Galaxy rotation curve

[ravell]

In Wikipedia:   https://en.wikipedia.org/wiki/Galaxy_rotation_curve

the flat curves of the observed velocities of stars in the discs of spiral galaxies are presented, which  according to physicists, differ significantly from calculated velocities of stars, resulting from the luminous mass of a given galaxy.

Such a significant discrepancy between the observed and calculated velocity of stars in spiral galaxies is currently explained in scientific publications,  by the alleged presence of an unvisible halo of some mysterious dark matter.  For example, in the textbook James B. Hartle "Gravity. An Introduction to Einstein's General Relativity " states that such an equal velocities of stars, for example in the disk of the Andromeda galaxy, indicates that the galaxy has an unvisible halo of dark matter  in an amount 10 times (!) of the luminous mass.

As it turns out, such explanation of the equal velocities  of stars in spiral galaxies as a result of the interaction of undetectable dark matter is wrong. The concept of dark matter arose as a result of adopting the wrong method of calculating the distribution of gravity in the disk of spiral galaxies (as for a sphere!).

Correct  calculations of the distribution of gravity for the galaxy disk clearly show, that flat curves of the velocities of stars in the discs of  spiral galaxies, result only from Newton's laws of motion and gravity for the natural distribution of luminous mass  in the disk, and any mysterious dark matter (non-baryonic) is not present there.

Detailed calculations proving it are available on the link:

https://www.dropbox.com/s/a1cu74xj4ep9iyq/SagitariusBRprogramForCalculationsOfSpeedOfStars.xlsx?dl=0

(To download the Excel file from Dropbox, you do not need to be logged in. You only have to choose the options: download> download directly> enable editing).

 

[Strange]

8 minutes ago, ravell said:

Such a significant discrepancy between the observed and calculated velocity of stars in spiral galaxies is currently explained in scientific publications,  by the alleged presence of an unvisible halo of some mysterious dark matter.

That is one explanation (and currently the best). There are others.

9 minutes ago, ravell said:

Correct  calculations of the distribution of gravity for the galaxy disk clearly show, that flat curves of the velocities of stars in the discs of  spiral galaxies, result only from Newton's laws of motion and gravity for the natural distribution of luminous mass  in the disk, and any mysterious dark matter (non-baryonic) is not present there.

Which peer-reviewed journal are these "correct" calculations published in.

Given your previously displayed ignorance, I am highly sceptical.

9 minutes ago, ravell said:

Detailed calculations proving it are available on the link:

I am not going to download a potentially hazardous file from an unknown source. And I would strongly recommend that no one else does.

Please comply with the rules of the forum and present your idea here. 

 

[swansont]

30 minutes ago, ravell said:

 

Detailed calculations proving it are available on the link:

 

https://www.dropbox.com/s/a1cu74xj4ep9iyq/SagitariusBRprogramForCalculationsOfSpeedOfStars.xlsx?dl=0

 

(To download the Excel file from Dropbox, you do not need to be logged in. You only have to choose the options: download> download directly> enable editing).

!

Moderator Note

You need to present them in the thread to be in compliance with the rules.

 

Moved to speculations.

 

[ravell]

On 30.09.2018 at 2:38 PM, Strange said:

I am not going to download a potentially hazardous file from an unknown source. And I would strongly recommend that no one else does.

The program Sagitarius BR is for many years available on the Internet and also on this forum has already been cited several times. The program is save and has many users.

The program Sagitarius BR (made in Excel) is very useful, because in an interesting, interactive way presents selected calculations in the field of astronomy. The program does not contain speculations  only legible, easy to verify the real calculations.

[Ghideon]

 

1 hour ago, ravell said:

The program Sagitarius BR is for many years available on the Internet

A lot of bad stuff have been on the internet for several years, @Strange's suggestion is absolutely correct. 

I tried google and found nothing of cosmological interest regarding the software. I didn't have time to read all details on the old thread in this forum but a few questions have been raised regarding the correctness of the model(s) in the software. 

On 2013-02-11 at 11:21 AM, Spyman said:

If the program "Sagitarius BR" has different results than mainstream science, then it must either use different methods or other estimates than what mainstream science does when they reach the consensus that the dark matter phenomen is real.

IMHO, I don't think random simulations made by strangers on the internet that uses conflicting methods and estimates to end up with contradicting results against conclusions made by mainstream science to be very convincing at all.

 

Edited October 6, 2018 by Ghideon
spelling

[Strange]

3 hours ago, ravell said:

The program Sagitarius BR is for many years available on the Internet and also on this forum has already been cited several times. The program is save and has many users.

 

The program Sagitarius BR (made in Excel) is very useful, because in an interesting, interactive way presents selected calculations in the field of astronomy. The program does not contain speculations  only legible, easy to verify the real calculations.

 

Being available and being downloaded by mugs is not evidence it is correct.

You can present those calculations here and compare them with observation. That way we can judge if they are "correct" or not. Given the nonsense you have posted previously, it seems very unlikely.

p.s. your link is broken, anyway

I had a look, and without some explanation it is meaningless. Just tables of numbers and some random graphs. So unless you want to actually explain what you are talking about, there is no point anyone looking at it.

[ravell]

On 6.10.2018 at 7:12 PM, Strange said:

I had a look, and without some explanation it is meaningless. Just tables of numbers and some random graphs. So unless you want to actually explain what you are talking about, there is no point anyone looking at it.

The method used to calculate the velocity of stars in the disks of spiral galaxies is clearly presented in the description of the Sagitarius BR program.  The link to the description of this program is given in the final part of the program. The link is as follows: https://www.dropbox.com/s/d2ywkaabxo0jd6m/SagitariusBRprogramDescription.pdf?dl=0

Below a fragment of this description concerning the applied calculation method:

“ The idea of the computation program Sagitarius BR is to split an analyzed galaxy disc into twenty concentric rings of the same width. The thickness of each ring is formed of 10 layers. The thickness of the layers in the rings are adopted accordingly to assumed profile of the galaxy.  Each layer is divided into 72 sectors (five degrees of arc) and the total mass of stars and gas contained in the each sector is presented as a single star of equivalent mass (Me). Thus, the model used for calculations is equivalent in size and mass with the analyzed galaxy, and it consists of 14400  Me stars, rotating in a galaxy disc on  200 orbits, with 72  Me stars on each of the orbit.

The program allows:

  -  to calculate and present a chart  of  the orbital velocity of stars in galaxies of any galaxy  mass, calculated in multiples of the Sun (Ms), and  with  any disc diameter, 

………..

The program first calculates the force of gravitational attraction of the Ms star, located on orbits in the consecutive rings, by each of 14 400  Me stars   (F (kn) = (G Me(kn) Ms) / L(kn)^2, where k is the ring number, n the sector number, L the distance between the Ms star and the Me star of a particular sector), and then calculates for the Ms star at a given orbit, the total resultant force of attraction F by all the 14 400 Me stars  of galaxy

On the basis of the calculated resultant forces  F of gravitational attraction for each orbit,  the program calculates the rotation velocity of the stars on these orbits, resulting from the formula for centrifugal force to balance the gravitational attraction for a given orbit (F = ( Ms V^2)/ r), where r is the radius of the orbit.

In total, the Sagitarius BR program version 4.0 performs over 200 000 calculations.

……………. ”

 

Quote

p.s. your link is broken, anyway

The link to the program is correct, but for some inexplicable reasons has been blocked here.   I therefore give it again:

https://www.dropbox.com/s/a1cu74xj4ep9iyq/SagitariusBRprogramForCalculationsOfSpeedOfStars.xlsx?dl=0

[Strange]

22 minutes ago, ravell said:

The link to the program is correct, but for some inexplicable reasons has been blocked here.

Perhaps because it is an unsafe file format.

22 minutes ago, ravell said:

in the each sector is presented as a single star of equivalent mass (Me).

How do you determine the value of Me?

[swansont]

!

Moderator Note

Your dropbox links are in violation of rule 2.7

This has already been explained to you. Please follow the rules.

 

[beecee]

On 9/30/2018 at 10:27 PM, ravell said:

As it turns out, such explanation of the equal velocities  of stars in spiral galaxies as a result of the interaction of undetectable dark matter is wrong.

Why do people immediately claim some incumbent theory/model is wrong when they come across some obscure text/claim on the Internet? There is an underlying reason...A-G-E-N-D-A

If it turns out that DM is wrong, then it will be science that discovers it...not some obscure random claim on the web. Science can and do make errors and false claims at time, but again, if and when that happens, it is always science that is self correcting, and again, certainly not some random claim on the web. eg: The BICEP2 experiment claimed to have discovered gravitational waves. The claim was made prematurely and later shown that the experiment was actually due to dust contamination. [Gravitational waves were of course discovered some time later by aLIGO] Another was a claim that the speed of light, "c" had been seemingly exceeded in some other remote experiment. Later data was forthcoming showing that this was an anomalous reading caused by a loose wire or something similar. Just about any fact and or incident in history is probably contradicted on the web by conspiracy nuts, or some other fanatical breed of fools that would like to attempt to refute known facts for their own benefit and satisfaction with regards to some agenda or personal belief.

DM of course as Strange has said is the best theory we have, and while being a "fudge factor" when first proposed, is now fairly well supported with many observed phenomena supporting the concept, the bullet cluster observation being the most notable.

Edited October 13, 2018 by beecee

[Strange]

7 hours ago, ravell said:

The method used to calculate the velocity of stars in the disks of spiral galaxies is clearly presented in the description of the Sagitarius BR program.  The link to the description of this program is given in the final part of the program.

Why haven't you submitted this model to a peer-reviewed journal? You are much more likely to get expert feedback that way.

On 30/09/2018 at 1:27 PM, ravell said:

As it turns out, such explanation of the equal velocities  of stars in spiral galaxies as a result of the interaction of undetectable dark matter is wrong.

How well does our model match the orbits of galaxy clusters?

And what about all the other evidence for dark matter?

[Markus Hanke]

18 hours ago, ravell said:

the total mass of stars and gas contained in the each sector is presented as a single star of equivalent mass (Me).

The gravitational field in the interior of a mass distribution such as a galaxy is not equivalent to the sum of gravitational interactions between discrete point masses arranged in a disk pattern. Also, I am pretty sure that General Relativistic effects cannot be neglected in this scenario, so Newtonian gravity is not the right theory to use.

The model’s basic assumptions are fatally flawed, which is why no one in the scientific community is using it.

[beecee]

15 hours ago, Markus Hanke said:

The gravitational field in the interior of a mass distribution such as a galaxy is not equivalent to the sum of gravitational interactions between discrete point masses arranged in a disk pattern. Also, I am pretty sure that General Relativistic effects cannot be neglected in this scenario, so Newtonian gravity is not the right theory to use.

The model’s basic assumptions are fatally flawed, which is why no one in the scientific community is using it.

Yes excellent point!

[ravell]

On 13.10.2018 at 3:11 PM, Strange said:

How do you determine the value of Me?

As can be seen from the description of the Sagitarius BR program, the mass Me of the equivalent star in the individual rings  of the galaxy is calculated as follows:
The modeled % mass for a given ring is divided equally into 72 sectors, and then the mass of the sector is divided equally into 10 layers of this sector. So there are 720 Me stars in each ring. Thus, if we model the total mass in a given ring by, for example, 5% of the mass of the galaxy, then the mass of each equivalent star in this ring will be Me = (5/72)/10 = 0.006944%  of the mass of the galaxy.

If, for example, for Milky Way, we assume a distribution of the galaxy mass  on individual rings 1-20  in %  as follows:

13,  1,  5,  6,  11,  1,  8,  6,  5,  5,5,  5,3,  4,9,  4,8,  4,6   4,5   4,  3,5,   3,  2,4  1,5

We get a graph of velocities of stars, which is generally consistent with the observations:

 

The observed velocities of the stars for the Milky Way :

 

Therefore, the calculation method adopted in the Sagitarius BR program can be considered as fully correct, which is confirmed by the observations.

[Strange]

40 minutes ago, ravell said:

Thus, if we model the total mass in a given ring by, for example, 5% of the mass of the galaxy

OK, so where’s does this 5% come from?

In other words what are you basing the mass distribution on?

Because, obviously, you can choose a mass distribution to produce any rotation curve you want

[ravell]

On 20.10.2018 at 4:18 PM, Strange said:

OK, so where’s does this 5% come from?

In other words what are you basing the mass distribution on?

Because, obviously, you can choose a mass distribution to produce any rotation curve you want

This is what the uniqueness of the Sagitarius BR program is all about.

You can, by trial method, model such mass distribution in the disk of the considered galaxy, which in turn results in a  rotation curve of stars in the galaxy, consistent with the observations.

  On this basis, the program allows to analytically verify the real mass value of the analyzed galaxy and its distribution in the disk.

 

[Strange]

36 minutes ago, ravell said:

You can, by trial method, model such mass distribution in the disk of the considered galaxy, which in turn results in a  rotation curve of stars in the galaxy, consistent with the observations.

But if that mass distribution doesn't match what we observe, then it isn't very useful. 

It is not clear if your program reproduces the actual observed velocities or just the shape of the rotation curve. 

If it is the former, then you must be deducing more mass than we actually observe. which is where dark matter comes in. 

Edited October 27, 2018 by Strange

[swansont]

1 hour ago, ravell said:

This is what the uniqueness of the Sagitarius BR program is all about.

 

You can, by trial method, model such mass distribution in the disk of the considered galaxy, which in turn results in a  rotation curve of stars in the galaxy, consistent with the observations.

 

  On this basis, the program allows to analytically verify the real mass value of the analyzed galaxy and its distribution in the disk.

If our notion of gravity is correct, we know that there has to be a mass distribution that will give rise to the rotation curves we see. But that's total mass, not visible mass. What you have not done is what Strange has pointed out: compare your result to what is observed.

[Ghideon]

 

7 hours ago, swansont said:

What you have not done is what Strange has pointed out: compare your result to what is observed.

When comparing your result to what is observed, please also address the issues already raised: 

On 2018-10-14 at 9:06 AM, Markus Hanke said:

The model’s basic assumptions are fatally flawed

and

On 2013-02-11 at 11:21 AM, Spyman said:

If the program "Sagitarius BR" has different results than mainstream science, then it must either use different methods or other estimates than what mainstream science does when they reach the consensus that the dark matter phenomen is real.

IMHO, I don't think random simulations made by strangers on the internet that uses conflicting methods and estimates to end up with contradicting results against conclusions made by mainstream science to be very convincing at all.

So in addition to comparison against observations, please provide evidence that the program has a valid model.

[ravell]

On 27.10.2018 at 3:09 PM, Strange said:

But if that mass distribution doesn't match what we observe, then it isn't very useful. 

It is not clear if your program reproduces the actual observed velocities or just the shape of the rotation curve. 

If it is the former, then you must be deducing more mass than we actually observe. which is where dark matter comes in. 

According to data from astronomical tables from 2002, the mass of the Milky Way is 5E+41 kg that is 2,5E+11 solar masses (Ms), and the diameter of the galaxy disk is 120 kly.

If we put this data into the Sagitarius BR program, with the previously given distribution of mass, but with the diameter of the galaxy enlarged to 200 kły, then we get the calculated rotation speed of the stars  exactly the same as we observe (ie about 220 km/s).

The change in the diameter or mass of the galaxy does not change the shape of the speed curve, but only raises or lowers the level of velocity obtained. For example, after adding that controversial dark matter, 10 times larger than normal mass (!?), the mass of the galaxy should then be about  2,5E+12 Ms, and the obtained star speed will  then be about 700 km/s!

For a full understanding of these relationships, I suggest you practice it yourself in the program Sagitarius BR.

[Strange]

3 minutes ago, ravell said:

According to data from astronomical tables from 2002, the mass of the Milky Way is 5E+41 kg that is 2,5E+11 solar masses (Ms), and the diameter of the galaxy disk is 120 kly.

What is the source for this? Does it include dark matter?

 

It looks like it does include dark matter:

Quote

The total mass of all the stars in the Milky Way is estimated to be between 4.6×10¹⁰ M_☉^[53] and 6.43×10¹⁰ M_☉.^[6] I

https://en.wikipedia.org/wiki/Milky_Way#Size_and_mass

So by simulating a mass distribution that includes dark matter to obtain the observed rotation curves, you appear to have  confirmed the dark matter hypothesis. Well done.

[swansont]

25 minutes ago, ravell said:

According to data from astronomical tables from 2002, the mass of the Milky Way is 5E+41 kg that is 2,5E+11 solar masses (Ms), and the diameter of the galaxy disk is 120 kly.

If we put this data into the Sagitarius BR program, with the previously given distribution of mass, but with the diameter of the galaxy enlarged to 200 kły, then we get the calculated rotation speed of the stars  exactly the same as we observe (ie about 220 km/s).

The change in the diameter or mass of the galaxy does not change the shape of the speed curve, but only raises or lowers the level of velocity obtained.

The issue was the mass distribution. You are giving examples of scaling, which is not really in question, though it still has to match. If you have to make the galaxy larger to match the answer, then your claim is wrong.

 

 

[ravell]

Quotes from the link provided by Strange:

 

„The Milky Way is a barred spiral galaxy with a diameter between 150,000 and 200,000 light-years (ly).

Estimates of the mass of the Milky Way vary, depending upon the method and data used. At the low end of the estimate range, the mass of the Milky Way is 5.8×10¹¹ solar masses

According to a study published in 2014, the mass of the entire Milky Way is estimated to be 8.5×10¹¹ M_☉, which is about half the mass of the Andromeda Galaxy

Mathematical models of the Milky Way suggest that the mass of dark matter is 1–1.5×10¹² M_☉. Recent studies indicate a range in mass, as large as 4.5×10¹² M_☉^] and as small as 8×10¹¹ M_☉.”

As you can see, there is no unambiguous data regarding the mass of Milky Way and its diameter.

As it results from the above, the assumed for calculations in the program  the diameter of the galaxy  200 kly  and the mass  around 2.5E+11 Ms,  is generally correct and gives correct  calculations of the speed, consistent with the observations.  This excludes unambiguously, the occurrence in the galaxy of a mysterious dark matter (non-baryonic) with a very large mass of 4.5E+12 Ms, that is (4.5E+12) / (2.5E+11) = 18 times greater than its normal (baryonic) mass !.

[Strange]

5 minutes ago, ravell said:

As it results from the above, the assumed for calculations in the program  the diameter of the galaxy  200 kly  and the mass  around 2.5E+11 Ms,  is generally correct and gives correct  calculations of the speed, consistent with the observations.  This excludes unambiguously, the occurrence in the galaxy of a mysterious dark matter (non-baryonic) with a very large mass of 4.5E+12 Ms, that is (4.5E+12) / (2.5E+11) = 18 times greater than its normal (baryonic) mass !.

The mass estimates for the galaxy include dark matter.

The text makes this clear and unambiguous in two ways:

1. It says that the mass estimates are based on measuring orbital velocities and includes phrases like "Because the orbital velocity depends on the total mass inside the orbital radius" or "a measurement of the radial velocity of halo stars found that the mass enclosed within 80 kiloparsecs is 7×10¹¹ M_☉". 
2. It has an estimate for the mass of stars which is an order of magnitude less than the total mass (because it doesn't include the dark matter): "The total mass of all the stars in the Milky Way is estimated to be between 4.6×10¹⁰ M_☉^[53] and 6.43×10¹⁰ M_☉.^[6] "

You can confirm that the estimates include dark matter by reading the referenced papers, which make it clear that these masses include DM.

So you seem to have undermined your claim that dark matter is not necessary. 

[swansont]

14 hours ago, ravell said:

Quotes from the link provided by Strange:

 

 

 

„The Milky Way is a barred spiral galaxy with a diameter between 150,000 and 200,000 light-years (ly).

 

Estimates of the mass of the Milky Way vary, depending upon the method and data used. At the low end of the estimate range, the mass of the Milky Way is 5.8×10¹¹ solar masses

 

According to a study published in 2014, the mass of the entire Milky Way is estimated to be 8.5×10¹¹ M_☉, which is about half the mass of the Andromeda Galaxy

 

Mathematical models of the Milky Way suggest that the mass of dark matter is 1–1.5×10¹² M_☉. Recent studies indicate a range in mass, as large as 4.5×10¹² M_☉^] and as small as 8×10¹¹ M_☉.”

 

As you can see, there is no unambiguous data regarding the mass of Milky Way and its diameter.

 

As it results from the above, the assumed for calculations in the program  the diameter of the galaxy  200 kly  and the mass  around 2.5E+11 Ms,  is generally correct and gives correct  calculations of the speed, consistent with the observations.  This excludes unambiguously, the occurrence in the galaxy of a mysterious dark matter (non-baryonic) with a very large mass of 4.5E+12 Ms, that is (4.5E+12) / (2.5E+11) = 18 times greater than its normal (baryonic) mass !.

 

The low-end estimate cited above is 5.8 x 10^11 solar masses, and the other number cited is 8.5, so any way you slice it, 2.5E+11 is too small.