Physical Characterisation of Near-Earth Asteroid (68346) 2001 KZ66 from Optical and Radar Observations

The (YORP) effect is a torque due to incident solar radiation and the subsequent recoil effect from the anisotropic emission of thermal photons on small bodies in the Solar System. The YORP effect can: change rotation rates and spin-axis orientations over relatively short time-scales; modify orbits (semi-major axis drift from the related Yarkovsky effect depends on the obliquity) and thus plays a key role in replenishment of the near-Earth asteroid (NEA) population; cause regolith mobility and resurfacing as spin rates increase, form binary asteroids through equatorial mass loss and re-aggregation and cause catastrophic disruption. When we began our systematic monitoring programme in 2010, the YORP effect had only been detected for three asteroids with a marginal detection following in 2012. That has now increased to six. We are conducting an observational programme of a sample of NEAs to detect YORP-induced rotational accelerations. For this, we use optical photometry from a range of small to medium size telescopes. This is supplemented by thermal-IR observations and thermophysical modelling to ascertain expected YORP strengths for comparison with observations. For selected objects, we use radar data to determine shape models. We will present our latest results for one of our sample NEAs, (68346) 2001 KZ66.