| Summary: | 碩士 === 國立中央大學 === 天文研究所 === 97 === Asteroids in Cometary Orbits (ACOs) belong to an unusual type of asteroids with large orbital eccentricity. The planet-crossing orbit will decrease the stability of their current orbit at a mean timescale of 4.5×107 years (Levison & Duncan, 1997). We can regard the ACOs as a transient state of the small body evolution, therefore it is an interesting topic to discuss the origin and evolution of ACOs.
In this work, I used the Lulin One-meter Telescope (LOT) to do the optical observation to get the color and light-curve of ACOs. To trace their origin, we compared our observation data to other asteroid groups which types are already known like the cometary nuclei, Centaur objects, and Trojan asteroids to find any possible relation. In addition, I also looked backward into the history of ACOs via orbital simulation with the Mercury package.
I got the color information of 41 ACOs, and rotation curves of 4 ACOs, and find a new quasi-active comet in last year. Limited by the aperture of LOT, the photometry accuracy is not enough for me. The preliminary result shows there has no significant trend of color distribution. We need more observations and ACO data to confirm whether they really have some possible relation between physical parameters and color. The result of orbital simulation shows that the current orbital parameters are not a good criterion to select the ACOs. Only 40% of my targets have clearly changed their orbital parameters in the past 100,000 years.
I plan to use the Pan-STARRS database to improve my current research in the future. The Moving Object Processing System (MOPS) can provide an extremely large photometry and astrometry data for analyzing the detail of ACOs.
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