- ID:
- ivo://CDS.VizieR/J/MNRAS/485/5168
- Title:
- Light curves of WASP-74
- Short Name:
- J/MNRAS/485/5168
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present broad-band photometry of 11 planetary transits of the hot Jupiter WASP-74 b, using three medium-class telescopes and employing the telescope-defocusing technique. Most of the transits were monitored through I filters and one was simultaneously observed in five optical (U, g', r', i', z') and three near-infrared (J, H, K) passbands, for a total of 18 light curves. We also obtained new high-resolution spectra of the host star. We used these new data to review the orbital and physical properties of the WASP-74 planetary system. We were able to better constrain the main system characteristics, measuring smaller radius and mass for both the hot Jupiter and its host star than previously reported in the literature. Joining our optical data with those taken with the HST in the near infrared, we built up an observational transmission spectrum of the planet, which suggests the presence of strong optical absorbers, as TiO and VO gases, in its atmosphere.
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- ID:
- ivo://CDS.VizieR/J/ApJ/708/717
- Title:
- Light curve templates of RR Lyrae stars
- Short Name:
- J/ApJ/708/717
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an improved analysis of halo substructure traced by RR Lyrae stars in the Sloan Digital Sky Survey (SDSS) stripe 82 region. With the addition of SDSS-II data, a revised selection method based on new ugriz light curve templates results in a sample of 483 RR Lyrae stars that is essentially free of contamination. The main result from our first study persists: the spatial distribution of halo stars at galactocentric distances 5-100kpc is highly inhomogeneous. At least 20% of halo stars within 30kpc from the Galactic center can be statistically associated with substructure. We present strong direct evidence, based on both RR Lyrae stars and main-sequence stars, that the halo stellar number density profile significantly steepens beyond a Galactocentric distance of ~30kpc, and a larger fraction of the stars are associated with substructure. By using a novel method that simultaneously combines data for RR Lyrae and main-sequence stars, and using photometric metallicity estimates for main-sequence stars derived from deep co-added u-band data, we measure the metallicity of the Sagittarius dSph tidal stream (trailing arm) toward RA~2h-3h and DE~0{deg} to be 0.3dex higher ([Fe/H]=-1.2) than that of surrounding halo field stars.
- ID:
- ivo://CDS.VizieR/J/A+A/574/A60
- Title:
- Light curve templates of SNe Ib/c from SDSS
- Short Name:
- J/A+A/574/A60
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present optical (ugriz) light curve templates of supernovae Ib/c from the SDSS II SN survey.
- ID:
- ivo://CDS.VizieR/J/ApJ/743/125
- Title:
- Likelihood method for QSOs selection
- Short Name:
- J/ApJ/743/125
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a new method for quasar target selection using photometric fluxes and a Bayesian probabilistic approach. For our purposes, we target quasars using Sloan Digital Sky Survey (SDSS) photometry to a magnitude limit of g=22. The efficiency and completeness of this technique are measured using the Baryon Oscillation Spectroscopic Survey (BOSS) data taken in 2010. This technique was used for the uniformly selected (CORE) sample of targets in BOSS year-one spectroscopy to be realized in the ninth SDSS data release. When targeting at a density of 40 objects deg^-2^ (the BOSS quasar targeting density), the efficiency of this technique in recovering z>2.2 quasars is 40%. The completeness compared to all quasars identified in BOSS data is 65%. This paper also describes possible extensions and improvements for this technique.
- ID:
- ivo://CDS.VizieR/J/A+A/529/A75
- Title:
- Limb-darkening coefficients
- Short Name:
- J/A+A/529/A75
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The degree of complexity of physics due to proximity effects in close binary stars is one of the most important challenges in theoretical stellar physics. The knowledge of how the specific intensity is distributed over the stellar disk is primordial to model the light curves of eclipsing binaries and planetary transits correctly. In order to provide theoretical input for light curve modelling codes, we present new calculations of gravity- and limb darkening coefficients for a wide range of effective temperatures, gravities, metallicities and microturbulent velocities. We have computed limb darkening coefficients for several atmosphere models, covering the transmission curves of the Kepler, CoRoT and Spitzer space missions as well as more widely used passbands (Stroemgren, Johnson-Cousins, Sloan). In addition to these computations, which were computed by adopting the Least-Square Method, we also performed calculations for the bi-parametric approximations by adopting the Flux Conservation Method to provide users with an additional tool to estimate the theoretical error bars. To facilitate the modelling of the effects of tidal and rotational distortions, we computed the GDCs y({lambda}) using the same models of stellar atmospheres as in the case of limb-darkening. Compared to previous work, a more general differential equation was used which now takes into account local gravity variations and the effects of convection. The limb darkening coefficients were computed with a larger numerical resolution (100um points instead of 15 or 17 as is often used in the ATLAS models) and five equations were used to describe the specific intensities (linear, quadratic, root-square, logarithmic and a 4-coefficient law (Equation 5)). Concerning the GDCs, the influence of the local gravity on y({lambda}) is shown as well as the effects of convection, which turn out to be very significant for cool stars. The results are tabulated for log(g)'s ranging from 0.0 to 5.0,-5.0<=log[M/H]<=+1, 2000K<=Teff<=50000K and for 5 values of the microturbulent velocity (0, 2, 4, 6, 8). ATLAS and PHOENIX plane-parallel atmosphere models were used for all the computations.
- ID:
- ivo://CDS.VizieR/J/A+A/634/A93
- Title:
- Limb-darkening coefficients for compact stars
- Short Name:
- J/A+A/634/A93
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The distribution of the specific intensity over the stellar disk is an essential tool for modeling the light curves in eclipsing binaries, planetary transits, and stellar diameters through interferometric techniques, line profiles in rotating stars, gravitational microlensing, etc. However, the available theoretical calculations are mostly restricted to stars on the main sequence or the giant branch, and very few calculations are available for compact stars. The main objective of the present work is to extend these investigations by computing the gravity and limb-darkening coefficients for white dwarf atmosphere models with hydrogen, helium, or mixed compositions (types DA, DB, and DBA). We computed gravity and limb-darkening coefficients for DA, DB, and DBA white dwarfs atmosphere models, covering the transmission curves of the Sloan, UBVRI, Kepler, TESS, and Gaia photometric systems. Specific calculations for the HiPERCAM instrument were also carried out. For all calculations of the limb-darkening coefficients we used the least-squares method. Concerning the effects of tidal and rotational distortions, we also computed for the first time the gravity-darkening coefficients $y(\lambda)$ for white dwarfs using the same models of stellar atmospheres as in the case of limb-darkening. A more general differential equation was introduced to derive these quantities, including the partial derivative <{\partial}lnI_o_(lambda)/{\partial}lng)_Teff_. Six laws were adopted to describe the specific intensity distribution: linear, quadratic, square root, logarithmic, power-2, and a more general one with four coefficients. The computations are presented for the chemical compositions log[H/He]=-10.0 (DB), -2.0 (DBA) and He/H=0 (DA), with logg varying between 5.0 and 9.5 and effective temperatures between 3750K-100000K. For effective temperatures higher than 40000K, the models were also computed adopting nonlocal thermal equilibrium (DA). The adopted mixing-length parameters are ML2/{alpha}= 0.8 (DA case) and 1.25 (DB and DBA). The results are presented in the form of 112 tables. Additional calculations, such as for other photometric systems and/or different values of log[H/He], logg, and Teff can be performed upon request.
- ID:
- ivo://CDS.VizieR/J/A+A/567/A3
- Title:
- Limb-darkening coefficients for MOST
- Short Name:
- J/A+A/567/A3
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new calculations of limb and gravity-darkening coefficients to be used as input in many fields of stellar physics such as synthetic light curves of double-lined eclipsing binaries and planetary transits, studies of stellar diameters or line profiles in rotating stars. We compute the limb-darkening coefficients specifically for the photometric system of the satellite MOST (Microvariability and Oscillations in STars). All computations were performed by adopting the least-square method, but for completeness we also performed calculations for the linear and bi-parametric approaches by adopting the flux conservation method. The passband gravity-darkening coefficients y({lambda}) were computed by adopting a more general differential equation, which also takes the effects of convection into account. We used two stellar atmosphere models: ATLAS (plane-parallel) and PHOENIX (spherical and quasi-spherical). We adopted six laws to describe the specific intensity distribution: linear, quadratic, square root, logarithmic, exponential, and a more general one with four terms. The covered ranges of T_eff_, log g, metallicities, and microturbulent velocities are [1500-50000K, 0-5.5,-5.0-1.0, 0-8km/s], respectively.
- ID:
- ivo://CDS.VizieR/J/A+A/641/A157
- Title:
- Limb-darkening coefficients for white dwarfs
- Short Name:
- J/A+A/641/A157
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Systematic theoretical calculations of Doppler beaming factors are very scarce in the literature, mainly in the case of white dwarfs. Additionally, there are no specific calculations for the limb-darkening coefficients of 3D white dwarf models. The objective of this research is to provide the astronomical community with Doppler beaming calculations for a wide range of effective temperatures, local gravities and hydrogen/metal content for white dwarfs as well as stars on both the main sequence and the giant branch. In addition, for the first time we also present the theoretical calculations of the limb-darkening coefficients for 3D white dwarfs models. We computed Doppler beaming factors for DA, DB and DBA white dwarf models, as well as for main sequence and giant stars covering the transmission curves of the Sloan, UBVRI, HiPERCAM, Kepler, TESS, and Gaia photometric systems. The calculations of the limb-darkening coefficients for 3D models were carried out using the least-squares method for the same mentioned photometric systems. The input physics of the white dwarf models for which we have computed the Doppler beaming factors are: chemical compositions log[H/He]=-10.0 (DB), -2.0 (DBA) and He/H=0 (DA), with logg varying between 5.0 and 9.5 and effective temperatures in the range 3750-100000K. The beaming factors were also calculated assuming non-local thermodynamic equilibrium (NLTE) for the case of DA white dwarfs with T_eff_>40000K. For the mixing-length parameters we adopted ML2/{alpha}=0.8 (DA case) and 1.25 (DB and DBA). The Doppler beaming factors for main sequence and giant stars were computed using the ATLAS9 version, characterized by metallicities ranging from [-2.5, 0.2] solar abundances, with logg varying between 0 and 5.0 and effective temperatures between 3500-50000K. The adopted microturbulent velocity for these models was 2.0km/s. The limb-darkening coefficients were computed for 3D DA and DB white dwarf models calculated with the CO^5^BOLD radiation-hydrodynamics code. The parameter range covered by 3D DA models spans logg values between 7.0 and 9.0, Teff between 6000 and 15000K and He/H=0. The 3D DB models cover a similar parameter range of logg between 7.5 and 9.0, Teff between 12000 and 34000K and logH/He=-10.0. We adopted six laws for the computation of the limb-darkening coefficients: linear, quadratic, square root, logarithmic, power-2, and a general one with four coefficients. The beaming factor calculations which use realistic models of stellar atmospheres show that the black body approximation is not accurate, mainly for the filters u, u', U, g, g' and B. The black body approach is only valid for high effective temperatures and/or long effective wavelengths. Therefore, for more accurate analyses of light curves, we recommend the use of the beaming factors presented in this paper. Concerning limb-darkening, the distribution of specific intensities for 3D models indicates that in general these models are less bright towards the limb than their 1D counterparts, which implies steeper profiles. To describe these intensities better, we recommend the use of the four-terms law (also for 1D models) given the level of precision that is being achieved with Earth-based instruments, as well as space missions such as Kepler, TESS or PLATO in the future.
- ID:
- ivo://CDS.VizieR/J/A+A/546/A14
- Title:
- Limb-darkening for CoRoT, Kepler, Spitzer
- Short Name:
- J/A+A/546/A14
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The knowledge of how the specific intensity is distributed over the stellar disk is crucial for interpreting the light curves of extrasolar transiting planets, double-lined eclipsing binaries, and other astrophysical phenomena. To provide theoretical inputs for light curve modelling codes, we present new calculations of limb-darkening coefficients for the spherically symmetric PHOENIX models. The limb-darkening coefficients were computed by covering the transmission curves of Kepler, CoRoT, and Spitzer space missions, as well as the passbands of the Stromgren, Johnson-Cousins, Sloan, and 2MASS. These computations adopted the least-square method. In addition, we also calculated the linear and bi-parametric approximations by adopting the flux conservation method as an additional tool for estimating the theoretical error bars in the limb-darkening coefficients. Six laws were used to describe the specific intensity distribution: linear, quadratic, square root, logarithmic, exponential, and a more general one with 4 terms. The computations are presented for the solar chemical composition, with logg varying between 2.5 and 5.5 and effective temperatures between 1500K-4800K. The adopted Microturbulent velocity and the mixing-length parameters are 2.0km/s and 2.0, respectively. Model are for solar metallicity.
- ID:
- ivo://CDS.VizieR/J/A+A/552/A16
- Title:
- Limb-darkening for CoRoT, Kepler, Spitzer. II.
- Short Name:
- J/A+A/552/A16
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an extension of our investigations on limb-darkening coefficients computed with spherical symmetrical PHOENIX models. The models investigated in this paper cover the range 5000K<=Teff<=10000K and complete our previous studies of low effective temperatures computed with the same code. The limb-darkening coefficients are computed for the transmission curves of the Kepler, CoRoT, and Spitzer space missions and the Stroemgren, Johnson-Cousins, Sloan, and 2MASS passbands. These computations were performed by adopting the least-squares method. We have used six laws to describe the specific intensity distribution: linear, quadratic, square root, logarithmic, exponential, and a general law with four terms. The computations are presented for the solar chemical composition and cover the range 3.0<=logg<=5.5. The adopted microturbulent velocity and the mixing-length parameter are 2.0km/s and 2.0.
