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1. Adiabatic mass loss in binary stars. II.
ID:
ivo://CDS.VizieR/J/ApJ/812/40
Title:
Adiabatic mass loss in binary stars. II.
Short Name:
J/ApJ/812/40
Date:
21 Oct 2021
Publisher:
CDS
Description:
In the limit of extremely rapid mass transfer, the response of a donor star in an interacting binary becomes asymptotically one of adiabatic expansion. We survey here adiabatic mass loss from Population I stars (Z=0.02) of mass 0.10M_{sun}_-100M_{sun}_ from the zero-age main sequence to the base of the giant branch, or to central hydrogen exhaustion for lower main sequence stars. The logarithmic derivatives of radius with respect to mass along adiabatic mass-loss sequences translate into critical mass ratios for runaway (dynamical timescale) mass transfer, evaluated here under the assumption of conservative mass transfer. For intermediate- and high-mass stars, dynamical mass transfer is preceded by an extended phase of thermal timescale mass transfer as the star is stripped of most of its envelope mass. The critical mass ratio q_ad_ (throughout this paper, we follow the convention of defining the binary mass ratio as q{equiv}M_donor_/M_accretor_) above which this delayed dynamical instability occurs increases with advancing evolutionary age of the donor star, by ever-increasing factors for more massive donors. Most intermediate- or high-mass binaries with nondegenerate accretors probably evolve into contact before manifesting this instability. As they approach the base of the giant branch, however, and begin developing a convective envelope, q_ad_ plummets dramatically among intermediate-mass stars, to values of order unity, and a prompt dynamical instability occurs. Among low-mass stars, the prompt instability prevails throughout main sequence evolution, with q_ad_ declining with decreasing mass, and asymptotically approaching q_ad_=2/3, appropriate to a classical isentropic n=3/2 polytrope. Our calculated q_ad_ values agree well with the behavior of time-dependent models by Chen & Han (2003MNRAS.341..662C) of intermediate-mass stars initiating mass transfer in the Hertzsprung gap. Application of our results to cataclysmic variables, as systems that must be stable against rapid mass transfer, nicely circumscribes the range in q_ad_ as a function of the orbital period in which they are found. These results are intended to advance the verisimilitude of population synthesis models of close binary evolution.
2. Adiabatic Mass Loss in Binary Stars. III.
ID:
ivo://CDS.VizieR/J/ApJ/899/132
Title:
Adiabatic Mass Loss in Binary Stars. III.
Short Name:
J/ApJ/899/132
Date:
14 Mar 2022 07:06:32
Publisher:
CDS
Description:
The distinguishing feature of the evolution of close binary stars is the role played by the mass exchange between the component stars. Whether or not the mass transfer is dynamically stable is one of the essential questions in binary evolution. In the limit of extremely rapid mass transfer, the response of a donor star in an interacting binary becomes asymptotically one of adiabatic expansion. We use the adiabatic mass-loss model to systematically survey the thresholds for dynamical timescale mass transfer over the entire span of possible donor star evolutionary states. We also simulate mass-loss process with isentropic envelopes, the specific entropy of which is fixed to be that at the base of the convective envelope, to artificially mimic the effect of such mass loss in superadiabatic surface convection regions, where the adiabatic approximation fails. We illustrate the general adiabatic response of 3.2M{odot} donor stars at different evolutionary stages. We extend our study to a grid of donor stars with different masses (from 0.1 to 100 M{sun} with Z=0.02) and at different evolutionary stages. We proceed to present our criteria for dynamically unstable mass transfer in both tabular and graphical forms. For red giant branch (RGB) and asymptotic giant branch (AGB) donors in systems with such mass ratios, they may have convective envelopes deep enough to evolve into common envelopes on a thermal timescale, if the donor star overfills its outer Lagrangian radius. Our results show that the RGB and AGB stars tend to be more stable than previously believed, and this may be helpful to explain the abundance of observed post-AGB binary stars with an orbital period of around 1000 days.
3. A framework for empirical galaxy phenomenology
ID:
ivo://CDS.VizieR/J/MNRAS/448/1430
Title:
A framework for empirical galaxy phenomenology
Short Name:
J/MNRAS/448/1430
Date:
21 Oct 2021
Publisher:
CDS
Description:
We develop a theoretical framework that extracts a deeper understanding of galaxy formation from empirically derived relations among galaxy properties by extending the main-sequence integration method for computing galaxy star formation histories. We properly account for scatter in the stellar mass-star formation rate relation and the evolving fraction of passive systems and find that the latter effect is almost solely responsible for the age distributions among z~0 galaxies with stellar masses above ~10^10^ M_{sun}_. However, while we qualitatively agree with the observed median stellar metallicity as a function of stellar mass, we attribute our inability to reproduce the distribution in detail largely to a combination of imperfect gas-phase metallicity and {alpha}/Fe ratio calibrations. Our formalism will benefit from new observational constraints and, in turn, improve interpretations of future data by providing self-consistent star formation histories for population synthesis modelling.
4. A standard stellar library
ID:
ivo://CDS.VizieR/J/A+AS/125/229
Title:
A standard stellar library
Short Name:
J/A+AS/125/229
Date:
21 Oct 2021
Publisher:
CDS
Description:
The present library provides an extensive and homogeneous grid of low-resolution theoretical flux distributions for a large range of stellar parameters : Teff=50,000K to K, logg=5.50 to -1.02 and [M/H]=-5.0 to +1.0. The library has been constructed from different grids of blanketed stellar atmosphere models (Bessell et al. (1989A&AS...77....1B, 1991A&AS...89..335B), Fluks et al. (1994, Cat. <J/A+AS/105/311>), Kurucz (1995, priv. comm.), Allard & Hauschildt (1995ApJ...445..433A). The models described in the accompanying paper (Lejeune et al. (1997A&AS..125..229L) are given here as part of a more extensive data set including M dwarf model spectra, which will be presented in a forthcoming paper (Lejeune et al., 1998, Cat. <J/A+AS/130/65>). A correction procedure has been applied to the theoretical energy in order to calibrate fluxes on empirical-temperature relations (see also Lejeune et al., 1998, Cat. <J/A+AS/130/65>). The library is given here in its two versions : the first one (files *.ori) containing the "original" flux distributions -- as given by the original grids of atmosphere models --, but rebinned on a common wavelength scale (see also Leitherer et al. 1996PASP..108..996L) and the second one (files *.cor) which provides the "corrected" flux distributions. Each version of the library contains an ASCII file of models for each of the 19 values of the metallicity ([M/H]=-5.0, -4.5, -4.0, -3.5, -3.0, -2.5, -2.0, -1.5, -1.0, -0.5, -0.3, -0.2, -0.1, 0.0, +0.1, +0.2, +0.3, +0.5 and +1.0), named as lcbxxx.yyy, where xxx designates the metallicity (ex: 'm15' --> [M/H]=-1.5), and yyy identifies the library version. For each model (out of the total of 8315 models), a flux spectrum is given for the (same) set of 1221 wavelength points covering the range 9.1 to 160000 nm, with a mean resolution of 10{AA} in the UV and 20{AA} in the visible. In addition to the 19 metallicity files, two individual files originating from the Kurucz (1991, in Precision Photometry: Astrophysics of the Galaxy, Davis Philip A.G., Upgren A.R. & Janes K.A. (eds.). Schenectady, NY, L. Davis Press, Inc., 1991, pp. 27-44)) models are given, lcbsun.ori and lcbvega.ori, which provide theoretical flux distributions for the Sun and Vega respectively.
5. A standard stellar library. II.
ID:
ivo://CDS.VizieR/J/A+AS/130/65
Title:
A standard stellar library. II.
Short Name:
J/A+AS/130/65
Date:
21 Oct 2021
Publisher:
CDS
Description:
A standard library of theoretical stellar spectra intended for multiple synthetic photometry applications including spectral evolutionary synthesis is presented. The grid includes M dwarf model spectra, hence complementing the first library version established in Paper I (Lejeune et al., 1997, Cat. <J/A+AS/125/229>). It covers the following wide ranges of fundamental parameters: Teff: 50,000 to 2000K, logg: 5.5 to -1.02, and [Fe/H]: +1.0 to -5.0. A correction procedure is also applied to the theoretical spectra in order to provide color-calibrated flux distributions over a large domain of effective temperatures. Empirical Teff-color calibrations are constructed between 11500K and 2000K, and semi-empirical calibrations for non-solar abundances ([Fe/H]=-3.5 to +1.0) are established. Model colors and bolometric corrections for both the original and the corrected spectra, synthesized in the UBV(RI)c(JHKLL'M) system, are given for the full range of stellar parameters. Synthetic colors: ---------------- Synthetic UBV(RI)c(JHKLM) colors have been computed from both the original and the corrected model flux distributions presented in Paper I (1997A&AS..125..229L; see catalog <J/A+AS/125/229>), as the files lcb98ori.dat and lcb98cor.dat respectively; the results are also presented in individual files lcb98xxx.ori and lcb98xxx.cor, where xxx designates the metallicity (ex: 'm15' --> [Fe/H]=-1.5). For each file, we give synthetic colors computed from energy-weighted and photon-weighted stellar fluxes. Semi-empirical calibrations: --------------------------- Empirical ([Fe/H]=0.0) and semi-empirical (-3.5<=[Fe/H]<=+1.0) Teff-colors (UBVRIJHKLM) calibrations are given in Tables 1 to 10.
6. Automatic observation rendering (AMORE)
ID:
ivo://CDS.VizieR/J/A+A/392/1129
Title:
Automatic observation rendering (AMORE)
Short Name:
J/A+A/392/1129
Date:
21 Oct 2021
Publisher:
CDS
Description:
A new method, AMORE (AutoMatic Observation REnderer) - based on a genetic algorithm optimizer, is presented for the automated study of colour-magnitude diagrams. The method combines several stellar population synthesis tools developed in the last decade by or in collaboration with the Padova group. Our method is able to recover, within the uncertainties, the parameters - distance, extinction, age, metallicity, index of a power-law initial mass function and the index of an exponential star formation rate - from a reference synthetic stellar population. No a priori information is inserted to recover the parameters, which is done simultaneously and not one at a time. Examples are given to demonstrate and to better understand biases in the results, if one of the input parameters is deliberately set fixed to a non-optimum value.
7. Basic tracks at Zinit=0.006
ID:
ivo://CDS.VizieR/J/A+A/541/A41
Title:
Basic tracks at Zinit=0.006
Short Name:
J/A+A/541/A41
Date:
21 Oct 2021
Publisher:
CDS
Description:
We present dense grids of stellar models suitable for comparison with observable quantities measured with great precision, such as those derived from binary systems or planet-hosting stars. We computed new Geneva models without rotation at metallicities Z=0.006, 0.01, 0.014, 0.02, 0.03, and 0.04 (i.e. [Fe/H] from -0.33 to +0.54) and with mass in small steps from 0.5 to 3.5M_{sun}_. Great care was taken in the procedure for interpolating between tracks in order to compute isochrones.
8. Binary compact object coalescence rates
ID:
ivo://CDS.VizieR/J/ApJ/716/615
Title:
Binary compact object coalescence rates
Short Name:
J/ApJ/716/615
Date:
21 Oct 2021
Publisher:
CDS
Description:
In this paper, we estimate binary compact object merger detection rates for LIGO, including the potentially significant contribution from binaries that are produced in elliptical galaxies near the epoch of peak star formation. Specifically, we convolve hundreds of model realizations of elliptical- and spiral-galaxy population syntheses with a model for elliptical- and spiral-galaxy star formation history as a function of redshift. Our results favor local merger rate densities of 4x10^-3^Mpc^-3^/Myr for binary black holes (BHs), 3x10^-2^Mpc^-3^/Myr for binary neutron stars (NSs), and 10^-2^Mpc^-3^/Myr for BH-NS binaries. Assuming a detection signal-to-noise ratio threshold of 8 for a single detector (in practice as part of a network, to reduce its noise), corresponding to radii Dbns of the effective volume inside of which a single LIGO detector could observe the inspiral of two 1.4M_{sun}_ NSs of 14Mpc and 197Mpc, for initial and advanced LIGO, we find event rates of any merger type of 2.9x10^-2^-0.46 and 25-400yr^-1^ (at 90% confidence level), respectively.
9. Binary evolution
ID:
ivo://CDS.VizieR/J/MNRAS/319/215
Title:
Binary evolution
Short Name:
J/MNRAS/319/215
Date:
21 Oct 2021
Publisher:
CDS
Description:
Using Eggleton's stellar evolution code, we carry out 150 runs of Population I binary evolution calculations with the initial primary mass between 1 and 8 solar masses, the initial mass ratio q=M_1/M_2 between 1.1 and 4, and the onset of Roche lobe overflow (RLOF) at an early, middle or late Hertzsprung-gap stage. We assume that the RLOF is conservative in the calculations. We list characteristics for binaries with different initial parameters at the beginning of RLOF, minimum luminosity during RLOF, the end of the last episode of RLOF and the end of the evolutionary calculations. The characteristics includes the age of the primary, its mass, mass transfer rate, its effective temperature, its luminosity, its radius, its helium core mass, its carbon-oxygen core mass, the hydrogen abundance at its surface, the mass ratio of the binary, and the orbital period.
10. Binary stellar evolution data for Kepler systems
ID:
ivo://CDS.VizieR/J/ApJ/832/183
Title:
Binary stellar evolution data for Kepler systems
Short Name:
J/ApJ/832/183
Date:
21 Oct 2021
Publisher:
CDS
Description:
Inspired by the recent Kepler discoveries of circumbinary planets orbiting nine close binary stars, we explore the fate of the former as the latter evolve off the main sequence. We combine binary star evolution models with dynamical simulations to study the orbital evolution of these planets as their hosts undergo common-envelope (CE) stages, losing in the process a tremendous amount of mass on dynamical timescales. Five of the systems experience at least one Roche-lobe overflow and CE stage (Kepler-1647 experiences three), and the binary stars either shrink to very short orbits or coalesce; two systems trigger a double-degenerate supernova explosion. Kepler's circumbinary planets predominantly remain gravitationally bound at the end of the CE phase, migrate to larger orbits, and may gain significant eccentricity; their orbital expansion can be more than an order of magnitude and can occur over the course of a single planetary orbit. The orbits these planets can reach are qualitatively consistent with those of the currently known post-CE, eclipse-time variations circumbinary candidates. Our results also show that circumbinary planets can experience both modes of orbital expansion (adiabatic and nonadiabatic) if their host binaries undergo more than one CE stage; multiplanet circumbinary systems like Kepler-47 can experience both modes during the same CE stage. Additionally, unlike Mercury orbiting the Sun, a circumbinary planet with the same semimajor axis can survive the CE evolution of a close binary star with a total mass of 1M_{sun}_.

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