The Formation of Chondrules: Petrologic Tests of the Shock Wave Model

Connolly, H. C.; Love, S. G.

doi:10.1126/science.280.5360.62

Cited by 127 publications

(116 citation statements)

References 19 publications

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“…First suggested by Wood (1963), gas dynamic shock waves in a low-temperature nebula are currently considered to be a plausible mechanism for providing the repetitive transient heating events that were apparently responsible for chondrule formation (Connolly and Love 1998;Jones et al 2000;Desch et al 2005). In support of this mechanism, it has been demonstrated that the shock wave model can simulate inferred chondrule thermal histories (heating rates, peak temperatures, cooling rates) for at least a limited range of input nebular and particle parameters (Desch and Connolly 2002;Ciesla and Hood 2002;Ciesla et al 2004b;Iida et al 2001;Hood et al 2005).…”

Section: Introductionmentioning

confidence: 99%

Nebular shock waves generated by planetesimals passing through Jovian resonances: Possible sites for chondrule formation

Hood

Ciesla

Artemieva

et al. 2009

Meteorit & Planetary Scien

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Abstract-The primordial asteroid belt contained at least several hundred and possibly as many as 10,000 bodies with diameters of 1000 km or larger. Following the formation of Jupiter, nebular gas drag combined with passage of such bodies through Jovian resonances produced high eccentricities (e = 0.3-0.5), low inclinations (i < 0.5°), and, therefore, high velocities (3-10 km/s) for "resonant" bodies relative to both nebular gas and non-resonant planetesimals. These high velocities would have produced shock waves in the nebular gas through two mechanisms. First, bow shocks would be produced by supersonic motion of resonant bodies relative to the nebula. Second, high-velocity collisions of resonant bodies with non-resonant bodies would have generated impact vapor plume shocks near the collision sites. Both types of shocks would be sufficient to melt chondrule precursors in the nebula, and both are consistent with isotopic evidence for a time delay of ~1-1.5 Myr between the formation of CAIs and most chondrules. Here, initial simulations are first reported of impact shock wave generation in the nebula and of the local nebular volumes that would be processed by these shocks as a function of impactor size and relative velocity. Second, the approximate maximum chondrule mass production is estimated for both bow shocks and impact-generated shocks assuming a simplified planetesimal population and a rate of inward migration into resonances consistent with previous simulations. Based on these initial first-order calculations, impact-generated shocks can explain only a small fraction of the minimum likely mass of chondrules in the primordial asteroid belt (~10 24 -10 25 g). However, bow shocks are potentially a more efficient source of chondrule production and can explain up to 10-100 times the estimated minimum chondrule mass.

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Section: Introductionmentioning

confidence: 99%

Nebular shock waves generated by planetesimals passing through Jovian resonances: Possible sites for chondrule formation

Hood

Ciesla

Artemieva

et al. 2009

Meteorit & Planetary Scien

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“…A successful theory of chondrule formation should at least meet the following constraints: (1) the extremely short heating timescale of roughly seconds to minutes (Connolly & Love 1998), (2) the cooling rate of 10 2 -10 3 K hr À1 (Radomsky & Hewins 1990;Lofgren & Lanier 1990), and (3) the narrow range of sizes (0.1-1 mm) inferred from laboratory analyses of textures and compositions as well as from attempts to reproduce chondrules. In addition, many chondrules show evidence of multiple heating events, so the heating event must have occurred more than once.…”

Section: Introductionmentioning

confidence: 99%

Chondrule Formation and Protoplanetary Disk Heating by Current Sheets in Nonideal Magnetohydrodynamic Turbulence

Joung¹,

Low²,

Ebel³

2004

ApJ

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We study magnetic field steepening due to ambipolar diffusion in protoplanetary disk environments and draw the following conclusions. Current sheets are generated in magnetically active regions of the disk where the ionization fraction is high enough for the magnetorotational instability to operate. In late stages of solar nebula evolution, the surface density is expected to decrease and dust grains are expected to gravitationally settle to the midplane. If the local dust-to-gas mass ratio near the midplane is increased above cosmic abundances by factors k10 3 , current sheets reach high enough temperatures to melt millimeter-sized dust grains and hence may provide the mechanism to form meteoritic chondrules. In addition, these current sheets possibly explain the near-infrared excesses observed in spectral energy distributions (SEDs) of young stellar objects. Direct imaging of protoplanetary disks via a nulling interferometer or, in the future, a multiband, adaptive optics coronagraph can test this hypothesis.

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“…Numerous models have been proposed to explain the formation of chondrules; however, none can yet be reconciled with the highly diverse mineralogical, chemical, and isotopic properties of these objects (e,g., Boss, 1996a). Arguably, the most successful models of chondrule formation suggest that chondrules form by the melting of preexisting dust particles by gas-drag heating in shock waves propagating through the solar nebula (Boss, 1996a,b;Connolly and Love, 1998). These theories predict many of the properties of chondrules and are also compatible with current models on the generation of shock waves (Connolly and Love, 1998).…”

Section: Introductionmentioning

confidence: 76%

Chondrule formation by the ablation of small planetesimals

Genge

2000

Meteorit & Planetary Scien

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Abstract-Numerous models have been proposed to explain the formation of chondrules, but none can be reconciled with the highly diverse properties of these objects. Here the formation of chondrules by the surface melting and ablation of small planetesimals in nebula shock waves is investigated using a numerical model. It is shown that bodies between -1 mm and 500 m in diameter would have produced molten droplets by ablation during gas drag in nebula shocks stronger than -2.0 Mach. The properties of chondrules produced by ablation are estimated by comparison with meteorite fusion crusts and through consideration of the environment within the bow shock envelope of ablating planetesimals. It is suggested that most ablation chondrules will have broadly chondritic compositions with depletions in siderophile and chalcophile elements and relatively high volatile contents and textures that are mainly porphyritic. The formation of chondrules by ablation of planetesimals in shock waves was probably most important at a late stage in nebula history and occurred at the same time as chondrules formed by the melting of dust particles. The high abundance of dust particles relative to larger bodies at all stages of accretion implies that only a proportion of chondrules may have been formed by ablation and that genetic groups of chondrules with very different origins may coexist in meteorites.

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The Formation of Chondrules: Petrologic Tests of the Shock Wave Model

Cited by 127 publications

References 19 publications

Nebular shock waves generated by planetesimals passing through Jovian resonances: Possible sites for chondrule formation

Nebular shock waves generated by planetesimals passing through Jovian resonances: Possible sites for chondrule formation

Chondrule Formation and Protoplanetary Disk Heating by Current Sheets in Nonideal Magnetohydrodynamic Turbulence

Chondrule formation by the ablation of small planetesimals

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