Solar Neighborhood Enigma

[Acme]

That movement -the oscillation- has a period of ~33 million years so we cross the galactic plane roughly 7.5 times for every orbit of the galactic center.

[Mordred]

( The bobbing action itself isn't that mysterious. The problem is that there was a rash of correlations to extinction events proposed due to this passing through the galactic plane etc. That got everyone's attention on it.). Not always rational lol.

[Acme]

I've seen this come up on other forums. The hypothesis is that a dark matter disk is involved.

Is this hypothesis something you have a reference for, or is it just from for a speculators?

Also that this passing through the galactic disk also coincides with the extinction of the dinosaurs. Etc etc etc.

That part is exactly the subject of the first paper I cited on the oscillation through the plane. It does not invoke dark matter.

 

Try this thought experiment. Start with our solar systems momentum which has an inclination to the galactic plane.

 

As it approaches the galactic plane it will gain momentum.

 

When it crosses the galactic plane it's momentum carries it past the galactic plane. Then the mass tried to overcome that momentum. The result is it starts losing momentum until it starts heading back towards the plane. (Sinusoidal arc). Then when it passes the galactic plane the same process continues.

Yes.

[Mordred]

That movement -the oscillation- has a period of ~33 million years so we cross the galactic plane roughly 7.5 times for every orbit of the galactic center.

Yeah that's what I understand as well on the frequency. I've seen no counter argument on those figures

[Acme]

( The bobbing action itself isn't that mysterious. The problem is that there was a rash of correlations to extinction events proposed due to this passing through the galactic plane etc. That got everyone's attention on it.). Not always rational lol.

Hold on...I misspoke. I didn't cite the extinction paper. Here that is:VARIABLE OORT CLOUD FLUX

DUE TO THE GALACTIC TIDE

The extinction idea is that Oort cloud comets'/meteoroids' orbits are disturbed and they head into the inner solar system.

Edited September 25, 2015 by Acme

[Mordred]

I understand that, I'm speaking of numerous other related papers I've read on the subject, albeit other forums. If you dig into it there are dozens of articles. They all usually include the solar winds and the Oort cloud. Some include the DM disk hypothesis. Many include extinction events.

 

All of The above isn't strongly supported.

 

The movement itself isn't debated. The effects it has on our solar system, in particular to the extinction events is debatable. However a bit off topic.

Edited September 25, 2015 by Mordred

[Acme]

I understand that, I'm speaking of numerous other related papers I've read on the subject, albeit other forums. If you dig into it there are dozens of articles. They all usually include the solar winds and the Oort cloud. Some include the DM disk hypothesis. Many include extinction events.

Yes; no end of misinterpretation and science popularizing of the grossest misleading kind extant. The Abstract & Summary of the paper I just cited:

Abstract: We review the subject of the time dependence of the component of Oort cloud comet flux due to the adiabatic Galactic tide, including the possibility of detecting such a signal in the terrestrial cratering record.

...

4. Summary

The Galactic tide dominates in making Oort cloud comets enter the planetary region during the present epoch, and likely over long time scales. Substantial modulation of the tidally induced comet flux must occur independent of the existence or non-existence of CDDM. This is due to the adiabatic variation of the local disk density during the Solar cycle. A Galactic oscillations model in which the Solar cycle is manifest in the cratering record will only be sustainable as a working hypothesis if the mean cycle period is found to include the interval 35.5 +- 1.5 Myr. Should the Holmberg-Flynn result be confirmed, we can reject Shoemaker's suggestion that impacts from long-period comets dominate large terrestrial crater formation.

Shoemaker is/was trying to exclude meteoroids as responsible for large impact craters in the solar system.

Whether comet or meteoroid, there is very good evidence for large impacts coincident to extinction events, the Chicxulub crater being of course the first and best known example.

[Mordred]

Oh I agree there is some agreement with possible influences. There is a decent list in this arxiv article.

 

Including Potential coincidence with ice ages and sunspots.

http://www.google.ca/url?sa=t&source=web&cd=5&rct=j&q=LONG-TERM%20VARIATIONS%20IN%20THE%20GALACTIC%20ENVIRONMENT%20OF%20THE%20SUN&ved=0CCUQFjAEahUKEwjqqPCYt5HIAhXCOIgKHcsyDMA&url=http%3A%2F%2Farxiv.org%2Fpdf%2Fastro-ph%2F0601356&usg=AFQjCNEFruciU7uMVzqOOUr70mxLLD3VHQ&sig2=dyrkswouqIWiOo56vY6lrg

Honestly though in my opinion we still need more data on the effects and possible influences.

( granted Shaviv did an excellent correlation to the ice age cycles with the data he had available)

 

 

http://link.springer.com/chapter/10.1007/1-4020-4557-3_5

 

Last link is the pertinant chapter by Shaviv. I bought a copy few years back

By the way +1 for an interesting discussion. ACME

Though if we wish to further discussion the extinction events and possible influences we should start a seperate thread.

We're running the risk of hijacking this thread from the OP

Edited September 25, 2015 by Mordred

[David Levy]

Yes; gravity keeps the solar system and all stars in the arms near the plane.

 

As pointed out in Sensei's link in post #3.

Stars escape velocity shows how to exit the Milky Way

So, even the fastest moving stars in the Milky Way do not have the velocity to escape the galaxy.

Yes. However that is not the oscillation of the solar system through the galactic plane which is what David was asking for clarification on.

 

Thanks

I hope that by now we all agree that gravity keeps the solar system and all stars in the arms near the plane.

The main source for this gravity should be - the nearby mass as stated by Sensei in pg. 5:

 

Stars attract other stars in their neighborhood... They're rotating around their common center of mass.

 

 

However, as stated by Sensei, there must be some center of mass for that nearby mass, (or in our case - the solar neighborhood)

 

This center of mass should be located somewhere in the spiral arm as the solar neighborhood is also located in the arm.

 

This center of mass generates the requested gravity which keeps the solar system and all stars in the arms near the galactic plane.

 

So, the sun might oscillate around this center of mass - up and down.

 

However, I assume that gravity should work in all directions from this center of mass:

 

Up, down, right and left.

 

We have to draw a circle around this center of mass with a radius which represents the maximum allowed amplitude for the sun oscillation.

 

The Sun can't escape from this gravity force at any direction.

 

Do you agree?

Edited September 25, 2015 by David Levy

[Strange]

We have to draw a circle around this center of mass with a radius which represents the maximum allowed amplitude for the sun oscillation.

 

The Sun can't escape from this gravity force at any direction.

 

Do you agree?

No.

 

You (as always) seem to be attempting to use an over-simplified model of gravity.

 

The Sun is part of a local group of stars which can be considered to orbit one another (while, at the same time orbiting the galaxy). But that group and all the stars within it are affected by the surrounding stars (and groups of stars), the surrounding plasma, the surrounding dark matter and the masses of all the objects in the galaxy.

 

In the case of two objects it is simple to calculate the forces between them, their centre of gravity, etc. When you have three (or more) objects then that becomes mathematically impossible. The only way to work out what will happen is to simulate the interactions and movements of the billions of bodies involved. People have done this and found they can reproduce the patterns we observe.

Edited September 25, 2015 by Strange

[Mordred]

The problem your having is thinking multiple body problems should all share a common centre of mass. In point of detail the use of CoM becomes impractical in multibody problems.

 

Place five dots on a sheet of paper (random). Draw as many lines connecting those dots. (You should have four lines per dot)

 

Now assume each dot represents objects of the same mass. So devide each line in half. Each of these points represent a different CoM.

 

The net effect you end up with more Centre of mass relations than the actual number of objects.

Now ask yourself How many different centres of mass relations are involved in the solar system? Count every individual planet/moon system if two moons influence each other count them too. Then count planet/sun, if two planets influence each other count them too.

 

Far too many to mathematically describe under a single Keplar style calculation.

Edited September 25, 2015 by Mordred

[David Levy]

Thanks Mordred

That is perfect explanation.

However, I assume that the nature doesn't need to set that kind complex arithmetic calculation. It should be automatically for each individual star. It doesn't matter if there are two stars, 100 or one million stars in its neighborhood.

So, for each star there might be a different CoM. Please also remember that this CoM moves (with the entire solar Neighborhood) at the average rotation speed of about 250 km per second. So technically, we might assume that each individual star rotate around its virtual CoM while this one moves at a rocket speed around the galactic center.

I estimate that if we could hold that CoM at one place, then we could get a perfect rotation as expected by Kepler or Newton.

Therefore, I assume that the sinusoidal movement of the Sun (and any other nearby star) is a direct outcome of its individual CoM movement.

That might be the solution for the solar enigma.

Please see the following presentation at pg 15 http://www.ifa.hawai...10/MilkyWay.pdf) which I have introduced in the first pg of this thread.

It gives an explanation why we see in our neighborhood stars which are moving at different velocities and different directions. However, even after billion years we might see similar neighborhood.

Edited September 25, 2015 by David Levy

[swansont]

 

I estimate that if we could hold that CoM at one place, then we could get a perfect rotation as expected by Kepler or Newton.

Therefore, I assume that the sinusoidal movement of the Sun (and any other nearby star) is a direct outcome of its individual CoM movement.

That might be the solution for the solar enigma.

 

 

!

Moderator Note

We are not going there. You get to ask questions. You do not get to re-introduce your "solution" to a problem that you have not established exists. We did that already. That discussion is closed.