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- ID:
- ivo://CDS.VizieR/J/A+A/585/A5
- Title:
- Exoplanet hosts/field stars age consistency
- Short Name:
- J/A+A/585/A5
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Transiting planets around stars are discovered mostly through photometric surveys. Unlike radial velocity surveys, photometric surveys do not tend to target slow rotators, inactive or metal-rich stars. Nevertheless, we suspect that observational biases could also impact transiting-planet hosts. This paper aims to evaluate how selection effects reflect on the evolutionary stage of both a limited sample of transiting-planet host stars (TPH) and a wider sample of planet-hosting stars detected through radial velocity analysis. Then, thanks to uniform derivation of stellar ages, a homogeneous comparison between exoplanet hosts and field star age distributions is developed. Stellar parameters have been computed through our custom-developed isochrone placement algorithm, according to Padova evolutionary models. The notable aspects of our algorithm include the treatment of element diffusion, activity checks in terms of logR'_HK_ and vsini, and the evaluation of the stellar evolutionary speed in the Hertzsprung-Russel diagram in order to better constrain age. Working with TPH, the observational stellar mean density {rho}_*_ allows us to compute stellar luminosity even if the distance is not available, by combining {rho}_* with the spectroscopic logg. The median value of the TPH ages is ~5Gyr. Even if this sample is not very large, however the result is very similar to what we found for the sample of spectroscopic hosts, whose modal and median values are [3, 3.5)Gyr and ~4.8Gyr, respectively. Thus, these stellar samples suffer almost the same selection effects. An analysis of MS stars of the solar neighbourhood belonging to the same spectral types bring to an age distribution similar to the previous ones and centered around solar age value. Therefore, the age of our Sun is consistent with the age distribution of solar neighbourhood stars with spectral types from late F to early K, regardless of whether they harbour planets or not. We considered the possibility that our selected samples are older than the average disc population.
- ID:
- ivo://CDS.VizieR/J/ApJ/608/405
- Title:
- Explosive yields of massive star (Z=0-Z_{sun}_)
- Short Name:
- J/ApJ/608/405
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a new and homogeneous set of explosive yields for masses 13, 15, 20, 25, 30, and 35M_{sun}_ and metallicities Z=0, 10^-6^, 10^-4^, 10^-3^, 6x10^-3^, and 2x10^-2^. A wide network extending up to Mo has been used in all computations. We show that at low metallicities (Z<=10^-4^), the final yields do not depend significantly on the initial chemical composition of the models, so a scaled solar distribution may be safely assumed at all metallicities. Moreover, no elements above Zn are produced by any mass in the grid up to a metallicity ~10-3. These yields are available for any choice of the mass cut on request.
- ID:
- ivo://CDS.VizieR/J/ApJS/255/22
- Title:
- FRII radio sources dynamical models
- Short Name:
- J/ApJS/255/22
- Date:
- 03 Dec 2021 13:25:10
- Publisher:
- CDS
- Description:
- Dynamical evolution models of 361 extragalactic Fanaroff-Riley type II radio sources selected from the Cambridge 3CRR, 6CE, 5C6, and 5C7 Sky Surveys, as well as the Bologna B2, Green Bank GB, and GB2 Surveys, are presented. Their spectra, compiled mostly from the recent catalogs of radio sources and the available NASA/IPAC and Astrophysical Catalogs Support System databases, along with morphological characteristics of the sources determined from their radio maps, have been modeled using the DYNAGE algorithm and/or its extension (KDA EXT) for the hypothetical case of further evolution after the jet's termination. The best-fit models provide estimates of a number of important physical parameters of the sources, as (i) the jet power, (ii) the density distribution of the external gaseous medium surrounding the radio core and the jet propagating through it, (iii) the initial energy distribution of the relativistic particles accelerated at the shock fronts, and (iv) the age of the observed radio structure. Additionally, estimates of some derivative parameters are provided, e.g., the radio lobes' pressure, their longitudinal expansion velocity, the magnetic field strength, and the total energy deposited in the lobes. The observed spectra and their best-fit models are included. Finally, one of the useful applications of the above models is presented, namely a strong correlation between the ambient medium density and the rest-frame two-point spectral index available directly from the observed spectra.
- ID:
- ivo://CDS.VizieR/VI/147
- Title:
- Galaxies Chemical and photometric evolution models
- Short Name:
- VI/147
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We summarize the updated set of multiphase chemical evolution models performed with 44 theoretical radial mass initial distributions and 10 possible values of efficiencies to form molecular clouds and stars. We present the results about the infall rate histories, the formation of the disk, and the evolution of the radial distributions of diffuse and molecular gas surface density, stellar profile, star formation rate surface density, and elemental abundances of C, N, O, and Fe, finding that the radial gradients for these elements begin steeper and flatten with increasing time or decreasing redshift, although the outer disks always show a certain flattening for all times. With the resulting star formation and enrichment histories, we calculate the spectral energy distributions (SEDs) for each radial region by using the ones for single stellar populations resulting from the evolutive synthesis model POPSTAR. With these SEDs we may compute finally the broad band magnitudes and colors radial distributions in the Johnson and in the SLOAN/SDSS systems which are the main result of this work. We present the evolution of these brightness and color profiles with the redshift.
- ID:
- ivo://CDS.VizieR/J/MNRAS/468/305
- Title:
- Galaxy chemical evolution models
- Short Name:
- J/MNRAS/468/305
- Date:
- 19 Jan 2022 13:29:27
- Publisher:
- CDS
- Description:
- In our classical grid of multiphase chemical evolution models, star formation in the disc occurs in two steps: first, molecular gas forms, and then stars are created by cloud-cloud collisions or interactions of massive stars with the surrounding molecular clouds. The formation of both molecular clouds and stars are treated through the use of free parameters we refer to as efficiencies. In this work, we modify the formation of molecular clouds based on several new prescriptions existing in the literature, and we compare the results obtained for a chemical evolution model of the Milky Way Galaxy regarding the evolution of the Solar region, the radial structure of the Galactic disc and the ratio between the diffuse and molecular components, H I/H_2_. Our results show that the six prescriptions we have tested reproduce fairly consistent most of the observed trends, differing mostly in their predictions for the (poorly constrained) outskirts of the Milky Way and the evolution in time of its radial structure. Among them, the model proposed by Ascasibar et al. (in preparation), where the conversion of diffuse gas into molecular clouds depends on the local stellar and gas densities as well as on the gas metallicity, seems to provide the best overall match to the observed data.
- ID:
- ivo://CDS.VizieR/J/A+A/617/A113
- Title:
- GalMer S0 remnants morphological properties
- Short Name:
- J/A+A/617/A113
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Major mergers are popularly considered too destructive to produce the relaxed regular structures and the morphological inner components (ICs) usually observed in lenticular (S0) galaxies. We have tested if major mergers can produce remnants with realistic S0 morphologies. We have selected a sample of relaxed discy remnants resulting from the dissipative merger simulations of the GalMer database and derived their morphological properties mimicking the typical conditions of current observational data. Only ~1-2Gyr after the full merger, we find that: 1) many remnants (67 major and 29 minor events) present relaxed structures and typical S0 or E/S0 morphologies, for a wide variety of orbits and even in gas-poor cases. 2) Most of them do not exhibit any morphological traces of their past merger origin under typical observing conditions and at distances as nearby as 30Mpc. 3) The merger relics are more persistent in minor mergers than in major ones for similar relaxing time periods. 4) No major-merger S0-like remnant develops a significant bar. 5) Nearly 58% of the major-merger S0 remnants host visually detectable ICs, such as embedded inner discs, rings, pseudo-rings, inner spirals, nuclear bars, and compact sources, very frequent in real S0s too. 6) All remnants contain a lens or oval, identically ubiquitous in local S0s. 7) These lenses and ovals do not come from bar dilution in major-merger cases, but are associated with stellar halos or embedded inner discs instead (thick or thin). We conclude that the relaxed morphologies, lenses, ovals, and other ICs of real S0s do not necessarily come from internal secular evolution, gas infall, or environmental mechanisms, as traditionally assumed, but they can result from major mergers as well.
- ID:
- ivo://CDS.VizieR/VI/102
- Title:
- Geneva stellar evolution tracks and isochrones
- Short Name:
- VI/102
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This database was created from an updated version of the empirically and semi-empirically calibrated BaSeL library of synthetic stellar spectra of Lejeune et al. (1997, Cat. <J/A+AS/125/229>, 1998, Cat. <J/A+AS/130/65>) and Westera et al. (1999, ASP Conference Series 192, 203-206) to calculate synthetic photometry in the (UBV)_J_(RI)_C_ JHKLL'M, HST-WFPC2, Geneva, and Washington systems for the entire set of non-rotating Geneva stellar evolution models covering masses from 0.4-0.8 to 120-150M_{sun}_ and metallicities Z=0.0004 (1/50Z_{sun}_) to 0.1 (5Z_{sun}_). The results are provided in a database which includes all individual stellar tracks and the corresponding isochrones covering ages from 10^3^yr to 16-20Gyr in time steps of {Delta}logt=0.05dex. The database also includes a new grid of stellar tracks of very metal-poor stars (Z=0.0004) from 0.8-150M_{sun}_ calculated with the Geneva stellar evolution code. The complete stellar grids are tabulated in the files table1.dat (summary), evol.dat (evolutionary models), and in the files ubv.dat, hst.dat, gen.dat and cmt.dat (synthetic colors in the different photometric systems). These grids are also available as mod* files in subdirectories evol, ubv, hst, gen and cmt. The isochrones for the different photometric systems are summarized in the file table2.dat; the parameters of the isochrones are tabulated in the file iso.dat, the detailed isochrones being available as files iso* in the subdirectories ubv, hst, gen and cmt.
- ID:
- ivo://CDS.VizieR/J/MNRAS/358/521
- Title:
- Grid of chemical evolution models for galaxies
- Short Name:
- J/MNRAS/358/521
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a generalization of the multiphase chemical evolution model applied to a wide set of theoretical galaxies with different masses and evolutionary rates. This generalized set of models has been computed using the so-called Universal Rotation Curve from Persic et al. (1996MNRAS.281...27P) to calculate the radial mass distribution of 44 theoretical protogalaxies. This distribution is a fundamental input which, besides its own effect on the galaxy evolution, defines the characteristic collapse time-scale or gas infall rate onto the disc. We have adopted 10 sets of values, between 0 and 1, for the molecular cloud and star formation efficiencies, as corresponding to their probability nature, for each one of the radial distributions of total mass. Thus, we have constructed a bi-parametric grid of models, depending on those efficiency sets and on the rotation velocity, whose results are valid in principle for any spiral or irregular galaxy. The model results provide the time evolution of different regions of the disc and the halo along galactocentric distance, measured by the gas (atomic and molecular) and stellar masses, the star formation rate and chemical abundances of 14 elements, for a total of 440 models. This grid may be used to estimate the evolution of a given galaxy for which only present time information, such as radial distributions of elemental abundances, gas densities and/or star formation, which are the usual observational constraints of chemical evolution models, is available.
- ID:
- ivo://CDS.VizieR/J/A+A/455/247
- Title:
- Grid of close binaries experiencing mass exchange
- Short Name:
- J/A+A/455/247
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- To simulate the population of the primordial blue stragglers in old open clusters, a grid of close binaries experiencing mass exchange is needed. To this aim, various combinations that can trigger mass exchange for the donor masses of 0.1M_{sun}_ to 2.0M_{sun}_ are calculated with a fine grid in parameters. The mass range of the accretor is from 0.1M_{sun}_ to the mass of the corresponding donor. The mass intervals of the donors and the accretors are all 0.1M_{sun}_. To cover all possible cases of close binaries, the orbit separation ranges from 1.0 to 50.0R_{sun}_ with a grid interval of 1.0R_{sun}_. Following the numerical scheme described above, a grid for six ages from 1.0Gyr to 6.0Gyr is obtained. In this table, mass, effective temperature, luminosity, gravity, Hydrogen abundance in the core, Helium abundance in the core, B magnitude, V magnitude, B-V color, mass ratio, orbital separation and period of the close binaries experiencing mass exchange are given.
