| Summary: | 碩士 === 國立中央大學 === 天文研究所 === 106 === Since its discovery, there has been a debate on the origin of the bimodal color distribution of Centaurs in the past few decades. In principle, two theories have been proposed to explain this bimodal color distribution: (1) evolutionary processes resulting in changes of the surface properties of Centaurs, and, (2) compositional differences inherited from the primordial origin of Centaurs. What might be more intriguing is that Centaurs also show a correlation between their orbital inclinations and colors that the blue (B-R≤1.4) and red (B-R>1.4) Centaurs tend to be characterized by high and low inclination distributions, respectively. In this study, we consider two hypotheses to explain the color-inclination relation based on the two major theories of explaining the bimodal
color distribution mentioned above. Namely, we consider: (1) Initially, the scattering Kuiper Belt objects (SKBOs) have no color-inclination relation. When they evolve into Centaurs with perihelion distances within Saturn’s orbit, the gravitational effect of Saturn or Jupiter becomes strong enough to greatly change the inclinations of Centaurs. At the same time, the thermal radiation is also strong enough to trigger cometary activities to produce the blue surface colors; (2) Assuming that the SKBOs also
have color-inclination relation (which is unclear yet), and this relation is statistically preserved when they evolved into Centaurs. We perform numerical simulations on 158 observed Centaurs (58 of them have color information) and 82 observed SKBOs to investigate their dynamical evolution. Our results show that the color-inclination relation of Centaurs is more likely to inherit from SKBOs. We find that our hypothesis (2) is more likely to explain
the color-inclination relation of Centaurs.
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