Aerodynamics of solid bodies in the solar nebula

Abstract. Both the core-accretion and disk-instability models suggest that at the last stage of the formation of a gas-giant, the core of this object is surrounded by an extended gaseous envelope. At this stage, while the envelope is contracting, planetesimals from the protoplanetary disk may be scattered into the protoplanets atmosphere and deposit some or all of their materials as they interact with the gas. We have carried out extensive simulations of approximately 10 4 planetesimals interacting with a envelope of a Jupiter-mass protoplanet including effects of gas drag, heating, and the effect of the protoplanets extended mass distribution. Simulations have been carried out for different radii and compositions of planetesimals so that all three processes occur to different degrees. We present the results of our simulations and discuss their implications for the enrichment of ices in giant planets. We also present statistics for the probability of capture (i.e. total mass-deposition) of planetesimals as a function of their size, composition, and closest approach to the center of the protoplanetary body.

Section: Effect Of Gaseous Envelopesupporting

confidence: 71%

Planetesimal Capture by an Evolving Giant Gaseous Protoplanet

Podolak¹,

Haghighipour²

2012

“…A massive gas atmosphere builds up around the rocky core if it reaches a critical mass of about 10 M ⊕ (e.g., Mizuno 1980). The CA model's main theoretical difficulty is in the very beginning of the growth: it is not clear how metresized rocks would stick together while colliding at high speeds, subject to high radial drifts into the parent star (Weidenschilling 1977(Weidenschilling , 1980, although gas-dust dynamical instabilities are suggested to help (e.g., Youdin & Goodman 2005;Johansen et al 2007). Nevertheless, believed to be the only viable model for terrestrial planet formation, the model has enjoyed an almost universal support (e.g., Ida & Lin 2008).…”

Section: Introductionmentioning

confidence: 99%

A new view on planet formation

Nayakshin¹

2010

Abstract. The standard picture of planet formation posits that giant gas planets are over-grown rocky planets massive enough to attract enormous gas atmospheres. It has been shown recently that the opposite point of view is physically plausible: the rocky terrestrial planets are former giant planet embryos dried of their gas "to the bone" by the influences of the parent star. Here we provide a brief overview of this "Tidal Downsizing" hypothesis in the context of the Solar System structure.

“…A mechanisms that can separate the gaseous and solid components was discussed by Weidenschilling (1977), but in a context where its consequences actually constituted a major problem for planet formation. Recent developments (Johansen & Lacerda 2010;Boley & Durisen 2010;Nayakshin 2010) have made it clear that the mechanism can be turned around into being instead beneficial for planet formation, and the mechanism has already been proven to allow very rapid formation of asteroid-size bodies.…”

Section: Discussionmentioning

confidence: 99%

“…The core accretion scenario also inherits the weaknesses of the general paradigm for rocky planet formation; the meter-size drift barrier (Weidenschilling 1977), the problem of getting pebbles and rocks to grow by sticking rather than braking apart due to collisions, and the general problem of finalizing planet building in a time sufficiently short to prevent Type I migration from being a problem (Morishima et al 2010).…”

Section: Planet Formation Mechanismsmentioning

confidence: 99%

“…One of the most important aspects of these new ideas is that they open up a way to not only avoid the meter size drift barrier (Weidenschilling 1977), but to actually turn the very same mechanism into an important part of planet formation. Johansen & Lacerda (2010) point out that accretion of cm-size particles ('pebbles') driven by the Weidenschilling (1977) mechanism leads to a natural explanation for a weak but clear tendency of prograde rotation of the largest asteroids.…”

Section: A New Paradigm For Planet Formationmentioning

confidence: 99%

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Formation of brown dwarfs and planets

Nordlund

2010

Abstract. Brown dwarfs and massive planets have similar structures, and there is probably an overlap in mass between the most massive planets and the lowest mass brown dwarfs. This raises questions as to what extent the structures of the most massive planets and lowest mass brown dwarfs differ, and what similarities (or not) there might be between their formation mechanisms. Here I discuss these issues on the background of recent numerical simulations of star formation, new evidence from cosmochemistry about the conditions in the early solar system, and recently discovered mechanisms that can expedite planetesimal and possibly planet formation greatly.