Can anything fall into the Sun?

[Robittybob1]

We're dealing with dust the size of sand on a beach, ever try heating one side and keeping the other side significantly cooler. Wouldn't take long for heat convection to balance the temperature.

 

Dust usually has some spin in space, minute variations in temperature, collisions with other particles impart spin. Follows the conservation of angular momentum just like any other object. I seriously doubt you would find a significant % of dust without some rotation.

 

Would actually be an extremely small %

Remember the size. 1 µm to 1 mm in diameter.= dust..or grains of sand if you prefer

The Poynting Robertson metric only affects this size range. However as this size range gradually conglomerates to larger rocks, such as the proto plasma disk, having a significant reduction of dust available prevents formation of larger bodies such as planets.

( This is where the debate on the lifetime of dust is so vital and highly contested.)

Very interesting. I have never worked with or considered these aspects before. OK, so something like an x ray hits one atom on a spinning dust particle, the atom heats up and the heat spreads (conduction) and radiates (radiation back into space) how much has it spun while this is happening? How instantaneous is it?

[Mordred]

 

 

Here lets do a fast and dirty breakdown of solar formation.(probably lead to some corrections lol)

 

Start with an isothermal sphere of plasma that is homogeneous and istotropic. Hit the plasma with a significant influence. One conjecture is a shock waves from a nearby super nova.

 

This causes anistropies. Aids in star formation as a higher density region of gas will condense due to gravity. Now as the sun condenses from all the gas particles conservation of momentum applies. Each particle imparts a minute influence on its rotation. It starts to spin. As it is the greatest mass other particles start orbitting that body. This orbitting causes the isothermal sphere to flatten into a disk. Density increases as the materials from the isothermal sphere compresses into the disk.

 

This allows particles to interact and combine in dust and asteroids. Larger asteroids start gathering other material via gravity. Now here is an important factor f=ma. Different particles start seperating into regions. (Same method as you can spin blood to seperate white blood cells, plasma and red blood cells). Different elements will develop different orbits.

 

However the force influence itself moves faster than the particles. So much like how galaxies form and the if Saturn form is via density waves.

 

Ever wonder why gas giants are where they are? Why different planets have different compositions?

 

Now the Sun has influence such as the ones mentioned in this thread, this causes a limit on planet formation.

 

 

There you have it extremely rough and dirty lol not my usual style.

Very interesting. I have never worked with or considered these aspects before. OK, so something like an x ray hits one atom on a spinning dust particle, the atom heats up and the heat spreads (conduction) and radiates (radiation back into space) how much has it spun while this is happening? How instantaneous is it?

Depends on the rate of temperature change primarily and duration of temperature variations

As well as the rate of spin prior to the xray (photon ) hitting it.

As well as trajectory of the photon.

All electromagnetic interactions are mediated via photons

( good way to understand conservation of angular momentum, study the game pool)

Also teaches deflection angles

 

 

Side note this has gone beyond the subject of the thread, however excellent information is coming from the side notes. Hopefully the mods allows a continuation or split the threads into its individual subjects.

(As you are showing a keen interest in learning the full physics. Albeit some misconceptions I have awarded you 3+

[Robittybob1]

Here lets do a fast and dirty breakdown of solar formation.(probably lead to some corrections lol)

 

Start with an isothermal sphere of plasma that is homogeneous and istotropic. Hit the plasma with a significant influence. One conjecture is a shock waves from a nearby super nova.

 

This causes anistropies. Aids in star formation as a higher density region of gas will condense due to gravity. Now as the sun condenses from all the gas particles conservation of momentum applies. Each particle imparts a minute influence on its rotation. It starts to spin. As it is the greatest mass other particles start orbitting that body. This orbitting causes the isothermal sphere to flatten into a disk. Density increases as the materials from the isothermal sphere compresses into the disk.

 

This allows particles to interact and combine in dust and asteroids. Larger asteroids start gathering other material via gravity. Now here is an important factor f=ma. Different particles start seperating into regions. (Same method as you can spin blood to seperate white blood cells, plasma and red blood cells). Different elements will develop different orbits.

 

However the force influence itself moves faster than the particles. So much like how galaxies form and the if Saturn form is via density waves.

 

Ever wonder why gas giants are where they are? Why different planets have different compositions?

 

Now the Sun has influence such as the ones mentioned in this thread, this causes a limit on planet formation.

 

 

There you have it extremely rough and dirty lol not my usual style.

 

Depends on the rate of temperature change primarily and duration of temperature variations

As well as the rate of spin prior to the xray (photon ) hitting it.

As well as trajectory of the photon.

All electromagnetic interactions are mediated via photons

( good way to understand conservation of angular momentum, study the game pool)

Also teaches deflection angles

 

 

Side note this has gone beyond the subject of the thread, however excellent information is coming from the side notes. Hopefully the mods allows a continuation or split the threads into its individual subjects.

(As you are showing a keen interest in learning the full physics. Albeit some misconceptions I have awarded you 3+

As I have said I have been working on a new concept of planet building process so I read what you say, and some of it still aligns with what I am proposing, but it is an ever changing topic as more and more is learned about the exoplanets (discovered around other stars).

Previously Janus and I discussed how fast the nebula had to collapse on another site, and it was quite incredible the speeds that the material had to attain to cover the vast distances involved in the original nebula and for it to all contract into the protosun in a period of 100,000 years or so. The material certainly couldn't get involved in any serious orbital motion or else it just wouldn't have made it. I don't see his posts around so much lately. It has been too much to remember it all, but from time to time I look up old threads and reminisce.

Thanks for the rep points.

Edited April 29, 2015 by Robittybob1

[Jazzy.Simba]

Nothing can fall into the sun, either a: the object has a smaller mass than the sun, it would be captured by its orbit or b: the object has more mass than the sun, the sunn would be captured by the other objects gravity

[Mordred]

Incorrect, the sun is no different than any other gravitational body such as planets. We certainly do have meteorites that strike the Earth. Yes objects can fall into an orbit but they can also strike the sun depending on its momentum and trajectory.

[Robittybob1]

Incorrect, the sun is no different than any other gravitational body such as planets. We certainly do have meteorites that strike the Earth. Yes objects can fall into an orbit but they can also strike the sun depending on its momentum and trajectory.

My point of the thread was to show the Sun was different that other cold gravitational bodies. The extreme heating that an object is subjected to as it goes through the atmosphere of the Sun reduces most objects to molecules which are then blown away in the Solar Wind.

Really massive objects might still be able to get through to the body of the Sun. There would be limits on how much could be evaporated in the limited time of an impact. Those events would be rare.

[Mordred]

Nothing can fall into the sun, either a: the object has a smaller mass than the sun, it would be captured by its orbit or b: the object has more mass than the sun, the sunn would be captured by the other objects gravity

My last post is in response to the above.

 

Don't forget only charged particles can be accelerated via the solar winds.

[Robittybob1]

My last post is in response to the above.

 

Don't forget only charged particles can be accelerated via the solar winds.

Heating of molecules can rip electrons off them and make them charged and one thing bumps into another and before you know it the whole mass of gas is moving even if it was the charged ions that were accelerated first and foremost. But I stand to be corrected. Thanks.

[Strange]

My point of the thread was to show the Sun was different that other cold gravitational bodies. The extreme heating that an object is subjected to as it goes through the atmosphere of the Sun reduces most objects to molecules which are then blown away in the Solar Wind.

Really massive objects might still be able to get through to the body of the Sun. There would be limits on how much could be evaporated in the limited time of an impact. Those events would be rare.

Any evidence or data to support this?

[Robittybob1]

Any evidence or data to support this?

Doesn't the solar wind strip molecules of the Earth and Mars? If this removes atmosphere off the distant planets the same would be happening on the Sun. I read the solar wind contains all the elements (a vast range at least) so where do they come from?

If you were to look closely at the photos referenced earlier that was visual evidence that most incoming comets had trouble get through to the body of the Sun. The heat of the Corona (I suppose) is just too hot for the comet to survive as a body (in the cases I've seen) and they seem to be gasified and blown away from the Sun's atmosphere.

Well that is my understanding of what I see. But how would this be proven?

Edited May 20, 2015 by Robittybob1

[Strange]

Doesn't the solar wind strip molecules of the Earth and Mars? If this removes atmosphere off the distant planets the same would be happening on the Sun. I read the solar wind contains all the elements (a vast range at least) so where do they come from?

 

As the Earth still has an atmosphere this provides no support at all for the claim that "the atmosphere of the Sun reduces most objects to molecules which are then blown away in the Solar Wind".

[Robittybob1]

 

As the Earth still has an atmosphere this provides no support at all for the claim that "the atmosphere of the Sun reduces most objects to molecules which are then blown away in the Solar Wind".

Have you followed the whole thread?

[Strange]

Have you followed the whole thread?

 

I haven't read every post. (But I suspect that, like most of your threads, the same arguments are made repeatedly ... )

 

Does that matter? I haven't seen any evidence for your claim that "the atmosphere of the Sun reduces most objects to molecules which are then blown away in the Solar Wind".

[Acme]

...If you were to look closely at the photos referenced earlier that was visual evidence that most incoming comets had trouble get through to the body of the Sun. The heat of the Corona (I suppose) is just too hot for the comet to survive as a body (in the cases I've seen) and they seem to be gasified and blown away from the Sun's atmosphere.

Well that is my understanding of what I see. But how would this be proven?

What I posted was 1 movie -not a photo- of a comet striking the Sun. Nothing in that movie indicates the comet slowed or otherwise had any 'trouble'. Moreover, there are many such movies which I linked to and not all such recorded comet strikes have coincident CMEs or other solar eruptions in the area of the strike. IIRC, in one recorded strike there was an eruption on the opposite side and the experts commented there was no known mechanism that would associate that eruption with the comet impact. Obviously that opposite eruption would not be blowing any of the comet material back into space.

[Strange]

Have you followed the whole thread?

 

So clearly I should have read more: evidence has been posted that demonstrates you are wrong, and yet you are maintaining the same position. How does that work?

[Acme]

I would also point out that since CMEs and flares originate from the surface of the Sun, that IF comets were causing them they would have to hit that surface.

[Acme]

In spite of Phil in the above video saying some comets hit the Sun, (and in spite of my same claim) I found detailed analysis that says only the most massive comets could impact the surface, i.e. the photosphere. Nonetheless, this analysis does not say or suggest that a 'sun-striker' comet's mass is ejected by the solar wind in toto at the time of the impact. As I earlier said, that mass is in effect added to the mass of the Sun.

Mass Loss, Destruction and Detection of Sun-grazing and -impacting Cometary Nuclei

Abstract
[Abridged] Sun-grazing comets almost never re-emerge, but their sublimative destruction near the sun has only recently been observed directly, while chromospheric impacts have not yet been seen, nor impact theory developed. Employing simple analytic models to describe comet destruction near the Sun and to enable the estimation of observable signatures, we find analytic solutions for the mass as a function of distance from the Sun, for insolation sublimation, impact ablation and explosion. Sun-grazers are found to fall into three regimes based on initial mass and perihelion: sublimation-, ablation-, and explosion-dominated. Most sun-grazers are destroyed sublimatively, and our analytic results are similar to numerical models. Larger masses (>10¹¹g) with small perihelion (q<1.01Rsun) ablation dominates but results are sensitive to nucleus strength, P_c, and entry angle to the vertical, phi.
Nuclei with initial mass >~10¹⁰g (P_c/10⁶ (dyne/cm^{^}2) sec (phi))³ are fully ablated before exploding, though the hot wake itself explodes. For most sun-impactors sec(phi)~1. For small perihelion the ablation regime applies to moderate masses ~10^13-16 g impactors unless P_c is very low. For higher masses, or smaller perihelia, nuclei reach higher densities where ram pressure causes catastrophic explosion. For perihelion < 1.01Rsun, initial mass > 10¹¹ g nuclei are destroyed by ablation or explosion (depending on phi and P_c) in the chromosphere, producing flare-like events with cometary abundance spectra. For all plausible masses and physical parameters, nuclei are destroyed above the photosphere.

The entire article in PDF format is here: Mass Loss, Destruction and Detection of Sun-grazing and -impacting Cometary Nuclei Edited May 21, 2015 by Acme

[Mordred]

I definitely enjoyed the last paper, it's well thought out and detailed. Thanks for posting it. Going to add it to my archives

[Acme]

I definitely enjoyed the last paper, it's well thought out and detailed. Thanks for posting it. Going to add it to my archives

You're welcome. I saved it too and I'm still reading it around other activities and thought of quoting some at length but the notation doesn't copy/paste well to this format and I don't have the time just now to do the editing. Nonetheless, I found this bit on page 3 telling:

...So ablated dust and ions stop abruptly and form an exploding wake as they blend with and heat the atmosphere, creating large local enhancements of heavy element abundances. ...

[Spring Theory]

Haven't seen a discussion of the tidal forces of the sun. An important aspect of anything falling into a large mass is the extreme tidal forces on the falling object (or grazing object) that tends to cause it to break apart. This is the result of the difference in gravitational force across the cross section of the falling body is greater than the forces holding the body together.

 

Anything can fall into the sun - just most of it will arrive there in pieces.

Edited May 21, 2015 by Spring Theory

[Acme]

Haven't seen a discussion of the tidal forces of the sun. An important aspect of anything falling into a large mass is the extreme tidal forces on the falling object (or grazing object) that tends to cause it to break apart. This is the result of the difference in gravitational force across the cross section of the falling body is greater than the forces holding the body together.

 

Anything can fall into the sun - just most of it will arrive there in pieces.

Tidal forces are mentioned in the study above. [bolding mine]

The processes leading to sublimation of the icy conglomerate mix (Whipple 1950) of cometary nuclei, and in some cases their splitting and fragmentation, were considered by Huebner (1967), Weissman and Kieffer (1981), Weissman (1983), Iseli et al. (2002), Sekanina (2003) and others. These models essentially solve for the insolative sublimation mass loss rates of icy-conglomerate mixes (the dust being carried away in the flow of these evolved components). They variously allow for the complicating factors of rotation, albedo, insulating surface dust layers, radiative cooling, interior thermal conduction, and fragmentation by tidal, thermal and volatile explosion effects. Huebner (1967) and Iseli et al. (2002), for example, found that, for high sublimation rates near the sun, these effects were secondary, the mass loss being reasonably approximated by a pure sublimation description : mass loss rate = heating rate/latent heat.

Jupiter not having the heat of a star, the tidal forces were not secondary for Comet ShoemakerLevy 9 which broke up before impact of the planet.

[imatfaal]

Haven't seen a discussion of the tidal forces of the sun. An important aspect of anything falling into a large mass is the extreme tidal forces on the falling object (or grazing object) that tends to cause it to break apart. This is the result of the difference in gravitational force across the cross section of the falling body is greater than the forces holding the body together.

 

Anything can fall into the sun - just most of it will arrive there in pieces.

 

Tidal forces are mentioned in the study above. [bolding mine]

 

Jupiter not having the heat of a star, the tidal forces were not secondary for Comet ShoemakerLevy 9 which broke up before impact of the planet.

 

Sorry - can you double check that tidal forces are important?

 

The difference in acceleration between two objects - say a metre or so apart will be of the order of fractions of millimetres per second per second at the "surface". Most objects will withstand that sort of direct linear pull

 

calcs

 

Tidal Accel equal to Delta r * 2 * G * M / R^3

 

so very roughly you get (10^-11) * (10^30) / (10^8)^3 which is something times 10^-5

 

I think break up tends to occur when in orbit, because of tumbling, and (especially non-uniform) heating

[Acme]

Sorry - can you double check that tidal forces are important?

The difference in acceleration between two objects - say a metre or so apart will be of the order of fractions of millimetres per second per second at the "surface". Most objects will withstand that sort of direct linear pull

calcs

Tidal Accel equal to Delta r * 2 * G * M / R^3

so very roughly you get (10^-11) * (10^30) / (10^8)^3 which is something times 10^-5

 

I think break up tends to occur when in orbit, because of tumbling, and (especially non-uniform) heating

Just reporting what I read at the time. Here's something on Shoemaker Levy 9 breakup written before impact that leaves the question open. Keep in mind how fragile comets are and that they tend to be irregularly shaped.

The Comet About to Smash into Jupiter

...On July 7, 1992, Comet Shoemaker-Levy 9 passed only 25,000 kilometers (15,500 miles) above the clouds of Jupiter, according to the latest calculations. The differential pull of the planet's enormous gravitational force on the near and far sides of the comet fragmented it into 21 or more large pieces and an enormous amount of smaller debris. It had been in a rapidly changing orbit around Jupiter for some time before this, probably for at least several decades. It did not fragment during earlier approaches to Jupiter, however, because these were at much greater distances than that of 1992; the comet probably approached no closer than about nine million kilometers in the orbit prior to that of 1992.

 

It is unlikely that the exact circumstances of the breakup of Shoemaker-Levy 9 will ever be known with certainty. But one model suggests that the original comet cannot have been much smaller that 9 kilometers (6 miles) in diameter and that it probably was rotating quite rapidly (perhaps once every eight hours.) The breakup and subsequent collisions between the fragments were not completed until about two hours after closest approach to Jupiter. All of the large fragments were soon strung out in nearly a straight line that pointed at Jupiter, and they will remain so until colliding into the planet.

 

At discovery in March 1993, the train of fragments was about 50 arcseconds or 162,000 kilometers in length as projected on the sky. (A circle is divided into 360 degrees, each degree into 60 minutes, and each minute into 60 seconds. The word "arc'' is added to denote angular measure rather than time. For example, the diameter of the Moon is about 30 arcminutes.) This linear distance had increased by about 50 percent by the time the comet was lost in the glare of the Sun in July 1993. The spreading is caused mainly by the fact that the piece closest to Jupiter at breakup was some nine kilometers closer than the farthest piece ( the diameter of the comet) and therefore entered a faster orbit. The fragment nearest to Jupiter at breakup remains nearest to it and will be the first to impact. Astronomers predict that the train will reach an apparent length of some 1,286 arcseconds at the time the first of the fragments enters Jupiter's atmosphere. The true length of the train will be 4,900,000 kilometers, and it will require 5.5 days for all of the major fragments to impact.

...

[imatfaal]

Uni G Const 6.67E-011 m3kg-1s-2

Mass_jupiter 2.00E+027 kg

Mass_test 1 kg

Radius 1 95,000,000 m

Radius 2 95,009,000 m

+GMm/R_1^2 14.7811634349 N

+GMm/R_2^2 14.7783631913 N

Delta F -2.80E-003 N

 

Force differential over 9km which is far the largest estimate I can find is still in the millinewtons range. Will have to read more

[Robittybob1]

Uni G Const 6.67E-011 m3kg-1s-2

Mass_jupiter 2.00E+027 kg

Mass_test 1 kg

Radius 1 95,000,000 m

Radius 2 95,009,000 m

+GMm/R_1^2 14.7811634349 N

+GMm/R_2^2 14.7783631913 N

Delta F -2.80E-003 N

 

Force differential over 9km which is far the largest estimate I can find is still in the millinewtons range. Will have to read more

Are you using the theory of the Roche Limit? http://en.wikipedia.org/wiki/Roche_limit

Typically, the Roche limit applies to a satellite's disintegrating due to tidal forces induced by its primary, the body about which it orbits. Parts of the satellite that are closer to the primary are attracted by stronger gravity from the primary, whereas parts farther away are repelled by stronger centrifugal force from the satellite's curved orbit. Some real satellites, both natural and artificial, can orbit within their Roche limits because they are held together by forces other than gravitation. Objects resting on the surface of such a satellite would be lifted away by tidal forces. A weaker satellite, such as a comet, could be broken up when it passes within its Roche limit.

 

in most cases the object falling toward the Sun is attempting to orbit the Sun's mass.

Edited May 22, 2015 by Robittybob1