- ID:
- ivo://CDS.VizieR/J/A+A/440/647
- Title:
- New grids of stellar models. II.
- Short Name:
- J/A+A/440/647
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- New stellar models spefically designed for the Small Magellanic Cloud are presented in this paper. In order to take into account the uncertainties in the metal content we computed two grids with different metallicities: Z=0.002 and Z=0.004. 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. We have introduced a recent measurement of the nuclear rate ^14^N(p,{gamma})^15^O. A comparison among models with the old and new rate was carried out revealed that the former are slightly hotter than the first ones. Such differences depend on the mass range. The opacities, the equation of state, the remaining nuclear reactions rates, the core overshooting parameterization and the convective transport of energy are the same as discussed previously by us. We also give, besides the classical evolutionary models outputs, the internal structure constants needed to investigate apsidal motion and tidal evolution in close binaries. This aspect acquires importance in the light of recent investigations on circularization and synchronization levels in binary systems belonging to the Magellanic Clouds. The role of rotation can also be investigated through the gravity-darkening exponents which allow us to compute the brightness distribution of a given stellar surface.
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- ID:
- ivo://CDS.VizieR/J/A+A/453/769
- Title:
- New grids of stellar models. III.
- Short Name:
- J/A+A/453/769
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- In this paper, we present new specific stellar models for the Large Magellanic Cloud. In order to take the observational uncertainties in the chemical composition into account, we have computed two grids: (X, Z) = (0.730, 0.010) and (0.739, 0.007). The covered mass range was 0.80 up to 125M_{sun}. The effects of rotation can be investigated by using the gravity-darkening exponents that are available for each track. The tidal constant E_2_, depth of the convective outer zone, and the radius of gyration are computed and presented in a suitable format for studying the tidal evolution of a given close binary. The isochrones (and also those corresponding to the previous grids) will be presented in a future paper.
- ID:
- ivo://CDS.VizieR/J/A+A/467/1389
- Title:
- New grids of stellar models. IV.
- Short Name:
- J/A+A/467/1389
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The aim of the present grid of stellar models is to complete our previous calculations and provide a tool for investigating the astrophysical properties of eclipsing binaries, stellar clusters, galactic bulges, and elliptical galaxies with a high metal content. To explore the applicability of high metallic models, we have computed three grids: (X, Z)=(0.64, 0.04), (0.58, 0.06), and (0.46, 0.10). For all these grids, we adopted an enrichment law {Delta}Y/{Delta}Z=2.0, as in our previous papers on this subject. The input physics is almost the same as adopted in our earlier work except for some numerical details, recent measurement of the rate for the reaction ^14^N(p,gamma)^15^O, and the recent mass-loss rate for the Wolf-Rayet stages. Two high-metallicity clusters, NGC 6253 and NGC 6791, were used to test the present calculations with very satisfactory results. On the other hand, as this series of grids was mainly designed to investigate the tidal evolution of close binaries, we analyse the present status of circularization times in both clusters and isolated binaries.
- ID:
- ivo://CDS.VizieR/J/A+A/580/A10
- Title:
- New MnII energy levels
- Short Name:
- J/A+A/580/A10
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The NIST database lists several MnI lines that were observed in the laboratory but not classified. They cannot be used in spectrum synthesis because their atomic line data are unknown. These lines are concentrated in the 2380-2700{AA} interval. We aimed to assign energy levels and loggf values to these lines. Semi-empirical line data for MnII computed by Kurucz were used to synthesize the ultraviolet spectrum of the slow-rotating, HgMn star HD 175640. The spectrum was compared with the high-resolution spectrum observed with the HST-STIS equipment. A UVES spectrum covering the 3050-10000{AA} region was also examined.
- ID:
- ivo://CDS.VizieR/J/PASJ/68/25
- Title:
- New Numerical Galaxy Catalog (nu^2^GC)
- Short Name:
- J/PASJ/68/25
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a new cosmological galaxy formation model, nu^2^GC, as an updated version of our previous model nuGC. We adopt the so-called "semi-analytic" approach, in which the formation history of dark matter halos is computed by N-body simulations, while the baryon physics such as gas cooling, star formation, and supernova feedback are simply modeled by phenomenological equations. Major updates of the model are as follows: (1) the merger trees of dark matter halos are constructed in state-of-the-art N-body simulations, (2) we introduce the formation and evolution process of supermassive black holes and the suppression of gas cooling due to active galactic nucleus (AGN) activity, (3) we include heating of the intergalactic gas by the cosmic UV background, and (4) we tune some free parameters related to the astrophysical processes using a Markov chain Monte Carlo method. Our N-body simulations of dark matter halos have unprecedented box size and mass resolution (the largest simulation contains 550 billion particles in a 1.12Gpc*h^-1^*box), enabling the study of much smaller and rarer objects. The model was tuned to fit the luminosity functions of local galaxies and mass function of neutral hydrogen. Local observations, such as the Tully-Fisher relation, the size-magnitude relation of spiral galaxies, and the scaling relation between the bulge mass and black hole mass were well reproduced by the model. Moreover, the model also reproduced well the cosmic star formation history and redshift evolution of rest-frame K-band luminosity functions. The numerical catalog of the simulated galaxies and AGNs is publicly available on the web.
- ID:
- ivo://CDS.VizieR/J/ApJ/705/1533
- Title:
- NGC 5128 globular clusters
- Short Name:
- J/ApJ/705/1533
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- An objective classification of the globular clusters (GCs) of NGC 5128 has been carried out by using a model-based approach of cluster analysis. The set of observable parameters includes structural parameters, spectroscopically determined Lick indices and radial velocities from the literature. The optimum set of parameters for this type of analysis is selected through a modified technique of principal component analysis, which differs from the classical one in the sense that it takes into consideration the effects of outliers present in the data. Then a mixture model based approach has been used to classify the GCs into groups. The efficiency of the techniques used is tested through the comparison of the misclassification probabilities with those obtained using the K-means clustering technique. On the basis of the above classification scheme three coherent groups of GCs have been found. We propose that the clusters of one group originated in the original cluster formation event that coincided with the formation of the elliptical galaxy, and that the clusters of the two other groups are of external origin, from tidally stripped dwarf galaxies on random orbits around NGC 5128 for one group, and from an accreted spiral galaxy for the other.
- ID:
- ivo://CDS.VizieR/J/A+A/363/1081
- Title:
- Non-linear limb-darkening law for LTE models
- Short Name:
- J/A+A/363/1081
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A new non-linear limb-darkening law, based on the Least-Squares Method (LSM), is presented. This law is able to describe the intensity distribution much more accurately than any of the old ones given that the differences I(model)-I(fitting) are of some order of magnitude smaller than those derived from other approximations. This new law shows several advantages: it represents well the intensity distribution, the flux is conserved with high accuracy and it permits the use of a single law for the whole HR Diagram since that the bi-parametric laws are only marginally valid in certain range of effective temperatures. The limb-darkening coefficients are computed for the 12 commonly used photometric bands u v b y U B V R I J H K. Bolometric and monochromatic calculations are also available. The computations are presented for 19 metallicities ranging from 10^-5^ up to 10^+1^ solar abundances, with log(g) varying between 0 and 5.0 and effective temperatures between 2000K-50000K. Results for microturbulent velocities of 0, 1, 2, 4, 8 km/s are also available. With this set of data it was possible to investigate, for the first time, the influence of such parameters in the limb-darkening. Limb-brightening, instead of limb-darkening, was detected for some models. It is shown that the limb-darkening coefficients derived using the Flux Conservation Method (FCM) do not describe very well the intensity distribution, mainly near the border of the disk. On the contrary, the present coefficients, based on the LSM, represent very well the function I({mu}) at any part of the disk for any filter or wavelength, log(g), effective temperature, metallicity and microturbulent velocity. The results are presented here as synthetic tables containing the limb-darkening coefficients. The 46 tables announced in the paper are also accessible as the "original.tar" file.
- ID:
- ivo://CDS.VizieR/J/A+A/401/657
- Title:
- Non-linear limb-darkening law for LTE models. II.
- Short Name:
- J/A+A/401/657
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- As an extension of our previous investigations on stellar atmospheres (Claret, 2000, Cat. <J/A+A/363/1081>), the limb-darkening coefficients for the Geneva and Walraven photometric systems are presented for the first time using the ATLAS and PHOENIX models. They cover a wide range of values of logg, T_eff_, metallicities and microturbulent velocities. In addition to the traditional applications of limb-darkening coefficients, the present ones are now being used in the interpretation of phase shift of B and A-F type pulsating stars.
- ID:
- ivo://CDS.VizieR/J/A+A/428/1001
- Title:
- Non-linear limb-darkening law for LTE models. III.
- Short Name:
- J/A+A/428/1001
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Continuing our studies on stellar atmospheres (Claret, 2000, Cat. <J/A+A/363/1081>, 2003, Cat. <J/A+A/401/657>), we present in this paper the limb-darkening coefficients for the Sloan photometric system. The calculations cover a wide range of values of logg, T_eff_, metallicities and microturbulent velocities. The atmosphere models used are ATLAS and PHOENIX. In addition to the traditional applications of the limb-darkening coefficients, the present ones will be useful since the Sloan filters are now being used in the interpretation of light curves of extrasolar transiting planets, for example. The present calculations may also be useful, as a complement, for the Kepler mission, dedicated to the search for terrestrial planets.
- ID:
- ivo://CDS.VizieR/J/A+A/618/A133
- Title:
- Non standard s-process in massive rotating stars
- Short Name:
- J/A+A/618/A133
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Recent studies show that rotation significantly affects the s-process in massive stars. We provide tables of yields for non-rotating and rotating massive stars between 10 and 150M_{sun}_ at Z=10^-3^([Fe/H]=-1.8). Tables for different mass cuts are provided. The complete s-process is followed during the whole evolution with a network of 737 isotopes, from Hydrogen to Polonium. A grid of stellar models with initial masses of 10, 15, 20, 25, 40, 60, 85, 120 and 150M_{sun}_ and with an initial rotation rate of both 0 or 40% of the critical velocity was computed. Three extra models were computed in order to investigate the effect of faster rotation (70% of the critical velocity) and of a lower ^17^O({alpha},{gamma}) reaction rate. At the considered metallicity, rotation has a strong impact on the production of s-elements for initial masses between 20 and 60M_{sun}_. In this range, the first s-process peak is boosted by 2-3dex if rotation is included. Above 60M_{sun}_, s-element yields of rotating and non-rotating models are similar. Increasing the initial rotation from 40% to 70% of the critical velocity enhances the production of 40<~Z<~60 elements by ~0.5-1dex. Adopting a reasonably lower ^17^O({alpha},{gamma}) rate in the fast rotating model (70% of the critical velocity) boosts again the yields of s-elements with 55<~Z<~82 by about 1dex. In particular, a modest amount of Pb is produced. Together with s-elements, some light elements (particularly fluorine) are strongly overproduced in rotating models.
