論文 - 佐藤　祐介

Photometric observations of a very young family-member asteroid (832) Karin

F Yoshida, B Dermawan, T Ito, Y Sawabe, M Haji, R Saito, M Hirai, T Nakamura, Y Sato, T Yanagisawa, R Malhotra

PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN ( OXFORD UNIV PRESS )  56 ( 6 ) 1105 - 1113   2004年12月  [査読有り]

　概要を見る

The asteroid (832) Karin is the largest member of the Karin family. which is thought to have been formed by a catastrophic collision 5.8 Myr ago. We performed photometric observations of Karin from 2003 July to September. and we report here on its lightcurve and colors in several visible bands. The rotational synodic period of Karin was determined to be 18.35 +/- 0.02 hr. Its absolute magnitude (H) and the slope parameter (G) of the Solar phase curve were 11.49 +/- 0.02 and 0.19 +/- 0.04, respectively. Based on our color observations. we confirmed that Karin is an S-type asteroid. In addition, we found that there is likely to be a color variation over the Surface of Karin. We infer that the color variation is due to the difference between the fresh surface. excavated by the family-forming disruption, and the weathered surface, exposed to space radiation and particle bombardment over a long period.

DOI

First result of June Boötid meteor spectrum

Kasuga, T, Watanabe, J, Ebizuka, N, Sugaya, T, Sato, Y

Astronomy and Astrophysics ( E D P SCIENCES )  424 ( 3 ) L35 - L38   2004年09月  [査読有り]

　概要を見る

This paper shows the first observational result of a spectrum of a June Bootid meteor obtained by the High-Definition TV observational system. The very faint spectrum appeared at 15(h)59(m)29.69(s) on 2004 June 23 UT, which was about 5th magnitude. Wavelengths between 360-620 nm were observed, and the strong emissions of neutral atoms as MgI, FeI and NaI were identified. Emissions of single ionized atoms were not observed. The abundances of metallic atoms, their excitation temperature were obtained under the Local Thermal Equilibrium (LTE) conditions. The results, Fe/Mg=0.15 and Na/M=0.00027 suggest the possibility that the abundances of June Bootid meteor are extremely different from the solar system abundances. The excitation temperature value, 3867+/-13 K is low in agreement with their slow moving velocity.

DOI

CCD photometry of the MUSES-C mission target: Asteroid (25143) 1998 SF36

B Dermawan, T Nakamura, H Fukushima, H Sato, F Yoshida, Y Sato

PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN ( OXFORD UNIV PRESS )  54 ( 4 ) 635 - 640   2002年08月  [査読有り]

　概要を見る

Near-Earth asteroid (25143) 1998 SF36 is now planned as the target for the Japanese MUSES-C sample return mission. We conducted extensive photometric observations at NAO-Mitaka from 2001 February 15 until March 19 to obtain its physical properties, such as asteroid's colors, rotation period, phase curve, and light curves. The colors of this asteroid were found to be S-type and in agreement with the spectroscopic result by Binzel et al. (2001, Meteor. Planet. Sci., 36, 1167). From the phase curve of this object, the visual absolute magnitude is obtained to be 18.61 +/- 0.18; we suggest that the albedo may be higher than that for typical S-type asteroids, after applying a known empirical relation between phase curve slope and geometric albedo. We also reveal that the synodic rotation period of this asteroid is 12.13 +/- 0.02hr and the peak-to-peak light variation amplitude at zero phase angle has been shown to be similar to 0.49 mag, which implies the ratio of the longest and intermediate ellipsoidal axes for the asteroid greater than or similar to 1.6.

DOI