ASTRO: NGC 3359

NGC 3359 is a nice barred spiral in Ursa Major about 50 light-years
distant (redshift says 53, the Gemini page says 49 and other sources say
about the same range). NED classes it as SB(rs)c, while the NGC project
says SBc. Both mention it has strong HII emission. So why am I imaging
a rather normal galaxy? It isn't as "normal" as it appears. For one it
has over 100 large star forming regions, far more than most spiral
galaxies and for another, the bar is thought to be only 400 to 500
million years old while the galaxy is likely at least 10 billion years
or older. What triggers bar formation is a rather long standing
problem. Once formed do they last or are they temporary? These are
still highly debatable subjects. At that distance I didn't really
expect to pick up many of its HII regions as most amateur images fail to
pick them up unless blending in H alpha light. I was pleasantly
surprised to discover the bigger ones did come through. Though to
appreciate the vast number present in this galaxy see the Gemini North
image at:
http://www.gemini.edu/gallery/v/astr...359v2.jpg.html

Their image is flipped to a mirror image with south (sort of) up and
west to the right while my image has north up and west to the right.
Theirs is a mirror image that wasn't corrected for display. You can
read all about the galaxy at the Gemini link. Another unanswered
question not mentioned at the Gemini link is why all the sudden star
formation in every corner of the galaxy? There are no nearby galaxies
to have triggered it. Nor does it look particularly disturbed yet the
bar and likely the HII regions are very young compared to the age of the
galaxy.

There is a smudge of a blue galaxy to the east northeast of NGC 3359.
Could it be involved in some way? It could if it was at the same
distance though its mass is too small to cause much interaction unless
it has already been stripped of its dust and gas in a close passage a
billion years or so ago. It is SDSS J104713.26+631629.2 but NED has no
redshift data so it could be too close or too distant to be involved.
For now it is an unknown. Though I see no hint of any tidal connection.

I've noted a galaxy in the upper left corner. NED shows it at 2.7
billion light-years yet it shows some rather obvious spiral structure.
NED lists it at 12.6" of arc in size. That would work out to be 165,000
light years in diameter. A pretty big spiral.

The galaxy cluster west and a bit north of NGC 3359 is GMBCG
J161.33127+63.27897 it and its anchor galaxy are listed at 4.2 billion
light-years measured photographically. It is said to have 8 members but
the size, as usual, is not given. Still there are 4 other fuzzies in
the immediate area and a few more a bit further out that are likely its
members. Just southwest of it is another cluster, WHL J104515.8+631614,
which is listed at 15 members. I see only the anchor galaxy which is
listed at magnitude 23.1. Again no size is given. Looks like 23.1 is
about the limit in this image.

Continuing with galaxy clusters, WHL J104452.7+631740 is near the right
edge. It is listed as having 7 members. No distance is listed for the
anchor galaxy which has the same coordinates as the cluster. GMBCG
J161.17919+63.24738 is yet another cluster near the west (right) edge of
the image. Only the cluster has redshift data but its coordinates match
that of the anchoring galaxy. The cluster is said to have 12 members
and be 4.4 billion light-years distant. No diameter was given for the
cluster. GMBCG J161.15360+63.38777 is in the upper right corner. It's
anchor galaxy is very red. While the distances to it and the cluster
are slightly different they both round to 4.0 billion light-years. The
cluster is listed as having 10 members in an unknown area. Even closer
to the top in the right corner is WHL J104444.9+632500. The
photographic distance estimate is 4.7 billion light-years with 8
members. The spectroscopic redshift of the BCG however shows a distance
of 4.4 billion light-years. I assume that is more accurate for the
cluster as well as the galaxy. Oddly the galaxy isn't as red as the
closer galaxy anchoring the other cluster in that corner.

14" LX200R @ f/10, L=4x10' RGB=2x10'x3, STL-11000XM, Paramount ME

Rick
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