Istituto di Scienza e Tecnologie dell'Informazione     
Rossi A., Marzari F., Scheeres D. J. Influence of the YORP effect on the spin rate distribution of the NEO population. In: SAIt 2009 - 53 Congresso della Societa' Astronomica Italiana (Pisa, Italia, 4-8 maggio 2009).
Two major mechanisms are suspected to alter the rotation rates and states of Near Earth Objects (NEO) once they get into planet crossing orbits: close encoun ters with the planets and the YORP effect. The YORP effect is due to the reflection and reemission of light by an irregularly shaped asteroid and leads to a net thermal torque acting on that body. The overall change of NEO spin rate due to these two effects is evaluated by using a Monte Carlo model. The steady state cumulative distribution of NEO spin rates obtained from our simulation nicely reproduces the observed one, once our results are biased to match the diameter distribution of the sample of objects included in the observational database. The excellent agreement strongly suggests that YORP is responsible for the concentration of spin at low rotation rates. In fact , in the absence of YORP the steady state population significantly deviates from the observed one. The spin evolution due to YORP is also so rapid for NEOs that the initial rotation rate distribution of any source population is quickly relaxed to that of the observed population. This has profound consequences for the study of NEO origin since we cannot trace the sources of NEOs from their rotation rate only.
Subject Asteroids
Rotational dynamics
YORP effect
Asteroid dynamics
J.2 Physical Sciences and Engineering
70F15 Celestial mechanics

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