ROTATIONALLY TIME-RESOLVED VIS-SPECTROSCOPY OF (3200) PHAETHON Daisuke Kinoshita Institute of Astronomy, National Central University, 300 Jhongda Rd., Chungli, Taoyuan, 320, Taiwan Katsuhito Ohtsuka Tokyo Meteor Network, Daisawa 1–27–5, Setagaya, Tokyo, 155–0032, Japan
[email protected] Takashi Ito Center for Computational Astrophysics, National Astronomical Observatory of Japan, Osawa 2–21–1, Mitaka, Tokyo, 181–8588, Japan Seidai Miyasaka Tokyo Metropolitan Government, Nishi-Shinjuku 2–8–1, Shinjuku, Tokyo, 163–8001, Japan Tomoki Nakamura Department of Earth science, Graduate School of Science, Tohoku University, 6–3, Aramaki Aza Aoba, Aoba, Sendai, Miyagi 980–8578, Japan arXiv:1703.00296v1 [astro-ph.EP] 1 Mar 2017 Shinsuke Abe Department of Aerospace Engineering, Nihon University, 7–24–1, Narashinodai, Funabashi, Chiba 274–8501, Japan Wen-Ping Chen 1Last updated: March 2, 2017 –2– Institute of Astronomy, National Central University, 300 Jhongda Rd., Chungli, Taoyuan, 320, Taiwan Received ; accepted –3– ABSTRACT Apollo-type near-Earth asteroid (3200) Phaethon, classified at the B/F-type taxonomy, probably the main mass of the Phaethon-Geminid stream complex (PGC), can be the most metamorphic C-complex asteroid in our solar system, since it is heated up to ∼ 1000 K by the solar radiation heating around its perihelion passages. Hence, the surface material of the asteroid may be easily decomposed in near-sun environment. Phaethon’s spectrum exhibits extremely blue-slope in the VIS-NIR region (so-called Phaethon Blue). Another candidate large member of the PGC, Apollo asteroid (155140) 2005 UD, shows a B/F- type color, however with a C-type-like red color over its ∼ 1/4 rotational part, which implies an exposition of less metamorphosed primordial internal structure of the PGC precursor by a splitting or breakup event long ago.