Near-infrared spectra of high-albedo outer main-belt asteroids

Toshihiro Kasuga, Fumihiko Usui, Mai Shirahata, Daisuke Kuroda, Takafumi Ootsubo, Natsuko Okamura, Sunao Hasegawa

Research output: Contribution to journalArticlepeer-review

Abstract

Most outer main-belt asteroids have low albedos because of their carbonaceouslike bodies. However, infrared satellite surveys have revealed that some asteroids have high albedos, which may suggest the presence of unusual surface minerals for those primitive objects. We present new near-infrared (1.1-2.5 μm) spectra of four outer mainbelt asteroids with albedos ≤ 0.1. The C-complex asteroids (555) Norma and (2542) Calpurnia are featureless and have (50%-60%) amorphous Mg pyroxenes that might explain the high albedos. Asteroids (701) Oriola (which is a C-complex asteroid) and (2670) Chuvashia (a D/T-type or M-type asteroid) show possible broad absorption bands (1.5-2.1 μm). The feature can be reproduced by either Mg-rich amorphous pyroxene (with 50%-60% and 80%-95% Mg, respectively) or orthopyroxene (crystalline silicate), which might be responsible for the high albedos. No absorption features of water ice (near 1.5 and 2.0 μm) are detected in the objects. We discuss the origin of high albedo components in the outer main-belt asteroids and their physical relations to comets.

Original languageEnglish
Article number37
JournalAstronomical Journal
Volume149
Issue number2
DOIs
Publication statusPublished - 2015 Feb 1

Keywords

  • Infrared: planetary systems
  • Minor planets, asteroids: general

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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