Physics
Scientific paper
Dec 2004
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2004agufm.p32a..02a&link_type=abstract
American Geophysical Union, Fall Meeting 2004, abstract #P32A-02
Physics
5410 Composition, 5450 Orbital And Rotational Dynamics, 5455 Origin And Evolution, 6235 Mercury
Scientific paper
The terrestrial planets are generally thought to have formed via the collisional accumulation of rocky bodies. The characteristics of the planets produced by this process are, to a large degree, determined by their collisional evolution, and their associated differentiation and thermal evolution. Studies of planet formation and planetary collisional evolution have typically been conducted separately. Most works of late-stage planet formation use perfectly inelastic mergers to model collisions (e.g. Agnor, Canup & Levison 1999, Chambers 2001, Levison & Agnor 2003), with certain recognized inadequacies, notably prohibitively large spin angular momentum acquired as a planet grows. To date, studies of the collisional evolution of terrestrial planets has focused on determining the efficacy of single impacts to account for particular planetary characteristics and the formation of satellites (e.g. Benz et al. 1988, Canup & Asphaug 2001, Canup 2004). It has been recognized for some time (Wetherill 1985) that the final characteristics (e.g. spin state, bulk composition, isotopic age) of an accreting planet are determined not by the last or single largest collision but by all of the major collisional encounters in a planet's history (Agnor, Canup & Levison 1999). As demonstrated by our impact models, each major impact changes the silicate to metal ratio, the thermal state, and the spin state, and sets the stage for the subsequent collision. We are studying collisional dynamics and outcomes common to the late stage of terrestrial planet formation. We use smooth particle hydrodynamics model collisions in an effort to identify the range of impact dynamics that allow for accretion (i.e. mass growth instead of mass loss). In our initial study we found that for dynamical environments typical of most late stage accretion models, about half of all collisions between equal mass planetary embryos do not result in accumulation into a larger embryo (Agnor & Asphaug 2004). We will present new results of collisions for a variety of mass ratios and will discuss the cumulative affect of giant impacts and non-accretionary collisions on planetary characteristics (e.g. Mercury's collisional mantle loss and bulk composition, planetary spin states) and the extent to which collisional processes may account for planetary heterogeneity.
Agnor Craig
Asphaug Erik
No associations
LandOfFree
Collisional Evolution of Terrestrial Planets does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Collisional Evolution of Terrestrial Planets, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Collisional Evolution of Terrestrial Planets will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1453365