The LATEST (only made available for public just a couple of hours ago!) from one of the world's foremost authority on planetary disks and the orgins of our Solar System - Adjunct Associate Professor Stepinski...


http://arxiv.org/pdf/astro-ph/0312471

Title: An alternative look at the snowline in protoplanetary disks
Authors: Kacper Kornet (1), Michal Rozyczka (1), Tomasz F. Stepinski (2) ((1) N. Copernicus Astronomical Center, (2) Lunar and Planetary Insitute)
Comments: Accepted for publication in A&A. 8 pages, 4 figures

We have calculated an evolution of protoplanetary disk from an extensive set of initial conditions using a time-dependent model capable of simultaneously keeping track of the global evolution of gas and water-ice. A number of simplifications and idealizations allows for an embodiment of gas-particle coupling, coagulation, sedimentation, and evaporation/condensation processes. We have shown that, when the evolution of ice is explicitly included, the location of the snowline has to be calculated directly as the inner edge of the region where ice is present and not as the radius where disk's temperature equals the evaporation temperature of water-ice. The final location of the snowline is set by an interplay between all involved processes and is farther from the star than implied by the location of the evaporation temperature radius. The evolution process naturally leads to an order of magnitude enhancement in surface density of icy material


EARLIER works in the SAME field...

Works below can be located at the following places:
http://adsabs.harvard.edu/abstract_service.html

http://adsabs.harvard.edu/bib_abs.html


Stepinski, T. F., 1997, "Modeling the evolutionary history of the solar nebula", Conference Paper, 28th Annual Lunar and Planetary Science Conference, p. 373

Abstract
According to the current concepts, the solar nebula was an active and changing environment. It appears that it is the evolutionary aspect of the nebula that shapes the global character of the solar system. Thus, solar system origin studies require an evolutionary model of the nebula. To address this situation we have constructed an analytic model of the evolving solar nebula based on the same set of physical principles used in numerical time-dependent models of protoplanetary disks. Final formulas are explicit and readily available to provide the structure of the gaseous solar nebula on demand. The analytic model is conceptually transparent; thus, in comparison with its numerical counterparts, it gives much deeper insights into the inner working of the evolving nebula. It also provides an 'easy-to-use', but physically solid, theoretical framework within which numerous 'origins' issues can be discussed.


Stepinski, T. F., 1998, "New Approach to Diagnosing Properties of Protoplanetary Disks", ApJ, 507, pp. 361-370

Abstract
In this paper we suggest that subjecting the observationally derived properties of protoplanetary disks to the evolutionary interpretation yields new insights into the working of those disks, and offers valuable constraints on their models. We propose that the global properties of individual disks, such as their accretion rates and disk masses, sorted by the mass of the central star, can be indexed by the age of the star to simulate the evolution of a single disk. Using data from published surveys of T Tauri stars, we show that accretion rate data, and disk mass data for the lowest mass stars, form well-defined evolutionary tracks. The higher mass stars show a definitive negative correlation between accretion rates and star ages. We use the time-dependent alpha-disk model of the viscous protoplanetary disk to link the theory to observations. The data are consistent with the standard theoretical paradigm, but not with the layered accretion model. The best fits to the data are obtained for the standard models that start with disks that are about one-third of the mass of the central star and have their angular momenta, j, and alpha-coefficients linked by the relationship j~M^3/2_*alpha^1/3. The proportionality constant in this relationship, when derived from the accretion rate data, differs from the constant derived from the disk mass data. We argue that the accretion rate data are more reliable. Taking into account typical values of the specific angular momentum of disk-forming matter, we obtain alpha >= 10^-2. A complete time-dependent standard disk model, built on the parameters determined from the best-fit procedure, is presented. Such a model constitutes a good point of departure for various theoretical studies aimed at the issue of formation of planetary systems and the character of protoplanetary disks.

Kornet, K., Stepinski, T. F., & Rózyczka, M., 2001, "Diversity of planetary systems from evolution of solids in protoplanetary disks", A&A, 378, p.180-191

Abstract
We have developed and applied a model designed to track simultaneously the evolution of gas and solids in protoplanetary disks from an early stage, when all solids are in the dust form, to the stage when most solids are in the form of a planetesimal swarm. The model is computationally efficient and allows for a global, comprehensive approach to the evolution of solid particles due to gas-solid coupling, coagulation, sedimentation, and evaporation/condensation. The co-evolution of gas and solids is calculated for 10^7 yr for several evolution regimes and starting from a comprehensive domain of initial conditions. The output of a single evolutionary run is a spatial distribution of mass locked in a planetesimal swarm. Because swarm's mass distribution is related to the architecture of a nascent planetary system, diversity of swarms is taken as a proxy for a diversity of planetary systems. We have found that disks with low values of specific angular momentum are bled out of solids and do not form planetary systems. Disks with high and intermediate values of specific angular momentum form diverse planetary systems. Solar-like planetary systems form from disks with initial masses <=0.02 Msun and angular momenta <=3x 10^52 g cm2 s-1. Planets more massive than Jupiter can form at locations as close as 1 AU from the central star according to our model.



Hueso, R., & Guillot, T., 2001, "Formation of planetesimals in the Solar Nebula", AAS, 33, p.1059

Abstract
We study the evolution of protoplanetary disks with gas and embedded particles using a classical alpha-disk model. Solid matter entrained in the gas is incorporated following the formalism of Stepinski and Valageas (A&A, 1996, 1997). Dust grains coagulate into larger particles until they eventually decouple from the gas. The coagulation process is modulated by the evaporation and condensation of dust in the disk. We simultaneously consider grains of ices and rock, which allows us to study the amount of different solid material available to form the different planets. In particular, we present consequences for the development of planetesimals in the Uranus and Neptune region. This is interesting in the light of interior models of these planets, which naturally tend to predict a low rock to ice ratio. We will also discuss the consequences of these results on the standard core-accretion formation scenario. Acknowledgements: This work has been supported by Programme National du Planetologie. R. Hueso acknowledges a post-doctoral fellowship from Gobierno Vasco.

Hope this helps!

Fascinating!

This is one of the earthcentricisms we have to break. So much of what we beleive is based on observations from million to billions of miles to light years away. We have actual results from earths conditions, conditions not prevalent in our own solar system let alone the observable universe. The other conditions are recreated in lads and sampled from probes and the space station.

I understand the problem of water ice on mars to be the thinness of the martion atmosphere, linked to the 1/4 gravity, yet water Ice is suppose to exisit in Guisers on triton and possibly under the surface of europa. I can accept water ice in the atmospheres of the gas giants in the solar system, but on pluto ? the thin atmoshpere again. The lack of gravity. But then we also have comets and TNOs, centaurs.

I would like to see core sampling from these bodies. Spectroscopy is one thing, there is an entirely different result that comes with confirmation from hands on science. Pick the quote;

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It does look a little challenging i.e. ice on outer solar system bodies. I believe whatever water ice there maybe, they are likely to be locked up underneath thick nitrogen, methane, ammonia ices. The atmospheres of giant planets though are another story altogether given the pressures that exist, enormous heat is built up and the troposheres on these planets are warmed enough to allow for the formation of water clouds.

:P