On the Limb Darkening, Spectral Energy Distribution, and Temperature Structure of Procyon

Aufdenberg, J. P.; Ludwig, H.‐G.; Kervella, P.

doi:10.1086/452622

Cited by 83 publications

(106 citation statements)

References 63 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Our results in Table 3 are in qualitative agreement with those obtained by Allend Prieto et al (2002), Aufdenberg et al (2005) and Bigot et al (2006) for dwarf stars, though the lower surface gravity of red giants might also play a role, since the size of surface related convective structures is roughly inversely proportional to the gravity. As we already discussed, the size of these inhomogeneities have an impact on the average intensity profile and thus on the interferometric observables.…”

Section: Estimation Of Diameter Correction: 1d Versus 3d Modelssupporting

confidence: 92%

Three-dimensional hydrodynamical simulations of red giant stars: semi-global models for interpreting interferometric observations

Chiavassa¹,

Collet²,

Casagrande³

et al. 2010

A&A

View full text Add to dashboard Cite

Context. Theoretical predictions from models of red giant branch stars are a valuable tool for various applications in astrophysics ranging from galactic chemical evolution to studies of exoplanetary systems. Aims. We use the radiative transfer code Optim3D and realistic 3D radiative-hydrodynamical (RHD) surface convection simulations of red giants to explore the impact of granulation on interferometric observables. We assess how 3D simulations of surface convection can be validated against observations. Methods. We computed intensity maps for the 3D simulation snapshots in two filters, the optical at 5000 ± 300 Å and the K band 2.14±0.26 μm FLUOR filter, corresponding to the wavelength-range of instruments mounted on the CHARA interferometer. From the intensity maps, we constructed images of the stellar disks and account for center-to-limb variations. We then derived interferometric visibility amplitudes and phases. We study their behavior with position angle and wavelength, and compare them with CHARA observations of the red giant star HD 214868. Results. We provide average limb darkening coefficients for different metallicities and wavelengths ranges. We explain prospects for detecting and characterizing granulation and center-to-limb variations of red giant stars with today's interferometers. Regarding interferometric observables, we find that the effect of convective-related surface structures depends on metallicity and surface gravity. We provide theoretical closure-phases that should be incorporated into the analysis of red giant planet companion closure phase signals. We estimate 3D−1D corrections to stellar radii determination: 3D models are ∼3.5% smaller to ∼1% larger in the optical than 1D, and roughly 0.5 to 1.5% smaller in the infrared. Even if these corrections are small, they are needed to properly set the zero point of effective temperature scale derived by interferometry and to strengthen the confidence of existing red giant catalogs of calibrating stars for interferometry. Finally, we show that our RHD simulations provide an excellent fit to the red giant HD 214868 even though more observations are needed at higher spatial frequencies and shorter wavelength.

show abstract

Section: Estimation Of Diameter Correction: 1d Versus 3d Modelssupporting

confidence: 92%

Three-dimensional hydrodynamical simulations of red giant stars: semi-global models for interpreting interferometric observations

Chiavassa¹,

Collet²,

Casagrande³

et al. 2010

A&A

View full text Add to dashboard Cite

show abstract

“…Advances in interferometric observations have allowed for observations of convective cells in Betelgeuse (Haubois et al 2009) and measurements of gravity darkening in Altair (van Belle et al 2001). In terms of model stellar atmospheres, Aufdenberg et al (2005) constrained threedimensional models using observations of Procyon.…”

Section: Introductionmentioning

confidence: 99%

Spherically-symmetric model stellar atmospheres and limb darkening

Neilson

Lester

2013

A&A

View full text Add to dashboard Cite

Model stellar atmospheres are fundamental tools for understanding stellar observations from interferometry, microlensing, eclipsing binaries and planetary transits. However, the calculations also include assumptions, such as the geometry of the model. We use intensity profiles computed for both plane-parallel and spherically symmetric model atmospheres to determine fitting coefficients in the BVRIHK, CoRot and Kepler wavebands for limb darkening using several different fitting laws, for gravity-darkening and for interferometric angular diameter corrections. Comparing predicted variables for each geometry, we find that the spherically symmetric model geometry leads to different predictions for surface gravities log g < 3. In particular, the most commonly used limb-darkening laws produce poor fits to the intensity profiles of spherically symmetric model atmospheres, which indicates the need for more sophisticated laws. Angular diameter corrections for spherically symmetric models range from 0.67 to 1, compared to the much smaller range from 0.95 to 1 for plane-parallel models.

show abstract

“…They found a diameter that is even smaller θ = 5.448 ±0.053 mas. Aufdenberg et al (2005) reanalyzed these data using hydrodynamical model atmospheres and found that θ = 5.404 ± 0.031 mas (see their Table 7). It is interesting to compare these angular diameters with those derived using the independent infrared flux method.…”

Section: Introductionmentioning

confidence: 99%

“…Allende Prieto et al also showed that the 3D limb darkening law differs significantly from the one-dimensional (1D) law, by up to ∼1.6%, leading to a correction of ΔT eff ≈ 50 K, which is non-negligible for precise stellar evolution modeling. Aufdenberg et al (2005) developed 3D models using the CO 5 BOLD code (Freytag et al 2002(Freytag et al , 2012 to calculate limb-darkened intensity profiles to analyze the visibility curves obtained by the Vinci instrument (Kervella et al 2003b) and Mark III. Their 3D analysis inferred a radius smaller by 0.04 mas than that of Kervella et al (2003b), who used a 1D limb-darkened law.…”

Section: Introductionmentioning

confidence: 99%

“…To establish the importance of a realistic hydrodynamical modeling of the atmosphere of Procyon, we re-analyze the interferometric and spectroscopic data at the different wavelengths of Aufdenberg et al (2005) using up-to-date line and continuum opacities (Gustafsson et al 2008) to derive a new radius. We propose a solution that agrees well with results derived using the astrometric, asteroseismologic, infrared flux method, and interferometric data.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Three-dimensional interferometric, spectrometric, and planetary views of Procyon

Chiavassa

Bigot

Kervella

et al. 2012

A&A

Self Cite

View full text Add to dashboard Cite

Context. Procyon is one of the brightest stars in the sky and one of our nearest neighbours. It is therefore an ideal benchmark object for stellar astrophysics studies using interferometric, spectroscopic, and asteroseismic techniques. Aims. We use a new realistic three-dimensional (3D) radiative-hydrodynamical (RHD) model atmosphere of Procyon generated with the Stagger Code and synthetic spectra computed with the radiative transfer code Optim3D to re-analyze interferometric and spectroscopic data from the optical to the infrared. We provide synthetic interferometric observables that can be validated using observations. Methods. We computed intensity maps from a RHD simulation in two optical filters centered on 500 and 800 nm (Mark III) and one infrared filter centered on 2.2 μm (Vinci). We constructed stellar disk images accounting for the center-to-limb variations and used them to derive visibility amplitudes and closure phases. We also computed the spatially and temporally averaged synthetic spectrum from the ultraviolet to the infrared. We compare these observables to Procyon data. Results. We study the impact of the granulation pattern on center-to-limb intensity profiles and provide limb-darkening coefficients in the optical as well as in the infrared. We show how the convection-related surface structures affect the visibility curves and closure phases with clear deviations from circular symmetry, from the 3rd lobe on. These deviations are detectable with current interferometers using closure phases. We derive new angular diameters at different wavelengths with two independent methods based on 3D simulations. We find that θ Vinci = 5.390 ± 0.03 mas, which we confirm by comparison with an independent asteroseismic estimation (θ seismic = 5.360 ± 0.07 mas. The resulting T eff is 6591 K (or 6556 K depending on the bolometric flux used), which is consistent with the value of T eff,IR = 6621 K found with the infrared flux method. We measure a surface gravity log g = 4.01 ± 0.03 [cm/s 2 ] that is higher by 0.05 dex than literature values. Spectrophotometric comparisons with observations provide very good agreement with the spectral energy distribution and photometric colors, allowing us to conclude that the thermal gradient in the simulation matches Procyon fairly well. Finally, we show that the granulation pattern of a planet-hosting Procyon-like star has a non-negligible impact on the detection of hot Jupiters in the infrared using interferometry closure phases. It is then crucial to have a comprehensive knowledge of the host star to directly detect and characterize hot Jupiters. In this respect, RHD simulations are very important to achieving this aim.

show abstract

On the Limb Darkening, Spectral Energy Distribution, and Temperature Structure of Procyon

Cited by 83 publications

References 63 publications

Three-dimensional hydrodynamical simulations of red giant stars: semi-global models for interpreting interferometric observations

Three-dimensional hydrodynamical simulations of red giant stars: semi-global models for interpreting interferometric observations

Spherically-symmetric model stellar atmospheres and limb darkening

Three-dimensional interferometric, spectrometric, and planetary views of Procyon

Contact Info

Product

Resources

About