Origins and evolution of Interplanetary Dust Particles

Abstract

This dissertation investigates the origin and evolution of Interplanetary Dust Particle (IDP) cloud complex. It is sure that there should be recent or continuous origins for the IDP, but previous estimations about fractional contribution of given source populations (asteroids, comet, etc.) to the IDPs vary according to methodology. We accepted that those discrepancy means some important factors are not considered in the previous models, and tried to investigate this problem with additional consideration. We observed the optical zodiacal light brightness around anti-solar direction, and measured the mean albedo of IDPs as 0.06 +- 0.01. We compared the measured albedo and spectral gradient of the zodiacal light with those of potential parent bodies in the solar system. From Bayesian inference, we could find that > 90 % of the IDPs are originated from comets (or their spectral analogs, D-type asteroids).

Next, we investigated the orbital evolution of cometary dust particles, with additional factors of non-compact dust shape and mutual collisions among IDPs, both were not incorporated with planetary gravity and solar radiation previously. We explained the dust size frequency distribution (SFD) measured around the Earth's orbit from the SFD measured at the comae of comets (1P/Halley, 67P/Churyumov-Gerasimenko, 73P/Schwassmann-Wachmann 3, and 81P/Wild 2).

Other new discoveries include followings: The spectrum of IDPs are similar with chondritic porous micrometeorites discovered at the Earth's stratosphere

There will be no mutual collisions between IDPs if they are dominated by cometary particles

Dust particles from Jupiter-Family Comets are usully kicked out to the outer solar system through close encounters with Jupiter, if it is larger than 100 micron

Total mass supply rate to the IDPs cloud complex is about 30-50 tons/s.