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Why are we so sure that there is a need for dark matter?


Dandav
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On 12/17/2022 at 2:17 PM, Dandav said:

I would like to remind you that with all the complex math that our scientists have used in their mega computation system, they have totally neglected the Bar segment.

  ... as evidenced by all the pictures and links to descriptions of the bar by those very neglectful scientists, and none by you.

On 12/17/2022 at 12:45 PM, Dandav said:

You were missing.

I was not bothering with nonsense that is over the top self contradictory.

On 12/17/2022 at 12:45 PM, Dandav said:

Please remember:

P1 = 2 * 3.14 * R

P2 = 2 * 3.14 * 2R

P2/P1 = 2

OK, this is a formula for the circumference of a circle of radius R. You have cleverly figured out that a circle that is twice as big has twice the circumference. You've managed to discover that 2*constant is twice 1*same-constant. I was hoping for some actual numbers.

On 12/17/2022 at 12:45 PM, Dandav said:

Therefore, a star at 2R should move twice faster than a star at R.

This doesn't follow. I can accept something like it with several conditions.  The pattern rotates without distortion, the stars move with the pattern, and the motion referenced above refers only to the tangential velocity.  From this, plus your little graph, how long does it take for the bar to go around once? That requires numbers. Can you do that? You've done no velocity math, only something concerning the circumference of a circle, and it is known that bar stars don't have circular orbits.

4 hours ago, Dandav said:

The Bar is the most important feature in the spiral arm.

The bar isn't a feature of a spiral arm. It's considered separate usually.

4 hours ago, Dandav said:

1. How could it be that those scientists from Nasa with deep knowledge in science could understand the real meaning of the bar and the real impact of tidal force? 

Maybe by having that "deep knowledge"

The bit about tidal force is tosh. The thing you quoted makes no mention of tides.

4 hours ago, Dandav said:

2. Do you agree that this "tiny elongations in the stars' orbits grow and they get locked into place" is a random process?

If it happens to one star, it might be a random process. If it happens to the majority of them, it's not random.

4 hours ago, Dandav said:

3. Why that [...] process always sets two symmetrical arms? Why never ever one arm, three or more?

Two is stable. Three is not.

4 hours ago, Dandav said:

why we have never ever observed even a bar in any globular cluster in the entire universe?

We do. They're called barred galaxies. Most globular clusters don't have very much angular momentum. Things with bars do.

4 hours ago, Dandav said:

5. How can you explain the following contradiction:

In one hand it is stated that stars are locked in the Bar: "The bar becomes even stronger as it locks more and more of these elongated orbits into place."

While on the other hand it is stated that the bar transfer gas towards the center: Bars are perhaps one of the most important catalysts for changing a galaxy. They force a large amount of gas towards the galactic center, fueling new star formation, building central bulges of stars, and feeding massive black holes.

Stars are not so easily deviated from their orbits. Gas clouds are quickly slowed by friction and can migrate closer to the center. This generates energy. The bar does leak material into the ring region, more stars than gas. The galaxy does lose energy overall and that must result in an overall falling of material towards the center.

4 hours ago, Dandav said:

6. How they couldn't understand that the Bar is a direct outcome of tidal force due to the ring + spiral arms that are located around the Bar?

Because that would be an understanding of nonsense. There's nothing supplying a tidal imbalance. Your picture completely contradicts how gravity works.

4 hours ago, Dandav said:

If we would verify the DNA of the stars in the MW galaxy, do you agree that we should find that all the Billions stars there without exception - carry the same DNA?

Any DNA molecule that approached an active star would be destroyed long before reaching it. Why kind of nonsense question is this? Are you now suggesting that stars are Earth animals?

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13 hours ago, Halc said:
18 hours ago, Dandav said:

why we have never ever observed even a bar in any globular cluster in the entire universe?

We do. They're called barred galaxies. Most globular clusters don't have very much angular momentum. Things with bars do.

You have just confirmed my message about the tidal impact!

 

A Bulge, Globular cluster or star cluster without the ring and the spiral arms around it would never ever set any sort of a bar shape.

Only a structure with spiral arms and ring can set the Bar.

If you would take out the Ring and the spiral arms from that barred galaxy, then the left-over bulge would lose Its Bar shape.

So, please can you offer ONE real image of Bulge or globular cluster (without ring & spiral arms) that could form a bar shape?

13 hours ago, Halc said:
18 hours ago, Dandav said:

3. Why that [...] process always sets two symmetrical arms? Why never ever one arm, three or more?

Two is stable. Three is not.

Two symmetrical arms are stable due to tidal gravity impact.

Three isn't stable as the tidal impact works on both symmetrical sides of the object.

There are no stable bar arms without tidal force!!!!

13 hours ago, Halc said:
18 hours ago, Dandav said:

6. How they couldn't understand that the Bar is a direct outcome of tidal force due to the ring + spiral arms that are located around the Bar?

Because that would be an understanding of nonsense. There's nothing supplying a tidal imbalance. Your picture completely contradicts how gravity works.

As you insist to ignore the ultimate impact of the Tidal, let's discuss it deeply.

Please look at the following image:

 

Field_tidal.svg

Do you confirm that tidal gravity force due to that satellite squeeze the central objects from upwards and downwards, while it would push matter from the central object at the direction of the satellite and also symmetrically from the other side?

Now, let's use a pure spherical cluster (at a radius R) and set one million satellites in a ring around it.

What would be the outcome?

Don't you agree that the combined tidal forces of those million satellites would squeeze the central object from upwards and downwards one million times stronger?

However, as for any direction around the cluster there is a satellite, then do you agree that the spherical cluster would change it shape to a nice symmetrical pita bread without any bar structure?

 

אורי מאיר-ציזיק | פיתות מבצק שאור מלא - אורי מאיר-ציזיק 

 

We actually see this structure.

It is called ring galaxy:

 

With a perfectly symmetrical ring circling a red sphere of stars, Hoag's object is one of the prettiest mysteries in the universe.

Please look carefully at this galaxy.

It has no bar and no two main spiral arms, only bulge and ring.

You don't know that yet, but this ring galaxy would be transformed in the future into full barred spiral galaxy with bar and two main spiral arms.

However, in the meantime, when you look at this image, do you think that the central Bulge has a pure sphere shape as a Mondial Ball?

If so, you have a severe mistake.

The central bulge already got a pita bread shape.

Therefore, if its diameter in this top view image is S, I can promise you that its diameter from the side view is significantly lower. It might be even lower than 1/2 S.

 

13 hours ago, Halc said:

The bar isn't a feature of a spiral arm. It's considered separate usually.

The Bar is a key feature of barred spiral galaxy.

If you take out the ring and spiral arms from the barred galaxy, there will be no bar.

Please also be aware the Bar is an integrated part of the Bulge.

Therefore, as the Bar rotates, the whole Bulge with its stars and gas clouds is also rotates.

It might be difficult for us to detect the rotation of the bulge, but it is there.

Conclusion:

Sorry, you can't ignore the great impact of tidal force.

Take out the tidal force from barred galaxy, and you have no bar.

Take out the bar and you have no twin spiral arms.

How long can you hold the dark matter imagination and reject real tidal gravity force?

Why do you insist to reject the impact of tidal force as it can explain the clear operation of the spiral galaxy without using even one gram of dark matter???

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14 hours ago, Dandav said:

However, as for any direction around the cluster there is a satellite, then do you agree that the spherical cluster would change it shape to a nice symmetrical pita bread without any bar structure?

You seem to change your mind. Before you said a ring would distort a spherical mass into a bar:

On 12/13/2022 at 12:08 PM, Dandav said:

As the cluster is not solid, the tidal force due to the ring would change the spherical shape of the cluster to symmetrical Bar structure.

The pita is closer, but the effect is pretty trivial. Earth is definitely pita shaped, but the tides only contribute a meter or two of variance, and that's the most significant tide in the solar system. Meanwhile, Earth is 44 km thicker around the equator than from top to bottom, and that's due to the same thing that creates the bar: angular momentum.

 

The ring galaxy you picture is Hoag's object, and it is known to have an unusually spherical central mass, which nicely contradicts your promise. Physics doesn't work by promises. It works by observation and mathematics.

Concerning mathematics, I gave you an absolutely trivial exercise to see if you had any arithmetic capability at all. You only showed that a circle that is twice as large has twice the circumference.

I asked how long it takes for the bar to go around once, and you ran away to hide. You apparently can't do it despite the existence of a nice graph giving you the answer. Not looking for lots of digits of precision. 1 digit will do.

 

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Dear Halc

Our scientists don't know why spiral arms in the base (3KPC) are so thick (3000LY) while at the far edge (15KPC) they are so narrow (only 400LY)

They don't even dare to ask themselves this question as they have totally got lost.

That by itself proves that they don't have a basic clue how spiral galaxy really works.

In the following article they fully admit that: "A spiral galaxy is at once a beautiful sight and a physical puzzle"

http://www.physics.smu.edu/jcotton/ph1311/ch14b.htm

"A spiral galaxy is at once a beautiful sight and a physical puzzle. The problem is understanding how the arms remain as stable long-term features."

Therefore, even today with all the imagination of dark matter, Density wave, Bar structure, "unstable regions"... our scientists still have a major problem of  "how the arms remain as stable long-term features".

In the following article it is stated:

https://academic.oup.com/mnras/article/478/1/932/4993268

"Spiral arms form due to unstable regions where self-gravity dominates, or from initially leading density waves, but are eventually broken up by the disc shear."

"Spiral arms can be transient in nature, but a long-lived swing amplified mode can exist in galaxy discs over several rotations"

 "spiral arms can be broken and re-made"

So, they clearly know that the idea of the "unstable regions" will help to set only several rotations of the spiral arms before they would break down.

But they hope that somehow, "spiral arms can be broken and re-made"

In this article it is stated clearly that there is no consistent theory and there is no single mechanism:

"a consistent theory to describe all galaxy spiral structure is elusive, and a single mechanism may not be responsible for all types of observed spiral structure."

Sorry, spiral arm isn't a physical puzzle.

I offer you a single mechanism that is based on real science and is called Tidal.

This Tidal can explain the full structure of all the complex galaxies in the Universe, how they had been evolved and why they wouldn't break down and remain as stable long-term features

But you prefer to reject real science and stay at the darkness while holding the dark matter that we would never ever see as it just proves that our scientists don't know how spiral galaxy really works.

 

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17 hours ago, Dandav said:

But you prefer to reject real science and stay at the darkness while holding the dark matter that we would never ever see as it just proves that our scientists don't know how spiral galaxy really works.

 

You have not proven anything regarding your tidal theory and it is you who that is staying in the darkness while rejecting the work of mainstream scientists. Mainstream scientists have done a great deal of research on Spiral structure in barred galaxies.

If you follow the link, you will find just one of many fine papers on the subject.

Here is just a brief abstract and even this shows a deep understanding about the spiral structure and the role the bar plays in the dynamical evolution of these galaxies:

Abstract

A method, which we have developed for determining corotation radii, has allowed us to map in detail the radial resonant structures of barred spiral galaxies. Here, we have combined this information with new determinations of the bar strength and the pitch angle of the innermost segment of the spiral arms to find relationships between these parameters of relevance to the dynamical evolution of the galaxies. We show how (1) the bar mass fraction, (2) the scaled bar angular momentum, (3) the pitch angle, and (4) the shear parameter vary along the Hubble sequence, and we also plot along the Hubble sequence (5) the scaled bar length, (6) the ratio of bar corotation radius to bar length, (7) the scaled bar pattern speed, and (8) the bar strength. It is of interest to note that the parameters (2), (5), (6), (7), and (8) all show breaks in their behaviour at type Scd. We find that bars with high shear have only small pitch angles, while bars with large pitch angles must have low shear; we also find a generally inverse trend of the pitch angle with bar strength. An inference that at first seems counter-intuitive is that the most massive bars rotate most slowly but have the largest angular momenta. Among a further set of detailed results, we pick out here the 2:1 ratio between the number of spiral arms and the number of corotations outside the bar. These results give a guideline to theories of disc–bar evolution.

 

I suggest you read the entire paper It certainly contradicts your claim that our scientists "don't have a basic clue how spiral galaxy really works".

It seems to me you are the one without a basic clue, but you are pushing your own basically crackpot theory as fact, without sufficient scientific support to back it up. If you continue to claim your own theory as fact while at the same time rejecting established mainstream theories, I may have to move this thread out of Astronomy and Space and into Alternate theory section of this forum.

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On 12/21/2022 at 1:05 AM, OceanBreeze said:

Mainstream scientists have done a great deal of research on Spiral structure in barred galaxies.

If you follow the link, you will find just one of many fine papers on the subject.

Here is just a brief abstract and even this shows a deep understanding about the spiral structure and the role the bar plays in the dynamical evolution of these galaxies:

Thanks for this article.

It offers deep data on Bars activities in wide kinds of spiral galaxies.

"We have measured here several parameters characterizing the bar, such as its length, the pattern speed, the angular momentum, and the bar strength. We have also determined some relevant properties of the arms of the galaxies: the pattern speed of the spiral structure and the pitch angle of the spiral arms. We study the influence of the bar on the spiral structure by interpreting the relationship between these two sets of parameters."

They hope that this data would help us to understand how spiral galaxy really works:

"These results give a guideline to theories of disc–bar evolution."

"In a more general way, the pitch angle can be used in tests of theories that show how the spiral arms are themselves formed."

 

They also offer recommendations:

"In general, the Lagrangian points L1,L2, L4, and L5, which define the corotation, are not aligned in a single circle (see fig. 3.14 of Binney & Tremaine 2008), this means that we should use the term corotation region rather than corotation radius, and this explains why we obtain peaks in the histogram of the phase-reversals"

 

They see a correlation between the spiral arms shape to the Bar:

"It is interesting to note that if the bar has either a very low value of the relative angular momentum or has a rather large value, then the spiral arms are tightly wound."

"This means that given a pitch angle of the spiral arms, those galaxies for which the disc mass fraction is minimum also host a bar with maximal relative angular momentum, and vice versa"

"The pitch angle varies uniformly with the radius, this means that the (θ, ln r) points of the spiral arm are better fitted by a polynomial than by a linear fit."

"the crossing point between the two envelope lines is at λbar  10−2, which means that the most wide open spiral arms are found in galaxies that have a bar with a relative angular momentum of 10−2"

"this shows that spiral galaxies with a stronger bar can only have a spiral structure with tightly wound arms, and also that an open spiral is found only in galaxies with a weaker bar. As shown in this figure, we do not find a galaxy in our sample that has a strong bar with open arms. This result does not favour the bar-driven spiral invariant manifold theory, which predicts that stronger bars should have less tightly wound arms (i.e. larger values of the pitch angle) than weaker bars"

As they see so deep correlation between the Bar to the Spiral arms, why they didn't ask themselves what kind of force can set a correlation?

Is it the dark matter or dark glue?

Why they didn't even consider the idea of tidal force?

 

However, they have noticed that the bars of the spiral galaxies are losing angular momentum, and therefore slowing down.

"we obtain that λ˙bar<0λ˙bar<0, which means that the bar loses relative angular momentum while is evolving."

"In consequence, it means that the bars of the spiral galaxies are losing angular momentum, and therefore slowing down while growing in size and mass."

For me, this is the most important message.

If the bar is slowing down, then why it doesn't stop? Why we have never ever observed any bar as it stops? how come that all the bars in every millions over billions spiral galaxy keep their rotation/motion while they are losing angular momentum?

Do they have an answer for that?

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Few more questions with regards to the following message:

3 hours ago, Dandav said:

"In consequence, it means that the bars of the spiral galaxies are losing angular momentum, and therefore slowing down while growing in size and mass."

1. How the Bar increases its size? From where that mass is coming from? Is it from the Bulge or from the spiral arms + ring?

2. Do you agree that if the Bar increases its size in the direction of the spiral arms, then it proves that it gets the matter from the Bulge and Vice versa?

3. If we ONLY observe that the Bar increases its size in the direction of the spiral arm, then why do we think that the matter in the bar is coming from outside the bar?

4. While we clearly observe that the bar is slowing down, do we also observe any sort of slowing down in the spiral arm motion?

5. If the answer is No, then how can we explain the situation that the spiral arm keeps its orbital motion, while the bar is slowing down?

6. If stars in the spiral arms are affected by the dark matter, then why stars in the bar are not affected by that dark matter.

Please be aware that the spiral arms in the Milky way starts at about 3KPC while the bar ends at almost the same distance (3KPC).

If they are all affected by dark matter, then why the bar has a Bar shape instead of spiral shape?

7. Why do we think that stars at the bar (even at the edge of the bar - 3KPC) must be locked to the Bar arm, while stars at the spiral arms (even at almost the same distance - 3KPC) can't be locked to the spiral arm?

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Please read the following message from NASA:

 

https://www.dailymail.co.uk/sciencetech/article-9906101/NASA-break-spiral-arm-Milky-Way-stretches-3-000-light-years.html

"NASA finds a break in one of the Milky Way's spiral arms that stretches 3,000 light-years and looks like a SPLINTER coming out of a piece of wood"

They even offer an image:

 

46833363-9906101-image-a-34_1629318635922.jpg

 

We see the SPLINTER (that Nasa claims that it looks as a piece of wood) while it cuts the Sagittarius arm from side to side  and it is there Infront our eyes.

That splinter starts at about 7,000LY away from us and ends at about 4,000LY

However, as it looks like a solid piece of wood, then why our scientists don't even consider the possibility that this structure represents an object where all the stars there are locked/bonded to each other by gravity force which means - gravitational arm?

They call it spiral arm break. Therefore, they do understand that this splinter had been broken from a spiral arm.

Therefore, as this splinter represents a gravitational arm structure that looks as a piece of wood, then why can't we understand that the broken arm from where it had been ejected must also be a gravitational arm structure.

Our scientists informed us that they have found 512 G stars in a spherical radius of 100LY around us. 

As the diameter of Orion arm is 1000 LY, then its radius should be 500LY.

Hence, there are 512 * 5^3 = 64,000 G stars is a 1000LY sphere of the Orion arm.

This doesn't include other kinds of stars, BHs Gas clouds... that should exist in the arm.

Based on this calculation, that splinter with its 3000LY size, should have more than 200,000 G Stars plus other stars BHs and gas clouds.

As it cut the Sagittarius from side to side, then it must come at high momentum.

In the image we see that it didn't break the Sagittarius arm.

The splinter just penetrates into the arm and it seems that it had been locked into the Sagittarius arm.

All of that without even a single collision between stars from both sides.

Based on that image the splinter is coming from the Scutum arm  at the direction of the galaxy center. We actually see that its current location is not too far away from one side of the Bar.

The Bar ends at 3KPC which means - 10,000LY.

The upwards side of the splinter is located 3000LY inwards to the center (let's say - 20,000 Ly from the center) while the downwards side is located at about 23,000LY from the center of the galaxy.

Therefore, a star at the upwards location should face a different gravity force due to dark matter than a one in the downwards side.

Therefore, how could it be that stars in the splinter at different radius from the center are not affected by the different dark matter gravity force and keep themselves all together in that splinter that looks as a piece of wood?

How the density wave theory could explain the existence of this solid structure in the spiral disc while based on that theory stars in the disc aren't locked together and affected by the dark matter gravity?

Could it be that this observation is the missing smoking gun that proves that the spiral arm is gravitational arm?

As our scientists fully confirm that stars in the bar are locked to each other by gravity, then why it is so difficult for them to accept the idea that stars in the spiral arms are also locked together by gravity force?

 

 

 

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In the following article, there is an explanation how the Bar in the galaxy could be form:

http://burro.astr.cwru.edu/Academics/Astr222/Galaxies/Spiral/bars.html

"What makes a galaxy barred? "

I would like to focus on the starting point of this explanation.

It is stated: 

"Take a disk where all the stars are rotating on perfectly circular orbits - relative to one another, the stars aren't moving."

Is it real?

Is it possible to ask the mother nature to offer us a disc of stars?

Please be aware, that they specifically discuss about stars without any sort of central mass.

Don't you agree that in the nature, if you set several stars next to each other you would get a star cluster or globular star cluster? which means sphere structure (not a disc).

There are millions over billions of spiral galaxies.

If all of them had started from a disc then we should find at least one similar disc of stars in the open space.

So please, did we ever see that kind of star disc where all the stars are rotating on perfectly circular orbits? (Please do not offer an image of spiral galaxy as the mission is to explain how the galaxy disc had been created at the first stage)

Don't you agree that it is a fatal mistake to start the story of the spiral galaxy from that kind of disc?

As the starting point is a fatal mistake, then how can we consider the rest of the story as real science?

They also can't explain many enigmas about the galaxy.

For example, why there are so different features in the same galaxy (Bulge, Bar, Ring and spiral arms), why there is so unique order in those features, why there is a ring (and it is there just between the bar to spiral arms), why we clearly see that the bar is slowing down but it never stops, why the Disc is thick at the base (3000LY) while so narrow at the edge (400LY) and many other questions.

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In order to explain the full structure of spiral galaxy and how it had been formed, our scientists should start their explanation with a real spherical shape of stars as globular cluster.

How could it be that they took the freedom to start their explanation with this unrealistic disk where all the stars are rotating on perfectly circular orbits?

Is it realistic?

Sorry, they should start the explanation with a spherical shape as globular cluster as this is realistic shape of stars in the Universe.

We see them by millions and billions.

Therefore, their mission is to start with a spherical shape as globular cluster or Bulge, and show how that cluster/bulge could be transformed into real spiral galaxy.

If they can't accomplish this mission, then why can't they admit that they really don't know how spiral galaxy had been evolved?

Why they refuse to consider the Tidal gravity impact?

How can I convince them to think about that key idea that is vital for the creation and operation of all the billions spiral galaxies in the universe?

I can only promise them that once they would be ready for the tidal impact, they would get answers to all the questions about spiral galaxy and all the other shapes of galaxies in the entire Universe without any need for dark matter, density wave or any other imagination.

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Please look at the following basic image of the Milky way: 

 

Milky Way's structure

 

Do you confirm that the thickness of the spiral arms at the base ( just at the end of the Bar) is maximal (3000LY) while as we move further away, the arm become narrower?

Can you please specify to which direction the bar rotates?

Is it in the direction of the spiral arms or further away?

Do you agree that if the Bar rotates in the direction of the arm, then we could understand that the bar funnel stars from the spiral arms to the Bulge?

However, as it rotates to the other direction, then why is it so difficult for us to understand that the bar funnels stars from the Bulge into the spiral arms?

This is similar to garden sprinkler.

Please see the following image:

The sprinkler Bar ejects water while it rotates to the other direction of the water flow.

Don't you agree that the water jet stream from the sprinkler looks spiral and it is less massive as we move further away from the bar and therefore, there is high similarity between the bar in the galaxy to the bar in the garden sprinkler?

 

71yn0V4j-yS._AC_SL1500_.jpg

 

Please be aware that the bars in each system ejects matter and rotates at the opposite direction of the jet stream.

However, while the matter flows from the bar sprinkler is water jet stream, the matter flows from the Bar galaxy is stars, Bhs & gas clouds jet stream, while both jets looks spiral.

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Our scientists at NASA fully confirm that "Half of All Stars Are Rogues Between Galaxies"

https://www.space.com/27682-rogue-stars-between-galaxies.html

"As many as half of all stars in the universe lie in the vast gulfs of space between galaxies, an unexpected discovery made in a new study using NASA rockets. These stars could help solve mysteries regarding missing light and particles that theory had suggested should exist, scientists say."

All of those stars had been ejected from their home galaxy as water from garden sprinkler.

 

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There is only one basic force that is responsible for the spiral galaxy activity. That force is called - Gravity force.

Its impact is as follow:

1. Gravitational arm impact - The Bar, the ring and the spiral arms are all gravitational arms. That means that stars are locked by gravity to each arm and they go with it wherever it goes.

2. Tidal gravity impact - Our scientists have found full correlation between the bar to the spiral arms. This correlation is due to the Tidal impact.

That's all. (No need for dark matter - Just pure gravity force between ordinary matter)

Once we agree on that, we can easily explain how spiral galaxy works and answer all the questions about its features.

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Orbital velocity of star in the gravitational arms (Bar, Ring & spiral arms):

The total orbital motion of a star in any kind of gravitational arm is based on three basic motions:

1. Local motion - This is the local motion that is needed to lock the star to the gravitational arm. It is similar to the motion of star in a multiple stars system as star cluster.

2. Arm Motion - The motion of the gravitational arm in the galaxy

3. Motion in the arm - The motion of the star in the gravitational arm

Hence

Star total motion in any gravitational arm = Local Motion + Arm Motion + Motion in the arm

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Bulge & Bar shape

Please remember the following forces on the Bulge due to tidal gravity impact.

Field_tidal.svg

Bulge shape In a ring galaxy:

With a perfectly symmetrical ring circling a red sphere of stars, Hoag's object is one of the prettiest mysteries in the universe.

 

Due to the symmetrical shape of the ring, the tidal gravity due to that ring would squeeze the bulge from upwards and downwards, and force it to get the pita bread shape.

In spiral galaxy:

Milky Way's structure

 

The base point of each spiral galaxy would set the maximal gravity force on the Bulge.

Therefore, the tidal force on the Bulge due to those two base points would squeeze the bulge into that bar shape.

Therefore, that bulge with its bar arms is one object. It should be called Bar shape bulge. The whole bulge would rotate with the rotation of the bars.

Due to that squeezing tidal force, the bulge would have to funnel matter/stars outwards through those two bars in the direction of the spiral arms.

By doing so, any star that funnels outwards from the bulge would be locked by gravity to the other nearby stars in the bar and they all would be forced to drift outwards. 

Therefore, the bar is the first element that force a free orbital motion star in the Bulge to be locked into the gravitational arm that is called "Bar".

However, the key question is as follow:

Why the bar rotates?

Please focus on the orbital motion of the stars in the bar based on the following image: 

 

image.png.01842fb035eb1a68af5119c8c5354af0.png

We clearly see that the star velocity is increasing dramatically as it drifts outwards in the Bar.

Hence, from where the Bar gets the requested energy to keep that motion?

How could it be that its rotation never stops?

Any Idea?

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