Japan Geoscience Union Meeting 2015

Presentation information


Symbol P (Space and Planetary Sciences) » P-CG Complex & General

[P-CG30] New Progress toward the Understanding of Small Solar System Bodies

Tue. May 26, 2015 12:00 PM - 12:45 PM A02 (APA HOTEL&RESORT TOKYO BAY MAKUHARI)

Convener:*Masahiko Arakawa(Graduate School of Science, Kobe University), Taishi Nakamoto(Tokyo Institute of Technology), Sei-ichiro WATANABE(Division of Earth and Planetary Sciences, Graduate School of Science, Nagoya University), Masanao Abe(Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency), MASATERU ISHIGURO(Department of Physics and Astronomy, Seoul National University), Chair:MASATERU ISHIGURO(Department of Physics and Astronomy, Seoul National University)

12:15 PM - 12:30 PM

[PCG30-02] Study of the opposition surge of Asteroid 4 Vesta

*Sunao HASEGAWA1, Seidai MIYASAKA2, Noritaka TOKIMASA2, Akito SOGAME3, Fumi YOSHIDA4, Shinobu OZAKI4, Masanao ABE5, Masateru ISHIGURO6, Daisuke KURODA4 (1.Tokyo Metropolitan Government, 2.Sayo Town Office, 3.Tokai University, 4.National Astronomical Observatory of Japan, 5.Japan Aerospace Exploration Agency, 6.Seoul National University)

Keywords:asteroid, Vesta, opposition effect

We present the results of photometric observations for the asteroid 4 Vesta in the B, Rc, and z' band at the minimum phase angle 0.1 deg has been performed at four small telescopes.
The magnitude reduced to unit distance and phase angle: M_B(1, 1, 0) = 3.85 +- 0.05 mag, M_Rc = 2.71+-0.04 mag, and M_z'(1, 1, 0) = 2.98 +- 0.03 were obtained in this study.
The absolute magnitude under the IAU H-G function are about0.1 mag darker than the magnitude at the phase angle of 0deg based on the Shevchenko function model and the Hapke model.
Porosity of the optically active regolith on Vesta are estimated with the Hapke model yielding rho = 0.4--0.7.
We found that the opposition effect for Vesta is made a contribution to not only the shadow-hiding effect but also the coherent backscattering effect which appears from around 1deg.
The amplitude of the coherent backscatter opposition effect of Vesta increases as the reflectance is brightening.
We suggested that multiple-scattering in optically active scale may contribute to the amplitude of the coherent backscatter opposition effect, B_C0, from the comparison with those for the other solar system bodies.