, down to the extremely metal-poor (XMP) value of -6.0, for late-type giant stars (MK luminosity class III, logg=2.0) of MK spectral class late-K to late-F (3750<Teff<6500K) of the type that are detected as "fossils" of early galaxy formation in the Galactic halo and in extra-galactic structures. Our investigation is based on synthetic index values, I, derived from atmospheric models and synthetic spectra computed with PHOENIX in Local Thermodynamic Equilibrium (LTE) and Non-LTE (NLTE), where the synthetic spectra have been convolved to the spectral resolution, R, of both IDS and SDSS (and LAMOST) spectroscopy. We identify nine indices, that we designate "Lick-XMP", that remain both detectable and significantly [M/H]-dependent down to [M/H] values of at least ~-5.0, and down to [M/H]~-6.0 in five cases, while also remaining well-behaved (single-valued as a function of [M/H] and positive in linear units). For these nine indices, we study the dependence of I on NLTE effects, and on spectral resolution. For our LTE I values for spectra of SDSS resolution, we present the fitted polynomial coefficients, C_n_, from multi-variate linear regression for I with terms up to third order in the independent variable pairs (Teff, [M/H]) and (V-K, [M/H]), and compare them to the fitted C_n_ values of Worthey et al. (1994, J/ApJS/94/687) at IDS spectral resolution.
- ID:
- ivo://CDS.VizieR/J/A+A/509/A14
- Title:
- Grid of solar-metallicity wind models
- Short Name:
- J/A+A/509/A14
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Knowing how the mass loss of carbon-rich AGB stars depends on stellar parameters is crucial for stellar evolution modelling, as well as for the understanding of when and how circumstellar structures emerge around these stars, e.g., dust shells and so-called detached shells of expelled gas. The purpose of this paper is to explore the stellar parameter space using a numerical radiation hydrodynamic (RHD) model of carbon-star atmospheres, including a detailed description of dust formation and frequency-dependent radiative transfer, in order to determine how the mass loss of carbon stars changes with stellar parameters.
- ID:
- ivo://CDS.VizieR/J/A+A/543/A108
- Title:
- Grid of stellar models, asteroseismology
- Short Name:
- J/A+A/543/A108
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The availability of asteroseismic constraints for a large sample of stars from the missions CoRoT and Kepler paves the way for various statistical studies of the seismic properties of stellar populations. We evaluate the impact of rotation-induced mixing and thermohaline instability on the global asteroseismic parameters at different stages of the stellar evolution from the zero age main sequence to the thermally pulsating asymptotic giant branch to distinguish stellar populations.
- ID:
- ivo://CDS.VizieR/J/ApJS/256/41
- Title:
- Grid of synthetic spectra for subdwarfs
- Short Name:
- J/ApJS/256/41
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- A new grid of detailed atmosphere model spectra for hot and moderately cool subdwarf stars is presented. High-resolution spectra and synthetic photometry are calculated in the range from 1000{AA} to 10,000{AA} using Non-LTE fully line- blanketed atmosphere structures. Our grid covers eight temperatures within 10000<Teff[K]<65000, three surface gravities in the range 4.5<logg[cgs]<6.5, two helium abundances matching two extreme helium-rich and helium-poor scenarios, and two limiting metallicity boundaries regarding both solar ([Fe/H]=0) and Galactic halo ([Fe/H]=-1.5 and [alpha/Fe]=+0.4). Besides its application in the determination of fundamental parameters of subdwarfs in isolation and in binaries, the resulting database is also of interest for population synthesis procedures in a wide variety of stellar systems.
- ID:
- ivo://CDS.VizieR/VI/134
- Title:
- Grids of ATLAS9 Model Atmospheres and MOOG spectra
- Short Name:
- VI/134
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A grid of ATLAS9 model atmospheres has been computed, spanning Teff in 3500--8000K, log.g in 0.0--5.0, [Fe/H] in -4.0--0.0, [{alpha}/Fe] in -0.08--1.2. These parameters are appropriate for stars in the red giant branch, subgiants, and the lower main sequence. The main difference from a previous, similar grid (Castelli & Kurucz 2003, "Modelling of Stellar Atmospheres", 210, astro-ph/0405087) is the range of [{alpha}/Fe] values. A grid of synthetic spectra, calculated from the model atmospheres, is also presented. The fluxes are computed every 0.02{AA} from 630nm to 910nm. The microturbulent velocity is given by a relation to the surface gravity. This relation is appropriate for giants, but not for subgiants or dwarfs. Therefore, caution is urged for the synthetic spectra with log.g>3.5.
- ID:
- ivo://CDS.VizieR/J/A+AS/98/523
- Title:
- Grids of stellar models. II.
- Short Name:
- J/A+AS/98/523
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Continuing the effort to provide a homogeneous base of extensive and accurate grids of stellar models covering a wide range of metallicities we present a new grid of stellar models at metallicity Z = 0.008, roughly corresponding to the Large Magellanic Cloud composition. The models have been computed for 0.8 to 120 solar masses, using up-to-date input physics and the new radiative opacities from Rogers and Iglesias (1992ApJS...79..507R) and Kurucz (1991). Mass loss and moderate core overshooting are taken into account. The resulting HR diagram and the lifetimes in the H-, He-, and C-burning phases as well as some general results on massive stars are discussed and compared with complementary grids, using the same input physics at metallicities Z of 0.020 and 0.001 used by Schaller et al. (1992, Cat. J/A+AS/96/269)
- ID:
- ivo://CDS.VizieR/J/A+AS/101/415
- Title:
- Grids of stellar models III.
- Short Name:
- J/A+AS/101/415
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Stellar evolutionary models with mass loss and moderate overshooting at metallicity Z = 0.004 in the 0.80 to 120 M{sun} range are presented. They complete the set of grids computed with the same up-input physics for Z=0.020 and 0.001 by Schaller et al. (1992, Cat. J/A+AS/96/269), for Z=0.008 by Schaerer et al. (1992A&A...263..129S, Cat. J/A+AS/98/523) and for Z=0.040 by Schaerer et al. (1993, Cat. J/A+AS/102/339).
- ID:
- ivo://CDS.VizieR/J/A+AS/102/339
- Title:
- Grids of stellar models IV
- Short Name:
- J/A+AS/102/339
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The present grid of evolutionary sequences at metallicity Z=0.040, completes the set of grids computed for Z=0.020 and 0.001 by Schaller et al. (1992, Cat. J/A+AS/96/269), Z=0.008 by Schaerer et al. (1992, Cat. J/A+AS/98/523) and Z=0.004 by Charbonnel et al. (1993, Cat. J/A+AS/101/415). The models with mass loss and moderate core overshooting have been computed for 0.8 to 120 M{sun} using up-to-date input physics and the new radiative opacities from Iglesias et al. (1992ApJ...397..717I) and Kurucz (1991).
