Chondrule Formation in Lightning Discharges

Horányi, M.; Morfill, G. E.; Goertz, C. K.; Levy, E. H.

doi:10.1006/icar.1995.1052

Cited by 57 publications

(40 citation statements)

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“…After the first proposal of the chondrule formation model by Sorby (1877), many models have been proposed so far; however, none of them has won the major acceptance. They include bipolar wind (Watanabe, 1994;Liffman and Brown, 1996;Shu et al, 1996Shu et al, , 1997Shu et al, , 2001, lightning (Horanyi and Robertson, 1996;Desch and Cuzzi, 2000), meteor ablation (Liffman, 1992), and shock wave heating (e.g. Wood, 1984;Hood Copy right c The Society of Geomagnetism and Earth, Planetary and Space Sciences (SGEPSS); The Seismological Society of Japan; The Volcanological Society of Japan; The Geodetic Society of Japan; The Japanese Society for Planetary Sciences.…”

Section: Introductionmentioning

confidence: 99%

Deformation and internal flow of a chondrule-precursor molten sphere in a shocked nebular gas

2014

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Chondrule formation due to a nebular shock wave heating is considered. We calculate the apparent gravitational acceleration, internal flow, and deformation of a chondrule precursor molten sphere in the shocked nebular gas. The gravitational acceleration and the internal flow are caused by momentum flux of gas molecules incident on the surface of the sphere. The gravitational acceleration just behind the shock wave is 1.1 to 330 times the terrestrial one. The velocity of the internal flow reaches around 0.1 m s −1 for the pre-shock nebular gas density and the shock wave velocity are 10 −6 kg m −3 and 8.7 km s −1 , respectively, and then chondrule melt is stirred well by the flow. As a consequence, if there is oxygen heterogeneity in the precursor particle, it must be homogenized by the high speed circulative flow in the molten sphere within a few seconds. The momentum flux also deforms the sphere. The variation of the radius of the molten sphere due to the deformation is less than 1% of the original radius for mm-sized sphere when the sphere re-solidifies. Because we used the hydrodynamic solution with the linear approximation, the applicability of our result of the internal flow is restricted to some region of the parameter space of the shock velocity, the nebular gas density, radius and viscosity of chondrule melt sphere. For larger values of those parameters than typical ones, nonlinear calculations are needed, which is left for future works.

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Section: Introductionmentioning

confidence: 99%

Deformation and internal flow of a chondrule-precursor molten sphere in a shocked nebular gas

2014

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“…Lightning is plausibly generated in a turbulent solar nebula (Desch and Cuzzi, 2000), and is capable ofmelting chondrules, either by heating from the discharge itself (Horanyi and Robertson, 1996), or by heating a large volume of gas, which then melts the chondrules (Desch, 2000). The cooling rates of chondrules have not been reproduced in detail, but are estimated to be comparable to those of observed chondrules (Desch, 2000).…”

Section: Introductionmentioning

confidence: 99%

A model of the thermal processing of particles in solar nebula shocks: Application to the cooling rates of chondrules

Desch

Connolly

2002

Meteorit & Planetary Scien

316

370

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Abstract-We present a model for the thermal processing of particles in shock waves typical of the solar nebula. This shock model improves on existing models in that the dissociation and recombination of Hj and the evaporation of particles are accounted for in their effects on the mass, momentum and energy fluxes. Also, besides thermal exchange with the gas and gas-drag heating, particles can be heated by absorbing the thermal radiation emitted by other particles. The flow ofradiation is calculated using the equations of radiative transfer in a slab geometry. We compute the thermal histories of particles as they encounter and pass through the shock.We apply this shock model to the melting and cooling of chondru1es in the solar nebula. We constrain the combinations of shock speed and gas density needed for chondru1es to reach melting temperatures, and show that these are consistent with shock waves generated by gravitational instabilities in the protop1anetary disk. After their melting, cooling rates of chondru1es in the range 10-1000 K h-l are naturally reproduced by the shock model. Chondru1es are kept warm by the reservoir of hot shocked gas, which cools only as fast as the dust grains and chondru1es themselves can radiate away the gas's energy. We predict a positive correlation between the concentration of chondru1es in a region and the cooling rates ofchondru1esin that region. This correlation is supported by the unusually high frequency of (rapidly cooled) barred chondru1es among compound chondru1es, which must have collided preferentially in regions of high chondru1e density. We discuss these and other compelling consistencies between the meteoritic record and the shock wave model ofchondru1e formation.

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“…In conventional models it is usually assumed that lightning occurs in the dusty midplane of the nebula (Horanyi et al 1995;Love et al 1995). However a GRB will preferentially interact with the outer region of the nebula that is in the direction of the GRB source.…”

Section: Absorption Of γ-Rays In the Nebulamentioning

confidence: 99%

Gamma-ray bursts and other sources of giant lightning discharges in protoplanetary systems

McBreen

Winston

McBreen

et al. 2005

A&A

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Abstract. Lightning in the solar nebula is considered to be one of the probable sources for producing the chondrules that are found in meteorites. Gamma-ray bursts (GRBs) provide a large flux of γ-rays that Compton scatter and create a charge separation in the gas because the electrons are displaced from the positive ions. The electric field easily exceeds the breakdown value of ≈1 V m −1 over distances of order 0.1 AU. The energy in a giant lightning discharge exceeds a terrestrial lightning flash by a factor of ∼1012 . The predicted post-burst emission of γ-rays from accretion into the newly formed black hole or spin-down of the magnetar is sufficiently intense to cause a lightning storm in the nebula that lasts for days and is more probable than the GRB because the radiation is beamed into a larger solid angle. The giant outbursts from nearby soft gamma-ray repeater sources (SGRs) are also capable of causing giant lightning discharges. The total amount of chondrules produced is in reasonable agreement with the observations of meteorites. Furthermore in the case of GRBs most chondrules were produced in a few major melting events by nearby GRBs and lightning occurred at effectively the same time over the whole nebula, and provide accurate time markers to the formation of chondrules and evolution of the solar nebula. This model provides a reasonable explanation for the delay between the formation of calcium aluminium inclusions (CAIs) and chondrules.

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Chondrule Formation in Lightning Discharges

Cited by 57 publications

References 0 publications

Deformation and internal flow of a chondrule-precursor molten sphere in a shocked nebular gas

Deformation and internal flow of a chondrule-precursor molten sphere in a shocked nebular gas

A model of the thermal processing of particles in solar nebula shocks: Application to the cooling rates of chondrules

Gamma-ray bursts and other sources of giant lightning discharges in protoplanetary systems

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