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Therefore, if one arm covers the upper half/almost half of the cycle, while the other arm covers the other half/almost half of the cycle, don't you agree that in the total we get a ring/almost ring
Please look at the following diagram about: NGC 1398: AN UTTERLY PERFECT SPIRAL GALAXYhttps://www.syfy.com/syfywire/ngc-1398-an-utterly-perfect-spiral-galaxyWe clearly see a ring at the center (at the edge of the bar which isn't fully clear).
It is also stated:"NGC 1398 is a barred spiral, with that rectangular-shaped feature running across the core and ending at the inner "ring." This is a common feature in spirals — the Milky Way has a big one — and they can affect how the stars and gas move around the galactic center (I describe this in the earlier post on NGC 1398)."I have no idea what is the radius of that ring or its width, but it shows that there is "inner ring" in barred spiral galaxy as at the Milky Way.
It is quite clear that this "inner ring" has a significant effect on "how the stars and gas move around the galactic center" as I will explain later on.
As I said, I can consider that a ring if you wish, but I see a clear spiral thereGreat! Other people call it a ring. Let's go with that.
So, the ring has almost a perfect cycle shape around the Bar. (Although if we look carefully inside the ring, we see clearly that it has a spiral shape.)Once we agree on that ring, we can now start looking at the structure/velocity of barred spiral galaxy
Let's start with the following question:What kind of gravity force that ring could generate?Let's assume that there is no SMBH at the center.Let's also assume that we set Billion of stars at a perfect ring of 3KPC and hold them ALL at their current position for very long time.(Please don't tell me what will happen to the ring after one minute. This is a theoretical question about stars ring)
What kind of gravity force we might find inside the ring?
Do you agree that all the stars together will set an equivalent gravity force on any object which is located inside that ring?
Therefore:1. If an object is located directly at the center - Do you agree that the impact of the gravity force from the stars in the ring at a distance of 3KPC in one side should cancel the impact of the stars in the other side of the ring? Therefore, the net gravity force on that object is - Zero?
2. If an object is located at 1.5KPC from the Center (Let's set it close to 12 (in clock) - The impact gravity force of the stars in 3 and 9 should cancel each other?
However, the distance to 12 is now 1.5 KPC while the distance to 6 is 4.5KPC.Therefore, do you agree that the net gravity force in the direction of 12 is quite strong?
3. If an object is located very close to 12 (let's say at 2.9 KPC). - The impact of the gravity force in 12 is almost maximal (as the distance is just 0.1KPC). However, the impact of 6 is minimal (as the distance is 5.9KPC). Remember that 3 cancel the impact of 9.
Therefore, do you agree that the impact of the ring gravity force is higher as the object is closer to the ring?
Without reading further, a hoop like that is in equilibrium and can orbit itself, with or without a central object. The mass within (not part of) the ring will contribute to higher speed of the ring, but a ring by itself will have some minimum speed. It isn't totally stable, but stable enough, just like our asteroid belt, which has a central mass. I can think of no example of a ring on its own.
Let's start by looking inwards:Let's set back the SMBH at the center of the galaxy.We have already found that the impact of the Ring at the center is virtually Zero.Therefore, any object which is located very close to the center is directly affected by the SMBH. It might be a star, gas cloud or even Atom.However, as we move further away from the center, the gravity force of the ring is more relevant.Please remember that the SMBH mass is estimated to be in the range of few millions Sun mass. However, the total estimated mass of the ring is in the range of several billions of sun mass.Based on that knowledge, let's look again on the orbital velocity at the range of Zero to 3KPC (about 10K LY).We know that the orbital velocity of the accretion disc is 0.3 speed of light.
The orbital velocity of S2 which is located at a distance of 2-10 Light days from the SMBH is 5000 Km/s
If we get to a distance of 0.1 KPC (326 LY) from the center the orbital velocity gets down to 150 Km/s.However as we get further away from this point, the orbital velocity stars to increase.At 0.5 KPC the orbital velocity gets to its pick of almost 250 Km/sec. So far so good.We can assume that this increase in the orbital velocity is directly affected by the ring.
However, as we go further away from the center and get closer to the ring the orbital velocity goes down again to its minimal value at the ring - 190Km/s. This is unexpected phenomena.
Why the orbital velocity goes down again as we get closer to the ring?In order to answer this question - Let's assume that we have only one object which orbits inside the ring.So, we have the ring, we have the SMBH but only one star which orbits there.We can easily calculate the estimated orbital velocity of this object at any radius from the accretion ring up to 3KPC.However, as there are millions (or billions of stars) in the bulge + in the Bar, they also set a gravity force on each other.Therefore, this could be the answer why we see that the velocity is going down as we get closer to the ring.
There is another factor.The ring is connected to spiral arms.So, it is used as a frame which holds the spiral arms and set their orbital velocity.
Therefore, it is clear that the ring is loaded by those spiral arms. This load could also have some impact on the orbital velocity of the ring and the orbital velocity of stars inside the ring.Do you agree with that?
Please also be aware to a very critical issue.There is no spiral shape inside the ring!!!The spiral shape is very clear in the ring itself and in the spiral arms.Therefore, it is clear that the ring has a significant impact of the spiral arms.I will discuss about it later on.
You treat the ring and arms as solid objects, talking about loads being put on them and such. They're not. They're collections of detached objects which don't alter paths if loads are put on other parts. You can't alter the speed of the ring by putting a force on part of the ring. That works only if it is an object.
agree that the spiral seems to end at 3 kps, not spiraling all the way into the center. There are some galaxies that do that, but they're in the minority.
Quote from: HalcYou treat the ring and arms as solid objects, talking about loads being put on them and such. They're not. They're collections of detached objects which don't alter paths if loads are put on other parts. You can't alter the speed of the ring by putting a force on part of the ring. That works only if it is an object.I disagree with you,The ring is an object by itself as the Earth is an object by itself.The Earth is made by many different of Atoms and molecular that are all bonded by gravity force.In the same token, the Ring is made by many Stars and dust that are all bonded by gravity force.
We see clearly that the arms are connected exactly at the opposite sides of the ring.In some galaxies it is quite difficult to see the ring, but we see clearly that spiral arms are connected exactly at the opposite sides of the ring and directly to the bar.This connection between the Arm to the Bar is very important.
Please look at the following image:http://hubblesite.org/image/1636/news_release/2005-01Please see the ratio between the bar radius to the arm maximal radius:Do you agree that the ratio is about 1:3?
In the Milky Way the bar gets to 3 KPC while the spiral arms gets to 45 KPC.So the ratio in the Milky way (with a ring) is 1:15.
Do you agree that without a ring (or with minimal ring) there is a maximal load (or maximal spiral arm size/radius) that spiral galaxy can take?
Our scientists only try to explain the orbital velocity in the arm, but they ignore completely the Bar. How could it be that they don't see that the bar is directly connected to the arm?
3. How could it be that at the ring, the orbital velocity is at its minimal value (190Km/s)?
If you look at the Milky Way image in your first link of the prior post, the bar ratio seems to be about 1:5 or 1:6, and a similar ratio for that 'perfect spiral' galaxy you link.So the ratio is higher, but not a lot higher.
QuoteOur scientists only try to explain the orbital velocity in the arm, but they ignore completely the Bar. How could it be that they don't see that the bar is directly connected to the arm?Probably because it isn't.
So, we agree that with a ring the ratio between the bars radius to the maximal arm radius is higher.If so, why do we ignore the outcome of this evidence?
5. Based on this image, it is clear the bar is orbit in clock wise.
8. So do you agree that we see clearly a symmetrical view from both end sides of the Bar?
Don't you think that there is a meaning for what we see?
As you don't like to call this spot as a "connection" point, do you estimate that the bar can move faster/slower than the starting point of the main arms and one day it should be disconnect from the arm?
QuoteAs you don't like to call this spot as a "connection" point, do you estimate that the bar can move faster/slower than the starting point of the main arms and one day it should be disconnect from the arm?You would have images of galaxies then where that happens. No, the [main] arms always start at the bar ends, just like the wake always starts at the duck despite not being connected .
As the bar had been set due to "density wave", can we claim that it is an object?If the ring isn't an object than how could it be that the bar is an object?
If it isn't an object, how can we compare it to duck?
Astronomers believe that galaxies have spiral arms because galaxies rotate – or spin around a central axis – and because of something called “density waves.”
So, the bar is there due to "density wave", while the spiral arms is there due to the same idea of "density wave".Hence, how could it be that the bar has a totally different shape and structure from the spiral arm while they both had been created based on the same concept of density wave?
I don't understand the dynamics of the bar. It seems to not be a density wave itself like the arms are, but I could be wrong about that. They give a reference to a paper on the subject, but it is heavy reading.
There are some really good illustrations that show what they're talking about.Here's a gif showing how a wave forms moving at one speed when all the material moves at a different speed.https://imgur.com/gallery/dtb8WrDFollow any particular star and it doesn't stay with either arm.
:https://en.wikipedia.org/wiki/Wake#/media/File:Bodensee_at_Lindau_-_DSC06962.JPGThe duck wake appears completely stationary to a camera that is following the duck, and has that overlapping fallen-dominos signature, not just one clean wave that angles out. The material of the waves does not follow the wave/duck however. The water is moving in a completely different direction than is the wake. The wake appears to be a solid object connected to the duck, but it is not connected at all.
I assume that even the scientist that wrote the article has no clue how the density wave creates the Bar.
I wonder how can we get any valid information from this illustration.There is no ring and no bar in the illustration.
We only see stars that are moving in and out in order to set the spiral arms.If that was correct, than by definition the 400 Billion stars that move in and out should collide with each other..
Let's look at your example about the duck wake:We see the wake - But it has a specific shape.For example - There is no way to get a wake in a ring shape, zig zag, or that moves in front of the duck.
So, if there is a density wave - it can't technically set all the variety shapes that we need (Bar, Ring, spiral arms, Bulge) and keep each shape at a specific radius and aria while the bar ends exactly at the starting point of the main spiral arms and this point cross the ring.This is too challenging request from a simple idea of - "Density wave"
QuoteSo, if there is a density wave - it can't technically set all the variety shapes that we need (Bar, Ring, spiral arms, Bulge) and keep each shape at a specific radius and aria while the bar ends exactly at the starting point of the main spiral arms and this point cross the ring.This is too challenging request from a simple idea of - "Density wave"Not knowing how it works, I am in no position to declare that it cannot work. They have simulations that reproduce it, and these simulations use only gravity acting on each thing, not physical connections. That means it is not too challenging of a request.
They needed to posit dark matter to get it to work, but no new laws like a 5th force or something.
I think a model of a solid spinning ring and bar with solid arms attached to it would result in an asterisk-shaped galaxy with the arms sticking straight out like they would if you spun out in space a ring with attached flexible arms like that . That is the best description I've seen so far of your model.
There would need to be a rope or some physical structure holding our sun to the arm so it isn't flung away with the spinning, but we see no structure attaching our sun to the arm.
You've suggested no model so far, posting only observations and little actual explanation for any of them.
Quote from: HalcThey needed to posit dark matter to get it to work, but no new laws like a 5th force or something.I have no idea what is the meaning of the 5th force, but there is no need for it. There is also no need for dark matter.Gravity force - That's all we need to set our galaxy.
It's time for me to present my model.However, the two basic elements are:1. There is a friction also in gravity force. This friction reduces the gravity force over time. The only way to reduce the gravity force of an object is by increasing its radius.
2. All the stars in the galaxy must orbit around some virtual host (I will explain it later on).
Once we know those two key elements – We have actually solved the Spiral galaxy enigma.