Speaker
Description
The degree of linear polarization of sunlight scattered by an asteroid contains valuable information for rapid characterization of the surface properties of Near-Earth objects (NEOs). In the case of atmosphereless bodies the state of linear polarization varies as a function of the phase angle (α) and is described using the so-called Pr parameter.
The properties of the phase-polarization curve of an asteroid are mostly defined by its albedo (pV). Numerous calibrations between polarization and pV have been proposed for main-belt asteroids [1, 2]. However, main-belt asteroids rarely exceed phase angle > 30° while near Earth object can be observed at phase angle as large as 100°. These observations at higher phase angles allow for deeper characterization of the observed object, but there is currently a lack of observations of NEOs in polarimetry to accurately calibrate the albedo-polarization relationship at high phase angles.
In this presentation, I will discuss the current state of NEO observations in polarimetry and how polarimetry could be used to obtain reliable information on the geometric albedo of NEOs. With a proper calibration of the polarization-albedo relation, one could reduce the uncertainty on a newly discovered object by a factor of 10 with one single polarimetric observation obtained at a phase angle > 40°.
[1] A. Cellino, R. Gil-Hutton, A. Dell’Oro, P. Bendjoya, M. Canada-Assandri, M. Di Martino, A new calibration of the albedo– ˜ polarization relation for the asteroids, Journal of Quantitative Spectroscopy and Radiative Transfer 113 (2012) 2552–2560.
[2] A. Cellino, S. Bagnulo, R. Gil-Hutton, P. Tanga, M. Canada-Assandri, E. Tedesco, On the calibration of the relation between ˜ geometric albedo and polarimetric properties for the asteroids, Monthly Notices of the Royal Astronomical Society 451 (2015) 3473–3488.
