Size Dependence of Dust Distribution around the Earth Orbit

Abstract

In the Solar System, interplanetary dust particles (IDPs) originating mainly from asteroid collisions and cometary activities drift to the Earth orbit due to the Poynting-Robertson drag. We analyzed the thermal emission from IDPs that was observed by the first Japanese infrared astronomical satellite, AKARI.The observed surface brightness in the trailing direction of the Earth orbit is 3.7% greater than that in the leading direction in the 9 µm band and 3.0% in the 18 µm band. In order to reveal dust properties causing the leading-trailing surface brightness asymmetry, we numerically integrated orbits of the Sun, the Earth, and a dust particle as a restricted three-body problem including radiation from the Sun. The initial orbits of particles are determined according to the orbits of main-belt asteroids or Jupiter-family comets. The orbital trapping in mean motion resonances results in a significant leading-trailing asymmetry so that intermediate sized dust (∼ 10-100 µm) produces a greater asymmetry than the zodiacal light has. The leading-trailing surface brightness difference integrated over the size distribution of the asteroidal dust is obtained to be the values of 27.7% and 25.3% in the 9 µm and 18 µm bands, respectively. In contrast, the brightness difference for cometary dust is calculated as the values of 3.6% and 3.1% in the 9 µm and 18 µm bands, respectively, if the maximum dust radius is set to be s max = 3000 µm. Taking into account these values and their errors, we conclude that the contribution of asteroidal dust to the zodiacal infrared emission is less than ∼ 10%, while cometary dust of the order of 1 mm mainly accounts for the zodiacal light in infrared.

Toward understanding the origin of asteroid geometries

“…(624) Hektor is a Jupiter trojan, and the others are mainbelt asteroids. In the main belt, the Keplerian velocity is v K ≈ 20 km s −1 and the mean impact velocity is roughly estimated to be e 2 ave + i 2 ave v K ≈ 4 km s −1 with the mean orbital eccentricity of e ave = 0.15 and inclination of i ave = 0.13 (Ueda et al 2017). This mean impact velocity is much higher than that treated in our simulations (v imp < 400 m s −1 ).…”

Evolution of Cometary Dust Particles to the Orbit of the Earth: Particle Size, Shape, and Mutual Collisions

“…Under these circumstances, Nesvorný et al (2011) reproduced observed helion meteor orbital distribution from dust ejected from Jupiter Family Comets (JFCs). However, as Ueda et al (2017) indicated, recent in situ measurements by Rosetta at the coma of 67P/Churyumov-Gerasimenkoby Fulle et al 2015;Hilchenbach et al 2016;Fulle et al 2016b;Bentley et al 2016;Agarwal et al 2016;Mannel et al 2016;Merouane et al 2016) suggested that initial dust density and size-frequency distribution (SFD) are different from those in Nesvorný et al (2011)'s initial condition. Furthermore, the in situ measurements by Giotto mission (Fulle et al 1995) and Stardust mission (Green et al 2004(Green et al , 2007 as well as the IR observation (Vaubaillon & Reach 2010) unanimously determined SFD similar to that determined by Rosetta mission, even though the authors studied different comets (1P/Halley, 81P/Wild 2, and 73P/Schwassmann-Wachmann 3).…”

Cosmic Dust IX

“…The results were well explained by the dynamics of dust particles released from their parent bodies, because dust particles smaller than millimeters are expelled by solar radiation pressure and dust particles larger that millimeters are too heavy to be emitted without intense activities near perihelion. Takahiro Ueda reported that such millimeter-sized particles could produce the asymmetry of the zodiacal light observed by AKARI in the mid-infrared, while smaller particles are the main contributors to the zodiacal light (Ueda et al, 2017). Coronagraphic images of debris disks have also revealed the presence of asymmetries in the disks at projected distances in which Kuiper-belt objects could reside (Kalas & Jewitt, 1995).…”