Center-to-limb polarization in continuum spectra of F, G, K stars

Костогрыз, Н. М.; Berdyugina, S. V.

doi:10.1051/0004-6361/201424844

Cited by 22 publications

(23 citation statements)

References 27 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Different types of lines correspond to different temperatures labeled in (a) panel. The data for these plots were calculated in Kostogryz & Berdyugina (2015).…”

Section: Methodsmentioning

confidence: 99%

“…Assuming no magnetic field present, we solved the radiative transfer equations for polarized light iteratively considering plane-parallel model atmosphere and various opacities. The method of radiative transfer equations and opacity contributions calculation are described in Kostogryz & Berdyugina (2015).…”

Section: Stellar Limb Darkening and Limb Polarizationmentioning

confidence: 99%

“…The log g was chosen to be 4.5 since most of the known transiting exoplanetary hosts have log g in the range between 4.3 to 4.7. As shown in Kostogryz & Berdyugina (2015), the CLVP and CLVI strongly depend on the value of log g. Using the look-up tables we interpolate them to get the CLVI and the CLVP for the host star of particular effective temperature and surface gravity.…”

Section: Stellar Limb Darkening and Limb Polarizationmentioning

confidence: 99%

“…The center-to-limb variation of the linear polarization across the stellar disk originates from scattering opacity contributing to the total opacity in the atmosphere. By solving the radiative transfer equation for polarized light, Kostogryz & Berdyugina (2015) calculated center-to-limb variations of the intensity and the linear polarization for stars of different spectral types accounting for various opacity sources. It was shown that low-gravity cool stars, while having weaker limb darkening, should exhibit significantly larger linear polarization in their continuum spectra as compared to solar-type stars.…”

Section: Introductionmentioning

confidence: 99%

“…In this paper, we present our results of modeling the transit polarimetric effect for known transiting exoplanets which orbit spotted stars using the modelled center-to-limb variations of the intensity and linear polarization by Kostogryz & Berdyugina (2015). In Section 2 we describe our semi-analytical method for modeling flux and linear polarization curves during planetary transits.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Polarization in Exoplanetary Systems Caused by Transits, Grazing Transits, and Starspots

Костогрыз

Yakobchuk

Berdyugina

2015

ApJ

Self Cite

View full text Add to dashboard Cite

We present results of numerical simulations of flux and linear polarization variations in transiting exoplanetary systems, caused by the host star disk symmetry breaking. We consider different configurations of planetary transits depending on orbital parameters. Starspot contribution to the polarized signal is also estimated. Applying the method to known systems and simulating observational conditions, a number of targets is selected where transit polarization effects could be detected. We investigate several principal benefits of the transit polarimetry, particularly, for determining orbital spatial orientation and distinguishing between grazing and near-grazing planets. Simulations show that polarization parameters are also sensitive to starspots, and they can be used to determine spot positions and sizes.

show abstract

“…Different types of lines correspond to different temperatures labeled in (a) panel. The data for these plots were calculated in Kostogryz & Berdyugina (2015).…”

Section: Methodsmentioning

confidence: 99%

Section: Stellar Limb Darkening and Limb Polarizationmentioning

confidence: 99%

Section: Stellar Limb Darkening and Limb Polarizationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Polarization in Exoplanetary Systems Caused by Transits, Grazing Transits, and Starspots

Костогрыз

Yakobchuk

Berdyugina

2015

ApJ

Self Cite

View full text Add to dashboard Cite

show abstract

Polarized Continuum Radiation from Stellar Atmospheres

Harrington

2014

Proc. IAU

View full text Add to dashboard Cite

Continuum scattering by free electrons can be significant in early type stars, while in late type stars Rayleigh scattering by hydrogen atoms or molecules may be important. Computer programs used to construct models of stellar atmospheres generally treat the scattering of the continuum radiation as isotropic and unpolarized, but this scattering has a dipole angular dependence and will produce polarization. We review an accurate method for evaluating the polarization and limb darkening of the radiation from model stellar atmospheres. We use this method to obtain results for: (i) Late type stars, based on the MARCS code models (Gustafsson et al. 2008), and (ii) Early type stars, based on the NLTE code TLUSTY (Lanz and Hubeny 2003). These results are tabulated at http://www.astro.umd.edu/~jph/Stellar_Polarization.html While the net polarization vanishes for an unresolved spherical star, this symmetry is broken by rapid rotation or by the masking of part of the star by a binary companion or during the transit of an exoplanet. We give some numerical results for these last cases.

show abstract

Center-to-limb variation of intensity and polarization in continuum spectra of FGK stars for spherical atmospheres

Костогрыз

Milić

Berdyugina

et al. 2016

A&A

Self Cite

View full text Add to dashboard Cite

Aims. One of the necessary parameters needed for the interpretation of the light curves of transiting exoplanets or eclipsing binary stars (as well as interferometric measurements of a star or microlensing events) is how the intensity and polarization of light changes from the center to the limb of a star. Scattering and absorption processes in the stellar atmosphere affect both the center-to-limb variation of intensity (CLVI) and polarization (CLVP). In this paper, we present a study of the CLVI and CLVP in continuum spectra, taking into consideration the different contributions of scattering and absorption opacity for a variety of spectral type stars with spherical atmospheres. Methods. We solve the radiative transfer equation for polarized light in the presence of a continuum scattering, taking into consideration the spherical model of a stellar atmosphere. To cross-check our results, we developed two independent codes that are based on Feautrier and short characteristics methods, respectively, Results. We calculate the center-to-limb variation of intensity (CLVI) and polarization (CLVP) in continuum for the Phoenix grid of spherical stellar model atmospheres for a range of effective temperatures (4000−7000 K), gravities (log g = 1.0−5.5), and wavelengths (4000−7000 Å), which are tabulated and available at the CDS. In addition, we present several tests of our codes and compare our calculations for the solar atmosphere with published photometric and polarimetric measurements. We also show that our two codes provide similar results in all considered cases. Conclusions. For sub-giant and dwarf stars (log g = 3.0−4.5), the lower gravity and lower effective temperature of a star lead to higher limb polarization of the star. For giant and supergiant stars (log g = 1.0−2.5), the highest effective temperature yields the largest polarization. By decreasing the effective temperature of a star down to 4500−5500 K (depending on log g), the limb polarization decreases and reaches a local minimum. It increases again with a corresponding decrease in temperature down to 4000 K. For the most compact dwarf stars (log g = 5.0−5.5), the limb polarization degree shows a maximum for models with effective temperatures in the range 4200−4600 K (depending on log g) and decreases toward higher and lower temperatures.

show abstract

Center-to-limb polarization in continuum spectra of F, G, K stars

Cited by 22 publications

References 27 publications

Polarization in Exoplanetary Systems Caused by Transits, Grazing Transits, and Starspots

Polarization in Exoplanetary Systems Caused by Transits, Grazing Transits, and Starspots

Polarized Continuum Radiation from Stellar Atmospheres

Center-to-limb variation of intensity and polarization in continuum spectra of FGK stars for spherical atmospheres

Contact Info

Product

Resources

About