Qshadow said:
Thanks for the explanations and the link.
I have updated the wiki article,
Frost line (astrophysics), ...
A minor nit: Your reference to the 2012 Martin & Livio paper is to the arxiv preprint. It should be to the MNRAS Letters article where it was published, with the arxiv link as a backup for those who don't have free access to the journal. Here's a reference, and a link:
Martin, R. G., & Livio, M. (2012). On the evolution of the snow line in protoplanetary discs.
Monthly Notices of the Royal Astronomical Society: Letters,
425(1), L6-L9.
http://mnrasl.oxfordjournals.org/content/425/1/L6.short.
Major nit: You've picked an article that doesn't have very many citations, and of those, many are self-citations by Martin or Livio. What Martin & Livio did in their paper was to try to reconcile the fact that models of location of the snow line in a protoplanetary disk disagree with what we see. Whether the Martin & Livio model becomes accepted science, it's a bit too early to tell.
What the models say is that the snow line migrates inward as the protostar and protoplanetary disk evolve (more below), with many models having the snow line migrating inside 1 AU. What observation says is that could not have been the case. Lecar et al. (see citation below) noted this problem in 2006.
Lecar, M., Podolak, M., Sasselov, D., & Chiang, E. (2006). On the location of the snow line in a protoplanetary disk.
The Astrophysical Journal,
640(2), 1115.
http://iopscience.iop.org/0004-637X/640/2/1115
Arxiv pre-print:
http://arxiv.org/abs/astro-ph/0602217
An even bigger problem is that you want one number. There is no one number. As mentioned above, the location of the snow line in a protoplanetary disk moves inward and then outward as the protostar and the protoplanetary disk evolved over time.
A very young protostar is much more luminous than its zero age main sequence counterpart. A one solar mass protostar first evolves along the Hayashi track, where luminosity decreases but temperature remains more or less constant. The core of the shrinking protostar ceases to be convective at some point, leading to a transition from the Hayashi track to the Henyey track, where temperature increases and luminosity remains more or less constant. Meanwhile, the protoplanetary disk also is evolving. Opacity, density, turbulence, and degree of ionization all play a role, and they all change.
Making a model that is consistent with physics and that is consistent with the observed makeup of our solar system (and now with other developing star systems) is still a work in progress.
Anyway, now the only big problem is that the previous edition of the "Frost line" wiki article stated 5 AU as the snow line without any reference and I removed it since all papers that i found were talking about ~3 AU.
Why did you do that? Right now, it's much better (in my opinion) to say that people agree to disagree and cite a range of figures. One way to look at it is that it's somewhere inside 5.2 AU because of the observed stability of Jupiter's Trojan asteroids, somewhere outside 3 AU because by that point incoming comets are spouting water vapor.
Another way to look at it is that the concept of a snow line in vacuum is a bit nonsensical. The existence of a snow line in a protoplanetary disk makes sense because the pressure in a protoplanetary disk, while low, is not that of an extremely high vacuum.
|Glitch| said:
The snow line should have been much closer to the protostar before the sun began hydrogen fusion than it is now.
You apparently are thinking that onset of fusion makes a protostar become more luminous. That isn't the case. What fusion does is the change the timescale of the evolution toward the protostar becoming a zero age main sequence star, where the star finally reaches equilibrium. You won't see a sudden change in luminosity as fusion begins. In fact, it's hard to pinpoint exactly when fusion does begin. It's not a quantum switch. The fusion rate instead gradually increases from near zero toward the quasi-stable value of a zero age main sequence star.
Qshadow said:
Well, this is exactly the confusion, 182K or even if it is 150K
The 182 K value arises from assuming a pressure of 10
-4 bar. Most planetary scientists think the pressure was a bit lower than that, resulting in a somewhat lower figure. How much lower? Scientists agree to disagree. That's why you see a range of figures.
