- ID:
- ivo://CDS.VizieR/J/A+A/615/A39
- Title:
- Exoplanets interior structures & Love numbers
- Short Name:
- J/A+A/615/A39
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Space missions such as CoRoT and Kepler have made the transit method the most successful technique in observing extrasolar planets. However, although the mean density of a planet can be derived from its measured mass and radius, no details about its interior structure, such as the density profile, can be inferred so far. If determined precisely enough, the shape of the transiting light curve might, in principle, reveal the shape of the planet, and in particular, its deviation from spherical symmetry. These deformations are caused, for instance, by the tidal interactions of the planet with the host star and by other planets that might orbit in the planetary system. The deformations depend on the interior structure of the planet and its composition and can be parameterized as Love numbers k_n_. This means that the diversity of possible interior models for extrasolar planets might be confined by measuring this quantity. We present results of a wide-ranging parameter study in planet mass, surface temperature, and layer mass fractions on such models for super-Earths and their corresponding Love numbers. Based on these data, we find that k_2_ is most useful in assessing the ratio of rocky material to iron and in ruling out certain compositional configurations for measured mass and radius values, such as a prominent core consisting of rocky material. Furthermore, we apply the procedure to exoplanets K2-3b and c and predict that K2-3c probably has a thick outer water layer.
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- ID:
- ivo://CDS.VizieR/J/ApJ/884/11
- Title:
- Exploring 6 AGN dusty torus models. II.
- Short Name:
- J/ApJ/884/11
- Date:
- 04 Dec 2021
- Publisher:
- CDS
- Description:
- This is the second in a series of papers devoted to exploring a set of six dusty models of active galactic nuclei (AGN) with available spectral energy distributions. These models are the smooth torus by Fritz+ (2006MNRAS.366..767F), the clumpy torus by Nenkova+ (2008ApJ...685..147N and 2008ApJ...685..160N), the clumpy torus by Honig & Kishimoto (2010A&A...523A..27H), the two-phase torus by Siebenmorgen+ (2015A&A...583A.120S), the two-phase torus by Stalevski+ (2012MNRAS.420.2756S and 2016MNRAS.458.2288S), and the wind model by Honig & Kishimoto (2017ApJ...838L..20H). The first paper explores discrimination among models and the parameter restriction using synthetic spectra. Here we perform spectral fitting of a sample of 110 AGN drawn from the Swift/BAT survey with Spitzer/IRS spectroscopic data. The aim is to explore which is the model that describes better the data and the resulting parameters. The clumpy wind-disk model by Honig & Kishimoto provides good fits for ~50% of the sample, and the clumpy torus model by Nenkova+ is good at describing ~30% of the objects. The wind-disk model by Honig & Kishimoto is better for reproducing the mid-infrared spectra of type 1 Seyferts (with 60% of the type 1 Seyferts well reproduced by this model compared to the 10% well represented by the clumpy torus model by Nenkova+), while type 2 Seyferts are equally fitted by both models (roughly 40% of the type 2 Seyferts). Large residuals are found irrespective of the model used, indicating that the AGN dust continuum emission is more complex than predicted by the models or that the parameter space is not well sampled. We found that all the resulting parameters for our AGN sample are roughly constrained to 10%-20% of the parameter space. Contrary to what is generally assumed, the derived outer radius of the torus is smaller (reaching up to a factor of ~5 smaller for 10pc tori) for the smooth torus by Fritz+ and the two-phase torus by Stalevski+ than the one derived from the clumpy torus by Nenkova+ Covering factors and line-of-sight viewing angles strongly depend on the model used. The total dust mass is the most robust derived quantity, giving equivalent results for four of these models.
- 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/A+A/632/A74
- Title:
- Extended main-sequence turn-offs isochrones
- Short Name:
- J/A+A/632/A74
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Extended main-sequence turn-offs (eMSTO) are a commonly observed property of young clusters. A global theoretical interpretation for the eMSTOs is still lacking, but stellar rotation is considered a necessary ingredient to explain the eMSTO. We aim to assess the importance of core-boundary and envelope mixing in stellar interiors for the interpretation of eMSTOs in terms of one coeval population. We construct isochrone-clouds based on interior mixing profiles of stars with a convective core calibrated from asteroseismology of isolated galactic field stars. We fit these isochrone-clouds to the measured eMSTO to estimate the age and core mass of the stars in the two young clusters NGC 1850 and NGC 884, assuming one coeval population and fixing the metallicity to the one measured from spectroscopy. We assess the correlations between the interior mixing properties of the cluster members and their rotational and pulsational properties. We find that stellar models based on asteroseismically-calibrated interior mixing profiles lead to enhanced core masses of eMSTO stars and can explain a good fraction of the observed eMSTOs of the two considered clusters in terms of one coeval population of stars, with similar ages to those in the literature, given the large uncertainties. The rotational and pulsational properties of the stars in NGC 884 are not sufficiently well known to perform asteroseismic modelling, as it is achieved for field stars from space photometry. The stars in NGC 884 for which we have vsini and a few pulsation frequencies show no correlation between these properties and the core masses of the stars that set the cluster age. Future cluster space asteroseismology may allow to interpret the values of the core masses in terms of the physical processes that cause them, based on the modelling of the interior mixing profiles for the individual member stars with suitable identified modes.
- ID:
- ivo://CDS.VizieR/J/A+A/417/1055
- Title:
- Extensive library of synthetic spectra
- Short Name:
- J/A+A/417/1055
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A library of 183588 synthetic spectra based on Kurucz's ATLAS9 models is presented for the far red spectral interval (7653-8747{AA}). It is characterized by 3500K<=T_eff_<=47500K, 0.0<=logg<=5.0, -3.0<=[M/H]<=+0.5, 0<=Vrot<=500km/s, {xi}=2km/s. The whole grid of spectra is calculated for resolving powers 8500, 11500 and 20000. A section of the grid is also computed for [{alpha}/Fe]=+0.4 and for microturbulent velocities 0 and 4km/s. The library covers the wavelength ranges and resolutions of the two ambitious spectroscopic surveys by the ground experiment RAVE and the space mission GAIA. Cross-sections across the multi-dimensional data-cube are used to illustrate the behaviour of the strongest spectral lines.
- ID:
- ivo://CDS.VizieR/J/ApJ/725/1215
- Title:
- Faint UV standards from Swift, GALEX and SDSS
- Short Name:
- J/ApJ/725/1215
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- At present, the precision of deep ultraviolet photometry is somewhat limited by the dearth of faint ultraviolet standard stars. In an effort to improve this situation, we present a uniform catalog of 11 new faint (u~17) ultraviolet standard stars. High-precision photometry of these stars has been taken from the Sloan Digital Sky Survey and Galaxy Evolution Explorer archives and combined with new data from the Swift Ultraviolet Optical Telescope to provide precise photometric measures extending from the near-infrared to the far-ultraviolet. These stars were chosen because they are known to be hot (20000<T_eff_<50000K) DA white dwarfs with published Sloan spectra that should be photometrically stable. This careful selection allows us to compare the combined photometry and Sloan spectroscopy to models of pure hydrogen atmospheres to both constrain the underlying properties of the white dwarfs and test the ability of white dwarf models to predict the photometric measures.
- ID:
- ivo://CDS.VizieR/J/ApJ/738/170
- Title:
- False positive Kepler planet candidates
- Short Name:
- J/ApJ/738/170
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a framework to conservatively estimate the probability that any particular planet-like transit signal observed by the Kepler mission is in fact a planet, prior to any ground-based follow-up efforts. We use Monte Carlo methods based on stellar population synthesis and Galactic structure models, and report false positive probabilities (FPPs) for every Kepler Object of Interest, assuming a 20% intrinsic occurrence rate of close-in planets in the radius range 0.5R_{earth}_<R_p_<20R_{earth}_. Nearly 90% of the 1235 candidates have FPP<10%, and over half have FPP<5%. This probability varies with the magnitude and Galactic latitude of the target star, and with the depth of the transit signal - deeper signals generally have higher FPPs than shallower signals. We establish that a single deep high-resolution image will be an effective follow-up tool for the shallowest (Earth-sized) transits, providing the quickest route toward probabilistically validating the smallest candidates by potentially decreasing the FPP of an Earth-sized transit around a faint star from >10% to <1%. Since Kepler has detected many more planetary signals than can be positively confirmed with ground-based follow-up efforts in the near term, these calculations will be crucial to using the ensemble of Kepler data to determine population characteristics of planetary systems. We also describe how our analysis complements the Kepler team's more detailed BLENDER false positive analysis for planet validation.
- ID:
- ivo://CDS.VizieR/J/A+A/404/661
- Title:
- Fe5270, Fe5335, Mgb and Mg_2_ synthetic indices
- Short Name:
- J/A+A/404/661
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have computed a grid of synthetic spectra in the wavelength range {lambda}{lambda}4600-5600{AA} using revised model atmospheres, for a range of atmospheric parameters and values of [alpha-elements/Fe]=0.0 and +0.4. The Lick indices Fe5270, Fe5335, Mgb and Mg_2_ are measured on the grid spectra, for FWHM=2 to 8.3{AA}. Relations between the indices Fe5270, Fe5335 and Mg_2_ and stellar parameters effective temperature T_eff_, logg, [Fe/H] and [alpha/Fe], valid in the range 4000K>=T_eff_>=7000K, are presented. These fitting functions are given for FWHM=3.5 and 8.3{AA}. The indices were also measured for a list of 97 reference stars with well-known stellar parameters observed at ESO and OHP, and these are compared to the computed indices. Finally, a comparison of the indices measured on the observed spectra and those derived from the fitting functions based on synthetic spectra is presented.
- ID:
- ivo://CDS.VizieR/J/MNRAS/453/2599
- Title:
- Fermi-LAT pulsar spectral data
- Short Name:
- J/MNRAS/453/2599
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- {gamma}-ray radiation from pulsars is usually thought to be mostly produced by the synchro-curvature (SC) losses of accelerated particles. Here, we present a systematic study of all currently reported, good-quality Fermi-LAT pulsar spectral data. We do so by applying a model which follows the particle dynamics and consistently computes the emission of SC radiation. By fitting observational data on a case by case basis, we are able to obtain constraints about the parallel electric field, the typical length-scale over which particles emit the bulk of the detected radiation, and the number of involved particles. The model copes well with data of several dozens of millisecond (MSPs) and young pulsars (YPs). By correlating the inferred model parameters with the observed timing properties, some trends are discovered. First, a non-negligible part of the radiation comes from the loss of perpendicular momentum soon after pair creation. Second, the electric field strongly correlates with both the inverse of the emission length-scale and the magnetic field at light cylinder, thus ruling out models with high-energy photon production close to the surface. These correlations unify young and millisecond pulsars under the same physical scenario, and predict that magnetars are intrinsically {gamma}-ray quiet via synchro-curvature processes, since magnetospheric particles are not accelerated enough to emit a detectable {gamma}-ray flux.
- ID:
- ivo://CDS.VizieR/J/A+A/556/A86
- Title:
- FGK dwarf stars limb darkening coefficients
- Short Name:
- J/A+A/556/A86
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Limb darkening is a fundamental ingredient for interpreting observations of planetary transits, eclipsing binaries, optical/infrared interferometry and microlensing events. However, this modeling traditionally represents limb darkening by a simple law having one or two coefficients that have been derived from plane-parallel model stellar atmospheres, which has been done by many researchers. More recently, researchers have gone beyond plane-parallel models and considered other geometries. We previously studied the limb-darkening coefficients from spherically symmetric and plane-parallel model stellar atmospheres for cool giant and supergiant stars, and in this investigation we apply the same techniques to FGK dwarf stars. We present limb-darkening coefficients, gravity-darkening coefficients and interferometric angular diameter corrections from Atlas and SAtlas model stellar atmospheres. We find that sphericity is important even for dwarf model atmospheres, leading to significant differences in the predicted coefficients.
