Object of the Week February 21,2016 NGC3081 The King of The Resonances Rings

NGC 3081

Hydra

Ra
09 59 29
Dec
-22 49 34

Type
Seyfert 2

Mag
12.8

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The last few years I have been observing SB type rings and so far this is the best of the resonances rings that I have found.

Attachment 1998

NGC 3081 was found by William Herschel on Dec 21, 1786. I wounder if he thought he had found another PN? According to professor Ron Buta's paper on NGC 3081 the are four rings in this unusual galaxy " NGC 3081 is a early-type barred spiral having four well-defined resonance rings: a nuclear ring, an inner ring, an outer R1 ring, and an outer R2."

Attachment 1999

He also says that there has been little to no interaction with other galaxies and this is why the rings are in a pristine shape. DR Buta,s Paper http://iopscience.iop.org/article/10...3365.text.html

Attachment 2000

From my observations of NGC 3081 RI and R2 rings are very faint and not seen visually and only shows up in deep images of the galaxy. The view of the inner rings are stunning and hard to put into words. Steve G, Howard B and I had a good view or the inner rings one night and Howard did a awesome drawing of it I hope he will post it here for us to see.

I hope you get a chance to view the King of the SB rings soon and will,

"Give it a go and let us know! "

That was quite of view of 3081 through your scope Jimi, and here's my notes and sketch:

"Excellent ring galaxy! Bright, concentrated core with a tiny stellar (nucleus). The ring is brightest on each end and they both have a subtle texture. 488x."

Attachment 2001 Attachment 2002

I have yet to look at 3081 with my own scopes, so this is my only observation of it so far - and it will certainly be hard to top!

I just visited the galaxy at June 2015. Location was Gamsberg in Namibia, perhaps one of the best observing places in the world. Funny thing, I used the smallest telescope that was available for visual observation - a 17.5" Dobson.

17,5"; 289x; NELM 7m+, Seeing III
Attachment 2003

I haven't observed this galaxy myself yet. However, I find it fascinating that the pictures show that the major axis of the nucleus doesn't align with the major axis of the ring, while both Howard and Uwe have drawn the major axes aligned. I wonder what it will look like through my telescope!

These are my eyepiece notes (observing with Howard and Jimi) of NGC 3081.

48" (4/18/15): This beautiful ring galaxy was viewed at 488x and 610x. It is very sharply concentrated with a very bright, roundish core (slightly oval at 610x) that gradually increases to a stellar nucleus. The surface brightness drops significantly in the inner halo, but then brightens at the edge to a well defined oval ring, extending 5:3 WSW-ENE, ~1.3'x0.8'. The ring is fairly narrow and brighten slightly at the ends of the major axis (southwest and northeast ends). This is a very distinctive object!

Good catch - the major axis of the nucleus doesn't match that of the outer ring in the photos, but through the eyepiece it was a different story. I've found this to be true with some planetary nebula that have oddly shaped inner halos but they look perfectly round visually.

Yes, I am well aware of objects appearing differently visually then they do on photo's. I suppose that's due to several causes among which photo's having been processed to bring out faint details more brightly than they are and our brains interpreting what we see while having a tendency to recognise patterns everywhere. Steve discribes the core to increase inbrightness inwards which very likely adds to the effect. That all is why I am looking forward to seeing this object with my own eyes!

Wow, what a fascinating galaxy Jimi, thanks for sharing. Can't wait to give it a try; although with only 15" of aperture, typical Ohio skies, and a transit altitude of only 30° I don't have high expectations.

Looking at the Hubble image there seems to be several galaxies in the foreground of NGC 3081. In particular around the 7-8 o'clock position there seems to a rather large loose-spiral galaxy and several much smaller galaxies, including one that is shaped like an eye. With a quick perusal of MegaStar and SkyTools I didn't see other galaxies noted. Are these foreground galaxies or are they part of 3081's structure?

The two galaxies at 7-8 PM are visible on the DSS, but appear stellar. The colorized WikiSky image shows them very well (zoom in on NGC 3081). Neither object is in NED or HyperLeda, so they don't appear to have galaxy designations, though the one on the east (left) side is in the 2MASS point-source catalogue as 09593161-2249525. NOMAD lists a B magnitude of 19.9 - don't know if that's reliable. The galaxy on the west (right) side looks like another ring of some type.