Seminar: CPS Seminar
date: 2016 January 13 (Wed) 15:30-
room: CPS Conference Room
speaker: Fumihiko Usui (Research Associate, Department of Astronomy, Graduate School of Science, The University of Tokyo )
organizer: Yoshiyuki Hayashi
title: Infrared Asteroid Survey with AKARI
abstract: The physical properties of asteroids are fundamental to understanding the formation process of our solar system. Size and albedo are the basic physical properties of asteroids. The most effective method for measuring size and albedo is to find from radiometry. Using radiometric measurements, a large number of objects can be observed in a short period of time, thus providing uniform data for large populations of asteroids. Infrared measurements using space-borne telescopes are suitable for this method.
We performed an asteroid survey with the Japanese infrared satellite AKARI, which was launched on February 2006. The infrared signals from asteroids were extracted and the Asteroid Catalog Using AKARI (AcuA) was constructed, which contains the size and albedo data for 5120 asteroids. The AKARI asteroid catalog, which was constructed based on 16 months of the all-sky survey data, is a 100% complete data set of all asteroids larger than 20 km, corresponding to more than 98% of the total mass of all asteroids in the main belt region. This unbiased homogeneous data set provides an important information for statistical analysis of asteroid populations and characterizing the physical properties of each asteroid.
AKARI had also the capability of performing deep imaging and/or spectroscopy in targeted observation mode. Low resolution spectroscopic observations were performed using the near-infrared channel of the Infrared Camera (IRC) at wavelengths of 2-5 micron, which provide valuable data in the next few decades because of its high sensitivity and unique wavelength coverage. As a part of the targeted spectroscopic observations, 70 asteroids were observed. From these observations, wide variety of the absorption feature associated with hydrated minerals on C-type asteroids has been clearly obtained.
In this talk, we present the detail of the AKARI mid-infrared asteroid survey, and also show the results of near-infrared spectroscopic observations of the selected asteroids.
keywords: AKARI, Infrared astronomy, asteroids