Results of polarimetric and photometric observations of NEAs 162082 (1998 HL1), 163373 (2002 PZ39), 52768 (1982 OR2), and 159402 (1999 AP10)

Abstract

ABSTRACT We present the results of polarimetric and photometric observations of four near-Earth asteroids (NEAs) 162082 (1998 HL1), 163373 (2002 PZ39), 52768 (1982 OR2), and 159402 (1999 AP10). The observations were carried out at the 2.6-m and 1.25-m telescopes of the Crimean Astrophysical Observatory, the 2.0-m telescope of the Peak Terskol Observatory, and the 6-m telescope of the Special Astrophysical Observatory during the period of 2019–2020. The phase angles covered in the observations were 3°–27°, 69°–109°, 70°–76°, and 32°–72° for NEAs 162082, 163373, 52768, and 159402, respectively. We estimated the main polarimetric parameters of the phase curves for each asteroid. The geometrical albedo for NEAs 162082, 163373, and 159402 were found to be 0.348 ± 0.050, 0.192 ± 0.050, and 0.124 ± 0.020, respectively. The diameters for asteroids 162082, 163373, 52768, and 159402 were determined as 0.37 ± 0.05, 0.50 ± 0.05, 2.61 ± 0.20, and 2.27 ± 0.20 km, respectively. The polarization data for NEA 52768 and 159402 are similar. Their orbital elements a, e, q, and periods for these asteroids also showed close similarities, indicating a potential common parent body in the past. We found deviation of the polarization of NEAs 163373, 52768, and 159402 from the synthetic phase dependences of the polarization of the main taxonomic С, S, and E classes. To explain this, the modified Sh-matrix method was used. The computer simulation has shown that different values of the maximum of positive polarization of asteroids can be explained by different content of highly absorbing carbon matter.