Fig. Asteroid Discovery and Light Curve Extraction Using the Hough Transform: A Rotation Period Study for Subkilometer Main-belt Asteroids
Dr. Chan-Kao Chang: Using the Hough transform, a line detecting algorithm, more than 3000 new asteroids were discovered from a high-cadence observation of the Pan-STARRS 1 (PS1). This observation was originally planned to collected asteroid lightcurves for rotation period measurement and conducted in October 2016. Because of the high cadence observation (i.e., images were continuously taken one after one for the entire night), the detections of an asteroid would line up as a straight line and, therefore, these line-up detections can be used to identify asteroids.
With the collected lightcurves of these new asteroids, 122 reliable rotation periods were obtained and 13 of them are super-fast rotators (i.e., asteroids in the size range of rubble-pile structure, a weak aggregate of large and small components held together by gravity rather than material strength, have rotation periods < 2 hr). This kind of asteroids is not expected because they suppose to be destroyed due to the exceedingly centrifugal force introduced by a rotation period of < 2hr. How these super-fast rotators can survive is still a mystery. (Lo, Kai-Jie, et al. (including Chan-Kao Chang; Wing-Huen Ip; Wen-Ping Chen) 2020, AJ, 159, 25L)