A young sun - a response

The biggest problem of inferring things from the extra-solar systems is our observational biases.We have only detected what we are likely to have detected with current capability.The modeling is incredibly difficult as shown by the fact that we have developed models with both inward and outward migration.The latest models I read about this summer involve magnetohydrodynamic process modeling in the accretion disk similar to the Balbus-Hawley mechanism for cataclysmic binary/ black hole accretion disks.I might be getting involved with this research myself. I have previously worked on the modeling of fragmentation of molecular clouds to form cloud cores using anisotropic turbulent cascades.

The mathmatics for the movement of Jupiter via asteroid flinging has to be staggering. But if planets like the Earth have a balanced orbit around the Sun with angular acceleration off setting the Suns gravitational attraction, is the Sun's Solar Wind able to change the Earth's orbit or push the Earth away from the Sun like it did the inner gasses? If so, will the Earth be pushed out faster as the Sun expands it's boarders as it ages?[This message has been edited by Lizard Breath, 12-01-2003]

Do you use a telescope to observe something like that happening and then try to come up with a mathmatical model that explains it.What I gather Science is doing is kind of like someone copying a painting in a catalog onto a wall. You place a transparency over the picture and trace around it and then project the transparency onto a wall and paint within the lines to match what the painting looks like. The transparency is the principles of mathmatics, the tracing is the individual formulas and the filling in is the multitudes of redundant calculations within the formulas. If the picture on the wall matches the painting, then the model is deemed sufficient to explain what you are observing through the telescope.Is this illustration correct or am I not doing the math model concept justice with this type of comparison?

No - the solar wind effect on the Earth is utterly negligible from a dynamical perspective.Eventually as the Sun expands, if it envelops the Earth the Earth will slowly spiral inwards and be destroyed.By the way, the math for asteroid deflection is easy. I can do that sort of calculation on the proverbial 'back of an envelope'. Well roughly anyway.The difficulty is solving the magnetohydrodynamical equations for an accretion disc plus condensing protoplanets and an irradiating stellar radiation field.

Well the models try to be more fundamental than that. Yes observation is a tool - after all you need to be able to reproduce them - but we don't have the capability to image another forming solar system - or at least not at the level of detail you are thinking of.Plus we try to build models from the ground up. Starting with the basic physics.Sleepy time for me.Bye for now.

Good evening,Thanks for taking all of the time you did to answer my questions. Have a good day tomorrow.The Lizard

I hope I'm not being redundant with my question - if so, please forgive me.Lizard asked some great questions and one of them sparked my question.Basically, what causes a collapsing/contracting stellar(?) cloud to begin spinning? Does it start from zero motion or like the ice skater, was there already some motion [or momentum] in that direction?

I was thinking the same thing as I recalled the Winter Olympics.BTW, what's this figure skating "Battle on the Ice" thing they are plugging on TV. Are they going to actually fight on the ice while doing jumps and flips? Will the penalty box be open? At least they won't have to waste time ripping off their gloves like the NHL.

It's too bad Eta has gone to bed. I have realized that I have a mental picture of the process that I have kinda made up over the years and it may not be right. I'll post it here and he can correct me if I'm waaaay off base.I picture a large cloud of dust and stuff. It has a lot of more or less random motion of the individual bits. But the chance of the sum of all those producing exactly zero angular momentum has to be pretty damn low, don't you think?As they start to collapse they interact and a spin axes starts to be defined around what would have been the mathematical axis when they were only weakly interacting due to gravity. They interact gravitationly enough to produce a collapsing cloud in which particles with the right momentum "spin out" (faster ones perpendicular to the spin axis and not directed away from the center). This produces and equatorial bulge.What I'm picturing is there are somewhat more particles in one plane (which is what would have to be true if there is a net angular momentum). That produces a gravitational pull to that plane for the others. So there is finally a "real" equalorial plane which is the bulge.Now finally, the ice skater effect can start to work just as we would visualize it.Mmmmm another thought just came to me. This whole cloud is already going to have some rotation since one side of it is a little further out in the galatic disk than the other. Does that work? Could it be that the angular momentum of the solar system is, partially, derived from the rotation of the galaxy?Ok, I give up. Time for someone who actually knows what he is talking about to take over.

You are basically correct. The odds of the initial cloud having zero angular momentum is, well, zero.Just by interactions with other bodies gravitationally will induce some motion. And even if this is very small because the collapse takes place over a large range of radius then the net angular momentum will be considerable. In fact too much in a naieve approach to the model.It would be like an ice skater having 200 mile long arms, if they pulled those in their angular velocity would be incredible.Yes, as the cloud spins up a disc is the most likely structure. There is a whole branch of fluid mechanics dedicated to the stability of rotating fluid spheroids. This was done several centuries ago by Maclaurin and then Jacobi.No the net effect of the differential rotation of the galaxy really would not be applicable here. The initial cloud would be too small for such an effect to have any import here.The properties of the initial cloud itself would be the determining factor BUT this information is really lost in the collapse. It's not a problem that really could be evolved backwards from today's conditions to predict the earliest events.

Thanks Nosy and Eta for helping me out here.Unless the adjacent space was unequal in it's distribution of other cosmic bodies, wouldn't the combined gravity cancel each other out? Unless it's interacting with the closest body, I suppose. So angular momentum is induced by locally adjacent stellar bodies?What about in a controlled environment, do the combined properties of particles in motion and collapse/contraction always result in a spinning motion? If so, why/how? Is the direction quantifiable or random? Is it related to the tendency for particles to seek order? Is it a conservation of energy thing?(I'm just throwing things out there.)

May curses be upon their houses.....I remember those suckahs from calculus and Diff. E., and that's been a long time now...

1. How old do you estimate a complete operating suddenly created sun would look like such as our sun in order to do what it is doing for the earth?2. As I was reading I see you admitted the word "hypothesis" in explanation of the cloud. Isn't that still the case with both the old and the new sun arguments?[This message has been edited by buzsaw, 12-14-2003]

OK I don't want to get crossed wires again so please explain your questions more clearly.

Well then let's go with question one. What don't you understand about the question?