scholarly journals Zodiacal Dust Bands

1994 ◽  
Vol 160 ◽  
pp. 127-142 ◽  
Author(s):  
S. F. Dermott ◽  
D. D. Durda ◽  
B. A. S. Gustafson ◽  
S. Jayaraman ◽  
J. C. Liou ◽  
...  

One of the outstanding problems in solar system science is the source of the particles that constitute the zodiacal cloud. The zodiacal dust bands discovered by IRAS have a pivotal role in this debate because, without doubt, they are the small, tail end products of asteroidal collisions. Geometrical arguments are probably the strongest and the plane of symmetry of the dust bands places their source firmly in the asteroid belt. A cometary source, Comet Encke for example, could exist at the distance of the mainbelt, but the dynamics of cometary orbits makes the formation of cometary dust bands impossible, unless, of course, there is a significant (comparable in volume to the asteroidal families) source of comets interior to the orbit of Jupiter with low (asteroidal) orbital eccentricities. We have suggested that the dust bands are associated with the prominent asteroidal families. The link with the Themis and Koronis families is good but the link with Eos remains to be proved. We show here by detailed modeling that even though the filtered infrared flux in the 25μm waveband associated with the dust bands is only ~1% of the total signal, this is only the “tip of the iceberg” and that asteroidal dust associated with the bands constitutes ~10% of the zodiacal cloud. This result, plus the observed size-frequency distribution of mainbelt asteroids and the observed ratio of the number of family to non-family asteroids allows us to estimate that asteroidal dust accounts for about one third of the zodiacal cloud. The discovery of the “leading-trailing” asymmetry of the zodiacal cloud in the IRAS data and our interpretation of this asymmetry in terms of a ring of asteroidal particles in resonant lock with the Earth is important for two reasons. (1) The existence of the ring strongly suggests that large (diameter ≥ 12μm) asteroidal particles (or particles with low orbital eccentricities) are transported to the inner solar system by drag forces. (2) The observed ratio of the trailing-leading asymmetry allows an independent estimate of the contribution of asteroidal particles to the zodiacal cloud. These new results have important implications for the source of the interplanetary dust particles (IDPs) collected at the Earth. Because asteroidal particles constitute about one third of the zodiacal cloud and are transported to the inner solar system by drag forces, gravitational focussing by the Earth that results in the preferential capture of particles from orbits with low inclinations and low eccentricities and the possible “funneling” effect of the ring itself, imply that nearly all of the unmelted IDPs collected at the Earth are asteroidal.

1996 ◽  
Vol 150 ◽  
pp. 155-158 ◽  
Author(s):  
Sumita Jayaraman ◽  
Stanley F. Dermott

AbstractThe Earth's resonant ring is populated primarily by asteroidal dust particles because cometary particles have higher Poynting-Robertson drag rates and the Earth's resonances are not strong enough to trap them (Gomes, 1995). It has been shown that asteroidal particles in a limited size range from 5 — 30μm are responsible for the observed trailing/leading flux asymmetry caused by the trailing dust cloud embedded in the ring (Jayaraman and Dermott 1995). The magnitude of the flux asymmetry is a direct function of the area of dust in the ring, which in turn depends upon the number of asteroidal particles in the zodiacal cloud. Using a dynamical model of the ring and the background zodiacal cloud and estimating the surface area of dust needed in the ring to match the observed flux asymmetry in the 25 micron COBE waveband, we have calculated the fraction of asteroidal dust in the zodiacal cloud as a function of p, the slope of the size-frequency distribution of particles.


2004 ◽  
Vol 202 ◽  
pp. 184-186
Author(s):  
Keith Grogan ◽  
S.F. Dermott ◽  
T.J.J. Kehoe

In this paper we demonstrate how the action of secular resonances near the inner edge of the asteroid belt strongly effects the inclinations and eccentricities of asteroidal dust particles, such that they lose the orbital characteristics of their parent body and are dispersed into the zodiacal background. As a consequence, it may not be possible to relate the distribution of interplanetary material at 1 AU to given asteroidal or cometary sources with the level of confidence previously imagined.


Author(s):  
George J. Flynn

Scattered sunlight from interplanetary dust particles, mostly produced by comets and asteroids, orbiting the Sun are visible at dusk or dawn as the Zodiacal Cloud. Impacts onto the space-exposed surfaces of Earth-orbiting satellites indicate that, in the current era, thousands of tons of interplanetary dust enters the Earth’s atmosphere every year. Some particles vaporize forming meteors while others survive atmospheric deceleration and settle to the surface of the Earth. NASA has collected interplanetary dust particles from the Earth’s stratosphere using high-altitude aircraft since the mid-1970s. Detailed characterization of these particles shows that some are unique samples of Solar System and presolar material, never affected by the aqueous and thermal processing that overprints the record of formation from the Solar Protoplanetary Disk in the meteorites. These particles preserve the record of grain and dust formation from the disk. This record suggests that many of the crystalline minerals, dominated by crystalline silicates (olivine and pyroxene) and Fe-sulfides, condensed from gas in the inner Solar System and were then transported outward to the colder outer Solar System where carbon-bearing ices condensed on the surfaces of the grains. Irradiation by solar ultraviolet light and cosmic rays produced thin organic coatings on the grain surfaces that likely aided in grain sticking, forming the first dust particles of the Solar System. This continuous, planet-wide rain of interplanetary dust particles can be monitored by the accumulation of 3He, implanted into the interplanetary dust particles by the Solar Wind while they were in space, in oceanic sediments. The interplanetary dust, which is rich in organic carbon, may have contributed important pre-biotic organic matter important to the development of life to the surface of the early Earth.


1996 ◽  
Vol 150 ◽  
pp. 141-153 ◽  
Author(s):  
S.F. Dermott ◽  
K. Grogan ◽  
B.Å.S. Gustafson ◽  
S. Jayaraman ◽  
S.J. Kortenkamp ◽  
...  

AbstractAsteroids, comets and interstellar dust are possible sources of the particles that constitute the dust in the inner solar system. Each of these components gives rise to particular, characteristic features, the amplitudes of which can be used to estimate the size of the associated source. The asteroidal component feeds the dust bands and the Earth's resonant ring, while the cometary component may account for the large scale height of the zodiacal cloud observed at 1 AU Previous discussions of the observed strengths of these various features indicated that the source of about one third of the thermal flux observed, for example, in the IRAS 25μm waveband is asteroidal, while two thirds is cometary. However, a variety of assumptions go into this calculation (the size-frequency distribution of the particles is particularly significant) and we now know that the result is highly dependent on these assumptions. The zodiacal cloud is also the source of the IDPs collected on Earth. Because of strong gravitational focusing by the Earth of particles in low e and I orbits, it is probable that the majority of IDPs originate from asteroids, particularly those asteroids in the Themis and Koronis families.


1996 ◽  
Vol 150 ◽  
pp. 31-34 ◽  
Author(s):  
Douglas P. Hamilton ◽  
Eberhard Grün ◽  
Michael Baguhl

AbstractCollisions of asteroids and among Zodiacal cloud particles produce large amounts of submicron-sized debris, much of which is immediately ejected from our solar system by electromagnetic forces. We investigate the trajectories of tiny grains started on circular uninclined orbits within the Zodiacal cloud and find that they reach high ecliptic latitudes during the current configuration of the solar magnetic.field, perhaps accounting for particles detected by the Ulysses spacecraft at latitudes up to 80°. When the solar magnetic field is reversed, particles are more strongly confined to the ecliptic plane and escape the solar system less readily. Both fluxes and spatial densities of sub-micron sized Zodiacal dust particles vary with time through the dependence of orbital dynamics on the 22-year solar cycle.


The assumption that the Zodiacal Cloud is a predominantly meteoritic rather than a meteoroidal complex is questioned. On the basis of (i) the observed exposure ages of interplanetary dust particles collected from the stratosphere, (ii) the compressive strength of the commonest fireballs, (iii) the existence of a broad ecliptic stream centred on the Taurids and (iv) the observation of substantial short-lived meteoroid swarms therein, a suitably consistent replenishment model is constructed in which the Zodiacal Cloud appears to derive from a now defunct large comet that arrived in an Earth-crossing orbit ca. 10-100 ka ago. A corollary of this model is that the latter’s remnant, a surviving large meteoroid, may be reactivated as a comet at intervals of ca. 1 ka giving rise to a variety of observable effects such as Zodiacal Cloud enhancements and rare multiple bombardments of the Earth by many bodies with masses at least 10 11 g, which typify a general process throughout Earth history responsible for climatic excursions and extinction events. It is recommended that a search be conducted for the large meteoroid or minor planet responsible for the dust now in the Solar System, to place our understanding of the latter’s evolution on a secure quantitative basis. If verified, this model would have profound implications so far as our understanding of the origin of comets is concerned because most of the cometary mass would apparently be contained in large differentiated bodies.


Author(s):  
Mario Trieloff

Although the second most abundant element in the cosmos is helium, noble gases are also called rare gases. The reason is that they are not abundant on terrestrial planets like the Earth, which is characterized by orders of magnitude depletion of—particularly light—noble gases when compared to the cosmic element abundance pattern. Indeed, geochemical depletion and enrichment processes mean that noble gases are highly versatile tracers of planetary formation and evolution. When our solar system formed—or even before—small grains and first condensates incorporated small amounts of noble gases from the surrounding gas of solar composition, resulting in depletion of light He and Ne relative to heavy Ar, Kr, and Xe, leading to the “planetary type” abundance pattern. Further noble gas depletion occurred during flash heating of mm- to cm-sized objects (chondrules and calcium, aluminum-rich inclusions), and subsequently during heating—and occasionally differentiation—on small planetesimals, which were precursors of planets. Some of these objects are present today in the asteroid belt and are the source of many meteorites. Many primitive meteorites contain very small (micron to sub-micron size) rare grains that are older than our Solar System and condensed billions of years ago in in the atmospheres of different stars, for example, Red Giant stars. These grains are characterized by nucleosynthetic anomalies, in particular the noble gases, such as so-called s-process xenon. While planetesimals acquired a depleted noble gas component strongly fractionated in favor of heavy noble gases, the Sun and also gas giants like Jupiter attracted a much larger amount of gas from the protosolar nebula by gravitational capture. This resulted in a cosmic or “solar type” abundance pattern, containing the full complement of light noble gases. In contrast, terrestrial planets accreted from planetesimals with only minor contributions from the gaseous component of the protosolar nebula, which accounts for their high degree of depletion and essentially “planetary” elemental abundance pattern. The strong depletion in noble gases facilitates their application as noble gas geo- and cosmochronometers; chronological applications are based on being able to determine noble gas isotopes formed by radioactive decay processes, for example, 40Ar by 40K decay, 129Xe by 129I decay, or fission Xe from 238U or 244Pu decay. Particularly ingrowth of radiogenic xenon is only possible due to the depletion of primordial nuclides, which allows insight into the chronology of fractionation of lithophile parent nuclides and atmophile noble gas daughters. Applied to large-scale planetary reservoirs, this helps to elucidate the timing of mantle degassing and evolution of planetary atmospheres. Applied to individual rocks and minerals, it allows radioisotope chronology using short-lived (e.g., 129I–129Xe) or long-lived (e.g., 40K–40Ar) systems. The dominance of 40Ar in the terrestrial atmosphere allowed von Weizsäcker to conclude that most of the terrestrial atmosphere originated by degassing of the solid Earth, which is an ongoing process today at mid-ocean ridges, as indicated by outgassing of primordial helium from newly forming ocean crust. Mantle degassing was much more massive in the past, with most of the terrestrial atmosphere probably formed during the first few 100 million years of Earth’s history, in response to major evolutionary processes of accretion, terrestrial core formation, and the terminal accretion stage of a giant impact that formed our Moon. During accretion, solar noble gases were added to the mantle, presumably by solar wind irradiation of the small planetesimals and dust accreting to form the Earth. While the Moon-forming impact likely dissipated a major fraction of the primordial atmosphere, today’s atmosphere originated by addition of a late veneer of asteroidal and possibly cometary material combined with a decreasing rate of mantle degassing over time. As other atmophile elements behave similarly to noble gases, they also trace the origin of major volatiles on Earth, for example, water, nitrogen, and carbon.


1996 ◽  
Vol 150 ◽  
pp. 163-166
Author(s):  
Jer-Chyi Liou ◽  
Herbert A. Zook ◽  
Stanley F. Dermott

AbstractThe recent discovery of the so-called Kuiper belt objects has prompted the idea that these objects produce dust grains that may contribute significantly to the interplanetary dust population at 1 AU. We have completed a numerical study of the orbital evolution of dust grains, of diameters 1 to 9 μm, that originate in the region of the Kuiper belt. Our results show that about 80% of the grains are ejected from the Solar System by the giant planets while the remaining 20% of the grains evolve all the way to the Sun. Surprisingly, these dust grains have small orbital eccentricities and inclinations when they cross the orbit of the Earth. This makes them behave more like asteroidal than cometary-type dust particles. This also enhances their chances to be captured by the Earth and makes them a possible source of the collected interplanetary dust particles (IDPs); in particular, they represent a possible source that brings primitive/organic materials from the outer Solar System to the Earth.When collisions with interstellar dust grains are considered, however, Kuiper belt dust grains larger than about 9 μm appear likely to be collisionally shattered before they can evolve to the inner part of the Solar System. Therefore, Kuiper belt dust grains may not, as they are expected to be small, contribute significantly to the zodiacal light.


1996 ◽  
Vol 150 ◽  
pp. 159-162
Author(s):  
Sumita Jayaraman ◽  
Stanley F. Dermott ◽  
Michael Werner

AbstractThe Space Infrared Telescope Facility (SIRTF) is planned for launch by NASA in 2001 in a heliocentric orbit at 1.01 AU The spacecraft will drift away from the Earth slowly, reaching a distance of 0.3 AU behind the Earth at the end of its 2.5 year mission. This implies that SIRTF will spiral through the Earth's resonant dust ring (Wright et al., 1995) and, in particular, that it will traverse the dust cloud in the ring that trails the Earth in its orbit. We have used a dynamical model of the ring (Dermott et al., 1994) followed by simulation of the SIRTF orbit to predict the variations in the zodiacal thermal emission due to the trailing dust cloud as seen by SIRTF. Because the dust ring is inclined to the ecliptic, the latitude of peak flux of the trailing cloud will have yearly oscillations about the ecliptic. The amplitude of the oscillations will increase as SIRTF approaches the cloud, reaching a maximum of 20 during the mission. The magnitude of the flux variations can be as high as 4 – 5% or 2–3 MJy/Sr, SIRTF's measurements of these effects will allow us to model the number density and thermal characteristics of asteroidal dust particles near the Earth.


2020 ◽  
Author(s):  
Stephen J. Mojzsis ◽  
Oleg Abramov

<p>Late accretionary bombardments in the first billion years of solar system history strongly affected the initial physical and chemical states of the Earth. Evidence of ancient impacts can be preserved in the oldest known terrestrial zircons with ages up to ca. 4.4 Ga. Here, we use the Hadean zircon record to directly assess the thermal effects of impact bombardment on the early Earth’s crust, couple the results to models of closure temperature-dependent diffusive loss and U-Pb age-resetting in zircon, derive zircon ages, and compare them to published ages.</p><p>The impact bombardment model consists of (i) a stochastic cratering model which populates the surface with craters within constraints derived from the lunar cratering record, the size/frequency distribution of the asteroid belt, and dynamical models; (ii) analytical expressions that calculate a temperature field for each crater; and (iii) a three-dimensional thermal model of the terrestrial lithosphere, where craters are allowed to cool by conduction and radiation. Equations for diffusion in zircon are coupled to these thermal models to estimate the amount of age-resetting.</p><p>We present modeling results for the Earth between 4.5 Ga and 3.5 Ga based new mass-production functions. Mean surface temperatures and geothermal gradients were assumed as 20 °C and 70 °C/km. Total delivered mass was estimated at 0.0013(M<sub>planet</sub>), or 7.8 × 10<sup>21</sup> kg. The size-frequency distributions of the impacts were derived from dynamical modeling. We begin model runs with a global magma ocean, which would have been formed by the Moon-forming impact. Mean impactor density of 3000 kg/m<sup>3</sup> and impactor velocity distribution from [1,2] was used, and impact angle of each impactor was stochastically generated from a gaussian centered at 45 degrees. The typical impact velocity of the Earth is ~21 km s<sup>-1</sup>.</p><p>It is important to note that the model age outputs we report omit normal processes of generation of zircon-saturated magmas that were operative in the Hadean. We find that as the impact flux decreases with time and becomes negligible for the purposes of thermal modeling by ca. 3.5 Ga. We find that the probability of randomly selecting a zircon of a given age increases with increasing age, predicting a large number of very old zircons. This contrasts with the actual age distribution of Hadean zircons, which, for >4 Ga, indicates the opposite case: the probability of selecting a zircon of a given age decreases with increasing age. We interpret this discrepancy to mean that impacts were not the dominant process in determining the ages of Hadean zircons. This is consistent with observations that the majority of Hadean zircons had formation temperature significantly lower than those expected for melt sheets and thermobarometry measurements suggesting formation of some Hadean zircons in a plate boundary environment.</p><p>[1] Mojzsis, S.J. et al. (2019). Astrophys. J., 881, 44. [2] Brasser, R. et al. (2020) Icarus 338, 113514. </p>


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