Planet Formation

[ccwebb]

I came across this article that talks about how in the HL Tauri system new planets can be seen forming around the star. Then later in the article it gives a link to "Its always wind around this baby star"

 

http://news.discovery.com/space/astronomy/revolutionary-new-view-of-baby-planets-forming-around-a-star-141106.htm

 

http://news.discovery.com/space/astronomy/its-always-a-windy-day-around-this-baby-star-14092.htm

 

 

Here is my question: Space is affected by mass, that space gets 'dimpled' by the planets thus giving us gravity.

 

How then can dust particles and small rocks create enough of a gravity well that will prevent the solar wind from blowing it away? How can gravity, a weak force already, have any kind of influence on dust and small particles if there is a stronger force that would seem to prevent it?

[MigL]

The small 'dimples' created by the dust and small particles don't matter.

Its the BIG dimple created by the star that's preventing them from being blown away.

[mathematic]

The "wind" is not like wind on earth. It consists of high energy particles originatiing in the star. Unless they come very close to a dust particle, the dust particle is unaffected.

[Robittybob1]

I came across this article that talks about how in the HL Tauri system new planets can be seen forming around the star. Then later in the article it gives a link to "Its always wind around this baby star"

 

http://news.discovery.com/space/astronomy/revolutionary-new-view-of-baby-planets-forming-around-a-star-141106.htm

 

http://news.discovery.com/space/astronomy/its-always-a-windy-day-around-this-baby-star-14092.htm

 

 

Here is my question: Space is affected by mass, that space gets 'dimpled' by the planets thus giving us gravity.

 

How then can dust particles and small rocks create enough of a gravity well that will prevent the solar wind from blowing it away? How can gravity, a weak force already, have any kind of influence on dust and small particles if there is a stronger force that would seem to prevent it?

The thing I object to is the statement in the article:

 

Observed by the powerful Atacama Large Millimeter/submillimeter Array (ALMA) in Chile, this is the most detailed view of the proto-planetary disk surrounding a young star 450 light-years away. And those concentric rings cutting through the glowing gas and dust? Those, my friends, are tracks etched out by planets being spawned inside the disk.

There is no reason a planet would orbit any faster that the gas dust rings themselves so why would they clear tacks?

Unless I am misunderstanding what they mean by "tracks etched out by planets".

 

Your question:

 

How then can dust particles and small rocks create enough of a gravity well that will prevent the solar wind from blowing it away? How can gravity, a weak force already, have any kind of influence on dust and small particles if there is a stronger force that would seem to prevent it?

My answer is that they can't so that is why close-in planet building has to occur prior to the T.Tauri stage, and prior to main sequence stages unless the matter is at extreme distances. Like I would say for our Solar System Mercury, Venus, Earth and Mars were pre- T.Tauri but the Asteroid belt was in the planet forming process at the time of the strong solar wind (T. Tauri stage). Jupiter and planets further out were formed later from the material blown further out by the wind.

[These views are based on my own analysis and differ from what has been said before, but there is plenty of

acknowledgement that the planet build process needed to be reassessed.]

Edited April 24, 2015 by Robittybob1

[Endy0816]

I know static electricity is thought to play a role early on.

[pavelcherepan]

 

 

How then can dust particles and small rocks create enough of a gravity well that will prevent the solar wind from blowing it away? How can gravity, a weak force already, have any kind of influence on dust and small particles if there is a stronger force that would seem to prevent it?

 

Generally most models show that initial coalescence of planetesimals is due to collisions of dust particles moving on highly elliptical orbits. Only when they're big enough - 10-1000 km in diameter a runaway growth labelled "oligarchic growth" stage begins where gravity is the leading cause of accretion.

 

ccwebb, have a look at these studies. I think they might help:

 

http://www.pnas.org/content/108/48/19165.full

http://books.google.com.au/books?hl=en&lr=&id=VlSVmxgPgGYC&oi=fnd&pg=PA297&dq=terrestrial+%26+formation&ots=-qic0--Ttp&sig=T-Wqi7VJr7XcQUhyO-Y1D3GH_d8&redir_esc=y#v=onepage&q=terrestrial%20%26%20formation&f=false

http://iopscience.iop.org/0004-637X/642/2/1131/pdf/0004-637X_642_2_1131.pdf

 

 

Like I would say for our Solar System Mercury, Venus, Earth and Mars were pre- T.Tauri but the Asteroid belt was in the planet forming process at the time of the strong solar wind (T. Tauri stage). Jupiter and planets further out were formed later from the material blown further out by the wind.

[These views are based on my own analysis and differ from what has been said before, but there is plenty of

acknowledgement that the planet build process needed to be reassessed.]

 

Robittybob1, I'd suggest you keep your unproven ideas away from accepted science forums.

[Robittybob1]

 

Generally most models show that initial coalescence of planetesimals is due to collisions of dust particles moving on highly elliptical orbits. Only when they're big enough - 10-1000 km in diameter a runaway growth labelled "oligarchic growth" stage begins where gravity is the leading cause of accretion.

 

ccwebb, have a look at these studies. I think they might help:

 

http://www.pnas.org/content/108/48/19165.full

http://books.google.com.au/books?hl=en&lr=&id=VlSVmxgPgGYC&oi=fnd&pg=PA297&dq=terrestrial+%26+formation&ots=-qic0--Ttp&sig=T-Wqi7VJr7XcQUhyO-Y1D3GH_d8&redir_esc=y#v=onepage&q=terrestrial%20%26%20formation&f=false

http://iopscience.iop.org/0004-637X/642/2/1131/pdf/0004-637X_642_2_1131.pdf

 

 

Robittybob1, I'd suggest you keep your unproven ideas away from accepted science forums.

Shall we do the maths then? I feel very confident that the ideas I have been working on for 15 years are as valid as other models. I'll take your advice and stick to the other thread http://www.scienceforums.net/topic/88686-was-the-earth-formed-as-an-accretion-disc/

 

I did see some interesting figures (last couple of days) for the power of the T. Tauri winds and it was quite incredible. I must see if I can locate them again.

Edited April 24, 2015 by Robittybob1

[Greg H.]

The thing I object to is the statement in the article:

There is no reason a planet would orbit any faster that the gas dust rings themselves so why would they clear tacks?

Unless I am misunderstanding what they mean by "tracks etched out by planets".

 

You see the same thing with the so called "shepherd" moons in a planetary ring system. It's down the ever increasing gravity of the proto planet perturbing the orbits of the particles nearest its orbit. These perturbations result in a path clearing that lines the orbit or the larger mass. As the mass continues to increase, it affects a wider area more noticeably. Once a balance is reached, you get what we see (for instance) around Saturn, sharply defined rings with little grooves in them where the moons are.

 

Also remember that not all particles in an orbit around a star will have the same velocity. As the mass of the protoplanet increases, so does its gravitational attraction to the star. In order to maintain a stable orbit it has to increase its orbital velocity (if I remember my physics correctly), otherwise the increased attraction just causes it to spiral into the star (and leave lines like a spirograph, not an etch a sketch).

[ccwebb]

ccwebb, have a look at these studies. I think they might help:

 

http://www.pnas.org/content/108/48/19165.full

http://books.google.com.au/books?hl=en&lr=&id=VlSVmxgPgGYC&oi=fnd&pg=PA297&dq=terrestrial+%26+formation&ots=-qic0--Ttp&sig=T-Wqi7VJr7XcQUhyO-Y1D3GH_d8&redir_esc=y#v=onepage&q=terrestrial%20%26%20formation&f=false

http://iopscience.iop.org/0004-637X/642/2/1131/pdf/0004-637X_642_2_1131.pdf

 

 

Thank you! I will defiantly look through these.

 

The "wind" is not like wind on earth. It consists of high energy particles originatiing in the star. Unless they come very close to a dust particle, the dust particle is unaffected.

 

The solar wind is responsible for creating the tails of comets.

 

http://hubblesite.org/reference_desk/faq/answer.php.id=18&cat=solarsystem

 

 

Also, it is believed that the solar winds are responsible for Mars' nearly lack of an atmosphere. "For clues, MAVEN will watch to see when and how gas is currently stripped off the top of the atmosphere—a process that is thought to be driven by interactions with the solar wind. “The question is whether over long periods of time this process or any of the other processes that are operating have been responsible for removing most of the gas,” ..."

 

http://www.scientificamerican.com/article/maven-spacecraft-mars-atmosphere/

 

The solar wind has been clocked at over 1 million miles per hour:

 

http://solarscience.msfc.nasa.gov/SolarWind.shtml

 

Then you have this explanation that actual states the solar winds blowing the dust away during the formation of the early solar system. "This is called the solar wind. Radiation pressure and the solar wind in the early solar system essentially blew all the excess gas out of the inner part of the solar system. That is why the terrestrial planets are so small -- the light gases were blown away."

 

http://www2.astro.psu.edu/users/caryl/a10/lec18_2d.html

 

I understand that solar winds having very little affect on planetesimals, now gravity from itself or the sun can prevent it from being blown away, but it appears that solar wind does have a very strong effect on dust size particles. Which now causes me to edit my original question.

Obviously planets form... How did solar wind not prevent this over the time period it take dust to form into planetesimals? The rings of our gas giants have the protection of their hosts' magnetosphere. Dust orbiting a star, does not have that protection.

[Robittybob1]

 

 

The solar wind is responsible for creating the tails of comets.

 

http://hubblesite.org/reference_desk/faq/answer.php.id=18&cat=solarsystem

 

 

Also, it is believed that the solar winds are responsible for Mars' nearly lack of an atmosphere.

 

http://www.scientificamerican.com/article/maven-spacecraft-mars-atmosphere/

 

The solar wind has been clocked at over 1 million miles per hour:

 

http://solarscience.msfc.nasa.gov/SolarWind.shtml

 

Then you have this explanation that actual states the solar winds blowing the dust away during the formation of the early solar system. "This is called the solar wind. Radiation pressure and the solar wind in the early solar system essentially blew all the excess gas out of the inner part of the solar system. That is why the terrestrial planets are so small -- the light gases were blown away."

 

http://www2.astro.psu.edu/users/caryl/a10/lec18_2d.html

 

I understand that solar winds having very little affect on planetesimals, now gravity from itself or the sun can prevent it from being blown away, but it appears that solar wind does have a very strong effect on dust size particles. Which now causes me to edit my original question.

Obviously planets form... How did solar wind not prevent this over the time period it take dust to form into planetesimals? The rings of our gas giants have the protection of their hosts' magnetosphere. Dust orbiting a star, does not have that protection.

Those are good points. Can you think of a time when there is no solar wind?

Edited April 24, 2015 by Robittybob1

[pavelcherepan]

Obviously planets form... How did solar wind not prevent this over the time period it take dust to form into planetesimals? The rings of our gas giants have the protection of their hosts' magnetosphere. Dust orbiting a star, does not have that protection.

 

I'd have to check my info but IIRC dust particles start forming prior to sun starting thermonuclear reactions and once it does, particles are a bit too large to get dragged around by the solar wind easily. Also, it's important to understand that even though solar wind moves very fast but it consists mostly of single protons and electrons and the particle density is extremely low, so much that to us it's a very high quality vacuum. It can, over time, make inner system depleted of light gases but can't really affect larger particles so much.

[Robittybob1]

You see the same thing with the so called "shepherd" moons in a planetary ring system. It's down the ever increasing gravity of the proto planet perturbing the orbits of the particles nearest its orbit. These perturbations result in a path clearing that lines the orbit or the larger mass. As the mass continues to increase, it affects a wider area more noticeably. Once a balance is reached, you get what we see (for instance) around Saturn, sharply defined rings with little grooves in them where the moons are.

 

Also remember that not all particles in an orbit around a star will have the same velocity. As the mass of the protoplanet increases, so does its gravitational attraction to the star. In order to maintain a stable orbit it has to increase its orbital velocity (if I remember my physics correctly), otherwise the increased attraction just causes it to spiral into the star (and leave lines like a spirograph, not an etch a sketch).

OK but those shepherd moons are still orbiting slower than the stuff closer in. Each radius has a specific orbital speed.

I tend to think of the material in the protoplanetary disc as having enough angular momentum to remain in the disk so the proto-sun is not increasing in mass. Once the Sun starts shining there is a net loss of mass all the time after that isn't there?

Even if masses of comets etc fell into the Sun it is not going to increase in mass, for there comes a time when the loss of mass due to radiation (heat loss and light) is much greater.

 

I'd have to check my info but IIRC dust particles start forming prior to sun starting thermonuclear reactions and once it does, particles are a bit too large to get dragged around by the solar wind easily. Also, it's important to understand that even though solar wind moves very fast but it consists mostly of single protons and electrons and the particle density is extremely low, so much that to us it's a very high quality vacuum. It can, over time, make inner system depleted of light gases but can't really affect larger particles so much.

But once the gases start moving would that not be like faced with a real wind? Those pictures in the OP show masses of dust being shifted.

....

How then can dust particles and small rocks create enough of a gravity well that will prevent the solar wind from blowing it away? How can gravity, a weak force already, have any kind of influence on dust and small particles if there is a stronger force that would seem to prevent it?

That to me is the clue. For it suggests compression. You've got the Solar winds blowing outward in one direction and gravity and inertia acting in the other, so in the interior of these "storms" the material will be under enormous pressures.

Edited April 24, 2015 by Robittybob1

[Greg H.]

Even if masses of comets etc fell into the Sun it is not going to increase in mass, for there comes a time when the loss of mass due to radiation (heat loss and light) is much greater.

 

How much mass do heat and light have exactly?

 

And if you do the maths. the amount of mass lost by fusion is nearly negligible compared to the total mass of the sun.

 

See: http://solar-center.stanford.edu/FAQ/Qshrink.html

Edited April 24, 2015 by Greg H.

[MigL]

Solar radiation essentially imparts kinetic energy to dust and gas which is trapped by the gravitational well of the star.

This kinetic energy causes lighter mass particles/molecules/ atoms to move farther up ( more distant ) the gravitational well.

In the case where gravitational wells of rocky planets reside within the huge well of the star, this kinetic energy is sometimes, enough to exceed the escape velocity of the planet.

That is why there is very little Hydrogen or Helium on Earth, and why Mercury is devoid of gaseous atmosphere. A massive distant planet planet like Jupiter or Saturn, on the other hand can retain all of its light elements in the atmosphere. The mean free speeds of the constituent molecules don't exceed escape velocity.

[Robittybob1]

 

How much mass do heat and light have exactly?

 

And if you do the maths. the amount of mass lost by fusion is nearly negligible compared to the total mass of the sun.

 

See: http://solar-center.stanford.edu/FAQ/Qshrink.html

That could be right, but only a very minute amount of the mass of the Solar System is in the form of comets so my guess might still be right, that the Sun is always losing mass not gaining it. The next major mass loss from the Sun was in the form of matter ejected in those Coronal Mass Ejections (CME). They might even account for a higher mass loss than from radiation.

So the point of this is that the gravitational force from the Sun is slightly dropping rather than increasing.

Solar radiation essentially imparts kinetic energy to dust and gas which is trapped by the gravitational well of the star.

This kinetic energy causes lighter mass particles/molecules/ atoms to move farther up ( more distant ) the gravitational well.

In the case where gravitational wells of rocky planets reside within the huge well of the star, this kinetic energy is sometimes, enough to exceed the escape velocity of the planet.

That is why there is very little Hydrogen or Helium on Earth, and why Mercury is devoid of gaseous atmosphere. A massive distant planet planet like Jupiter or Saturn, on the other hand can retain all of its light elements in the atmosphere. The mean free speeds of the constituent molecules don't exceed escape velocity.

If your idea of planets forming as accretion disks was right then their rotation rates could be such that the outer gaseous material exceeds orbital speed. If that was the case it would not take as much energy to knock a molecule off a planet.

Edited April 25, 2015 by Robittybob1

[MigL]

I don't follow your reasoning, RobbityBob, why would the outer orbiting gases exceed orbital seed ?

( and if they did they wouldn't be part of any accretion disc )

 

And incidentally, the Sun converts over 4 million tons of mass into energy, due to the mass/energy difference between a Helium nucleus and four Hydrogen nucleii.

And that's every second !!!

[Robittybob1]

I don't follow your reasoning, RobbityBob, why would the outer orbiting gases exceed orbital seed ?

( and if they did they wouldn't be part of any accretion disc )

 

And incidentally, the Sun converts over 4 million tons of mass into energy, due to the mass/energy difference between a Helium nucleus and four Hydrogen nucleii.

And that's every second !!!

It would just move out to a higher orbit where the escape velocity is less.

[ccwebb]

Solar radiation essentially imparts kinetic energy to dust and gas which is trapped by the gravitational well of the star.

This kinetic energy causes lighter mass particles/molecules/ atoms to move farther up ( more distant ) the gravitational well.

In the case where gravitational wells of rocky planets reside within the huge well of the star, this kinetic energy is sometimes, enough to exceed the escape velocity of the planet.

That is why there is very little Hydrogen or Helium on Earth, and why Mercury is devoid of gaseous atmosphere. A massive distant planet planet like Jupiter or Saturn, on the other hand can retain all of its light elements in the atmosphere. The mean free speeds of the constituent molecules don't exceed escape velocity.

 

That makes sense. Then, we find "Hot Jupiters" just to muck everything up!

 

I know the going theory is they formed then got trapped by their accompanying star:

http://www.universetoday.com/109269/what-are-hot-jupiters/

[Robittybob1]

 

That makes sense. Then, we find "Hot Jupiters" just to muck everything up!

 

I know the going theory is they formed then got trapped by their accompanying star:

http://www.universetoday.com/109269/what-are-hot-jupiters/

The speaker thought they could not be formed there, therefore moved there, but could it not have formed there prior to the star going thermonuclear?