title: Spin rate of asteroid (54509) 2000 PH5 increasing due to the YORP effect.
abstract: Radar and optical observations reveal that the continuous increase in the spin rate of near-Earth asteroid (54509) 2000 PH5 can be attributed to the Yarkovsky-O'Keefe-Radzievskii-Paddack (YORP) effect, a torque due to sunlight. The change in spin rate is in reasonable agreement with theoretical predictions for the YORP acceleration of a body with the radar-determined size, shape, and spin state of 2000 PH5. The detection of asteroid spin-up supports the YORP effect as an explanation for the anomalous distribution of spin rates for asteroids under 10 kilometers in diameter and as a binary formation mechanism.
authors.affiliation: Department of Astronomy, Cornell University, Ithaca, NY 14853-6801, USA. ptaylor@astro.cornell.edu
authors.forename: Patrick A
authors.initials: PA
authors.lastname: Taylor
authors.forename: Jean-Luc
authors.initials: JL
authors.lastname: Margot
authors.forename: David
authors.initials: D
authors.lastname: Vokrouhlicky
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Scheeres
authors.forename: Petr
authors.initials: P
authors.lastname: Pravec
authors.forename: Stephen C
authors.initials: SC
authors.lastname: Lowry
authors.forename: Alan
authors.initials: A
authors.lastname: Fitzsimmons
authors.forename: Michael C
authors.initials: MC
authors.lastname: Nolan
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Ostro
authors.forename: Lance A M
authors.initials: LA
authors.lastname: Benner
authors.forename: Jon D
authors.initials: JD
authors.lastname: Giorgini
authors.forename: Christopher
authors.initials: C
authors.lastname: Magri