59 research outputs found
Orbital evolution under action of fast interstellar gas flow
Orbital evolution of an interplanetary dust particle under action of an
interstellar gas flow is investigated. Secular time derivatives of the particle
orbital elements, for arbitrary orbit orientation, are presented. An important
result concerns secular evolution of semi-major axis. Secular semi-major axis
of the particle on a bound orbit decreases under the action of fast
interstellar gas flow. Possible types of evolution of other Keplerian orbital
elements are discussed. The paper compares influences of the Poynting-Robertson
effect, the radial solar wind and the interstellar gas flow on dynamics of the
dust particle in outer planetary region of the Solar System and beyond it, up
to 100 AU.
Evolution of putative dust ring in the zone of the Edgeworth-Kuiper belt is
studied. Also non-radial solar wind and gravitational effect of major planets
may play an important role. Low inclination orbits of micron-sized dust
particles in the belt are not stable due to fast increase of eccentricity
caused by the interstellar gas flow and subsequent planetary perturbations -
the increase of eccentricity leads to planet crossing orbits of the particles.
Gravitational and non-gravitational effects are treated in a way which fully
respects physics. As a consequence, some of the published results turned out to
be incorrect. Moreover, the paper treats the problem in a more general way than
it has been presented up to now.
The influence of the fast interstellar neutral gas flow might not be ignored
in modeling of evolution of dust particles beyond planets.Comment: 12 pages, 7 figure
Orbital evolution under the action of fast interstellar gas flow with non-constant drag coefficient
The acceleration of a spherical dust particle caused by an interstellar gas
flow depends on the drag coefficient which is, for the given particle and flow
of interstellar gas, a specific function of the relative speed of the dust
particle with respect to the interstellar gas. We investigate the motion of a
dust particle in the case when the acceleration caused by the interstellar gas
flow represent a small perturbation to the gravity of a central star. We
present the secular time derivatives of the Keplerian orbital elements of the
dust particle under the action of the acceleration from the interstellar gas
flow for arbitrary orbit orientation. The semimajor axis of the dust particle
is a decreasing function of time for an interstellar gas flow acceleration with
constant drag coefficient and also for such an acceleration with the linearly
variable drag coefficient. The decrease of the semimajor axis is slower for the
interstellar gas flow acceleration with the variable drag coefficient. The
minimal and maximal values of the decrease of the semimajor axis are
determined. In the planar case, when the interstellar gas flow velocity lies in
the orbital plane of the particle, the orbit always approaches the position
with the maximal value of the transversal component of the interstellar gas
flow velocity vector measured at perihelion.
The properties of the orbital evolution derived from the secular time
derivatives are consistent with numerical integrations of the equation of
motion. If the interstellar gas flow speed is much larger than the speed of the
dust particle, then the linear approximation of dependence of the drag
coefficient on the relative speed of the dust particle with respect to the
interstellar gas is usable for practically arbitrary (no close to zero) values
of the molecular speed ratios (Mach numbers).Comment: 12 pages, 6 figures, 2 equations added in v
Motion of dust in mean-motion resonances with planets
Effect of stellar electromagnetic radiation on motion of spherical dust
particle in mean-motion orbital resonances with a planet is investigated.
Planar circular restricted three-body problem with the Poynting-Robertson (P-R)
effect yields monotonous secular evolution of eccentricity when the particle is
trapped in the resonance. Elliptically restricted three-body problem with the
P-R effect enables nonmonotonous secular evolution of eccentricity and the
evolution of eccentricity is qualitatively consistent with the published
results for the complicated case of interaction of electromagnetic radiation
with nonspherical dust grain. Thus, it is sufficient to allow either nonzero
eccentricity of the planet or nonsphericity of the grain and the orbital
evolutions in the resonances are qualitatively equal for the two cases. This
holds both for exterior and interior mean-motion orbital resonances. Evolutions
of longitude of pericenter in the planar circular and elliptical restricted
three-body problems are shown. Our numerical integrations suggest that any
analytic expression for secular time derivative of the particle's longitude of
pericenter does not exist, if a dependence on semi-major axis, eccentricity and
longitude of pericenter is considered (the P-R effect and mean-motion resonance
with the planet in circular orbit is taken into account).
Change of optical properties of the spherical grain with the heliocentric
distance is also considered. The change of the optical properties: i) does not
have any significant influence on secular evolution of eccentricity, ii) causes
that the shift of pericenter is mainly in the same direction/orientation as the
particle motion around the Sun. The statements hold both for circular and
noncircular planetary orbits.Comment: 22 pages, 12 figure
Fragmentation of a viscoelastic food by human mastication
Fragment-size distributions have been studied experimentally in masticated
viscoelastic food (fish sausage).The mastication experiment in seven subjects
was examined. We classified the obtained results into two groups, namely, a
single lognormal distribution group and a lognormal distribution with
exponential tail group. The facts suggest that the individual variability might
affect the fragmentation pattern when the food sample has a much more
complicated physical property. In particular, the latter result (lognormal
distribution with exponential tail) indicates that the fragmentation pattern by
human mastication for fish sausage is different from the fragmentation pattern
for raw carrot shown in our previous study. The excellent data fitting by the
lognormal distribution with exponential tail implies that the fragmentation
process has a size-segregation-structure between large and small parts.In order
to explain this structure, we propose a mastication model for fish sausage
based on stochastic processes.Comment: JPSJ3, 4 pages, 8 figures, minor corrections made for publication in
J. Phys. Soc. Jp
Millimeter Wave Scattering from Neutral and Charged Water Droplets
We investigated 94GHz millimeter wave (MMW) scattering from neutral and
charged water mist produced in the laboratory with an ultrasonic atomizer.
Diffusion charging of the mist was accomplished with a negative ion generator
(NIG). We observed increased forward and backscattering of MMW from charged
mist, as compared to MMW scattering from an uncharged mist. In order to
interpret the experimental results, we developed a model based on classical
electrodynamics theory of scattering from a dielectric sphere with
diffusion-deposited mobile surface charge. In this approach, scattering and
extinction cross-sections are calculated for a charged Rayleigh particle with
effective dielectric constant consisting of the volume dielectric function of
the neutral sphere and surface dielectric function due to the oscillation of
the surface charge in the presence of applied electric field. For small
droplets with (radius smaller than 100nm), this model predicts increased MMW
scattering from charged mist, which is qualitatively consistent with the
experimental observations. The objective of this work is to develop indirect
remote sensing of radioactive gases via their charging action on atmospheric
humid air.Comment: 18 pages, 8 figure
Meteor showers of comet C/1917 F1 Mellish
December Monocerotids and November Orionids are weak but established annual
meteor showers active throughout November and December. Analysis of a high
quality orbits subset of the SonotaCo video meteor database shows that the
distribution of orbital elements, geocentric velocity and also the orbital
evolution of the meteors and potential parent body may imply a common origin
for these meteors coming from the parent comet C/1917 F1 Mellish. This is also
confirmed by the physical properties and activity of these shower meteors. An
assumed release of meteoroids at the perihelion of the comet in the past and
the sky-plane radiant distribution reveal that the December Monocerotid stream
might be younger than the November Orionids. A meteoroid transversal component
of ejection velocity at the perihelion must be larger than 100 m/s. A few
authors have also associated December Canis Minorids with the comet C/1917 F1
Mellish. However, we did not find any connection.Comment: 11 pages, 11 figures and 5 table
Dust Ejection from Planetary Bodies by Temperature Gradients: Laboratory Experiments
Laboratory experiments show that dusty bodies in a gaseous environment eject
dust particles if they are illuminated. We find that even more intense dust
eruptions occur when the light source is turned off. We attribute this to a
compression of gas by thermal creep in response to the changing temperature
gradients in the top dust layers. The effect is studied at a light flux of 13
kW/(m*m) and 1 mbar ambient pressure. The effect is applicable to
protoplanetary disks and Mars. In the inner part of protoplanetary disks,
planetesimals can be eroded especially at the terminator of a rotating body.
This leads to the production of dust which can then be transported towards the
disk edges or the outer disk regions. The generated dust might constitute a
significant fraction of the warm dust observed in extrasolar protoplanetary
disks. We estimate erosion rates of about 1 kg/s for 100 m parent bodies. The
dust might also contribute to subsequent planetary growth in different
locations or on existing protoplanets which are large enough not to be
susceptible to particle loss by light induced ejection. Due to the ejections,
planetesimals and smaller bodies will be accelerated or decelerated and drift
outward or inward, respectively. The effect might also explain the entrainment
of dust in dust devils on Mars, especially at high altitudes where gas drag
alone might not be sufficient.Comment: 7 pages, 10 figure
Radial migration of the Sun in galactic disk
Physics of the gravitational effect of the galactic bar and spiral structure
is presented. Physical equations differ from the conventionally used equations.
Application to the motion of the Sun is treated. The speed of the Sun is
taken to be consistent with the Oort constants.
Galactic radial migration of the Sun is less than +- 0.4 kpc for the
four-armed spiral structure. The Sun remains about 75 % of its existence within
galactocentric distances (7.8 - 8.2) kpc and the results are practically
independent on the spiral structure strength. Thus, the radial distance changes
only within 5 % from the value of 8 kpc.
Galactic radial migration of the Sun is less than +- (0.3 - 1.2) kpc, for the
two-armed spiral structure. The Sun remains (29 - 95) % of its existence within
galactocentric distances (7.8 - 8.2) kpc and the results strongly depend on the
spiral structure strength and the angular speed of the spiral arms. The radial
distance changes within (3.8 - 15.0) % from the value of 8 kpc.
If observational arguments prefer relevant radial migration of the Sun, then
the Milky Way is characterized by the two-arm spiral structure.Comment: 9 page
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