Polarimetric and Photometric Observations of NEAs; (422699) 2000 PD3 and (3200) Phaethon with the 1.6m Pirka Telescope

TL;DR

This study presents polarimetric and photometric observations of two NEAs, revealing their surface properties, size, and heterogeneity, with implications for understanding asteroid composition and surface variation.

Contribution

First polarimetric and photometric analysis of NEAs 2000 PD3 and Phaethon using the 1.6m Pirka telescope, providing new insights into their surface characteristics.

Findings

2000 PD3 has a geometric albedo of 0.22 ± 0.06.

2000 PD3's diameter is approximately 0.69 km.

Phaethon's polarimetric data shows surface heterogeneity.

Abstract

We report on optical polarimetric observations of two Apollo type near-Earth asteroids, (422699) 2000 PD3 and (3200) Phaethon, and BVRI photometric observations of 2000 PD3 using the 1.6m Pirka telescope in 2017. We derived the geometric albedo of pv = 0.22 +- 0.06 and the color indices (B-V = 0.282 +- 0.072, V-R = 0.198 +- 0.035 and V-I = 0.203 +- 0.022) for 2000 PD3 which are consistent with those of S-type asteroids (including Q-types). The effective diameter of 2000 PD3 was derived as 0.69 +- 0.15 km using our derived geometric albedo. We found that our polarimetric data of Phaethon in 2017 is deviated from the polarimetric profile taken at different epoch of 2016 using the identical instrument setting (Ito et al., 2018). This result suggests that Phaethon would have a regional heterogeneity in grain size and/or albedo on its surface.