Accretional Remanence of Magnetized Dust in the Solar Nebula

Nübold, Henrik; Glaßmeier, Karl‐Heinz

doi:10.1006/icar.1999.6273

Cited by 29 publications

(21 citation statements)

References 26 publications

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“…Figure 1 shows the normalized magnetic moment of a cluster, µ/µ 0 , where µ 0 is the magnetization of a single grain, as a function of aggregate size. The trend line indicates the magnetic moment increases as µ ∝ µ 0 N 0.53 , similar to previously published results [8]. This is in contrast to the electric dipole moment, which is only weakly dependent on N. The magnetic dipole moment tends to grow with the addition of each monomer or aggregate, as the magnetic dipoles tend to align independent of the point of collision.…”

Section: A Collision Probabilitysupporting

confidence: 88%

“…If dust grains in a population charge to a potential of the same sign, the coagulation rate can be reduced or even halt altogether due to the resulting electrostatic repulsion depending on the relative speeds between the grains. In like manner, grain composition can also influence the coagulation rate: both numerical simulations and experimental data have shown that nanometer sized iron grains often coagulate rapidly into small aggregates due to the alignment of their magnetic dipoles [8,9,10]. This alignment of the magnetic dipoles creates a weak, attractive force between the grains increasing the probability of contact as one grain approaches another.…”

Section: Introductionmentioning

confidence: 99%

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Dipole–Dipole Interactions of Charged-Magnetic Grains

Perry

Matthews

Hyde

2010

IEEE Trans. Plasma Sci.

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Abstract-The interaction between dust grains is an important process in fields as diverse as planetesimal formation or the plasma processing of silicon wafers into computer chips. This interaction depends in large part on the material properties of the grains, for example whether the grains are conducting, nonconducting, ferrous or non-ferrous. This work considers the effects that electrostatic and magnetic forces, alone or in combination, can have on the coagulation of dust in various environments. A numerical model is used to simulate the coagulation of charged, charged-magnetic and magnetic dust aggregates formed from ferrous material and the results are compared to each other as well as to those from uncharged, nonmagnetic material. The interactions between extended dust aggregates are also examined, specifically looking at how the arrangement of charge over the aggregate surface or the inclusion of magnetic material produces dipole-dipole interactions. It will be shown that these dipole-dipole interactions can affect the orientation and structural formation of aggregates as they collide and stick. Analysis of the resulting dust populations will also demonstrate the impact that grain composition and/or charge can have on the structure of the aggregate as characterized by the resulting fractal dimension.

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Section: A Collision Probabilitysupporting

confidence: 88%

Section: Introductionmentioning

confidence: 99%

Dipole–Dipole Interactions of Charged-Magnetic Grains

Perry

Matthews

Hyde

2010

IEEE Trans. Plasma Sci.

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“…(21) we have to insert the functional dependence µ(m) of the aggregate dipole moment on the aggregate mass. As shown in the previous section, this dependence has been found in numerical simulations (Nübold 1998, Nübold andGlassmeier 2000) to be µ(N ) = µ(m) ∝ m γ with γ = 0.63. In combination with Eq.…”

Section: Aggregation Dynamicsmentioning

confidence: 71%

Magnetic Aggregation: Dynamics and Numerical Modeling

Dominik¹,

Nübold

2002

Icarus

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“…Based on magnetic field measurements during the descent and subsequent triple landing of the ROSETTA lander PHILAE on comet 67P/Churyumov--Gerasimenko, we show that no global magnetic field was detected within the limitations of analysis. The ROMAP suite of sensors measured an upper magnetic field magnitude of less than 2 nT at the cometary surface at multiple locations with the upper specific magnetic moment being < 3.1·•10 --5 Am 2 /kg for meter--size homogeneous magnetized boulders and the maximum dipole moment of 67P/Churyumov--Gerasimenko is 1.6·•10 8 Am 2 . We conclude that on this scale magnetic alignment in the pre--planetary nebular is of minor importance.…”

mentioning

confidence: 99%

“…Up to 1% of the Fe content can be present as magnetite. Processes like accretional remanent magnetization (8) or detrital remanent magnetization (9) are possible candidates to form larger scale magnetic dust grains and cometesimals. These in turn allow the possibility for a comet to possess a larger scale remanent magnetic field.…”

mentioning

confidence: 99%

The nonmagnetic nucleus of comet 67P/Churyumov-Gerasimenko

Auster

Apáthy

Berghofer

et al. 2015

Science

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Knowledge of the magnetization of planetary bodies allows far--reaching conclusions on their formation processes, and the conditions in the solar nebular at that time. Based on magnetic field measurements during the descent and subsequent triple landing of the ROSETTA lander PHILAE on comet 67P/Churyumov--Gerasimenko, we show that no global magnetic field was detected within the limitations of analysis. The ROMAP suite of sensors measured an upper magnetic field magnitude of less than 2 nT at the cometary surface at multiple locations with the upper specific magnetic moment being < 3.1·•10 --5 Am 2 /kg for meter--size homogeneous magnetized boulders and the maximum dipole moment of 67P/Churyumov--Gerasimenko is 1.6·•10 8 Am 2 . We conclude that on this scale magnetic alignment in the pre--planetary nebular is of minor importance.One Sentence Summary: High--precision magnetic field measurements obtained during the triple landing of ROSETTA's lander PHILAE demonstrate that the Jupiter family comet 67P/Churyumov--Gerasimenko is unmagnetized (<3.1·•10 --5 A m 2 /kg).Main Text: Comets are believed to have been formed in the outer solar nebula beyond the snow line, where icy aggregates can grow in size to form larger bodies (1--3). Both the Kuiper belts as well as the Oort cloud are possible reservoirs of comets, with different processes leading to their formation (3). The dust--to--ice ratio of comets is of the order 1 (4, 5). Thus, a large fraction of cometary material is refractory material. Analysis of Stardust samples indicates a high contribution of Fe to this refractory material (6, 7). Up to 1% of the Fe content can be present as magnetite. Processes like accretional remanent magnetization (8) or detrital remanent magnetization (9) are possible candidates to form larger scale magnetic dust grains and cometesimals. These in turn allow the possibility for a comet to possess a larger scale remanent magnetic field.Detection of any cometary magnetization is difficult as a dipole field decreases with the cube of the distance from the object. Global magnetization of small solar system bodies can be detected either by spacecraft flybys or direct measurements on the surface. Whereas the flybys of the Galileo and Deep Space spacecraft at asteroids 951 Gaspra and 9969 Braille suggested the possibility of notable magnetization of these bodies (10,11), the distant flybys of the ROSETTA spacecraft (12) at asteroids 2867 Steins and 21 Lutetia provided an upper limit on the specific magnetic moment of 10 --6 Am 2 /kg (13, 14).Magnetic field measurements obtained during the flyby of the GIOTTO spacecraft at comet 1P/Halley offered an opportunity to estimate cometary magnetization as they revealed an almost magnetic field free (<50 pT) region around the nucleus (16,17). Taking into account the closest approach distance of 596 km to Halley's nucleus this corresponds to a formal dipole magnetic moment of < 5·•10 13 Am 2 or an upper specific magnetic moment of < 0.25 Am 2 /kg, an unreasonably large value indicating the l...

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Accretional Remanence of Magnetized Dust in the Solar Nebula

Cited by 29 publications

References 26 publications

Dipole–Dipole Interactions of Charged-Magnetic Grains

Dipole–Dipole Interactions of Charged-Magnetic Grains

Magnetic Aggregation: Dynamics and Numerical Modeling

The nonmagnetic nucleus of comet 67P/Churyumov-Gerasimenko

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