- ID:
- ivo://CDS.VizieR/J/AJ/147/87
- Title:
- From binaries to multiples. II. Statistical data
- Short Name:
- J/AJ/147/87
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Statistics of hierarchical multiplicity among solar-type dwarfs are studied using the distance-limited sample of 4847 targets presented in the accompanying Paper I. Known facts about binaries (multiplicity fraction 0.46, lognormal period distribution with median period 100yr and logarithmic dispersion 2.4, and nearly uniform mass-ratio distribution independent of the period) are confirmed with a high statistical significance. The fraction of hierarchies with three or more components is 0.13+/-0.01, and the fractions of targets with n=1,2,3,... components are 54:33:8:4:1. Subsystems in the secondary components are almost as frequent as in the primary components, but in half of such cases both inner pairs are present. The high frequency of those 2+2 hierarchies (4%) suggests that both inner pairs were formed by a common process. The statistics of hierarchies can be reproduced by simulations, assuming that the field is a mixture coming from binary-rich and binary-poor environments. Periods of the outer and inner binaries are selected recursively from the same lognormal distribution, subject to the stability constraint and accounting for the correlation between inner subsystems. The simulator can be used to evaluate the frequency of multiple systems with specified parameters. However, it does not reproduce the observed excess of inner periods shorter than 10days, caused by tidal evolution.
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- ID:
- ivo://CDS.VizieR/J/AJ/147/86
- Title:
- From binaries to multiples. I. The FG-67 sample
- Short Name:
- J/AJ/147/86
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Data on the multiplicity of F- and G-type dwarf stars within 67pc of the Sun are presented. This distance-limited sample based on the Hipparcos catalog contains 4847 primary stars (targets) with 0.5<V-I_C_<0.8 and is >90% complete. There are 2196 known stellar pairs; some of them belong to 361 hierarchical systems from triples to quintuples. Models of companion detection by radial velocity, astrometric acceleration, direct resolution, and common proper motion are developed. They serve to compute completeness for each target, using the information on its coverage collected here. About 80% of companions to the primary stars are detected, but the census of subsystems in the secondary components is only about 30%. Masses of binary components are estimated from their absolute magnitudes or by other methods; the periods of wide pairs are evaluated from their projected separations. A third of binaries with periods shorter than ~100yr are spectroscopic and/or astrometric pairs with yet unknown periods and mass ratios. These data are used in the accompanying Paper II to derive unbiased statistics of hierarchical multiple systems.
- ID:
- ivo://CDS.VizieR/J/MNRAS/452/2127
- Title:
- Fundamental parameters of Kepler stars
- Short Name:
- J/MNRAS/452/2127
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a study of 33 Kepler planet-candidate host stars for which asteroseismic observations have sufficiently high signal-to-noise ratio to allow extraction of individual pulsation frequencies. We implement a new Bayesian scheme that is flexible in its input to process individual oscillation frequencies, combinations of them, and average asteroseismic parameters, and derive robust fundamental properties for these targets. Applying this scheme to grids of evolutionary models yields stellar properties with median statistical uncertainties of 1.2 per cent (radius), 1.7 per cent (density), 3.3 per cent (mass), 4.4 per cent (distance), and 14 per cent (age), making this the exoplanet host-star sample with the most precise and uniformly determined fundamental parameters to date. We assess the systematics from changes in the solar abundances and mixing-length parameter, showing that they are smaller than the statistical errors. We also determine the stellar properties with three other fitting algorithms and explore the systematics arising from using different evolution and pulsation codes, resulting in 1 per cent in density and radius, and 2 per cent and 7 per cent in mass and age, respectively. We confirm previous findings of the initial helium abundance being a source of systematics comparable to our statistical uncertainties, and discuss future prospects for constraining this parameter by combining asteroseismology and data from space missions. Finally, we compare our derived properties with those obtained using the global average asteroseismic observables along with effective temperature and metallicity, finding excellent level of agreement. Owing to selection effects, our results show that the majority of the high signal-to-noise ratio asteroseismic Kepler host stars are older than the Sun.
- ID:
- ivo://CDS.VizieR/J/A+A/352/555
- Title:
- Fundamental parameters of stars
- Short Name:
- J/A+A/352/555
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Hipparcos mission has made it possible to constrain the positions of nearby field stars in the colour-magnitude diagram with very high accuracy. These positions can be compared with the predictions of stellar evolutionary calculations to provide information on the basic parameters of the stars: masses, radii, effective temperatures, ages, and chemical composition. The degeneracy between mass, age, and metallicity is not so large as to prevent a reliable estimate of masses, radii and effective temperatures, at least for stars of solar metallicity. The evolutionary models of Bertelli et al. (1994, Cat. <J/A+AS/106/275>) predict those parameters finely, and furthermore, the applied transformation from the theoretical log(g)-T_eff_ to the observational M_v_-B-V plane is precise enough to derive radii with an uncertainty of ~6%, masses within 8%, and Teffs within ~2% for a certain range of the stellar parameters. This is demonstrated by means of comparison with the measurements in eclipsing binaries and the InfraRed Flux Method. The application of the interpolation procedure in the theoretical isochrones to the stars within 100pc from the Sun observed with Hipparcos provides estimates for 17,219 stars included in this Table.
- ID:
- ivo://CDS.VizieR/J/AJ/155/30
- Title:
- Fundamental parameters of 87 stars from the NPOI
- Short Name:
- J/AJ/155/30
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the fundamental properties of 87 stars based on angular diameter measurements from the Navy Precision Optical Interferometer, 36 of which have not been measured previously using interferometry. Our sample consists of 5 dwarfs, 3 subgiants, 69 giants, 3 bright giants, and 7 supergiants, and span a wide range of spectral classes from B to M. We combined our angular diameters with photometric and distance information from the literature to determine each star's physical radius, effective temperature, bolometric flux, luminosity, mass, and age.
- ID:
- ivo://CDS.VizieR/J/MNRAS/445/4395
- Title:
- Fundamental properties of giant gas planets
- Short Name:
- J/MNRAS/445/4395
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- It is already stated in the previous studies that the radius of the giant planets is affected by stellar irradiation. The confirmed relation between radius and incident flux depends on planetary mass intervals. In this study, we show that there is a single relation between radius and irradiated energy per gram per second (l-), for all mass intervals. There is an extra increase in radius of planets if l- is higher than 1100 times energy received by the Earth (l_{earth}_). This is likely due to dissociation of molecules. The tidal interaction as a heating mechanism is also considered and found that its maximum effect on the inflation of planets is about 15 percent. We also compute age and heavy element abundances from the properties of host stars, given in the TEPCat catalogue (Southworth). The metallicity given in the literature is as [Fe/H]. However, the most abundant element is oxygen, and there is a reverse relation between the observed abundances [Fe/H] and [O/Fe]. Therefore, we first compute [O/H] from [Fe/H] by using observed abundances, and then find heavy element abundance from [O/H]. We also develop a new method for age determination. Using the ages we find, we analyse variation of both radius and mass of the planets with respect to time, and estimate the initial mass of the planets from the relation we derive for the first time. According to our results, the highly irradiated gas giants lose 5 percent of their mass in every 1Gyr.
- ID:
- ivo://CDS.VizieR/J/MNRAS/465/2849
- Title:
- Gaia DR1 mass-radius relation of white dwarfs
- Short Name:
- J/MNRAS/465/2849
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The Gaia Data Release 1 (DR1) sample of white dwarf parallaxes is presented, including six directly observed degenerates and 46 white dwarfs in wide binaries. This data set is combined with spectroscopic atmospheric parameters to study the white dwarf mass-radius relationship (MRR). Gaia parallaxes and G magnitudes are used to derive model atmosphere-dependent white dwarf radii, which can then be compared to the predictions of a theoretical MRR. We find a good agreement between Gaia DR1 parallaxes, published effective temperatures (T_eff_) and surface gravities (logg), and theoretical MRRs. As it was the case for Hipparcos, the precision of the data does not allow for the characterization of hydrogen envelope masses. The uncertainties on the spectroscopic atmospheric parameters are found to dominate the error budget and current error estimates for well-known and bright white dwarfs may be slightly optimistic. With the much larger Gaia DR2 white dwarf sample, it will be possible to explore the MRR over a much wider range of mass, T_eff_, and spectral types.
- ID:
- ivo://CDS.VizieR/J/A+A/620/A128
- Title:
- Gaia DR2 study of Herbig Ae/Be stars
- Short Name:
- J/A+A/620/A128
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We use Gaia Data Release 2 (DR2, Cat. I/345) to place 252 Herbig Ae/Be stars in the HR diagram and investigate their characteristics and properties. For all known Herbig Ae/Be stars with parallaxes in Gaia DR2, we collected their atmospheric parameters and photometric and extinction values from the literature. To these data we added near- and mid-infrared photometry, collected Halpha emission line properties such as equivalent widths and line profiles, and their binarity status. In addition, we developed a photometric variability indicator from Gaia's DR2 information. We provide masses, ages, luminosities, distances, photometric variabilities and infrared excesses homogeneously derived for the most complete sample of Herbig Ae/Be stars to date. We find that high mass stars have a much smaller infrared excess and have much lower optical variabilities compared to lower mass stars, with the break at around 7M_{sun}_. Halpha emission is generally correlated with infrared excess, with the correlation being stronger for infrared emission at wavelengths tracing the hot dust closest to the star. The variability indicator as developed by us shows that approximately 25% of all Herbig Ae/Be stars are strongly variable. We observe that the strongly variable objects display doubly peaked Halpha line profiles, indicating an edge-on disk. The fraction of strongly variable Herbig Ae stars is close to that found for A-type UX Ori stars. It had been suggested that this variability is in most cases due to asymmetric dusty disk structures seen edge-on. The observation here is in strong support of this hypothesis. Finally, the difference in dust properties occurs at 7M_{sun}_, while various properties traced at UV/optical wavelengths differ at a lower mass, 3M_{sun}_. The latter has been linked to different accretion mechanisms at work whereas the differing infrared properties and photometric variabilities are related to different or differently acting (dust-)disk dispersal mechanisms.
- ID:
- ivo://CDS.VizieR/J/A+A/601/A97
- Title:
- Gaia-ESO Survey: Cha I members
- Short Name:
- J/A+A/601/A97
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Investigating the physical mechanisms driving the dynamical evolution of young star clusters is fundamental to our understanding of the star formation process and the properties of the Galactic field stars. The young (~2Myr) and partially embedded cluster Chamaeleon I is one of the closest laboratories to study the early stages of star cluster dynamics in a low-density environment. The aim of this work is to study the structural and kinematical properties of this cluster combining parameters from the high-resolution spectroscopic observations of the Gaia-ESO Survey with data from the literature. Our main result is the evidence of a large discrepancy between the velocity dispersion ({sigma}_stars_=1.14+/-0.35km/s) of the stellar population and the dispersion of the pre-stellar cores (~0.3km/s) derived from submillimeter observations. The origin of this discrepancy, which has been observed in other young star clusters is not clear. It has been suggested that it may be due to either the effect of the magnetic field on the protostars and the filaments, or to the dynamical evolution of stars driven by two-body interactions. Furthermore, the analysis of the kinematic properties of the stellar population put in evidence a significant velocity shift (~1~km/s) between the two sub-clusters located around the North and South main clouds of the cluster. This result further supports a scenario, where clusters form from the evolution of multiple substructures rather than from a monolithic collapse.Using three independent spectroscopic indicators (the gravity indicator {gamma}, the equivalent width of the Li line at 6708{AA}, and the H{alpha} 10% width), we performed a new membership selection. We found six new cluster members all located in the outer region of the cluster, proving that Chamaeleon I is probably more extended than previously thought. Starting from the positions and masses of the cluster members, we derived the level of substructure Q, the surface density {Sigma} and the level of mass segregation {Lambda}_MSR_ of the cluster. The comparison between these structural properties and the results of N-body simulations suggests that the cluster formed in a low density environment, in virial equilibrium or supervirial, and highly substructured.
- ID:
- ivo://CDS.VizieR/J/AJ/159/280
- Title:
- Gaia-Kepler stellar properties catalog.I. KIC stars
- Short Name:
- J/AJ/159/280
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- An accurate and precise Kepler Stellar Properties Catalog is essential for the interpretation of the Kepler exoplanet survey results. Previous Kepler Stellar Properties Catalogs have focused on reporting the best-available parameters for each star, but this has required combining data from a variety of heterogeneous sources. We present the Gaia-Kepler Stellar Properties Catalog, a set of stellar properties of 186301 Kepler stars, homogeneously derived from isochrones and broadband photometry, Gaia Data Release 2 parallaxes, and spectroscopic metallicities, where available. Our photometric effective temperatures, derived from g to Ks colors, are calibrated on stars with interferometric angular diameters. Median catalog uncertainties are 112K for Teff, 0.05dex for logg, 4% for R_*_, 7% for M_*_, 13% for {rho}_*_, 10% for L_*_, and 56% for stellar age. These precise constraints on stellar properties for this sample of stars will allow unprecedented investigations into trends in stellar and exoplanet properties as a function of stellar mass and age. In addition, our homogeneous parameter determinations will permit more accurate calculations of planet occurrence and trends with stellar properties.
