Mystery of the hidden cosmos.

On 7/19/2015 5:47 PM, Gary Harnagel wrote:
On Saturday, July 18, 2015 at 11:37:18 PM UTC-6, Nicolaas Vroom wrote:
Op donderdag 16 juli 2015 22:24:07 UTC+2 schreef Jos Bergervoet:
On 7/16/2015 3:38 AM, Gary Harnagel wrote:

Yes, there is a real deficit problem unless the microlensing technique
can demonstrate that planet-sized objects are thicker than fleas on a dog
(i.e., my extrapolation wildly underestimates the number of these bodies
by several orders of magnitude).

Do we actually have strong limits on the total mass
of our own Oort cloud?

Maybe there are more questions.
The first question is slightly different:
What is the shape of the Oort Cloud ?
When you study the shape and size of Oort cloud
in: https://en.wikipedia.org/wiki/Oort_cloud than you can see
that its inner radius is small compared to its outer radius
which is 10 times as large.

The next question to answer is what is the mass of three times
the inner radius multiplied by the average density of the Oort
Cloud
When this number is more or less the same you get an impression
of how much baryonic matter there is in the Oort Cloud.

Your link says the outer (spherical) Oort cloud has an estimated mass of
about five earths.

That statement is accompanied by "assuming that Halley's Comet
is a suitable prototype for comets within the outer Oort cloud"
And in the same paragraph concludes by saying that we nowadays
have "lower estimates" than some time ago.

So that's why I asked if we have any strong limits at all!

...
It appears to me that even with there being more and more stuff at smaller
and smaller diameters throughout interstellar space, their volumes (and
therefore their masses) goes as 1/r^3, so the maximum mass fraction occurs
at the red dwarf/brown dwarf level.

Unless the numerical abundance goes up faster than 1/r^3 for
even smaller r. So the question remains: how is all this
restricted by experimental limits (from e.g. microlensing, or
extinction effects anywhere in the EM or particle spectrum?)

--
Jos

[[Mod. note -- The typical comet in the outer Oort cloud has never
(yet) had a close passage by the Sun. So Halley's Comet (which has
had ~25 observed passages, and probably many more before the first
recorded observations), is unlikely to be "typical".
-- jt]]

Op zondag 19 juli 2015 17:47:09 UTC+2 schreef Gary Harnagel:

Your link says the outer (spherical) Oort cloud has an estimated
mass of about five earths.

One important document I have studied is document 3 which is mentioned
often in https://en.wikipedia.org/wiki/Oort_cloud

[[Mod. note -- I think the author is referring to
Morbidelli,
"Origin and Dynamical Evolution of Comets and their Reservoirs"
http://arxiv.org/abs/astro-ph/0512256
-- jt]]

My understanding was that the Oort Cloud contains the building blocks
of the creation of the Sun and the planets. This process continues in
the form of planets.
At the same time these same building blocks can also form larger objects
which stay inside the Oort Cloud.
Document 3 gives a much more complex description in chapter 4.
"Imagine an early time when the Oort cloud was still empty and the giant
planets' neighborhoods were full of icy planetesimals." etc.
A typical sentence in this document is at page 44:
"This requires that Jupiter and Saturn were more effective in the real
Oort cloud building process than in the simulations of [30]"
The bottom part of page 44 is important starting with: "The way out"

The document does not mention darkmatter.
To include darkmatter in this document makes everything much more complex.
Specific you have to mentioned how much dm there is in the Oort Cloud
and almost everything related to Chapter 4.

In theory there are Oort clouds around each star. Document 3 mentions
that also. See for example page 30.
The inter-Oort-cloud-space defines all space outside these Oort clouds
The question is what are its constituents ie its composition.
Its small objects are all invisible.
Is that baryonic matter or are that Wimp's or wimpsicals?

The third question is:
Is there really an Oort Cloud around each star with empty
space between the Oort Cloud of each star.
It is easy possible that this huge region is not empty which
can inhabitate a lot of mass.

Your wiki link says the Oort cloud goes out two light years, which means
that huge region is not empty, but it has been accounted for (apparently)
in the five earth masses.

The Oort cloud goes to 50000 AU in document 3, based on simulations.
See page 31. I did not check the 2 ly.
IMO what is outside this 50000 AU is not accounted for.
Document 3 is highly based on simulations. In principle there
is nothing wrong with this.
These simulations for example can be very convincing if they show
the right masses and distributions of our solar system but at the same
time it does not mean that their predictions are correct towards
on the mass and size of the Oort Cloud if not confirmed by observations.
And this last part is very difficult.

It appears to me that even with there being more and more stuff at
smaller and smaller diameters throughout interstellar space, their
volumes (and therefore their masses) goes as 1/r^3, so the maximum mass
fraction occurs at the red dwarf/brown dwarf level. Not nearly enough to
account for dark matter.

Gary

When you study the 1992 article you can see that the total number of Red
and White dwarfs is much larger than the K dwarfs.
For the amount of mass the same logic applies.
My reasoning is that the R and W dwarfs are like the building blocks
for the K dwarfs and the K dwarfs are the building blocks the G stars etc.
What is missing are the building blocks of the R and W dwarfs.

The 1992 article at the end reads: "For these reasons we know that the
universe has more dark matter than luminous matter. But no one knows
what dm is. It could be faint stars, like R and W dwarfs or it could be
subatomic particles. Whatever it is dm may be the Grand Illusion in its
most sinister incarnation: the universe is full of something that our
instruments cannot see"

The SA article writes:
In addition to the normal "baryonic" matter in the cosmos, some hidden
form of matter matter must be out there, gravitationally tugging on
galaxies to keep them spinning as fast as they do and holding galaxies
together.
IMO let us first stictly investigate our own galaxy the Milky Way
and come to an agreement what the solution of the dm issue is.
This is already difficult enough.
Do we need any dm? If so how much and where should it be?
Inside the disc or outside the disc or both?
If inside the disc where? etc
Reading document 3 this whole picture becomes more complex.

Nicolaas Vroom.