Discovery of eclipse polarization in Algol

Kemp, J. C.; Henson, G. D.; Barbour, M. S.; Kraus, Dominik; Collins, George E.

doi:10.1086/184135

Cited by 36 publications

(31 citation statements)

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“…For the eclipse coverage reported in Kemp et al (1983) the minimum width A min of the averaging kernel at the limb is 0.0199 R disc , even in the zero-noise limit.…”

Section: The Algol System: a Worked Examplementioning

confidence: 91%

“…The graphs presented by Kemp et al (1983) have 25 data points in the eclipse phase. The same paper states that, in the Algol primary star, 50% of the polarized flux comes from an annulus on the limb of width less than 0.005 R disc .…”

Section: The Algol System: a Worked Examplementioning

confidence: 99%

“…The first detection of this "Chandrasekhar effect" was in the Algol system (Kemp et al 1983). This data was analysed by Wilson & Liou (1993), but the complexity of the system and the amount of modelling involved in the analysis prevented them from making any reliable estimate of the limb polarization.…”

Section: Introductionmentioning

confidence: 99%

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Inversion of polarimetric data from eclipsing binaries

Coleman

Gray

Simmons

1998

Astron. Astrophys. Suppl. Ser.

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Abstract. We describe a method for determining the limb polarization and limb darkening of stars in eclipsing binary systems, by inverting photometric and polarimetric light curves.Because of the ill-conditioning of the problem, we use the Backus-Gilbert method to control the resolution and stability of the recovered solution, and to make quantitative estimates of the maximum accuracy possible. Using this method we confirm that the limb polarization can indeed be recovered, and demonstrate this with simulated data, thus determining the level of observational accuracy required to achieve a given accuracy of reconstruction. This allows us to set out an optimal observational strategy, and to critcally assess the claimed detection of limb polarization in the Algol system.The use of polarization in stars has been proposed as a diagnostic tool in microlensing surveys by Simmons et al. (1995), and we discuss the extension of this work to the case of microlensing of extended sources.

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“…For the eclipse coverage reported in Kemp et al (1983) the minimum width A min of the averaging kernel at the limb is 0.0199 R disc , even in the zero-noise limit.…”

Section: The Algol System: a Worked Examplementioning

confidence: 91%

Section: The Algol System: a Worked Examplementioning

confidence: 99%

See 1 more Smart Citation

Inversion of polarimetric data from eclipsing binaries

Coleman

Gray

Simmons

1998

Astron. Astrophys. Suppl. Ser.

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“…As some polarization phenomena are episodic rather than periodic, time records are essential -and require no more journal space than phases. A good start on the observational side was made with polarization curves of Algol by Kemp et al (1983), but to date there have been no extensions of time-dependent polarization to fainter stars, either by refinement of polarimeters or by use of large telescopes. However Hoffman, Whitney & Nordsieck (2003) made exploratory radiative transfer computations of polarization due to multiple Thomson scattering in illuminated thin and thick circumstellar binary system disks.…”

Section: Polarizationmentioning

confidence: 99%

Close Binary Star Observables: Modeling Innovations 2003-06

Wilson

2006

Proc. IAU

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Abstract. Innovative work on close binary models in 2003-06 improved upon synthesized line spectra, line profiles, and polarimetry; developed new ways of parameter estimation; and increased solution effectiveness and efficiency. Recent applications demonstrate the analytic power of binary system line spectrum models that pre-date the triennium. X-ray binary line profiles and radial velocity curves were refined by solution of the radiative transfer problem with specific inclusion of X-irradiation. Model polarization curves were generated by Monte Carlo experiments with multiple Thomson scattering in thin and thick binary system disks. In the parameter estimation area, independent developments by two groups now allow measurement of ephemerides, apsidal motion, and third body parameters from whole light and velocity curves, to supplement the traditional way of eclipse timings. Although the new route to those parameters is not well known within the ephemeris community, there are accuracy advantages and the number of applications is increasing. Numerical solution experiments on photometric mass ratios have checked two views of their intuitive basis, and show that mass ratios are well determined where star radii and limiting lobe radii are both well determined, which is for semi-detached or over-contact binaries with total-annular eclipses. Solution efficiency and automatic operation is needed for processing of light curves from large surveys, and will also be valuable for preliminary solutions of individually observed binaries. Neural networks have mainly been used for classification, and now a neural network program reliably finds preliminary solutions for W UMa binaries. Archived model light curves and Fourier fitting also are being pursued for classification and for preliminary solutions. Light curves in physical units such as erg · sec −1 · cm −3 now allow direct distance estimation by combining the absolute accuracy of model stellar atmospheres with the astrophysical detail of a physical close binary model, by means of rigorous scaling between surface emission and observable flux. A Temperature-distance (T-d) theorem specifies conditions under which temperatures of both stars and distance can be found from light and velocity curves.

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“…Center-to-limb variation (i.e., the angular variation) of intensity (CLVI) and polarization (CLVP) are necessary to interpret the light curves of a star during exoplanetary transits (e.g., Müller et al 2013; of eclipsing binary systems (e.g., Bass et al 2012;Kemp et al 1983) as well as for interpreting interferometric observations (e.g., Wittkowski et al 2004;Chiavassa et al 2010), microlensing observations (e.g., An et al 2002), and helioseismology (Kuhn et al 1997;Toutain et al 1999;Kuhn et al 2012).…”

Section: Introductionmentioning

confidence: 99%

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

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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.

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Discovery of eclipse polarization in Algol

Cited by 36 publications

References 0 publications

Inversion of polarimetric data from eclipsing binaries

Inversion of polarimetric data from eclipsing binaries

Close Binary Star Observables: Modeling Innovations 2003-06

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

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