Shape And Size Of (90) Antiope Derived From An Exceptional Stellar Occultation On July 19 2011
Résumé
On July 19 2011 UT, the (90) Antiope double system occulted a 6.7-mag star (LQ Aquarii) with a path predicted to pass over much of northern California. The shape and separation of the components were predicted based on Descamps et al. (2009) model, plus additional Keck AO observations (Merline, Neyman, Tamblyn, Owen) collected on July 13 and 15, 2011 UT. Through a large collaboration in cooperation with the IOTA we organized a campaign of bservations involving 42 observers and 92 stations spread along the path of the occultation in northern California, Nevada, and Idaho to sample both components. The stellar occultation was successfully recorded by 41 stations with a maximum duration of ~33 s. A preliminary analysis of the data that are being processed and analyzed shows that an improved shape model of both components could be derived based on this campaign. We will present the final analysis of this campaign, which allow us to derive a more accurate period and separation for the binary system and also an improved density. We will discuss the origin of (90) Antiope based on the detection of a large concavity, possibly interpreted as a large impact crater on one of the components, already suggested by Descamps et al (2009). This research is partially supported by the NSF grant AAG-0807468, NASA grant NNX11AD62G and CNRS. We thank the many other members of IOTA who took part in this campaign.