PI: Henry Hsieh, PSI, email@example.com
Address: n/a, 1700 East Fort Lowell Rd, Suite 106, Tucson, AZ 85719 United States
CoI: Audrey Thirouin, Lowell Observatory
Title: The (Slow?) Rotation Rate of Active Asteroid 311P/PANSTARRS
Abstract: The comet-like mass loss observed in 2013 for active asteroid 311P/PANSTARRS, has been hypothesized to be due to rotational disruption. Under this hypothesis, the object was believed to have a rotation rate close to the spin disruption limit (e.g., $sim$2-3~hr; where gravity is no longer able to exert enough centripetal force to hold a strengthless rubble pile together for a given rotation rate), and was perhaps pushed beyond that limit by radiative spin-up due to the YORP effect. Given sufficient angular momentum loss due to the disruption event, 311P's rotation rate may have slowed such that the object is no longer disrupting, but it should still be characterized by anomalously rapid rotation. A previous attempt using SOAR to measure this object's rotation rate suggested that the object is far from a fast rotator though, with a period of $sim$6~hr, putting the rotational disruption hypothesis in serious doubt. Technical problems prevented us from obtaining a full lightcurve, however, and so we request additional time on SOAR to confirm this slow rotation rate. If slow rotation is confirmed for 311P, it would seriously challenge rotational disruption as a plausible mechanism for 311P's activity and demand renewed efforts to understand the cause of activity in this apparently still mysterious object.
Program Type: Standard/Solar System
Run 1 (2016A): SOAR/SOI -- 1n on Jul 26 2016
National Optical Astronomy Observatory, 950 North Cherry Avenue, P.O. Box 26732, Tucson, Arizona 85726, Phone: (520) 318-8000, Fax: (520) 318-8360