Comet Shoemaker-Levy 9: Impact on Jupiter and Plume Evolution

Takata, Toshiko; O’Keefe, J. D.; Ahrens, Thomas J.; Orton, Glenn S.

doi:10.1006/icar.1994.1074

Cited by 61 publications

(52 citation statements)

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“…The alternative to the simplified approach is to use 4) full-scale hydrodynamic models in which the projectile is treated as a strengthless continuous body Takata et al 1994;Crawford et al 1995), as a body with some kind of strength (Ivanov and Melosh 1994), or as a cloud of fragments (Svetsov et al 1995). Since the internal properties of comets and asteroids are poorly known, simplified approaches are competitive with more comprehensive hydrodynamic models because they allow us to investigate systematically a wide range of input parameters over a short period of time.…”

Section: Numerical Models For Atmospheric Entrymentioning

confidence: 99%

“…However, this simplification leads to unrealistically thin and wide projectiles and to extremely low final velocities (essentially, deceleration is inversely proportional to the projectile's thickness). Numerical models (Ivanov et al 1992;Ahrens et al 1994;Takata et al 1994;Crawford et al 1995) carried out around the same time that the pancake model was developed (i.e., the time of the collision of comet Shoemaker-Levy 9 with Jupiter) clearly showed that although flattening ("pancaking") is a typical behavior of disrupted projectiles, it is mostly restricted to a flattening factor of 1.7-2.3. Further, widening is arrested by the growth of Kelvin-Helmholtz (K-H) and Rayleigh-Taylor (R-T) instabilities and the resulting projectile fragmentation into smaller pieces.…”

Section: Separated Fragments (Sf) Model and Pancake Modelmentioning

confidence: 99%

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The Canyon Diablo impact event: Projectile motion through the atmosphere

Artemieva

Pierazzo

2009

Meteorit & Planetary Scien

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Abstract-Meteor Crater is one of the first impact structures systematically studied on Earth. Its location in arid northern Arizona has been ideal for the preservation of the structure and the surviving meteoric material. The recovery of a large amount of meteoritic material in and around the crater has allowed a rough reconstruction of the impact event: an iron object 50 m in diameter impacted the Earth's surface after breaking up in the atmosphere. The details of the disruption, however, are still debated. The final crater morphology (deep, bowl-shaped crater) rules out the formation of the crater by an open or dispersed swarm of fragments, in which the ratio of swarm radius to initial projectile radius C d is larger than 3 (the final crater results from the sum of the craters formed by individual fragments). On the other hand, the lack of significant impact melt in the crater has been used to suggest that the impactor was slowed down to 12 km/s by the atmosphere, implying significant fragmentation and fragments' separation up to 4 initial radii. This paper focuses on the problem of entry and motion through the atmosphere for a possible Canyon Diablo impactor as a first but necessary step for constraining the initial conditions of the impact event which created Meteor Crater.After evaluating typical models used to investigate meteoroid disruption, such as the pancake and separated fragment models, we have carried out a series of hydrodynamic simulations using the 3D code SOVA to model the impactor flight through the atmosphere, both as a continuum object and a disrupted swarm.Our results indicate that the most probable pre-atmospheric mass of the Meteor Crater projectile was in the range of 4⋅10 8 to 1.2⋅10 9 kg (equivalent to a sphere 46-66 m in diameter). During the entry process the projectile lost probably 30% to 70% of its mass, mainly because of mechanical ablation and gross fragmentation. Even in the case of a tight swarm of particles (C d <3), small fragments can separate from the crater-forming swarm and land on the plains (tens of km away from the crater) as individual meteorites. Starting from an impactor pre-atmospheric velocity of ~18 km/s, which represents an average value for Earth-crossing asteroids, we find that after disruption, the most probable impact velocity at the Earth's surface for a tight swarm is around 15 km/s or higher. A highly dispersed swarm would result in a much stronger deceleration of the fragments but would produce a final crater much shallower than observed at Meteor Crater.

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Section: Numerical Models For Atmospheric Entrymentioning

confidence: 99%

Section: Separated Fragments (Sf) Model and Pancake Modelmentioning

confidence: 99%

The Canyon Diablo impact event: Projectile motion through the atmosphere

Artemieva

Pierazzo

2009

Meteorit & Planetary Scien

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“…Previous 3D impact models were obtained for impacts on Jupiter (see discussion by Mac Low 1996), by Takata et al (1994) using an SPH at an effective resolution of about R4, and by Crawford using an Eulerian code at an effective resolution of about R10. The SPH results show little structure and are clearly underesolved; Crawford's results are intriguing but again unlikely to be adequately resolved.…”

Section: Previous Modelsmentioning

confidence: 99%

High-Resolution Simulations of the Impacts of Asteroids into the Venusian Atmosphere II: 3D Models

Korycansky¹,

Zahnle

Low

2002

Icarus

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We compare high-resolution 2D and 3D numerical hydrocode simulations of asteroids striking the atmosphere of Venus. Our focus is on aerobraking and its effect on the size of impact craters. We consider impacts both by spheres and by the real asteroid 4769 Castalia, a severely nonspherical body in a Venus-crossing orbit. We compute mass and momentum fluxes as functions of altitude as global measures of the asteroid's progress. We find that, on average, the 2D and 3D simulations are in broad agreement over how quickly an asteroid slows down, but that the scatter about the average is much larger for the 2D models than for the 3D models. The 2D models appear to be rather strongly susceptible to the "butterfly effect," in which tiny changes in initial conditions (e.g., 0.05% change in the impact velocity) produce quite different chaotic evolutions. By contrast, the global properties of the 3D models appear more reproducible despite seemingly large differences in initial conditions. We argue that this difference between 2D and 3D models has its root in the greater geometrical constraints present in any 2D model, and in particular in the global conservation of enstrophy in 2D that forces energy to pool in large-scale structures. It is the interaction of these artificial large-scale structures that causes slightly different 2D models to diverge so greatly. These constraints do not apply in 3D and large scale structures are not observed to form. A one-parameter modified pancake model reproduces the expected crater diameters of the 3D Castalias reasonably well. c 2002 Elsevier Science (USA)

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“…In other words, the projectile in SIM2 must plow through more envelope to reach the same depth as the projectile in SIM1, and thus kinetic energy deposition as a function of depth is more efficient in off-axis collisions. This kinetic energy is deposited in the form of heat, which gives rise to a growing plume rising toward the surface (see Takata et al 1994, for detailed studies of this subject).…”

Section: Energy Deposition Inside the Envelopementioning

confidence: 99%

Giant collisions involving young Jupiter

Anic¹,

Alibert²,

Benz³

2007

A&A

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We present high-resolution, three-dimensional simulations using a smooth particle hydrodynamics (SPH) code of giant impacts involving young Jupiter-like planets. Our aim is to explore the effect of such impacts on the structure and evolution of the planet and discuss the likelihood of detecting these post-impact planets. For this, we considered head-on and off-axis impacts by an Earth-like planet onto a young Jupiter at five different ages: 1 Myr, 10 Myr, 30 Myr, 100 Myr, and 1 Gyr. We briefly discuss the short-term post-impact evolution and concentrate on computing the long-term cooling of the planet. We find that the bright IR afterglow lasts for about 10 6 yr if the impact involves a 1 Myr old planet and up to 10 8 yr if the impact occurs on an older planet (∼30 Myr). We estimate that, about 10 to 100 young planetary systems must be observed to detect one candidate for such post-impact object. Given that their luminosity is only increased by a roughly 50%, this frequency does not make them ideal observing targets. We note nevertheless that the detection of this kind of post giant-impact planet would represent an important milestone in observationally establishing the current planet formation theories that are based on collisions.

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Comet Shoemaker-Levy 9: Impact on Jupiter and Plume Evolution

Cited by 61 publications

References 0 publications

The Canyon Diablo impact event: Projectile motion through the atmosphere

The Canyon Diablo impact event: Projectile motion through the atmosphere

High-Resolution Simulations of the Impacts of Asteroids into the Venusian Atmosphere II: 3D Models

Giant collisions involving young Jupiter

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