ASTRO: NGC 784 A WLM look-a-like but much bigger

NGC 784 appears rather similar to the WLM galaxy in my previous post.
Though it may be quite different. It is located in Triangulum about 15
million light-years distant. While it appears smaller than WLM it is
more than 4 times further away so is actually nearly three times larger
at 30,000 light-years. NED classifies it as SBdm: meaning it is a
barred dwarf spiral similar to the Magellanic Cloud galaxies. It was
discovered by Heinrich d'Arrest in 1865 with an 11" refractor. As it is
a fairly easy galaxy in my 10" visually it is a wonder it wasn't found
earlier. Notes at NED indicate it isn't fully resolved into stars
indicating it is much further distant than its redshift would indicate
(less than 2 million light-years by that measurement). Even the 15
million light-year distant would be close enough for it to be well
resolved I'd think. That likely means most of the star-like objects I'm
showing are star knots. A few are star clusters which can be seen in
the annotated image though you might have to blow it up a couple times
to find them. One is far removed from NGC 784. Does it belong to LEDA
166065, also at about 15 million light-years and thus likely related to
NGC 784? It seems far removed from it as well. NED doesn't distinguish
open clusters from globular clusters in distant galaxies so I can't say
which these are. Most have a slight red color so I'm going to assume
they are globulars but can't prove it.

The field is rather poorly studied. Only 2 other galaxies had redshift
data and only 5 others were even listed in NED! All are shown in the
annotated image. One asteroid did make an appearance. You'll note it
as a streak then a gap then one short streak. This is because I started
a second luminance round of 4 images hoping to get some of the fainter
parts of NGC 784 but clouds had another idea and cut me off after only
one luminance image from the second series. I never had a similarly
good night to get more data without hurting my resolution so went with
what I had.

Like the WLM galaxy I did the same night the observatory floor lights
were on during this image session. It did add a rather nasty gradient
across the image, far worse than in the WLM galaxy for some reason
(light in the back of the camera?). The strong measures to remove it
resulted in a rather artificial looking background. The clouds that cut
off the night saved any further harm as I found the error before the
next clear night.

14" LX200R @ f/10, L=5x10' RGB=2x10, STL-11000XM, Paramount ME

Rick
--
Prefix is correct. Domain is arvig dot net

Rick,

nice galaxy, although it can't keep up with WLM because of it's distance.
Just checked my images and found only one try from 2002, so I might be able
to do better than then ;-)

Stefan


"Rick Johnson" schrieb im Newsbeitrag
...

NGC 784 appears rather similar to the WLM galaxy in my previous post.
Though it may be quite different. It is located in Triangulum about 15
million light-years distant. While it appears smaller than WLM it is
more than 4 times further away so is actually nearly three times larger
at 30,000 light-years. NED classifies it as SBdm: meaning it is a
barred dwarf spiral similar to the Magellanic Cloud galaxies. It was
discovered by Heinrich d'Arrest in 1865 with an 11" refractor. As it is
a fairly easy galaxy in my 10" visually it is a wonder it wasn't found
earlier. Notes at NED indicate it isn't fully resolved into stars
indicating it is much further distant than its redshift would indicate
(less than 2 million light-years by that measurement). Even the 15
million light-year distant would be close enough for it to be well
resolved I'd think. That likely means most of the star-like objects I'm
showing are star knots. A few are star clusters which can be seen in
the annotated image though you might have to blow it up a couple times
to find them. One is far removed from NGC 784. Does it belong to LEDA
166065, also at about 15 million light-years and thus likely related to
NGC 784? It seems far removed from it as well. NED doesn't distinguish
open clusters from globular clusters in distant galaxies so I can't say
which these are. Most have a slight red color so I'm going to assume
they are globulars but can't prove it.

The field is rather poorly studied. Only 2 other galaxies had redshift
data and only 5 others were even listed in NED! All are shown in the
annotated image. One asteroid did make an appearance. You'll note it
as a streak then a gap then one short streak. This is because I started
a second luminance round of 4 images hoping to get some of the fainter
parts of NGC 784 but clouds had another idea and cut me off after only
one luminance image from the second series. I never had a similarly
good night to get more data without hurting my resolution so went with
what I had.

Like the WLM galaxy I did the same night the observatory floor lights
were on during this image session. It did add a rather nasty gradient
across the image, far worse than in the WLM galaxy for some reason
(light in the back of the camera?). The strong measures to remove it
resulted in a rather artificial looking background. The clouds that cut
off the night saved any further harm as I found the error before the
next clear night.

14" LX200R @ f/10, L=5x10' RGB=2x10, STL-11000XM, Paramount ME

Rick
--
Prefix is correct. Domain is arvig dot net