[madbadgalaxyman (Robert)]

Hello again, Mike and friends,

Check out the pattern of the HII regions.....it traces a completely different pattern than the smooth tight arms.

I wrote the following about IC 5332 in this (edited) email to my favourite professional astronomer:
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It is likely that this is one of those sub-luminous spiral galaxies
that are about a magnitude or two down on the luminosity of the Milky
Way. It has a low surface brightness, and the contrast of the spiral
structure is low when it is imaged in the optical regime.

The first thing that strikes my eye is the long, small pitch angle,
yellow, smooth-armed spiral pattern in the central region of this
galaxy, which (perhaps) looks like one of the "old stellar spirals" of
the sort that I have been reading about in a series of papers (by you,
David Block, Puerari, Kenneth C. Freeman, etc).......
except that this smooth & long & two-armed pattern is plainly visible
in the optical regime and does not require NIR imaging to "dig it out"
from the confusion of OB stars and dust and other extreme Population I
material.

I have read some of those papers by you and your co-workers on the
"duality" or "dichotomy" of spiral structure in galaxies;
so perhaps, in itself, the symmetric two-armed spiral pattern in the
old stellar disk of IC 5332 is not so remarkable.....though I am
struck by the remarkable length and regularity of the smooth spiral
pattern, and by its low contrast. There does not seem to be any
evident star formation associated with this inner spiral, so perhaps
it is caused by a weak density wave.

But I did get a bit of shock when I compared an optical image of this galaxy with the GALEX image (in FUV and NUV bandpasses) of this galaxy that I accessed using the GalexView interface.

(( authors note: GALEX far-ultraviolet images emphasize nearly-exclusively the very-young stars in a galaxy;
namely, the hot blue overluminous OB stars are shown, and everything else is de-emphasized in FUV images ))

Well, what a colossal contrast!!
This young material in this galaxy has a completely different spiral
pattern. It looks like a very rough and entropic multiple-armed
pattern.
The contrast between the entropic spiral pattern of this young
Population I material and the well-behaved spiral pattern of the old
yellow-colored spiral is incredibly pronounced in this galaxy.
One might conceivably classify this galaxy as an Sa/Sd, in the spirit
of some of Alan Sandage's type assignments in the Carnegie Atlas where
he was unable to assign to a galaxy a single unique Hubble class, and
was therefore forced to classify a specific galaxy as "either this
Hubble type or that Hubble type, or perhaps both types at the same
time".

In summary, from what I have been reading of your work and that of
Block & Puerari etc., it would seem that this is not an entirely
unexpected morphology;
but what a brilliant illustration of the completely different
behaviour of the Population I spiral and the Population II spiral.

While the morphology of IC 5332 is not completely unique, it is
certainly distinctive and I personally have not seen other galaxies
that look just like this one.

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I have the galex FUV image showing the raggedy spiral pattern in the young stars, and also an 8 micron Spitzer image showing the smooth long old spiral.......so I shall display them in this thread when I access another computer.

Cheers, Robert