Physical characterization of NEA Large Super-Fast Rotator (436724) 2011 UW158

摘要

Asteroids of size larger than 0.15 km generally do not have periods smaller than 2.2 hours, a limit known as cohesionless spin barrier. This barrier can be explained by the cohesionless rubble-pile structure model. There are few exceptions to this "rule", called LSFRs (Large Super-Fast Rotators), as (455213) 2001 OE84, (335433) 2005 UW163 and 2011 XA3. The near-Earth asteroid (436724) 2011 UW158 was followed by an international team of optical and radar observers in 2015 during the flyby with Earth. It was discovered that this NEA is a new candidate LSFR. With the collected lightcurves from optical observations we are able to obtain the amplitude-phase relationship, sideral rotation period (PS = 0.610752 +/- 0.000001 h), a unique spin axis solution with ecliptic coordinates lambda = 290 degrees +/- 3 degrees, beta = 39 degrees +/- 2 degrees and the asteroid 3D model. This model is in qualitative agreement with the results from radar observations.