- ID:
- ivo://CDS.VizieR/J/ApJ/764/21
- Title:
- Stellar evolutionary models with 13-120Msun
- Short Name:
- J/ApJ/764/21
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the first set of a new generation of models of massive stars with a solar composition extending between 13 and 120M_{sun}_, computed with and without the effects of rotation. We included two instabilities induced by rotation: the meridional circulation and the shear instability. We implemented two alternative schemes to treat the transport of the angular momentum: the advection-diffusion formalism and the simpler purely diffusive one. The full evolution from the pre-main sequence up to the pre-supernova stage is followed in detail with a very extended nuclear network. The explosive yields are provided for a variety of possible mass cuts and are available at the Web site http://www.iasf-roma.inaf.it/orfeo/public_html. We find that both the He and the CO core masses are larger than those of their non-rotating counterparts. Also the C abundance left by the He burning is lower than in the non-rotating case, especially for stars with an initial mass of 13-25M_{sun}_, and this affects the final mass-radius relation, basically the final binding energy, at the pre-supernova stage. The elemental yields produced by a generation of stars rotating initially at 300km/s do not change substantially with respect to those produced by a generation of non-rotating massive stars, the main differences being a slight overproduction of the weak s-component and a larger production of F. Since rotation also affects the mass-loss rate, either directly or indirectly, we find substantial differences in the lifetimes as O-type and Wolf-Rayet subtypes between the rotating and non-rotating models. The maximum mass exploding as Type IIP supernova ranges between 15 and 20M _{sun}_ in both sets of models (this value depends basically on the larger mass-loss rates in the red supergiant phase due to the inclusion of the dust-driven wind). This limiting value is in remarkably good agreement with current estimates.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/299/755
- Title:
- Stellar evolution. II. Post-AGB
- Short Name:
- J/A+A/299/755
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a set of evolutionary tracks for central stars of planetary nebulae in the range from 0.53 to 0.94M_{sun}_. These models are based on extensive stellar evolution calculations for initial masses between 1 and 7M_{sun}_ which have been carried out all the way from the main sequence through the AGB towards the stage of white dwarfs.
- ID:
- ivo://CDS.VizieR/J/MNRAS/298/525
- Title:
- Stellar evolution models for Z = 0.0001 to 0.03
- Short Name:
- J/MNRAS/298/525
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have calculated a grid of empirically well tested evolutionary tracks with masses M between 0.5 and 50M_{sun}_, spaced by approximately 0.1 in log M, and with metallicities Z=0.0001, 0.0003, 0.001, 0.004, 0.01, 0.02 and 0.03. We use a robust and fast evolution code with a self-adaptive non-Lagrangian mesh, which employs the mixing-length theory but treats convective mixing as a diffusion process, solving simultaneously for the structure and the chemical composition. The hydrogen and helium abundances are chosen as functions of the metallicity: X=0.76-3.0Z and Y=0.24+2.0Z. Two sets of models were computed, one without and one with a certain amount of enhanced mixing or 'overshooting'.
- ID:
- ivo://CDS.VizieR/J/ApJ/786/L10
- Title:
- Stellar IMF mass normalization for z~1 galaxies
- Short Name:
- J/ApJ/786/L10
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The stellar initial mass function (IMF) is a key parameter for studying galaxy evolution. Here we measure the IMF mass normalization for a sample of 68 field galaxies in the redshift range 0.7-0.9 within the Extended Groth Strip. To do this we derive the total (stellar + dark matter) mass-to-light [(M/L)] ratio using axisymmetric dynamical models. Within the region where we have kinematics (about one half-light radius), the models assume (1) that mass follows light, implying negligible differences between the slope of the stellar and total density profiles, (2) constant velocity anisotropy ({beta}_z_=1-{sigma}_z_^2^/{sigma}_R_^2^=0.2), and (3) that galaxies are seen at the average inclination for random orientations (i.e., i=60{deg}, where i=90{deg} represents edge-on). The dynamical models are based on anisotropic Jeans equations, constrained by Hubble Space Telescope/Advanced Camera for Surveys imaging and the central velocity dispersion of the galaxies, extracted from good-quality spectra taken by the DEEP2 survey. The population (M/L) are derived from full-spectrum fitting of the same spectra with a grid of simple stellar population models. Recent dynamical modeling results from the ATLAS^3D^ project and numerical simulations of galaxy evolution indicate that the dark matter fraction within the central regions of our galaxies should be small. This suggests that our derived total (M/L) should closely approximate the stellar M/L. Our comparison of the dynamical (M/L) and the population (M/L) then implies that for galaxies with stellar mass M_*_>~10^11^ M_{sun}_, the average normalization of the IMF is consistent with a Salpeter slope, with a substantial scatter. This is similar to what is found within a similar mass range for nearby galaxies.
- ID:
- ivo://CDS.VizieR/J/A+A/510/A21
- Title:
- Stellar Limb-Darkening Coefficients
- Short Name:
- J/A+A/510/A21
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Transiting exoplanets provide unparalleled access to the fundamental parameters of both extrasolar planets and their host stars. We present limb-darkening coefficients (LDCs) for the exoplanet hunting CoRot and Kepler missions. The LDCs are calculated with ATLAS stellar atmospheric model grids and span a wide range of T_eff_, logg, and metallically [M/H]. Both CoRot and Kepler use wide nonstandard photometric filters, and are producing a large inventory of high- quality transiting lightcurves, sensitive to stellar limb darkening. Comparing the stellar model limb darkening to results from the first seven CoRot planets, we find better fits are found when two model intensities at the limb are excluded in the coefficient calculations. This calculation method can help to avoid a major deficiency present at the limbs of the 1D stellar models.
- ID:
- ivo://CDS.VizieR/J/A+A/624/A137
- Title:
- Stellar models and isochrones
- Short Name:
- J/A+A/624/A137
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Grids of stellar models are useful tools to derive the properties of stellar clusters, in particular young clusters hosting massive stars, and to provide information on the star formation process in various mass ranges. Because of their short evolutionary timescale, massive stars end their life while their low-mass siblings are still on the pre-main sequence (pre-MS) phase. Thus the study of young clusters requires consistent consideration of all the phases of stellar evolution. But despite the large number of grids that are available in the literature, a grid accounting for the evolution from the pre-MS accretion phase to the post-MS phase in the whole stellar mass range is still lacking. We build a grid of stellar models at solar metallicity with masses from 0.8M_{sun}_ to 120M_{sun}_, including pre-MS phase with accretion. We use the GENEC code to run stellar models on this mass range. The accretion law is chosen to match the observations of pre-MS objects on the Hertzsprung-Russell diagram. We describe the evolutionary tracks and isochrones of our models. The grid is connected to previous MS and post-MS grids computed with the same numerical method and physical assumptions, which provides the widest grid in mass and age to date.
- ID:
- ivo://CDS.VizieR/J/A+AS/96/269
- Title:
- Stellar Models from 0.8 to 120 Msolar
- Short Name:
- J/A+AS/96/269
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- New grids of stellar evolutionary models covering the range of 0.8 to 120 solar masses have been computed for metallicites Z=0.020 and Z=0.001. The models use the new opacities by Rogers and Iglesias (1992ApJS...79..507R) and by Kurucz (1991) at low T. The consequent changes in the solar helium content, in the mixing length ratio and in the overshooting parameter are taken into account after careful calibrations. Important physical ingredients as the nuclear reaction rates and the neutrino loss rates have been updated. The ionization of the main heavy elements is calculated in details. Results of the models are given in a compact way at corresponding evolutionary stages in each model. In addition to the tables, we shortly present some general results on the tracks in the HR diagrams, the lifetimes in the H-, He-, C-burning phases, and on massive and WR stars.
- ID:
- ivo://CDS.VizieR/J/A+A/628/A29
- Title:
- Stellar models grids (Z=0.0134-0.00134) 0.8-35Msun
- Short Name:
- J/A+A/628/A29
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The theoretical apsidal motion constants are key tools to investigate the stellar interiors in close eccentric binary systems. In addition, these constants and the moment of inertia are also important to investigate the tidal evolution of close binary stars as well as of exo-planetary systems. The aim of the paper is to present new evolutionary models, based on the MESA package, that include the internal structure constants (k_2_, k_3_, and k_4_), the radius of gyration, and the gravitational potential energy for configurations computed from the pre-main-sequence (PMS) up to the first ascent giant branch or beyond. The calculations are available for the three metallicities [Fe/H] = 0.00, -0.50, and -1.00, which take the recent investigations in less metallic environments into account. This new set of models replaces the old ones, published about 15 years ago, using the code GRANADA. Core overshooting was taken into account using the mass-f_ov_ relationship, which was derived semi-empirically for models more massive than 1.2M_{sun}_. The differential equations governing the apsidal motion constants, moment of inertia, and the gravitational potential energy were integrated simultaneously through a fifth-order Runge-Kutta method with a tolerance level of 10^-7^. The resulting models (from 0.8 up to 35.0M_{sun}_) are presented in 54 tables for the three metallicities, containing the usual characteristics of an evolutionary model (age, initial masses, logT_eff_, logg, and logL), the constants of internal structure (k_2_, k_3_, and k_4_), the radius of gyration {beta} and the factor {alpha} that is related with the gravitational potential energy.
- ID:
- ivo://CDS.VizieR/J/A+A/424/919
- Title:
- Stellar models grids. Z=0.02, M=0.8 to 125
- Short Name:
- J/A+A/424/919
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new stellar models based on updated physics (opacities, expanded nuclear network and mass loss rates). We compute stellar models suitable for the mean solar neighborhood, i.e. for Z=0.02 and X=0.70. The covered mass range is from 0.8 up to 125M_{sun}_ and the models are followed until the exhaustion of carbon in the core, for the more massive ones. In addition, the effective temperatures of the more massive models are corrected for the effects of stellar winds, while models with lower effective temperatures are computed using a special treatment of the equation of state (CEFF). Convective core overshooting is assumed to be moderate and is modelled with alpha_ov_=0.20. Besides the classical ingredients of stellar models, we also provide the internal structure constants needed to investigate apsidal motion and tidal evolution in close binaries. The latter constants are made public for the first time. According to the current theories of tidal evolution, the time scales for synchronization and circularization for cool stars depend -- apart from the mass, radius and effective temperature -- on the depth of the convective envelope x_bf_ and on the radius of gyration {beta}. For stars with higher effective temperatures, these dependencies are mainly incorporated in the tidal torque constant E_2_. All these parameters are steep functions of mass and time, and thus require a special numerical treatment. The new mass loss formalism produces more mass concentrated configurations than previously, especially for more massive and more evolved stellar models. As the present grid is designed mainly for the study of double-lined eclipsing binaries, the gravity-darkening exponents necessary to calculate the surface brightness distribution in rotationally and/or tidally distorted stars are computed following the method described recently by Claret (1998, Cat. <J/A+AS/133/123>), and made available for each point of every evolutionary track.
- ID:
- ivo://CDS.VizieR/J/A+A/605/A102
- Title:
- Stellar models. 0.85<M<6, Z=0.0001-0.014
- Short Name:
- J/A+A/605/A102
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Recent spectropolarimetric observations of otherwise ordinary (in terms e.g. of surface rotation and chemical properties) G, K, and M giants have revealed localized magnetic strips in the Hertzsprung-Russell diagram coincident with the regions where the first dredge-up and core helium burning occur. We seek to understand the origin of magnetic fields in such late-type giant stars, which is currently unexplained. In analogy with late-type dwarf stars, we focus primarily on parameters known to influence the generation of magnetic fields in the outer convective envelope. We compute the classical dynamo parameters along the evolutionary tracks of low- and intermediate-mass stars at various metallicities using stellar models that have been extensively tested by spectroscopic and asteroseismic observations. Specifically, these include convective turnover timescales and convective Rossby numbers, computed from the pre-main sequence (PMS) to the tip of the red giant branch (RGB) or the early asymptotic giant branch (AGB) phase. To investigate the effects of the very extended outer convective envelope, we compute these parameters both for the entire convective envelope and locally, that is, at different depths within the envelope. We also compute the turnover timescales and corresponding Rossby numbers for the convective cores of intermediate-mass stars on the main sequence. Our models show that the Rossby number of the convective envelope becomes lower than unity in the well-delimited locations of the Hertzsprung-Russell diagram where magnetic fields have indeed been detected. We show that {alpha}-{Omega} dynamo processes might not be continuously operating, but that they are favored in the stellar convective envelope at two specific moments along the evolution tracks, that is, during the first dredge-up at the base of the RGB and during central helium burning in the helium-burning phase and early-AGB. This general behavior can explain the so-called magnetic strips recently discovered by dedicated spectropolarimetric surveys of evolved stars.
