scholarly journals Dynamics of Micrometeoroids

1980 ◽  
Vol 90 ◽  
pp. 293-298 ◽  
Author(s):  
E. Grün ◽  
H. A. Zook
Keyword(s):  
Heliocentric Distance ◽  
Ecliptic Plane ◽  
Interplanetary Dust ◽  
Spatial Density ◽  
Orbital Elements ◽  
Zodiacal Light ◽  
Consistent Picture ◽  
Time Variations ◽  
Pioneer 10

Recent observations of zodiacal light have established a reliable and consistent picture of the spatial distribution of interplanetary dust in the ecliptic plane. The spatial density nr varies with heliocentric distance r according to a power law nr ∝ r−ν. From Helios observations an exponent v = 1.3 is derived for the distance interval from 0.08 A.U. to 1 A.U. (Link et al. 1976). Outside the earth's orbit the Pioneer 10 and 11 results suggest a higher exponent v = 1.5 for the distance interval from 1 A.U. to 3.3. A.U. (Hanner et al., 1976). Giese and Grün (1976) showed that the results from zodiacal light observations are compatible with the micrometeoroid fluxes derived from in situ measurements and lunar crater statistics. They found that micrometeoroids in the size range from 10 μm to 100 μm radii (corresponding roughly to 10−8g to 10−5g) contribute most to the zodiacal light brightness.The orbital distribution of large interplanetary particles (10−6 g < m < 10−3g) is known from meteor observations. Sekanina and Southworth (1975) reported average orbital elements of these particles: ā ∼ 1.25 A.U., ē ∼ 0.4 and ī ∼ 20°. Orbital information on micrometeoroids (m < 10−8g) is obtained from in situ detectors on board the Pioneer 8 and 9 and Helios 1 spaceprobes and the HEOS-2 satellite. Characteristics of the different micrometeoroid experiments are given in Table 1. There is almost no time overlap in the data taking intervals of the experiments. Therefore one has to assume that there are no time variations of the meteoroid flux on the time scale of 1 to 10 years if one compares the results from the different experiments. This assumption may be violated for the smallest of the observed particles (m < 10−13g) due to strong electromagnetic interaction of these particles with the interplanetary magnetic field (Morfill and Grün 1979).

scholarly journals Evidence that the Properties of Interplanetary Dust Beyond 1 AU are Not Homogeneous

1980 ◽  
Vol 90 ◽  
pp. 71-74 ◽  
Author(s):  
Donald W. Schuerman
Keyword(s):  
Cross Section ◽  
Heliocentric Distance ◽  
Interplanetary Dust ◽  
Scattering Cross Section ◽  
Zodiacal Light ◽  
Dust Density ◽  
Scattering Cross ◽  
Pioneer 10

Traditionally, earth-based observations of the zodiacal light (ZL) require two assumptions for further analysis: (A1) the dust density (n) is a power of heliocentric distance (R), n ∝ R−ν; (A2) the nature (scattering cross section, σ) of the dust is independent of location, σ(r,h,θ)=σ(θ). Observations from Pioneer 10 do not verify these assumptions.

scholarly journals 1.3.3 Consequences of the Inclination of the Zodiacal Cloud on the Ecliptic

1976 ◽  
Vol 31 ◽  
pp. 121-121
Author(s):  
R. Robley
Keyword(s):  
Solar System ◽  
Exponential Distribution ◽  
Inclination Angle ◽  
Radial Direction ◽  
Heliocentric Distance ◽  
Ecliptic Plane ◽  
Interplanetary Dust ◽  
Zodiacal Light ◽  
Invariant Plane ◽  
Zodiacal Cloud

Assuming that the decrease in the density of the interplanetary dust follows an exponential distribution both in the transverse and radial direction, we can write n = no Exp(-(h/H)-(r-l/R)), where h is the distance from the ecliptic plane and r the heliocentric distance both expressed in astronomical units (a.u.); then we show that the modulation of the radiance B(90, 0) of the zodiacal light observed at the ecliptic pole defines the parameter H as a function of the inclination angle B between the zodiacal cloud and the ecliptic plane; moreover, the experimental value of the ratio B(90, 0)/B(90, 90) defines the parameter R. It can be deduced that the flatness of the zodiacal cloud, expressed by R/H, is < 5 and that the plane of symmetry of the zodiacal cloud is very close to that of the invariant plane of the solar system (B<2°).

scholarly journals The Change in Near-Ecliptic Zodiacal Light Brightness with Heliocentric Distance

1985 ◽  
Vol 85 ◽  
pp. 21-25
Author(s):  
G.N. Toller ◽  
J.L. Weinberg
Keyword(s):  
Heliocentric Distance ◽  
Asteroid Belt ◽  
Zodiacal Light ◽  
The Earth ◽  
Pioneer 10

AbstractBackground starlight observed by the Pioneer 10 Imaging Photopolarimeter from beyond the asteroid belt is used to isolate zodiacal light in Pioneer observations at heliocentric distances R between 1 and 3 AU. Near-ecliptic zodiacal light brightness data in the range 65° to 180° elongation ε are used to depict changes in the shape of the zodiacal light with ε and R and are compared to the corresponding views seen from the Earth and from the Helios 1 and 2 spacecraft.

scholarly journals The Zodiacal Cloud Complex

1991 ◽  
Vol 126 ◽  
pp. 131-138
Author(s):  
A.C. Levasseur-Regourd ◽  
J.B. Renard ◽  
R. Dumont
Keyword(s):  
Optical Properties ◽  
Symmetry Plane ◽  
Ecliptic Plane ◽  
Interplanetary Dust ◽  
The Sun ◽  
Zodiacal Light ◽  
Zodiacal Cloud ◽  
Classical Models ◽  
Cloud Complex ◽  
Two Populations

AbstractThe physical properties of the interplanetary dust grains are, out of the ecliptic plane, mainly derived from observations of zodiacal light in the visual or infrared domains. The bulk optical properties (polarization, albedo) of the grains are demonstrated to depend upon their distance to the Sun (at least in a 0.1 AU to 1.7 AU range in the symmetry plane) and upon the inclination of their orbits (at least up to 22°). Classical models assuming the homogeneity of the zodiacal cloud are no longer acceptable. A hybrid model, with a mixture of two populations, is proposed. It suggests that various sources (periodic comets, asteroids, non periodic comets...) play an important role in the replenishment of the zodiacal cloud complex.

scholarly journals Dust Measurements in the Outer Solar System

1994 ◽  
Vol 160 ◽  
pp. 367-380
Author(s):  
Eberhard Grün
Keyword(s):  
Solar System ◽  
Interstellar Dust ◽  
Thermal Emission ◽  
Scattered Light ◽  
Interplanetary Dust ◽  
Dust Particles ◽  
Spatial Density ◽  
Outer Solar System ◽  
The Sun

In-situ measurements of micrometeoroids provide information on the spatial distribution of interplanetary dust and its dynamical properties. Pioneers 10 and 11, Galileo and Ulysses spaceprobes took measurements of interplanetary dust from 0.7 to 18 AU distance from the sun. Distinctly different populations of dust particles exist in the inner and outer solar system. In the inner solar system, out to about 3 AU, zodiacal dust particles are recognized by their scattered light, their thermal emission and by in-situ detection from spaceprobes. These particles orbit the sun on low inclination (i ≤ 30°) and moderate eccentricity (e ≤ 0.6) orbits. Their spatial density falls off with approximately the inverse of the solar distance. Dust particles on high inclination or even retrograde trajectories dominate the dust population outside about 3 AU. The dust detector on board the Ulysses spaceprobe identified interstellar dust sweeping through the outer solar system on hyperbolic trajectories. Within about 2 AU from Jupiter Ulysses discovered periodic streams of dust particles originating from within the jovian system.

scholarly journals The Infrared Zodiacal Light

1991 ◽  
Vol 126 ◽  
pp. 171-178
Author(s):  
Martha S. Hanner
Keyword(s):  
Optical Properties ◽  
Solar Eclipse ◽  
Heliocentric Distance ◽  
Thermal Emission ◽  
Diffuse Radiation ◽  
Interplanetary Dust ◽  
Zodiacal Light

AbstractThermal emission from interplanetary dust is the main source of diffuse radiation atλ5-50 μm. Analysis of infrared sky maps from IRAS and ZIP lead to the result that the average optical properties of the dust change with heliocentric distance. The present uncertainties in calibration should be resolved by COBE. Existence of a dust sublimation zone at 4 solar radii awaits confirmation at the next solar eclipse.

scholarly journals Dust Near the Sun

1996 ◽  
Vol 150 ◽  
pp. 315-320
Author(s):  
I. Mann
Keyword(s):  
Near Infrared ◽  
Dust Cloud ◽  
Interplanetary Dust ◽  
Present Knowledge ◽  
The Sun ◽  
Zodiacal Light ◽  
Particle Properties ◽  
In Situ Experiments ◽  
Near Future

AbstractYielding the inner continuation of the interplanetary dust cloud, the dust at about 0.3 AU and closer to the Sun is studied under observing conditions different from those of the Zodiacal light. The F-coronal brightness indicates its optical particle properties as well as its overall spatial distribution. The present knowledge is based on visible and near infrared F-coronal observations and may be improved from data of the SOHO satellite in the near future. Some dynamical effects become particulary important for sub-μm particles in the solar vicinity. However, these particles seem to have only a small effect on the observable corona brightness, but are more accessible to in-situ experiments.

scholarly journals Optical Properties of Interplanetary Dust in the Tangential Plane

1991 ◽  
Vol 126 ◽  
pp. 199-202
Author(s):  
J.B. Renard ◽  
A.C. Levasseur-Regourd ◽  
R. Dumont
Keyword(s):  
Optical Properties ◽  
Symmetry Plane ◽  
Ecliptic Plane ◽  
Interplanetary Dust ◽  
Polarization Degree ◽  
Zodiacal Light ◽  
Tangential Plane ◽  
Zodiacal Cloud ◽  
Local Polarization ◽  
Local Intensity

AbstractLocal intensity and emissivity, and consequently local polarization degree, temperature and albedo, can be retrieved from optical and thermal observations of zodiacal light. The local polarization degree (normalized at constant solar distance and phase angle) is found to decrease with elevation above the symmetry plane of the zodiacal cloud. The heterogeneity of the cloud, established towards the symmetry pole, is here demonstrated in the tangential plane (almost perpendicular to the ecliptic plane at 1 AU). We present a map of the local polarization degree in this plane.

scholarly journals Helios spacecraft data revisited: detection of cometary meteoroid trails by following in situ dust impacts

2020 ◽  
Vol 643 ◽  
pp. A96
Author(s):  
Harald Krüger ◽  
Peter Strub ◽  
Max Sommer ◽  
Nicolas Altobelli ◽  
Hiroshi Kimura ◽  
...  
Keyword(s):  
Solar System ◽  
Dust Cloud ◽  
Interplanetary Dust ◽  
Dust Particles ◽  
True Anomaly ◽  
Spatial Density ◽  
The Sun ◽  
Narrow Region ◽  
Spacecraft Data

Context. Cometary meteoroid trails exist in the vicinity of comets, forming a fine structure of the interplanetary dust cloud. The trails consist predominantly of the largest cometary particles (with sizes of approximately 0.1 mm–1 cm), which are ejected at low speeds and remain very close to the comet orbit for several revolutions around the Sun. In the 1970s, two Helios spacecraft were launched towards the inner Solar System. The spacecraft were equipped with in situ dust sensors which measured the distribution of interplanetary dust in the inner Solar System for the first time. Recently, when re-analysing the Helios data, a clustering of seven impacts was found, detected by Helios in a very narrow region of space at a true anomaly angle of 135 ± 1°, which the authors considered as potential cometary trail particles. However, at the time, this hypothesis could not be studied further. Aims. We re-analyse these candidate cometary trail particles in the Helios dust data to investigate the possibility that some or all of them indeed originate from cometary trails and we constrain their source comets. Methods. The Interplanetary Meteoroid Environment for eXploration (IMEX) dust streams in space model is a new and recently published universal model for cometary meteoroid streams in the inner Solar System. We use IMEX to study the traverses of cometary trails made by Helios. Results. During ten revolutions around the Sun, the Helios spacecraft intersected 13 cometary trails. For the majority of these traverses the predicted dust fluxes are very low. In the narrow region of space where Helios detected the candidate dust particles, the spacecraft repeatedly traversed the trails of comets 45P/Honda-Mrkos-Pajdušáková and 72P/Denning-Fujikawa with relatively high predicted dust fluxes. The analysis of the detection times and particle impact directions shows that four detected particles are compatible with an origin from these two comets. By combining measurements and simulations we find a dust spatial density in these trails of approximately 10−8–10−7 m−3. Conclusions. The identification of potential cometary trail particles in the Helios data greatly benefited from the clustering of trail traverses in a rather narrow region of space. The in situ detection and analysis of meteoroid trail particles which can be traced back to their source bodies by spacecraft-based dust analysers provides a new opportunity for remote compositional analysis of comets and asteroids without the necessity to fly a spacecraft to or even land on those celestial bodies. This provides new science opportunities for future missions like DESTINY+ (Demonstration and Experiment of Space Technology for INterplanetary voYage with Phaethon fLyby and dUst Science), Europa Clipper, and the Interstellar Mapping and Acceleration Probe.

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