- ID:
- ivo://CDS.VizieR/J/MNRAS/387/105
- Title:
- Isochrone database for single- and binary-star SSPs
- Short Name:
- J/MNRAS/387/105
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We first presented an isochrone data base that can be widely used for stellar population synthesis studies and colour-magnitude diagram (CMD) fitting. The data base consists of the isochrones of both single-star and binary-star simple stellar populations (ss-SSPs and bs-SSPs). The ranges for the age and metallicity of populations are 0-15Gyr and 0.0001-0.03, respectively. All data are available for populations with two widely used initial mass functions (IMFs), that is, Salpeter IMF and Chabrier IMF. The uncertainty caused by the data base (about 0.81 per cent) is designed to be smaller than those caused by the Hurley code and widely used stellar spectra libraries (e.g. BaSeL 3.1) when it is used for stellar population synthesis. Based on the isochrone data base, we then built a rapid stellar population synthesis (RPS) model and calculated the high-resolution (0.03nm) integrated spectral energy distributions, Lick indices and colour indices for bs-SSPs and ss-SSPs. In particular, we calculated the UBVRIJHKLM colours, ugriz colours and some composite colours that consist of magnitudes on different systems. These colours are useful for disentangling the well-known stellar age-metallicity degeneracy according to our previous work. As an example for applying the isochrone data base for CMD fitting, we fitted the CMDs of two star clusters (M67 and NGC1868) and obtained their distance moduli, colour excesses, stellar metallicities and ages. The results showed that the isochrones of bs-SSPs are closer to those of real star clusters. It suggests that we should take the effects of binary interactions into account in stellar population synthesis. We also discussed on the limitations of the application of the isochrone data base and the results of the RPS model.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+AS/122/399
- Title:
- K and evolutionary corrections
- Short Name:
- J/A+AS/122/399
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- K and evolutionary corrections are given for the E, Sa and Sc Hubble types for the following filters up to the redshift z=3: Johnson-Bessell & Brett photometric system: U, B, V, R, I, J, H, K filters Modified Thuan & Gunn system: gri filters Cousins system: Rc Ic filters Bj, Rf, In filters.
- ID:
- ivo://CDS.VizieR/J/MNRAS/370/1181
- Title:
- Library of Lick/IDS indices for binaries
- Short Name:
- J/MNRAS/370/1181
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using evolutionary population synthesis, we present 13 refined absorption-line indices defined by the Lick Observatory Image Dissector Scanner (Lick/IDS) system for an extensive set of instantaneous-burst binary stellar populations (BSPs) at high resolution (~0.3{AA}), and 38 indices at intermediate resolution (3{AA}). The ages of the populations are at an interval of 1Gyr in the range 115 Gyr, and the metallicities are in the range 0.004-0.03. These indices are obtained by two methods: (i) using the empirical fitting functions (FFs method); (ii) measured directly from the synthetic spectra (DC method). Together with our previous paper, a data base of Lick/IDS spectral absorption-line indices for BSPs at high and intermediate resolutions is provided. This set of indices includes 21 indices of Worthey et al. (1994, Cat. <J/ApJS/94/687>), four Balmer indices defined by Worthey & Ottaviani (1997, Cat. <J/ApJS/111/377>), and 13 indices with the new passband definitions of Trager et al. (1998, Cat. <J/ApJS/116/1>, hereafter T98.
- ID:
- ivo://CDS.VizieR/J/A+A/359/18
- Title:
- Line-strength predictions in Elliptical Galaxies
- Short Name:
- J/A+A/359/18
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This table shows the line-strength predictions computed for: CaT, NaI, and MgI in the near infrared and Mgb, Mg2, Fe52, Fe53, NaD and H{beta}, in the blue-visible range, for Single Stellar Population (SSP) of 6 different metallicities, (Z=0.0004, 0.001, 0.004, 0.008, 0.02 and 0.05), and ages from log(age)=6.60 (4Gyr) to log(age)=10.30 (20Gyr), in steps of 0.10dex from 6.60 until 10.00, and 0.02 afterwards. (Therefore there are 50 records for each metallicity except that Z=0.001 has only 47). All indices have been computed taken the model atmospheres from Lejeune et al. (1997, Cat. <J/A+AS/125/229>, 1998, Cat. <J/A+AS/130/65>) and Clegg & Middlemass (1987MNRAS.228..759C) for hot stars (Teff > 50000 K). The used isochrones are from the Padova group (Bressan et al., 1993, Cat. <J/A+AS/100/647>). The total mass of every SSP is 10^9^M_{sun}_ with a Salpeter-type IMF, Phi(m)=m^-{alpha}^, with {alpha}=2.35, from m_low=0.6M_{sun}_ to m_up_=100M_{sun}_. The fitting functions for blue indices are those from Worthey et al. (1994, Cat. <J/ApJS/94/687>).
- ID:
- ivo://CDS.VizieR/J/A+A/595/A35
- Title:
- Low-mass helium white dwarfs evolutionary models
- Short Name:
- J/A+A/595/A35
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A large number of extremely low-mass helium white dwarfs (ELM WDs) have been discovered in recent years. The majority of them are found in close binary systems suggesting they are formed either through a common-envelope phase or via stable mass transfer in a low-mass X-ray binary (LMXB) or a cataclysmic variable (CV) system. Here, we investigate the formation of these objects through the LMXB channel with emphasis on the proto-WD evolution in environments with different metallicities. We study for the first time the combined ects of rotational mixing and element diffusion (e.g. gravitational settling, thermal and chemical diffusion) on the evolution of proto-WDs and on the cooling properties of the resulting WDs. We present state-of-the-art binary stellar evolution models computed with MESA for metallicities of Z=0.02, 0.01, 0.001 and 0.0002, producing WDs with masses between ~0.16-0.45M_{sun}_. Our results confirm that element diffusion plays a significant role in the evolution of proto-WDs that experience hydrogen shell flashes. The occurrence of these flashes produces a clear dichotomy in the cooling timescales of ELM WDs, which has important consequences e.g. for the age determination of binary millisecond pulsars. In addition, we confirm that the threshold mass at which this dichotomy occurs depends on metallicity. Rotational mixing is found to counteract the effect of gravitational settling in the surface layers of young, bloated ELM proto-WDs and therefore plays a key role in determining their surface chemical abundances, i.e. the observed presence of metals in their atmospheres. We predict that these proto-WDs have helium-rich envelopes through a significant part of their lifetime. This is of great importance as helium is a crucial ingredient in the driving of the {kappa}-mechanism suggested for the newly observed ELM proto-WD pulsators. However, we find that the number of hydrogen shell flashes and, as a result, the hydrogen envelope mass at the beginning of the cooling track, are not influenced significantly by rotational mixing. In addition to being dependent on proto-WD mass and metallicity, the hydrogen envelope mass of the newly formed proto-WDs depends on whether or not the donor star experiences a temporary contraction when the H-burning shell crosses the hydrogen discontinuity left behind by the convective envelope. The hydrogen envelope at detachment, although small compared to the total mass of the WD, contains enough angular momentum such that the spin frequency of the resulting WD on the cooling track is well above the orbital frequency.
76. Low-mass stars
- ID:
- ivo://CDS.VizieR/J/A+A/285/473
- Title:
- Low-mass stars
- Short Name:
- J/A+A/285/473
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- (no description available)
- ID:
- ivo://CDS.VizieR/J/A+A/337/403
- Title:
- Low-mass stars evolutionary models
- Short Name:
- J/A+A/337/403
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Physical properties and absolute magnitudes of low-mass stars for different initial metallicity [M/H], helium mass fraction Y and mixing length parameter Lmix: mass (in solar mass), age (in Gyrs) effective temperature (in K), log of gravity (in cgs) and absolute magnitudes. The VRI magnitudes are in the Johnson-Cousins system and the JHK magnitudes in the CIT system. Note that the bolometric magnitude corresponds to M_bol(Sun)=4.64. The lowest mass corresponds to the hydrogen-burning limit.
- ID:
- ivo://CDS.VizieR/J/A+AS/141/371
- Title:
- Low-mass stars evolutionary tracks & isochrones
- Short Name:
- J/A+AS/141/371
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- These files contain a large database of stellar models that are suitable to modelling star clusters and galaxies by means of population synthesis. They are based on a large grid of stellar evolutionary tracks for the initial chemical compositions [Z=0.0004, Y=0.23], [Z=0.001, Y=0.23], [Z=0.004, Y=0.24], [Z=0.008, Y=0.25], [Z=0.019, Y=0.273] (solar composition), and [Z=0.03, Y=0.30]. Tracks are computed with updated opacities and equation of state, and a moderate amount of convective overshoot. The range of initial masses goes from 0.15M_{sun}_ to 7M_{sun}_, and the evolutionary phases extend from the zero age main sequence (ZAMS) till either the thermally pulsing AGB regime or carbon ignition. We also present an additional set of models with solar composition, computed using the classical Schwarzschild's criterion for convective boundaries. From all these models, we derive: (1) Tables with the main quantities that characterize the stellar structure along the evolutionary tracks; (2) tables of surface chemical composition after the first and second dredge-up events; (3) extended theoretical isochrones in the Johnson-Cousins UBVRIJHK broad-band photometric system, together with summary tables; (4) integrated colours of single-burst stellar populations.
- ID:
- ivo://CDS.VizieR/J/A+A/631/A77
- Title:
- Low-mass stellar models and isochrones
- Short Name:
- J/A+A/631/A77
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an extended grid of state-of-the art stellar models for low-mass stars including updated physics (nuclear reaction rates, surface boundary condition, mass-loss rate, angular momentum transport, rotation-induced mixing, and torque prescriptions). We evaluate the impact of wind braking, realistic atmospheric treatment, rotation, and rotation-induced mixing on the structural and rotational evolution from the pre-main sequence (PMS) to the turn-off. Using the STAREVOL code, we provide an updated PMS grid. We computed stellar models for seven different metallicities, from [Fe/H]=-1dex to [Fe/H]=+0.3dex with a solar composition corresponding to Z=0.0134. The initial stellar mass ranges from 0.2 to 1.5M_{sun}_ with extra grid refinement around one solar mass. We also provide rotating models for three different initial rotation rates (slow, median, and fast) with prescriptions for the wind braking and disc-coupling timescale calibrated on observed properties of young open clusters. The rotational mixing includes the most recent description of the turbulence anisotropy in stably stratified regions. The overall behaviour of our models at solar metallicity, and their constitutive physics, are validated through a detailed comparison with a variety of distributed evolutionary tracks. The main differences arise from the choice of surface boundary conditions and initial solar composition. The models including rotation with our prescription for angular momentum extraction and self-consistent formalism for angular momentum transport are able to reproduce the rotation period distribution observed in young open clusters over a wide range of mass values. These models are publicly available and can be used to analyse data coming from present and forthcoming asteroseismic and spectroscopic surveys such as Gaia, TESS, and PLATO.The overall behaviour of our models at solar metallicity, and their constitutive physics, are validated through a detailed comparison with a variety of distributed evolutionary tracks. The main differences arise from the choice of surface boundary conditions and initial solar composition. The models including rotation with our prescription for angular momentum extraction and self-consistent formalism for angular momentum transport are able to reproduce the rotation period distribution observed in young open clusters over a wide range of mass values. These models are publicly available and can be used to analyse data coming from present and forthcoming asteroseismic and spectroscopic surveys such as Gaia, TESS, and PLATO.
- ID:
- ivo://CDS.VizieR/J/A+A/557/A19
- Title:
- Mass and age of extreme low-mass white dwarfs
- Short Name:
- J/A+A/557/A19
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The number of detected extremely low mass (ELM) white dwarf stars has increased drastically in recent year thanks to the results of many surveys. In addition, some of these stars have been found to exhibit pulsations, making them potential targets for asteroseismology. We provide a fine and homogeneous grid of evolutionary sequences for helium (He) core white dwarfs for the whole range of their expected masses (0.15<~M_*_/M_{sun}_<~0.45), including the mass range for ELM white dwarfs (M_*_/M_{sun}_<~0.20). The grid is appropriate for mass and age determination of these stars, as well as to study their adiatabic pulsational properties. White dwarf sequences have been computed by performing full evolutionary calculations that consider the main energy sources and processes of chemical abundance changes during white dwarf evolution.
