Asteroid polarimetry in the Gaia era

Abstract

Asteroid polarimetry has been thriving in recent years. This has been the consequence of observing programs carried out by different teams, who have used in many cases small-size telescopes. Systematic activities aimed at obtaining better phase-polarisation curves have produced improved calibrations of some important relations between polarimetric parameters and physical properties. These include primarily the geometric albedo, as well as some features characterising the regolith particles on the surfaces of different asteroids. In addition, new interesting classes of objects exhibiting anomalous polarimetric properties have been discovered. Ground-based polarimetric data nicely complement the results of asteroid spectroscopy. This is particularly important in the current situation, in which a very large amount of new asteroid reflectance spectra has been published in the third release of Gaia data. Even a relatively small sample of asteroids whose polarimetric behaviour is well determined, can be very useful in a comprehensive analysis and interpretation of Gaia spectroscopic and photometric data, with an overall improvement of the scientific interpretation and exploitation of the collected data.