Experimental Phase Function and Degree of Linear Polarization Curves of Millimeter-sized Cosmic Dust Analogs

Muñoz, Olga; Moreno, F.; Gómez-Martín, Juan Carlos; Vargas-Martı́n, Fernando; Guirado, D.; Ramos, José Luis Martínez; Bustamante, I.; Bertini, Ivano; Frattin, E.; Markannen, J.; Tubiana, C.; Fulle, M.; Güttler, C.; Sierks, H.; Rotundi, A.; Corte, Vincenzo Della; Ivanovski, S.; Захаров, Владимир; Bockelée‐Morvan, Dominique; Blum, Jürgen; Merouane, S.; Levasseur-Regourd, A. C.; Kolokolova, L.; Jardiel, Teresa; Caballero, A. C.

doi:10.3847/1538-4365/ab6851

Cited by 26 publications

(22 citation statements)

References 73 publications

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“…λ) the phase function shows significant differences at the side-and back-scattering regions. Figure 5 also displays the experimental phase function of a millimeter-sized (r = 1.6 mm) quartzite pebble (Muñoz et al 2020). The refractive index of quartzite (m = 1.58+i2 10 −5 ) is similar to that of the forsterite samples.…”

Section: Phase Functionsmentioning

confidence: 89%

“…To our knowledge, these measurements constitute the first experimental evidence for a strong dependence of the position and magnitude of the NPB on the grain size range. Previous DLP curves for compact millimeter-sized particles obtained at 514 nm also show shallow NPBs, with the position of their inversion angles dependent on the particle composition (Muñoz et al 2020). For such large grains, micron-sized surface roughness and/or internal structures are likely responsible for the measured negative branch.…”

Section: Degree Of Linear Polarizationmentioning

confidence: 91%

“…The maximum DLP max (20.3%) is obtained for the sample consisting of particles with sizes in the Rayleigh-resonance transition regime, i.e., sample XS. As the size of the particles increases into the resonance regime, the value of DLP max decreases from 12.9% for sample S to 9.4% for sample L. The tendency of a decrease DLP max with the size parameter is reversed as we approach the geometric optics regime, obtaining a value of 15.9% for sample XL and increasing up to 20.3% for the millimeter-sized quartzite pebble (Muñoz et al 2020). As the size of the scattering particles increases into the geometric optics regime, the position of DLP max shifts toward larger phase angles (see also Liu et al 2015;Escobar-Cerezo et al 2018).…”

Section: Degree Of Linear Polarizationmentioning

confidence: 92%

“…For instance, the simultaneous analysis of the observed phase function and DLP curves places emphasis on the limitations of the spherical particle model for characterizing real dust particles in debris disks (Graham et al 2007;Arriaga et al 2020;Engler et al 2020). Further, the simultaneous analysis of the OSIRIS data set combined with ground-based DLP observations of comet 67P/ Churyumov-Gerasimenko has exposed challenging contradictions in the retrieved physical properties of cometary dust (Hadamcik et al 2016;Markkanen et al 2018;Moreno et al 2018;Muñoz et al 2020). Understanding fundamental aspects of the interaction of electromagnetic radiation and dust particles is key to a breakthrough in the interpretation of photopolarimetric observations.…”

Section: Introductionmentioning

confidence: 99%

“…Extrapolated phase functions ( q F 11 ext ( )) curves at 514 nm for forsterite XL (triangle), L (squares), M (diamonds), S (circles), and XS (upside-down triangle). Black stars correspond to the experimental F 11 (θ) curve of a quartzite pebble (r = 1.6 mm) afterMuñoz et al (2020). The experimental phase function for quartzite is arbitrarily normalized to unity at 150°.…”

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confidence: 99%

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Retrieving Dust Grain Sizes from Photopolarimetry: An Experimental Approach

Muñoz

Frattin

Jardiel

et al. 2021

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We present the experimental phase function, degree of linear polarization (DLP), and linear depolarization (δ L ) curves of a set of forsterite samples representative of low-absorbing cosmic dust particles. The samples are prepared using state-of-the-art size-segregating techniques to obtain narrow size distributions spanning a broad range of the scattering size parameter domain. We conclude that the behavior of the phase function at the side-and back-scattering regions provides information on the size regime, the position and magnitude of the maximum of the DLP curve are strongly dependent on particle size, the negative polarization branch is mainly produced by particles with size parameters in the ∼6 to ∼20 range, and the δ L is strongly dependent on particle size at all measured phase angles except for the exact backward direction. From a direct comparison of the experimental data with computations for spherical particles, it becomes clear that the use of the spherical model for simulating the phase function and DLP curves of irregular dust produces dramatic errors in the retrieved composition and size of the scattering particles: The experimental phase functions are reproduced by assuming unrealistically high values of the imaginary part of the refractive index. The spherical model does not reproduce the bell-shaped DLP curve of dust particles with sizes in the resonance and/or geometric optics size domain. Thus, the use of the Mie model for analyzing polarimetric observations might prevent locating dust particles with sizes of the order of or larger than the wavelength of the incident light.

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Section: Phase Functionsmentioning

confidence: 89%

Section: Degree Of Linear Polarizationmentioning

confidence: 91%