High-Resolution Calculations of Asteroid Impacts into the Venusian Atmosphere

Korycansky, D. G.; Zahnle, Kevin; Law, Mordecai-Mark Mac

doi:10.1006/icar.2000.6426

Cited by 29 publications

(15 citation statements)

References 34 publications

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“…Instead of a pancaking effect, which would appear when small objects penetrate the atmosphere, we observe the collateral flattening of the projectile. This behavior has already been described by Korycansky et al (2000), who shows that the mass loss of large bodies is due to mechanical ablation rather than thermal ablation. These authors show that hydrodynamic instabilities (Rayleigh-Taylor, Kelvin-Helmhotz) grow before compressional waves have time to cross the projectile.…”

Section: Outcomes Of Collisionssupporting

confidence: 66%

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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Section: Outcomes Of Collisionssupporting

confidence: 66%

Giant collisions involving young Jupiter

Anic¹,

Alibert²,

Benz³

2007

A&A

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“…These effects occur in two different regimes. In the first one (static regime, when the aerodynamic pressure loading builds up on a time-scale larger than the time required for a sound wave to travel through the body, see Svetsov et al 1995;Korykansky et al 2000), we use a model which combines the effects of lateral spreading (using the so called "pancake" model of Zahnle 1992) and the growth of Rayleigh-Taylor instabilities (Sharp 1984;Roulsten & Ahrens 1997;Korycansky et al 2000) at the front of the fluidized impactor to obtain a multi-staged fragmentation model. In the second (dynamical regime, when the pressure loading is dynamical), where no lateral spreading is observed (Svetsov et al 1995;Korycansky et al 2000) but where instead mass is removed at the front of the bolide, we use a simple model for mechanical ablation which is also based on the growth of RT instabilities.…”

Section: Mechanical Destructionmentioning

confidence: 99%

Models of giant planet formation with migration and disc evolution

Alibert¹,

Mordasini²,

Benz³

et al. 2005

A&A

633

795

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Abstract. We present a new model of giant planet formation that extends the core-accretion model of Pollack et al. (1996, Icarus, 124, 62) to include migration, disc evolution and gap formation. We show that taking these effects into account can lead to much more rapid formation of giant planets, making it compatible with the typical disc lifetimes inferred from observations of young circumstellar discs. This speed up is due to the fact that migration prevents the severe depletion of the feeding zone as observed in in situ calculations. Hence, the growing planet is never isolated and it can reach cross-over mass on a much shorter timescale. To illustrate the range of planets that can form in our model, we describe a set of simulations in which we have varied some of the initial parameters and compare the final masses and semi-major axes with those inferred from observed extra-solar planets.

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“…For the mechanical disruption, we use the "pancake" model (Zahnle 1992), but couple it to a model for the growth of Rayleigh-Taylor instabilities that develop on the front side of the impactor that behaves approximately as a fluid at dynamic pressures that exceed significantly the impactor's tensile strength or self-gravity (e.g., Roulston & Ahrens 1997;Korycansky et al 2000) . The model was tested by comparing it to simulations of different impacts, namely of the Lost City meteorite (Revelle 1979), the Tunguska event (Chyba et al 1993), impacts of km sized impactors into Venus (Zahnle 1992), and most importantly, the SL9 collision with Jupiter (e.g., Zahnle & Mac Low 1994;Boslough et al 1994).…”

Section: Population Synthesis Models: Background and Implementationmentioning

confidence: 99%

A Framework for Characterizing the Atmospheres of Low-Mass Low-Density Transiting Planets

Fortney

Mordasini

Nettelmann

et al. 2013

ApJ

276

267

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We perform modeling investigations to aid in understanding the atmospheres and composition of small planets of ∼2-4 Earth radii, which are now known to be common in our galaxy. GJ 1214b is a well studied example whose atmospheric transmission spectrum has been observed by many investigators. Here we take a step back from GJ 1214b to investigate the role that planetary mass, composition, and temperature play in impacting the transmission spectra of these low-mass low-density (LMLD) planets. Under the assumption that these planets accrete modest hydrogen-dominated atmospheres and planetesimals, we use population synthesis models to show that predicted metal enrichments of the H/He envelope are high, with metal mass fraction Z env values commonly 0.6 to 0.9, or ∼100 to 400+ times solar. The high mean molecular weight of such atmospheres (µ ≈ 5 − 12) would naturally help to flatten the transmission spectrum of most LMLD planets. The high metal abundance would also provide significant condensible material for cloud formation. It is known that the H/He abundance in Uranus and Neptune decreases with depth, and we show that atmospheric evaporation of LMLD planets could expose atmospheric layers with gradually higher Z env . However, values of Z env close to solar composition can also arise, so diversity should be expected. Photochemically produced hazes, potentially due to methane photolysis, are another possibility for obscuring transmission spectra. Such hazes may not form above T eq of ∼ 800 − 1100 K, which is testable if such warm, otherwise low mean molecular weight atmospheres are stable against atmospheric evaporation. We find that available transmission data are consistent with relatively high mean molecular weight atmospheres for GJ 1214b and "warm Neptune" GJ 436b. We examine future prospects for characterizing GJ 1214b with Hubble and the James Webb Space Telescope.

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High-Resolution Calculations of Asteroid Impacts into the Venusian Atmosphere

Cited by 29 publications

References 34 publications

Giant collisions involving young Jupiter

Giant collisions involving young Jupiter

Models of giant planet formation with migration and disc evolution

A Framework for Characterizing the Atmospheres of Low-Mass Low-Density Transiting Planets

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