LAUSR

Abstract The results of polarimetric observations of the asteroid (599) Luisa carried out on the same type of aperture photoelectric polarimeters of the 2.6-m reflector of the Crimean Astrophysical Observatory and the Zeiss 2000 telescope of the Terskol Peak Observatory in November 2018 and February 2019 are presented. Based on these and available literature data, the parameters of the composite phase dependence of the polarization degree are obtained: P min = –1.68%, α min = 14.7°, α inv = 29.2°, which indicates that the asteroid belongs to the class of “Barbarians”. The absolute value of the negative polarization degree of the asteroid in the range of the BVRI photometric bands is shown to increase with wavelength, which contradicts the data of Bagnulo et al. (2015) but is consistent with the spectral polarization behavior of other silicate S-, K-, and L-type asteroids, including well-known Barbarians. Possible causes of differences in the spectral behavior of the polarization degree of this asteroid are discussed. The properties of the asteroid (599) Luisa are unique in that it combines spectral properties of silicate L-type asteroids and polarization properties ( P min and the slope h ) of low-albedo C and Ch asteroids.