Showing papers by "E. C. Beshore published in 2008"
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Charles University in Prague1, University of Helsinki2, Jet Propulsion Laboratory3, University of Arizona4, University of Kharkiv5, Korea Astronomy and Space Science Institute6, University of Colorado Colorado Springs7, Academy of Sciences of Uzbekistan8, Keldysh Institute of Applied Mathematics9, Adam Mickiewicz University in Poznań10, University of Tokyo11
TL;DR: In this paper, the authors used the lightcurve inversion method to model the shape and spin state of Apollo and obtained a longer time line of the rotation period and its linear change in time.
Abstract: Aims. Asteroid (1862) Apollo is one of two asteroids in which the YORP effect was detected. We carried out new photometric observations of Apollo in April 2007 to enlarge the time line and to derive a more precise shape and spin state model. We also observed another YORP-candidate, asteroid (25143) Itokawa, in December 2006 and January 2007 to obtain a longer time line. An estimation of the YORP strength on Itokawa based on its precise shape model from the Hayabusa mission predicted the deceleration to be already observable during the 2007 apparition. Methods. We used the lightcurve inversion method to model the shape and spin state of Apollo. For Itokawa, the shape and pole direction are known to a high degree of accuracy from the Hayabusa mission, so we used a modified version of lightcurve inversion with only two free parameters – the rotation period and its linear change in time. Results. The new model of Apollo confirms earlier results. The observed acceleration of Apollo’s rotation rate is (5.5 ± 1.2) × 10 −8 rad d −2 , which is in agreement with the theoretically predicted value. For Itokawa, the theoretical YORP value is sensitive to the resolution of the shape model and lies in the range from − 2t o−3 × 10 −7 rad d −2 . This is inconsistent with results of lightcurve inversion that place an upper limit to the change of Itokawa’s rotation rate ∼1.5 × 10 −7 rad d −2 .
59 citations
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TL;DR: In this paper, the authors present the first observational measurement of the orbit and size distribution of small Solar System objects whose orbits are wholly interior to the Earth's (Inner Earth Objects, IEOs, with aphelion H distribution).
24 citations