Amazing image revealing planetary genesis

Awesome photo. So much for the claim that creation was a one-time event. I wonder what deity gets to lord over this system.

Steve S
 
MG1962 said:
Not with this clarity - there have been images of proto discs around for a while, but nothing like this
Click to expand...

slyjoe said:
No. The system is hidden in the visible range, and ALMA (the telescope array) operates in millimeter wavelengths, with the longest baseline (15 km) ever used.
Click to expand...

Thanks. It surprises me that it surprises you guys that there should be early planetary formation. Not that I know anything of the subject but just that I would expect planets to be condensing in the disk right away. Why has it been thought otherwise?
 
It's the first time it's been imaged so clearly. Nobody is surprised by it, just impressed by the image.
 
anglolawyer said:
Thanks. It surprises me that it surprises you guys that there should be early planetary formation. Not that I know anything of the subject but just that I would expect planets to be condensing in the disk right away. Why has it been thought otherwise?
Click to expand...

Yeah it is also a beautiful validation of the theory. Look at it this way we knew women got pregnant for a long time before ultrasound technology came along to show us what it looked like real time - In a sense this is an ultra sound of a solar system being birthed.
 
I'm curious: What would a person see with their eyes if they were cruising through a forming star/planet system like this in a spaceship? Would they at all be able to notice, in any way, the disk of dust?

I'm curious about this because I've heard the "asteroid belt" is not an asteroid thicket like you see in movies (which is silly, because of gravity), and not only is it not so dense, but is so rarefied that were you standing on an asteroid, you could not even see the next asteroid over without a telescope. But I'd imagine the disk on a forming star would be denser and dustier.
 
Last edited:
anglolawyer said:
Thanks. It surprises me that it surprises you guys that there should be early planetary formation. Not that I know anything of the subject but just that I would expect planets to be condensing in the disk right away. Why has it been thought otherwise?
Click to expand...


Because a million years is a fleeting moment in the time-scale of a planetary system; the star has hardly ignited yet. The models suggest that the protoplanetary disk would remain as gas and dust as particles slowly accumulate through direct contact, i.e. with little if any gravitational attraction, and start clumping into masses only a few centimetres in size. It was expected that these would form into clumps up to 200 metres in diameter, which in turn collide to form larger bodies over the next several million years until they form planetesimals around 10km in size.

If what we can see in HL Tauri really is clumping caused by the formation of planet sized bodies, then they are a LOT bigger than 10km in diameter, they would need to already be planet sized bodies for us to be able to see them like this, a stage that was not expected to be reached to for another 5-10 million years. Essentially, this means planetary formation is taking place 5 - 10 times faster than expected.
 
smartcooky said:
If what we can see in HL Tauri really is clumping caused by the formation of planet sized bodies, then they are a LOT bigger than 10km in diameter, they would need to already be planet sized bodies for us to be able to see them like this, a stage that was not expected to be reached to for another 5-10 million years. Essentially, this means planetary formation is taking place 5 - 10 times faster than expected.
Click to expand...

Well as I mentioned early, last year on the ISS one of the visiting scientists did some informal experiments with various types of dust. It was always thought the initial static charge driven step in the process was very slow. They found significant clumping could occur in a matter of minutes.
 
smartcooky said:
Because a million years is a fleeting moment in the time-scale of a planetary system; the star has hardly ignited yet. The models suggest that the protoplanetary disk would remain as gas and dust as particles slowly accumulate through direct contact, i.e. with little if any gravitational attraction, and start clumping into masses only a few centimetres in size. It was expected that these would form into clumps up to 200 metres in diameter, which in turn collide to form larger bodies over the next several million years until they form planetesimals around 10km in size.

If what we can see in HL Tauri really is clumping caused by the formation of planet sized bodies, then they are a LOT bigger than 10km in diameter, they would need to already be planet sized bodies for us to be able to see them like this, a stage that was not expected to be reached to for another 5-10 million years. Essentially, this means planetary formation is taking place 5 - 10 times faster than expected.
Click to expand...

Interesting, thanks. I would think this kind of thing could be accurately modelled by a computer programme: give some virtual objects mass, trajectory and momentum and see how things evolve. Obviously not.
 
anglolawyer said:
Interesting, thanks. I would think this kind of thing could be accurately modelled by a computer programme: give some virtual objects mass, trajectory and momentum and see how things evolve. Obviously not.
Click to expand...


I agree, but as the old saying goes GIGO. The program can only result in an accurate model if the input data, parameters and assumptions are accurate.
 
smartcooky said:
I agree, but as the old saying goes GIGO. The program can only result in an accurate model if the input data, parameters and assumptions are accurate.
Click to expand...

What is the difficulty? Why can't a computer simulate these interactions pretty well? Give the objects a total mass, I dunno how but get them into a rotating disk, switch on gravity and watch what happens. Re - start with slightly different initial conditions. The interactions of snooker balls can be simulated pretty well, even with spin and stun etc. There are computer models for the earth's climate which must be much more complicated. I am obviously missing some uncomputable element(s) but can't think what it/they could be. Scale?

ETA sorry, the answer to my question is in your answer to the last one. There must be a wide range of possible start positions for a solar system in its initial stages. Surely one can try a few. We know the mass of our solar system (?) - start with that, turn it into a dust cloud and set it on spin.
 
Last edited:
anglolawyer said:
What is the difficulty? Why can't a computer simulate these interactions pretty well? Give the objects a total mass, I dunno how but get them into a rotating disk, switch on gravity and watch what happens. Re - start with slightly different initial conditions. The interactions of snooker balls can be simulated pretty well, even with spin and stun etc. There are computer models for the earth's climate which must be much more complicated. I am obviously missing some uncomputable element(s) but can't think what it/they could be. Scale?

ETA sorry, the answer to my question is in your answer to the last one. There must be a wide range of possible start positions for a solar system in its initial stages. Surely one can try a few. We know the mass of our solar system (?) - start with that, turn it into a dust cloud and set it on spin.
Click to expand...

Not only that but as MG1962 hints at in post #35, one of the basic assumptions in the nebular hypothesis of planetary formation might be erroneous. It holds that electrostatic interactions between submicron-sized dust particles in the accretion disk starts the initial clumping of materials, with gravitation taking over as the clump sizes increase. The electrostatic process was thought to take a long time. MG1962 points out that an informal experiment on the ISS found that electrostatic clumping took place a lot quicker than they expected.

On the other side of the coin, there have been studies that would indicate this clumping could be slowed down under certain circumstances.

https://www.cps-jp.org/~dust/Program_IV_files/PS02-A014-PDF.pdf

These conflicting ideas could leave the poor guy who is programming the computer modelling in something of a quandary.
 
Last edited:
smartcooky said:
Not only that but as MG1962 hints at in post #35, one of the basic assumptions in the nebular hypothesis of planetary formation might be erroneous. It holds that electrostatic interactions between submicron-sized dust particles in the accretion disk starts the initial clumping of materials, with gravitation taking over as the clump sizes increase. The electrostatic process was thought to take a long time. MG1962 points out that an informal experiment on the ISS found that electrostatic clumping took place a lot quicker than they expected.

On the other side of the coin, there have been studies that would indicate this clumping could be slowed down under certain circumstances.

https://www.cps-jp.org/~dust/Program_IV_files/PS02-A014-PDF.pdf

These conflicting ideas could leave the poor guy who is programming the computer modelling in something of a quandary.
Click to expand...
Um, yes. Having already swum far out of my depth I shall now retire to the sidelines and watch from afar. Thanks for your replies.
 
You must log in or register to reply here.

Back
Top Bottom