The slope of the rotation curve

According to CDM and MOND the Milky way's rotation curve is flat or
slightly rising at the radius of the Sun. The Newtonian prediction is
for a slope of about -4 km/s/kpc. I did a check on the populations of
thin disc stars I have been using for the Doppler test. Again
correlations are very low and not much weight can be put on individual
results of tests, but one should expect a fifty-fifty split, or slightly
more populations with a positive gradient for the rotation curve within
200pc of sun. The results we

Population No.Stars Slope (km/s/kpc) Correlation
CRVAD A main seq 2078 -0.9 -0.005
CRVAD B main seq 594 8.5 0.08
CRVAD AB Giants 256 -11.2 -0.08
G-CS FG Dwarf 2490 -7.6 -0.03
CRVAD FG Dwarf 469 -19.3 -.1
CRVAD FG Giants 511 -15.03 -.09
CRVAD KM Giants 459 -17.8 -0.1
Famaey KM Giants 320 -11.4 -0.01

Mean slope 7177 -6.6

7 out of 8 is 96% confidence that the standard model of a flat rotation
curve is wrong.

Regards

--
Charles Francis
moderator sci.physics.foundations.
substitute charles for NotI to email

Thus spake Oh No
The Newtonian prediction is for a slope of about -4 km/s/kpc.

Apologies, I of course meant the Newtonian prediction without CDM. Also,
with the revision of distance to SgrA* implied by the model, this figure
should be about -5km/s/kpc.

Regards

--
Charles Francis
moderator sci.physics.foundations.
substitute charles for NotI to email

On 14 Mar, 11:32, Oh No wrote:
According to CDM and MOND the Milky way's rotation curve is flat or
slightly rising at the radius of the Sun. The Newtonian prediction is
for a slope of about -4 km/s/kpc. I did a check on the populations of
thin disc stars I have been using for the Doppler test. Again
correlations are very low and not much weight can be put on individual
results of tests, but one should expect a fifty-fifty split, or slightly
more populations with a positive gradient for the rotation curve within
200pc of sun. The results we

Population No.Stars Slope (km/s/kpc) Correlation
CRVAD A main seq 2078 -0.9 -0.005
CRVAD B main seq 594 8.5 0.08
CRVAD AB Giants 256 -11.2 -0.08
G-CS FG Dwarf 2490 -7.6 -0.03
CRVAD FG Dwarf 469 -19.3 -.1
CRVAD FG Giants 511 -15.03 -.09
CRVAD KM Giants 459 -17.8 -0.1
Famaey KM Giants 320 -11.4 -0.01

Mean slope 7177 -6.6

7 out of 8 is 96% confidence that the standard model of a flat rotation
curve is wrong.


Well, that wouldn't surprise me, because the flat rotation curves are
usually obtained by measuring the velocity of gas (i.e. 21-cm
radiation of neutral hydrogen) but not of stars. Now during times when
the gas is ionized, it becomes trapped by magnetic fields, and angular
momentum can thus easily be transferred to the gas from the inner to
the outer region of the galaxy (see my page http://www.physicsmyths.org.uk/darkmatter.htm
for more).

Thomas

Thus spake Thomas Smid
On 14 Mar, 11:32, Oh No wrote:
According to CDM and MOND the Milky way's rotation curve is flat or
slightly rising at the radius of the Sun. The Newtonian prediction is
for a slope of about -4 km/s/kpc. I did a check on the populations of
thin disc stars I have been using for the Doppler test. Again
correlations are very low and not much weight can be put on individual
results of tests, but one should expect a fifty-fifty split, or slightly
more populations with a positive gradient for the rotation curve within
200pc of sun. The results we

Population No.Stars Slope (km/s/kpc) Correlation
CRVAD A main seq 2078 -0.9 -0.005
CRVAD B main seq 594 8.5 0.08
CRVAD AB Giants 256 -11.2 -0.08
G-CS FG Dwarf 2490 -7.6 -0.03
CRVAD FG Dwarf 469 -19.3 -.1
CRVAD FG Giants 511 -15.03 -.09
CRVAD KM Giants 459 -17.8 -0.1
Famaey KM Giants 320 -11.4 -0.01

Mean slope 7177 -6.6

7 out of 8 is 96% confidence that the standard model of a flat rotation
curve is wrong.


Well, that wouldn't surprise me, because the flat rotation curves are
usually obtained by measuring the velocity of gas (i.e. 21-cm
radiation of neutral hydrogen) but not of stars.

That isn't true. For distant galaxies stars are measured in all cases
that I have seen. I doubt it is even possible to measure gas velocities
except for the very nearest. For the Milky Way it is measured both ways.
The results are in broad agreement.


Regards

--
Charles Francis
moderator sci.physics.foundations.
substitute charles for NotI to email

"Oh No" schreef in bericht
...
According to CDM and MOND the Milky way's rotation curve is flat or
slightly rising at the radius of the Sun. The Newtonian prediction is
for a slope of about -4 km/s/kpc.

What I'am missing in your message is the measured speeds involved.
I don't understand this above prediction of -4km/s/kpc
What I'am also missing is an estimated mass distribution based on all
visible mass including brown dwarf.
Using this mass distribution and Newton's Law you can calculate the rotation
curve and predict the slope in the neighbourhood of the Sun.
Based on your thread "Doppler Test on Local Stars" you must have done
something like that. You are indicating there speeds of 220 and 160 km/sec.
( In that thread you write: "I have for some while been looking for a way
to test this" This is a rather tricky sentence.
How and when do you use the words:
test, measure, predict and calculate ?)

The interesting part is what are the differences between those two
rotation curves.

If the difference is small than no CDM is required.
If their is a slope than readers are requested to read my thread:
"Disk stability MOND and darkmatter"

I did a check on the populations of
thin disc stars I have been using for the Doppler test. Again
correlations are very low and not much weight can be put on individual
results of tests, but one should expect a fifty-fifty split, or slightly
more populations with a positive gradient for the rotation curve within
200pc of sun. The results we

Population No.Stars Slope (km/s/kpc) Correlation
CRVAD A main seq 2078 -0.9 -0.005
CRVAD B main seq 594 8.5 0.08
CRVAD AB Giants 256 -11.2 -0.08
G-CS FG Dwarf 2490 -7.6 -0.03
CRVAD FG Dwarf 469 -19.3 -.1
CRVAD FG Giants 511 -15.03 -.09
CRVAD KM Giants 459 -17.8 -0.1
Famaey KM Giants 320 -11.4 -0.01

Mean slope 7177 -6.6

7 out of 8 is 96% confidence that the standard model of a flat rotation
curve is wrong.


Anyway what you are showing is very interesting.

Nicolaas Vroom

Thus spake Nicolaas Vroom
"Oh No" schreef in bericht
...
According to CDM and MOND the Milky way's rotation curve is flat or
slightly rising at the radius of the Sun. The Newtonian prediction is
for a slope of about -4 km/s/kpc.

What I'am missing in your message is the measured speeds involved.

I can't put it up in a text file. For the raw data you could google for
CRVAD, Geneva-Copenhagen Survey or Famaey K&M Giants, also Pulkovo
Compilation of Radial Velocities. If you are experienced spreadsheets
and in astronomical calculations and coordinate changes it should take a
day or so to reproduce what I have done. I have been doing scatter plots
of the transverse (to galactic radial coordinate) motion of the stars in
the various samples against radial distance from the sun. The overall
image is a more or less circular scatter - as I say, very low
correlations.

I don't understand this above prediction of -4km/s/kpc
What I'am also missing is an estimated mass distribution based on all
visible mass including brown dwarf.
Using this mass distribution and Newton's Law you can calculate the rotation
curve and predict the slope in the neighbourhood of the Sun.

Yes. I have given a plot in gr-qc/0604047, and there are various others
on the web. That paper is overdue for revision, btw, but broadly the
thesis is unchanged. I got the figure of -4km/s/kpc by measuring the
gradient of that plot for the Newtonian motion based on conventional
mass. The mass distribution used was a theoretical model gleaned from
the literature and fitted to observation, following something close to
(but not as precise as) the method of the authors from whom I got it.
There are various similar plots of the rotation curve available on the
web and some in papers if one really searches. e.g.

http://www.astronomynotes.com/ismnotes/s7.htm

The gradient shown there is similar.


Based on your thread "Doppler Test on Local Stars" you must have done
something like that. You are indicating there speeds of 220 and 160 km/sec.
( In that thread you write: "I have for some while been looking for a way
to test this" This is a rather tricky sentence.
How and when do you use the words:
test, measure, predict and calculate ?)

The prediction is that all astronomical measurements using Doppler are
affected by a shift with a cosmological cause. The test is to calculate
a correlation between total velocity and angle of approach/recession.
For nearby stars, there should be no correlation between how fast a star
is going and its position in space. In practice I have found a
correlation which I can only put down to a systematic measurement error
15%.


The interesting part is what are the differences between those two
rotation curves.

If the difference is small than no CDM is required.
If their is a slope than readers are requested to read my thread:
"Disk stability MOND and darkmatter"

I did have a look.


Regards

--
Charles Francis
moderator sci.physics.foundations.
substitute charles for NotI to email

On 14 Mar, 23:27, Oh No wrote:
Thus spake Thomas Smid



On 14 Mar, 11:32, Oh No wrote:
According to CDM and MOND the Milky way's rotation curve is flat or
slightly rising at the radius of the Sun. The Newtonian prediction is
for a slope of about -4 km/s/kpc. I did a check on the populations of
thin disc stars I have been using for the Doppler test. Again
correlations are very low and not much weight can be put on individual
results of tests, but one should expect a fifty-fifty split, or slightly
more populations with a positive gradient for the rotation curve within
200pc of sun. The results we

Population No.Stars Slope (km/s/kpc) Correlation
CRVAD A main seq 2078 -0.9 -0.005
CRVAD B main seq 594 8.5 0.08
CRVAD AB Giants 256 -11.2 -0.08
G-CS FG Dwarf 2490 -7.6 -0.03
CRVAD FG Dwarf 469 -19.3 -.1
CRVAD FG Giants 511 -15.03 -.09
CRVAD KM Giants 459 -17.8 -0.1
Famaey KM Giants 320 -11.4 -0.01

Mean slope 7177 -6.6

7 out of 8 is 96% confidence that the standard model of a flat rotation
curve is wrong.

Well, that wouldn't surprise me, because the flat rotation curves are
usually obtained by measuring the velocity of gas (i.e. 21-cm
radiation of neutral hydrogen) but not of stars.

That isn't true. For distant galaxies stars are measured in all cases
that I have seen. I doubt it is even possible to measure gas velocities
except for the very nearest. For the Milky Way it is measured both ways.
The results are in broad agreement.

This is not what these references say:

"To determine the rotation curve of the Galaxy, stars are not used due
to interstellar extinction. Instead, 21-cm maps of neutral hydrogen
are used. When this is done, one finds that the rotation curve of the
Galaxy stays flat out to large distances, instead of falling off as in
the figure above" ( http://abyss.uoregon.edu/~js/ast222/lectures/lec19.html
)


"Paradoxically, the rotation curve of the nearest galaxy remains
poorly known. Extinction is too large to observe the stars and too
small to observe the gas. It is preferable to observe the gas, either
at 21 cm or at 2.7 mm, because it extends at much greater radii. Thus
we must rely on the corotation of both the stellar and the gaseous
systems, an assumption that is not always justified" (
http://nedwww.ipac.caltech.edu/level...ner/node9.html )


"Another problem may arise from the fact that the rotation curve is
usually measured at 21 cm but the stellar disk in the optical. The
stellar disk and the gas in the disk usually corotate, but due to
frequent mergers and the accretion of clouds, captures, etc, this is
not always the case. Unfortunately, non-corotation is more frequent
than is generally assumed and very often the rotation curve of stars
and of the gas differ greatly" ( http://nedwww.ipac.caltech.edu/level...ner/node5.html
).

And of course your own data would very much confirm this (altough I
find actually your very small correlation coefficients somewhat of a
concern).

Thomas

In article , Oh No
writes:

According to CDM and MOND the Milky way's rotation curve is flat or
slightly rising at the radius of the Sun.

Actually, flat rotation curves are an OBSERVATION which it is sought to
explain within the context of a particular theory, be it CDM or MOND or
something else.

7 out of 8 is 96% confidence that the standard model of a flat rotation
curve is wrong.

What about the enormous amount of evidence IN FAVOUR OF flat rotation
curves?

Thus spake Thomas Smid
On 14 Mar, 23:27, Oh No wrote:

"To determine the rotation curve of the Galaxy, stars are not used due
to interstellar extinction. Instead, 21-cm maps of neutral hydrogen
are used. When this is done, one finds that the rotation curve of the
Galaxy stays flat out to large distances, instead of falling off as in
the figure above" ( http://abyss.uoregon.edu/~js/ast222/lectures/lec19.html
)
It is true that from plotting the radial motion of stars which subtend
an angle of 90deg between ourselves and the galactic centre one will
only get a part of the rotation curve. Nonetheless, I have seen this
method used.

"Paradoxically, the rotation curve of the nearest galaxy remains
poorly known. Extinction is too large to observe the stars and too
small to observe the gas. It is preferable to observe the gas, either
at 21 cm or at 2.7 mm, because it extends at much greater radii. Thus
we must rely on the corotation of both the stellar and the gaseous
systems, an assumption that is not always justified" (
http://nedwww.ipac.caltech.edu/level...ner/node9.html )


"Another problem may arise from the fact that the rotation curve is
usually measured at 21 cm but the stellar disk in the optical. The
stellar disk and the gas in the disk usually corotate, but due to
frequent mergers and the accretion of clouds, captures, etc, this is
not always the case. Unfortunately, non-corotation is more frequent
than is generally assumed and very often the rotation curve of stars
and of the gas differ greatly" ( http://nedwww.ipac.caltech.edu/level5/
March01/Battaner/node5.html
).
Thank you for the clarification. On checking I find you are right. One
should certainly expect there to be a difference between the curves.
Among other things, I think stars generally have more elliptical orbits
than gas. That would lead to a quantitative difference, but not
necessarily a qualitative one.

And of course your own data would very much confirm this (altough I
find actually your very small correlation coefficients somewhat of a
concern).

I agree that the correlation coefficients I have are very small, also
that I am only looking at a very small section of a stellar based
rotation curve local to the sun. I don't attach a huge weight to the
calculation of the gradient, but I found it interesting. When examined
more carefully, certain of the plots show that the regression was
influenced by moving groups and less weight can be attached to those -
not surprising in view that they are relatively young stars and not a
huge sample this was particularly so of the class B stars, the only one
to give a positive gradient.

A lot of the time in a science like astronomy it is impossible to get
really accurate data, and even if one does get accurate data the true
physical situation may be complicated, making analysis difficult.
Regarding this particular test, I thought the low correlations made it
impossible to put a meaningful figure or margin of error on the local
gradient of the rotation curve, but that 7 out of 8 results having a
negative gradient was sufficiently unlikely to be worthy of comment. I
don't think 96% confidence is conclusive.

In practice, for the tests I did correlating radial and transverse
velocities my feeling had been that I would need at least 99% confidence
in at least three populations to get the kind of weight of evidence that
would make my case undeniable. In the event I ended up with very much
better than that, and experience of posting here suggests that there is
still room to deny the case. That is to be expected. To call a
scientific theory proven it has to stand up to whatever challenges are
thrown at it. At the moment I think the weakest part of my case is that
only I and my collaborator have run tests. Although what we have done is
fairly straightforward and it is difficult to find room for mathematical
error after cross checking e.g. our figures for UVW velocities with
published figures, until the tests are run independently I would expect
any objective astronomer to suspect that our results could be caused for
that reason.


Regards

--
Charles Francis
moderator sci.physics.foundations.
substitute charles for NotI to email

Thus spake Phillip Helbig---remove CLOTHES to reply
LOTHESvax.de
In article , Oh No
writes:

According to CDM and MOND the Milky way's rotation curve is flat or
slightly rising at the radius of the Sun.

Actually, flat rotation curves are an OBSERVATION which it is sought to
explain within the context of a particular theory, be it CDM or MOND or
something else.

This is true. I should have said according the usual analysis of data.

7 out of 8 is 96% confidence that the standard model of a flat rotation
curve is wrong.

What about the enormous amount of evidence IN FAVOUR OF flat rotation
curves?

You have not read the posts prior to this one. From an analysis of
radial velocities together with Hipparcos parallax distances and Tycho
proper motions in 10 populations containing over 7000 stars within 200pc
of the sun (500pc for halo and thick disk stars) I have found systematic
errors in quoted radial velocities at a level of confidence within
10^-23 of certainty. The test doesn't reveal the actual size of the
error, but I have found at 99.8% confidence that it cannot be accounted
for by 10% error in distance for class A and class B stars and a 15%
error for halo and thick disc stars (or equivalent error in proper
motions). The only conclusion I can see from the tests is that the
standard Doppler formula is not correct for light from stellar objects.

Of course that supports a prediction I have made by replacing the affine
connection. A more detailed form of that prediction is that, when the
cosmological correction to Doppler is taken into account, rotation
curves are not flat. They are Newtonian.



Regards

--
Charles Francis
moderator sci.physics.foundations.
substitute charles for NotI to email