- ID:
- ivo://CDS.VizieR/J/A+A/553/A24
- Title:
- Models for rotating stars
- Short Name:
- J/A+A/553/A24
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- B-type stars are known to rotate at various velocities, including very fast rotators near the critical velocity as the Be stars. In this paper, we provide stellar models covering the mass range between 1.7 to 15M_{sun}_, which includes the typical mass of known Be stars, at Z=0.014, 0.006 and 0.002 and for an extended range of initial velocities on the zero-age main sequence. We use the Geneva stellar-evolution code including the effects of shellular rotation and with a numerical treatment that has been improved in order for the code to track in a precise way the variation of the angular momentum content of the star as it changes under the influence of radiative winds and/or mechanical mass loss. We discuss the impact of the initial rotation rate on the tracks in the Hertzsprung-Russell diagram, the main-sequence (MS) lifetimes, the evolution of the surface rotation and abundances, as well as on the ejected masses of various isotopes. Among the new results obtained from the present grid we have that: 1) fast rotating stars with initial masses around 1.7M_{sun}_ present at the beginning of the core hydrogen-burning phase quite small convective cores with respect to their slowly rotating counterparts. This fact may be interesting to keep in mind in the frame of the asteroseismic studies of such stars; 2) the contrast between the core and surface angular velocity is higher in slower rotating stars. The values presently obtained are quite in the range of the very few values obtained for B-type stars from asteroseismology; 3) at Z=0.002, the stars in the mass range of 1.7 to 3M_{sun}_ with a mean velocity on the MS of the order of 150km/s show N/H enhancement superior to 0.2dex at mid-MS, and superior to 0.4dex at the end of the MS phase. At solar metallicity the corresponding values are below 0.2dex at any time in the MS. An extended database of stellar models containing 270 evolutionary tracks is provided to the community.
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Search Results
- ID:
- ivo://CDS.VizieR/J/MNRAS/425/1696
- Title:
- Models of a young star cluster ejecta
- Short Name:
- J/MNRAS/425/1696
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have computed with a fine time grid the evolution of the elemental abundances of He, C, N and O ejected by young (t<20Myr) and massive (M=10^6^M_{sun}_) coeval stellar cluster with a Salpeter initial mass function (IMF) over a wide range of initial abundances. Our computations incorporate the mass loss from massive stars (M>=30M_{sun}_) during their wind phase including the Wolf-Rayet phase and the ejecta from the core-collapse supernovae. We find that during the Wolf-Rayet phase (t<5Myr) the cluster ejecta composition suddenly becomes vastly overabundant in N for all initial abundances and in He, C and O for initial abundances higher than one-fifth of the solar. The C and O abundances in the cluster ejecta can reach over 50 times the solar value with important consequences for the chemical and hydrodynamical evolution of the surrounding interstellar medium.
- ID:
- ivo://CDS.VizieR/J/A+AS/126/39
- Title:
- Models of circumstellar dust shells
- Short Name:
- J/A+AS/126/39
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Main properties of the steady state hydrodynamical models of circumstellar gas/dust shells around late type giants, computed for different stellar parameters (mass, luminosity, effective temperature) and dust composition (astronomical silicates, graphite, or amorphous carbon, with properties given in Tab.1 and Fig.1). Each table lists the results as a function of the adopted mass loss rate for fixed stellar parameters and dust properties. Tables 2 - 11 are related to Figures 2 - 11: Each of the figures shows the velocity structure and the resulting spectral energy distribution for a subset of models listed in the respective table.
- ID:
- ivo://CDS.VizieR/J/ApJS/169/439
- Title:
- Models of solar magnetic structures
- Short Name:
- J/ApJS/169/439
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This paper presents semiempirical models of various solar magnetic structures, extending from the photosphere to the chromosphere. The models have been derived from non-LTE inversions of high-resolution spectropolarimetric observations of four CaII and FeI lines. The observed targets are dark and bright components of a sunspot umbra; dark and bright components of a sunspot penumbra; a canopy between two sunspots; a facula; and a network element. These models may be employed, e.g., to compute realistic synthetic Stokes spectra of photospheric and chromospheric lines.
- ID:
- ivo://CDS.VizieR/J/ApJ/690/20
- Title:
- Models of the AGN and black hole populations
- Short Name:
- J/ApJ/690/20
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We construct evolutionary models of the populations of active galactic nuclei (AGNs) and supermassive black holes, in which the black hole mass function grows at the rate implied by the observed luminosity function, given assumptions about the radiative efficiency and the luminosity in Eddington units. We draw on a variety of recent X-ray and optical measurements to estimate the bolometric AGN luminosity function and compare to X-ray background data and the independent estimate of Hopkins et al. to assess remaining systematic uncertainties. The integrated AGN emissivity closely tracks the cosmic star-formation history, suggesting that star formation and black hole growth are closely linked at all redshifts.
- ID:
- ivo://CDS.VizieR/J/ApJ/819/46
- Title:
- Models of thermonuclear X-ray bursters
- Short Name:
- J/ApJ/819/46
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using the KEPLER 1D hydrodynamics code (Woosley et al. 2004ApJS..151...75W), 464 models of thermonuclear X-ray bursters were performed across a range of accretion rates and compositions. We present the library of simulated burst profiles from this sample, and examine variations in the simulated light curve for different model conditions. We find that the recurrence time varies as a power law against accretion rate, and measure its slope while mixed H/He burning is occurring for a range of metallicities, finding the power law gradient to vary from {eta}=1.1 to 1.24. We identify the accretion rates at which mixed H/He burning stops and a transition occurs to different burning regimes. We explore how varying the accretion rate and metallicity affects burst morphology in both the rise and tail.
- ID:
- ivo://CDS.VizieR/J/ApJ/707/482
- Title:
- Models of the solar atmosphere. III.
- Short Name:
- J/ApJ/707/482
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Semiempirical atmospheric models of solar surface features as observed at moderate resolution are useful tools for understanding the observed solar spectral irradiance variations. Paper I described a set of models constructed to reproduce the observed radiance spectrum for solar surface features at ~2 arcsec resolution that constitute an average over small-scale features such as granulation. Paper II showed that a revision of previous models of low-chromospheric inter-network regions explains the observed infrared CO lines in addition to the UV and radio continuum from submillimeter to centimetric wavelengths. The present paper (1) shows that the CaII H and K line wing observations are also explained by the new quiet-Sun-composite model, (2) introduces new low-chromospheric models of magnetic features that follow the ideas in Paper II (Fontenla et al. 2007ApJ...667.1243F), (3) introduces new upper chromospheric structures for all quiet-Sun and active-region models, and (4) shows how the new set of models explains EUV/FUV observations of spectral radiance and irradiance. This paper also discusses the chromospheric radiative-loss estimates in each of the magnetic features. The new set of models provides a basis for the spectral irradiance synthesis at EUV/FUV wavelengths based on the features observed on the solar surface.
- ID:
- ivo://CDS.VizieR/J/MNRAS/505/979
- Title:
- Model spectra for identifying age spreads
- Short Name:
- J/MNRAS/505/979
- Date:
- 22 Feb 2022
- Publisher:
- CDS
- Description:
- In this third paper of a series on the precision of obtaining ages of stellar populations using the full spectrum fitting technique, we examine the precision of this technique in deriving possible age spreads within a star cluster. We test how well an internal age spread can be resolved as a function of cluster age, population mass fraction, and signal-to-noise (S/N) ratio. For this test, the two ages (Age (SSP1) and Age (SSP2)) are free parameters along with the mass fraction of SSP1. We perform the analysis on 118,800 mock star clusters covering all ages in the range 6.8<log(age/yr)<10.2, with mass fractions from 10% to 90% for two age gaps (0.2dex and 0.5dex). Random noise is added to the model spectra to achieve S/N ratios between 50 to 100 per wavelength pixel. We find that the mean of the derived Age (SSP1) generally matches the real Age (SSP1) to within 0.1dex up to ages around log(age/yr)=9.5. The precision decreases for log(age/yr)>9.6 for any mass fraction or S/N, due to the similarity of SED shapes for those ages. In terms of the recovery of age spreads, we find that the derived age spreads are often larger than the real ones, especially for log(age/yr)<8.0 and high mass fractions of SSP1. Increasing the age gap in the mock clusters improves the derived parameters, but Age (SSP2) is still overestimated for the younger ages.
- ID:
- ivo://CDS.VizieR/J/A+A/558/A131
- Title:
- Model spectra of hot stars at the pre-SN stage
- Short Name:
- J/A+A/558/A131
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate the fundamental properties of core-collapse Supernova (SN) progenitors from single stars at solar metallicity. We combine Geneva stellar evolutionary models with initial masses of Mini=20-120M_{sun}_ with atmospheric/wind models using CMFGEN. We provide synthetic photometry and high-resolution spectra of hot stars at the pre-SN stage. For Mini=9-20M_{sun}_, we supplement our analysis using publicly available MARCS model atmospheres of RSGs. We employ observational criteria of spectroscopic classification and find that massive stars, depending on Mini and rotation, end their lives as red supergiants (RSG), yellow hypergiants (YHG), luminous blue variables (LBV), and Wolf-Rayet (WR) stars of the WN and WO spectral types. For rotating models, we obtain the following types of SN progenitors: WO1-3 (Mini<=32M_{sun}_), WN10-11 (25<Mini< 32M_{sun}_), LBV (20<=Mini<25M_{sun}_), G1 Ia+ (18<Mini<20M_{sun}_), and RSGs (9<=Mini<=18M_{sun}_). For non-rotating models, we find spectral types WO1-3 (Mini>40M_{sun}_), WN7-8 (25<Mini<=40M_{sun}_), WN11h/LBV (20<Mini<=25M_{sun}_), and RSGs (9<=Mini<=20M_{sun}_). Our rotating models indicate that SN IIP progenitors are all RSG, SN IIL/b progenitors are 56% LBVs and 44% YHGs, SN Ib progenitors are 96% WN10-11 and 4% WOs, and SN Ic progenitors are all WO stars. We find that not necessarily the most massive and luminous SN progenitors are the brighter ones in a given filter. We show that SN IIP progenitors (RSGs) are bright in the RIJHK_S filters and faint in the UB filters. SN IIL/b progenitors (LBVs and YHGs), and SN Ib progenitors (WNs) are relatively bright in optical/IR filters, while SN Ic progenitors (WOs) are faint in all optical filters. We argue that SN Ib and Ic progenitors from single stars should be undetectable in the available pre-explosion images with the current magnitude limits, in agreement with observational results.
- ID:
- ivo://CDS.VizieR/J/A+A/609/A30
- Title:
- Monochromatic conversion factors to LIR & Mdust
- Short Name:
- J/A+A/609/A30
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a new, publicly available library of dust spectral energy distributions (SEDs). These SEDs are characterized by only three parameters: the dust mass (Mdust), the dust temperature (Tdust), and the mid-to-total infrared color (IR8=LIR/L8). The latter measures the relative contribution of polycyclic aromatic hydrocarbon (PAH) molecules to the total infrared luminosity. We used this library to model star-forming galaxies at 0.5<z<4 in the deep CANDELS fields, using both individual detections and stacks of Herschel and ALMA imaging, and extending this sample to z=0 using the Herschel Reference Survey. At first order, the dust SED of a galaxy was observed to be independent of stellar mass, but evolving with redshift. We found trends of increasing Tdust and IR8 with redshift and distance from the SFR-M* main sequence, and quantified for the first time their intrinsic scatter. Half of the observed variations of these parameters was captured by the above empirical relations, and after subtracting the measurement errors we found residual scatters of {delta}Tdust/Tdust=12% and {delta}logIR8=0.18dex. We observed second order variations with stellar mass: massive galaxies (M*>10^119M_{sun}_) at z<=1 have slightly lower temperatures indicative of a reduced star formation efficiency, while low mass galaxies (M*<10^10^M_{sun}_) at z>=1 showed reduced PAH emission, possibly linked to their lower metallicities. Building on these results, we constructed high-fidelity mock galaxy catalogs to predict the accuracy of infrared luminosities and dust masses determined using a single broadband measurement. Using a single James Webb Space Telescope (JWST) MIRI band, we found that LIR is typically uncertain by 0.15dex, with a maximum of 0.25dex when probing the rest-frame 8um, and this is not significantly impacted by typical redshift uncertainties. On the other hand, we found that ALMA bands 8 to 7 and 6 to 3 measured the dust mass at better than 0.2 and 0.15dex, respectively, and independently of redshift, while bands 9 to 6 only measured LIR at better than 0.2dex at z>1, 3.2, 3.8, and 5.7, respectively. Starburst galaxies had their LIR significantly underestimated when measured by a single JWST or ALMA band, while their dust mass from a single ALMA band were moderately overestimated. This dust library and the results of this paper can be used immediately to improve the design of observing proposals, and interpret more accurately the large amount of archival data from Spitzer, Herschel and ALMA.
