Issue |
A&A
Volume 415, Number 2, February IV 2004
|
|
---|---|---|
Page(s) | 781 - 790 | |
Section | Planets and planetary systems | |
DOI | https://doi.org/10.1051/0004-6361:20031777 | |
Published online | 11 February 2004 |
Attogram dust grains in the solar system
Forming mechanism, properties and dynamics
1
SOLERC, PO Box 30, Kharkov, 61052, Ukraine e-mail: vicv@vil.com.ua
2
Kharkov National University, PO Box 60, Kharkov, 61052, Ukraine e-mail: Alex.I.Kalinichenko@univer.kharkov.ua
3
SVV Technology Innovations, Inc., PO Box 375, West Sacramento, CA 95691, USA
Corresponding author: S. V. Vasylyev, vasilyev@svvti.com
Received:
27
March
2001
Accepted:
23
December
2003
In this paper we conceptually develop the theory of attogram dust
grain formation by the cosmic-ray ion-enhanced brittle microerosion of
atmosphereless solar system bodies. According to our theory, the multicharged
cosmic ray ions penetrating into the solid material of planetary satellites,
asteroids, comets and smaller space bodies give rise to microscopic cylindrical overheated zones and generate mechanical impulses and thermoelastic stresses
exceeding the material tensile strength. The impulses may cause micro-scale
shattering of the surfaces and the ejection of ultrafine (attogram) dust particles off the parent body. The attogram grains formed by this mechanism (the so-called
track-breaking mechanism) have an average mass of 10-19–10-17 g,
a very flaky shape and ejection velocities of from tens to hundreds .
Depending on the ejection velocity and a large array of
non-gravitational forces, such grains can deposit and accumulate on the parent body surface,
orbit around the body thus forming a bound dust cocoon, or finally, escape
the body as ultrafine-dust wind.
Quantitative data on dust contributions to these varieties of attogram
population depending on the sizes and parameters of parent body material are
obtained and discussed. The volumetric track-breaking resulting in attogram
grain deposition in the ice-rock mixture of cometary nuclei during the whole
period of their formation is analysed.
Taking the example of Halley's comet we demonstrate that the mechanism under study
makes it possible to quantitatively explain the in situ
measured considerable excess of attogram grains within the cometary
environment in its circum-solar path sections. The problem of track-breaking
disintegration of small-sized bodies in the Kuiper Belt, which are permanently subjected to
a cosmic-ray ion-enhanced brittle microerosion heavier than in the Main Belt,
is investigated. The track-breaking survival
timescale for submicron and over hundred micron-sized grains is found to be
considerably smaller than the escape timescale of the Poynting-Robertson
and plasma drags, as well as the collisional mechanism. Track-breaking can also be
competitive to the collisional escape in the range of grain sizes of 1 to 100 microns.
A quantitative analysis of the calculations shows that the present theory may adequately explain
both the observable micron/submicron dust grain depletion of the Kuiper Belt
and the loss of its bulk mass during evolution. Some possible observational
tests for the future revealing the predicted populations of attogram dust in the
solar system are also discussed.
Key words: comets: general / comets: individual: Halley / solar system: general / interplanetary medium
© ESO, 2004
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