Quadrant polarization parameters for the scattered light of circumstellar disks

Context. Modern imaging polarimetry provides spatially resolved observations for many circumstellar disks and quantitative results the measured polarization which can be used comparisons with model calculations systematic studies of disk samples. Aims. This paper introduces quadrant parameters Q 000 , 090 180 270 Stokes U 045 135 225 315 describes their use polarimetric characterization dust in debris disks. Methods. We define xxx illustrate properties measurements around HR 4796A from Milli et al. (2019, A&A, 626, A54).. calculate simple models rotationally symmetric optically thin provide diagnostic diagrams determination scattering asymmetry dust. method is tested data compared detailed phase curve extractions literature. Results. The are ideal a well-defined azimuthal dependence polarized light because they based on “natural” pattern produced by scattering. For normalized to integrated ∕ ϕ or ratios like depend only inclination i function f ( θ ) dust, do not radial distribution emissivity. Because usually well known observations, we derive shape angle range sampled quadrants. finding also applies vertical extensions as observed Diagnostic calculated all several parameter g Henyey-Greenstein ). apply these measurement 4796A, find that one does reproduce well. better solution three-parameter 1 2 w ), but it noted well-observed complex cannot described full detail parameters. Conclusions. very useful quantifying illuminated central star. They test deviations geometry axisymmetry constrain without fitting images. easy therefore suited