On 1/6/17 10:03 AM, Phillip Helbig (undress to reply) wrote:
In article , "Richard D.
Saam" writes:

the quantities are
determined, as is everything, by the constants of nature and by initial
conditions,

Since most of the mass of a planetary system is in the star, the limit
to its mass is the limit of the mass of a star.

I'm not sure what you mean. Above a certain mass, nuclear fusion will
set in, so anything more massive is a star, by definition. (There is
also the Hayashi limit related to convection, so the lower limit for
stable nuclear fusion might be a bit higher, around 0.08 solar masses.)
The upper limit for a star is a few hundred solar masses. (Probably
anything more massive can't form before what has already contracted has
ignited, keeping out additional material.) I'm not an expert here, but
the mass range in stars is 2--3 orders of magnitude. It is not directly
(and if indirectly, very indirectly) to any size of the universe.

Assuming your 2--3 orders of magnitude range
galactic size (presently ~10^20 - ~10^24cm)
and star planetary system size (presently ~10^13 - ~10^17 cm)
contained in a Hubble radius (presently ~10^28 cm)
What establishes the voids
on the order of 3 orders of magnitude between
and do these ratios maintain themselves with redshift
and within what theoretical framework?

Richard D Saam

[[Mod. note -- This wording presupposes that there are "voids" and that
they are "established". I know of no good reasons to reject the null
hypothesis that there's no particular connection between these size
scales.
-- jt]]

It is acknowledged that
the universe size (uniform?) distribution parameters
are not at equilibrium.

Indeed. Note that galaxies range over more orders of magnitude in mass.

Size may be more important parameter.

Between solar-system scale and galactic scale there are things like
giant molecular clouds; between galactic scale and Hubble-length scale

No, the molecular clouds are between planetary and galactic radius
in a size range 15-600 light years (1.4x10^19 - 5.7x10^20 cm)
The literature indicates these to be star planetary system precursors
or perhaps star planetary systems that did not make it.

there are groups of galaxies, clusters, superclusters.

but the unit of measure is the galaxy as in clusters of
and the filamentous, layered structure of these superclusters
may be an indication of galaxy orthokinetic formation by shear
associated with H = c/Hubble Radius.

There is also
the structure of dark matter, about which less is known.

A very closely studied dark matter entity is the Bullet Cluster
with size ~.5 Mpc (1.5x10^24 cm) falling within galaxy size.
There may be more diffuse dark matter structures
with a precursor star planetary characteristic
analogous to molecular clouds above.

To a first approximation, the sizes of solar systems and galaxies don't
change with the expansion of the universe.

Our solar system is the star planetary system reference
with its size going out to the Kuiper Belt at
20 - 50 AU (3.0x10^14 - 7.5x10^14 cm)
and out to the Oort cloud at
0.8 - 3.2 light year (7.6x10^17 - 3.0x10^18 cm)
The Kepler spacecraft has found planets in other star planet systems
but is not sensitive to more diffuse Kuiper and Oort like structures
that probably exist.
Future spacecraft may obtain information
on analog Kuiper and Oort components in these star planet systems.

Aren't the early galaxies (~million years after the big bang)
much smaller (primitive) than present galaxies
suggesting that star planetary systems had not formed at that time?

The Hubble radius changes if
the Hubble constant changes. The Hubble constant has increased since
the big bang, but as the universe approaches exponential expansion
asymptotically, the Hubble radius will approach a constant value.

as perhaps galactic and star planetary system sizes
approach a constant value.

[[Mod. note -- In addition to the things the poster mentioned, globular
clusters and dwarf galaxies are some other important astro-things that
lie between solar-system and galactic size.
-- jt]]

In as much as a globular cluster is a spherical collection of stars
that orbits a galactic core as a satellite,
a globular cluster may be considered stars as part of a galaxy
and within the galaxy size.

Dwarf galaxies sizes fall within galaxy size range
(compared to the milky way) as follows:

milky way 200000 lightyear (1.9x10^23 cm) 2.5x10^11 solar mass
Ursa Major II Dwarf 1800 lightyear (1.7x10^21 cm) 5.0x10^6 solar mass
NGC 2419 520 lightyear (4.9x10^20 cm) 900,000 solar mass

The two Dwarf galaxy masses compared to their size
indicate that they are less dense than the milky way
further indicating that size
is a better structure comparative parameter.

Richard D Saam