A Quick Test on Rotation Period Clustering for the Small Members of the Koronis Family

Rotation period clustering in prograde/retrograde rotators might indicate the preliminary indication of the Slivan state in the Koronis family as a result of the YORP effect. We follow the general scenario of dispersion in semimajor axis of the asteroid family members to separate prograde and retrograde rotators in the Koronis family. From the available rotation periods obtained from PTF/iPTF, we can not found the rotation period clustering of objects with H grater than 12 mag in the Koronis family. This could be the result of the intermittent collisional process of small asteroids (D less than ~20 km) which leads to astray Yarkovsky drifting. Measurement of the pole orientations of our sample will verify our preliminary result and validate our method.