Phase Dependent Variation in the Reflectivity of Kuiper Belt Object 2002 MS4




Peng, Jinghan

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The Kuiper Belt Objects (KBOs) are the newly-discovered solar system objects located beyond the orbit of Neptune. Observations and study of the KBOs are vital to understanding the origin and evolution of our solar system. The KBO 2002MS4 is a large KBO, dwarf planet, and is my research focus. In order to study the phys- ical properties, I used archival observations from the 3.6 m Canada-France Hawaii Telescope on Maunakea in Hawaii, combined with observations from the New Hori- zon spacecraft, to derive 2002 MS ’s rotational period and phase function. I find 4 that this object does not have an obvious opposition surge and that the phase coeffi- cient / geometric albedo correlation of 2002 MS4 is inconsistent with the correlation expected for C-type asteroids, casting doubt on the concept that C-type asteroids originated in the Kuiper belt. Using occultation observations, obtained at Anarchist Mountain Observatory, I determine an estimate of the minimum size of 2002 MS4 of D > 820±20km, consistent with other occultation measurements of D = 800±20km. This size is smaller than that derived from thermal observations where 2002 MS4 is modeled as a zero-spin body. The reasonable resolution of this result is that 2002 MS4 has a thermal inertia that must be included in its thermal model, which is left for future work.