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تسجيل مستخدم جديدThe binary asteroid 22 Kalliope: Linus orbit determination on the basis of speckle interferometric observations
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In this paper we present the orbital elements of Linus satellite of 22 Kalliope asteroid. Orbital element determination is based on the speckle interferometry data obtained with the 6-meter BTA telescope operated by SAO RAS. We processed 9 accurate positions of Linus orbiting around the main component of 22 Kalliope between 10 and 16 December, 2011. In order to determine the orbital elements of the Linus we have applied the direct geometric method. The formal errors are about 5 mas. This accuracy makes it possible to study the variations of the Linus orbital elements influenced by different perturbations over the course of time. Estimates of six classical orbital elements, such as the semi-major axis of the Linus orbit a = 1109 +- 6 km, eccentricity e = 0.016 +- 0.004, inclination i = 101{deg} +- 1{deg} to the ecliptic plane and others, are presented in this work.
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In 2007, the M-type binary asteroid 22 Kalliope reached one of its annual equinoxes. As a consequence, the orbit plane of its small moon, Linus, was aligned closely to the Suns line of sight, giving rise to a mutual eclipse season. A dedicated intern
ational campaign of photometric observations, based on amateur-professional collaboration, was organized and coordinated by the IMCCE in order to catch several of these events. The set of the compiled observations is released in this work. We developed a relevant model of these events, including a topographic shape model of Kalliope refined in the present work, the orbit solution of Linus as well as the photometric effect of the shadow of one component falling on the other. By fitting this model to the only two full recorded events, we derived a new estimation of the equivalent diameter of Kalliope of 166.2+/-2.8km, 8% smaller than its IRAS diameter. As to the diameter of Linus, considered as purely spherical, it is estimated to 28+/-2 km. This substantial shortening of Kalliope gives a bulk density of 3.35+/-0.33g/cm3, significantly higher than past determinations but more consistent with its taxonomic type. Some constraints can be inferred on the composition.
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