High-resolution modelling of meteoroid ablation

Campbell-Brown, M.; Borovička, J.; Brown, Peter; Stokan, E.

doi:10.1051/0004-6361/201322005

Cited by 38 publications

(31 citation statements)

References 21 publications

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“…In some cases, there was a disagreement with observation. This fact strengthens the conclusion of Campbell-Brown et al (2013) that the erosion model we used is not accurate in the simulation of wakes. Future work on the formation of wakes will be needed.…”

Section: Meteor Wakessupporting

confidence: 85%

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Properties of small meteoroids studied by meteor video observations

Vojáček

Borovička

Koten

et al. 2019

A&A

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Aims. The complex study of millimetre-sized meteoroids can reveal more about the structure and origin of population of these meteoroids. Methods. Double-station video observations, paired with spectroscopic video observations, were used to study small meteoroids. In total 152 sporadic and shower meteors of maximum brightness between magnitude −5 and +3 were analysed. Spectral classification was based on time-integrated intensities of lines of Na, Mg, and Fe. Meteor light curves and deceleration were fitted by the grain erosion model. Heliocentric orbits of all meteors were computed. Monochromatic light curves were constructed in order to study differential ablation. The length of meteor wakes was evaluated as well.Results. The variety of properties among millimetre-sized meteoroids proved different sources and histories of this material. Meteoroids that contain small grains tend to release their sodium early. For given grain sizes, the sodium in Na-poor meteoroids is released earlier than in meteors without sodium depletion. Overall, meteoroids with sodium depletion are revealed to have different structures: they have stronger material without very small grains and they do not show very bright wakes. Two iron meteoroids on Halley-type orbits were observed, thereby supporting the idea of large-scale mixing of material in the early solar system. The distribution of grain sizes of Jupiter-family members was in good agreement with results from the COSIMA instrument on the ROSETTA probe.

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Section: Meteor Wakessupporting

confidence: 85%

“…It is believed that wakes are formed by eroded grains from the meteoroid body (Campbell-Brown et al 2013). Smaller grains are decelerated more than grains of larger sizes.…”

Section: Morphologymentioning

confidence: 99%

Properties of small meteoroids studied by meteor video observations

Vojáček

Borovička

Koten

et al. 2019

A&A

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“…As a result, most part of the meteoroid surface produces smaller particles, creating the bi−modal distribution in droplet sizes. The two−mode distribution can be seen in paper Campbell-Brown et al (2013) in the analysis of low-speed meteor 20101016_070052. Table 1 shows that the meteor path, l, for the iron meteoroid is shorter than for the stony one.…”

Section: Resultsmentioning

confidence: 94%

“…The mass fraction of those particles, which have radii greater than r med , constitutes 0.74m 0 . These values can be compared with those obtained with the use of the thermal disruption model in Campbell-Brown et al (2013) for meteor 20101103_053624, which had a little greater velocity (V ∞ = 66.4 km s −1 ) and less radius (R 0 = 0.7 mm). Namely, the particle sizes ranged from 81 µm to 272 µm.…”

Section: Resultsmentioning

confidence: 99%

A hydrodynamic mechanism of meteor ablation

Girin

2017

A&A

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Context. Hydrodynamic conditions are similar in a molten meteoroid and a liquid drop in a high-speed airflow. Despite the fact that the latter is well-studied, both experimentally and theoretically, hydrodynamic instability theory has not been applied to study the fragmentation of molten meteoroids. Aims. We aim to treat quasi-continuous spraying of meteoroid melt due to hydrodynamic instability as a possible mechanism of ablation. Our objectives are to calculate the time development of particle release, the released particle sizes and their distribution by sizes, as well as the meteoroid mass loss law. Methods. We have applied gradient instability theory to model the behaviour of the meteoroid melt layer and its interaction with the atmosphere. We have assumed a spherical meteoroid and that the meteoroid has a shallow entry angle, such that the density of the air stream interacting with the meteoroid is nearly constant. Results. High-frequency spraying of the molten meteoroid is numerically simulated. The intermediate and final size distributions of released particles are calculated, as well as the meteoroid mass loss law. Fast and slow meteoroids of iron and stone compositions are modelled, resulting in significant differences in the size distribution of melt particles sprayed from each meteoroid. Less viscous iron melt produces finer particles and a denser aerosol wake than a stony one does. Conclusions. Analysis of the critical conditions for the gradient instability mechanism shows that the dynamic pressure of the airstream at heights up to 100 km is sufficient to overcome surface tension forces and pull out liquid particles from the meteoroid melt by means of unstable disturbances. Hence, the proposed melt-spraying model is able to explain quasi-continuous mode of meteoroid fragmentation at large heights and low dynamic pressures. A closed-form solution of the meteoroid ablation problem is obtained due to the melt-spraying model usage, at the meteoroid composition, initial radius and velocity being given.

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“…While the atmospheric friction slows the meteoroid down, the light curve reaches one or more maxima, depending on the physical evolution, and fragmentation may occur causing flares. When the bolide velocity drops below 3−4 km s −1 , the light emission suddenly ceases; see Pecina & Koten (2009), Campbell-Brown et al (2013 for a comprehensive overview of atmospheric dynamic and ablation of the meteoroid. This is reflected in a highly dynamic intensity range, from very faint to very bright and even saturated images for the brightest bolides.…”

Section: Final Astrometric Errormentioning

confidence: 99%

Astrometric calibration for all-sky cameras revisited

Barghini

Gardiol

Carbognani

et al. 2019

A&A

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Context. Several fireball networks deploy all-sky cameras for the observation of bright meteors and bolides. Because the field is heavily distorted, a dedicated astrometric reduction is needed. A precise computation of the astrometric solution is essential to determine reliable orbital elements of the parent body and to recover possible fragments on ground. Aims. The purpose of this article is to assess the astrometric performances of this type of instruments, which is characterized by a wide field of view and small apertures. The currently available parametric models show a high level of complexity and generally suffer from parameter crosstalk and local minimum confinement if the initial estimates are not precisely provided. We address these issues here and propose a solution by adopting a new explicit parametrisation. Methods. The mismatch between the optical axis and the local zenith direction requires a geometric description that includes two centres of symmetry that lie very close to each other on the focal plane, causing an unreliable estimate of the related parameters. The introduction of new physical coordinates overcomes these issues, allowing a direct and independent estimation. We assessed the performances of different centroiding algorithms in the experimental conditions of an undersampled point spread function of reference stars and saturated bolides on video records. We implemented the algorithm for an automatic identification of bright sources on calibration frames and subsequent correlation with catalogue positions using astrometric projections of increasing complexity. Results. The algorithm and the new parametrisation of the astrometric solution are tested against real data from the PRISMA Italian fireball network and ensure good convergence properties for all cameras we tested so far. By processing astrometric data with a few months' statistics, we can achieve a random projection indeterminacy of the order of 10 arcsec, which is negligible with respect to single measurement errors on the bolide position.

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High-resolution modelling of meteoroid ablation

Cited by 38 publications

References 21 publications

Properties of small meteoroids studied by meteor video observations

Properties of small meteoroids studied by meteor video observations

A hydrodynamic mechanism of meteor ablation

Astrometric calibration for all-sky cameras revisited

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