Jump to content

 

1825338873_SNRPN2021banner.jpg.68bf12c7791f26559c66cf7bce79fe3d.jpg

 

RING GALAXIES THREAD


Mike JW
 Share

Recommended Posts

This thread is for adding in your observations of RING GALAXIES.

Here is my somewhat basic understanding of ring galaxies.

Ring Galaxies – a galaxy with a ring (torus like structure) of stars. If only it was that simple. There seems to be various ways that a ring may form. About 50% of spirals have rings or partial rings and are most common in barred galaxies. The bar of stars sets up some sort of resonance pattern in the orbiting stars.

Three principle current theories of ring formation.

If the galaxy has a bar that becomes unstable as the galaxy rotates then the stars in the bar are migrated outwards to form a ring structure. (this is my simple version – dark matter and Byronic pressure are involved……)

Galaxy collisions such as in Arp 147 can result in a ring. If a galaxy passes straight through another galaxy then a ring is likely to form. A slanting blow, near misses are less likely to form a ring. As the smaller galaxy plunges into the bigger one, pressure wave ripple outwards (radially propagating density waves to be precise) collecting up the gas and compressing it at the same time and initiating star formation in a ring.

The third mechanism is where there is the formation of a very large spiral from the surrounding intergalactic medium. As material flows inwards and if conditions are right, rings of hot blue stars are formed rather than spiral arms.

The above is good enough for me. There are many technical articles out there for those who like the in-depth detail. Today I discovered an article suggesting that way back near the start of things there were magnetic wormholes and I quote

‘hypothesis that at least some of such rings could be remnants of relic magnetic wormholes. It turns out that magnetic wormholes may directly collect ring clumps of baryons in a process which is not based on the development of perturbations in dark matter component This means that the dark matter halo in such structures may have peculiar features, different from those observed in galaxies, In particular, in the case of wormholes the dark matter halo can be almost absent. This argument however does not work, if dark matter phenomenon has a pure topological origin, or it appears due to some extension of general relativity. The only stringent feature of such objects is the presence of a large-scale toroidal magnetic field. In the rest, the final form of the ring galaxy formed by a wormhole does not differ from that predicted by standard mechanisms. Indeed, upon the recombination epoch in the case when the wormhole collapses the ring may contain a more dense and old collection of stars (a small galaxy) in the center of the ring (as in the case of the Hoag’s object), or, when the wormhole expands further, the center part of the ring may remain empty.

See the link https://link.springer.com/article/10.1140/epjc/s10052-020-8395-7

This link is at about my level with a nice simple video: https://www.syfy.com/syfywire/one-ring-galaxy-to-bring-them-all-and-in-the-darkness-bind-them

This link https://medium.com/swlh/giant-ring-galaxy-existed-in-the-young-universe-ad65899126cd gives exciting info on the oldest collisional ring galaxy to be discovered - R5519 at about 10.8 billion years ago.

Ring Galaxy classification gets complicated.

An ‘r’ in the notation indicates a ring – no surprises there then!

(R) at the start indicates an outside ring, (RR) indicates two outside rings and (R’) indicates an outside pseudoring. A pseudo ring looks like a ring but isn’t. (r) indicates an internal ring.

However, rings can become lenses (‘L’ for outer or’ l’ for inner). I think rings evolve into lenses but I cannot find a simple definition of a lense. I am not even sure I could recognise a galaxy lense despite looking at various illustrations. My best guess is a ring is a well-defined structure and a lense is wider and fuzzy in appearance.

Now for the final complication, there are nuclear rings – these tend to be tight and bright around the nucleus, with the ‘n’ notation.

https://ned.ipac.caltech.edu/level5/Sept11/Buta/Buta6.html - will take you to more info on rings

try these for some light reading!!!!!! https://arxiv.org/pdf/1906.08124.pdf  https://arxiv.org/pdf/1501.00454.pdf  https://arxiv.org/pdf/1707.06589.pdf

I hope the above has got you excited to go out there and spot a ring or two.

PS – if you have any other info or spot mistakes in the above let me know and I can add it in/change things.

Have fun observing,

Mike

A list of ring galaxies to get us started.

Ring Galaxy.xlsx

  • Like 3
Link to comment
Share on other sites

Posted (edited)

First up is an old friend, Arp 148 in UMa. Not the easiest of targets  to view. Its to the right of centre in the wide shot. It is a classic example of a galaxy doing a direct hit on another one. This pair are known as Mayall's object and lie about 500 million lyrs away. The offending galaxy has gone through the centre and is now heading out the other side. The shock wave creating the ring. Search out Hubble's image for this pair.

50810940_Arp14815Mar21_09_35_47.png.f3dd2824cca39bbda796f3bf7a967fc8.png484926767_Arp14815Mar21_09_37_17.png.0c5d8d077999a719eb94a1aed3e42718.png

 

 Arp  336  in UMa - NGC 2685 takes us to the nightmare of galaxy designations - it is (R) SBO^ / pec (Sy 2) = outside ring, barred lenticular, messed up and very active nucleus (I do not know what the ^ stands for - any suggestions?). It is  an example of a Polar Ring (ring goes around the poles rather than around the ecliptic). It is also called the Helix galaxy. Two galaxies have collided causing one to wind around the other and creating a large ring of stars. The spindle in the middle is more or less a normal SO galaxy and in my shot you can get hints of the spiral pattern (helix) of the second one which has wound around the central  galaxy. There are some beautiful images on the web.

Seyfert 2 galaxies - black hole doing its thing at the centre with a bright nucleus (visual) and bright in the infrared, indicating much dust/gas.

1788788181_NGC268515Mar21_13_48_52.png.d7f73762a3501dc8e55e9141558cc14e.png.

UGC 6309 in UMA  is a lovely sight and is classified as SBc - barred spiral with arms not too tight but personally when I compare to standard galaxy pictures it looks more like SBb. Then there is the small matter of the ring or is it? I cannot find any official ring classification so I am suggesting it should be (R')SBb - pseudoring barred spiral..........

 

668658918_UGC630915Mar21_14_41_47.png.410f62ffcaf2ab80b299e7b3c0e87218.png970848898_UGC630915Mar21_14_44_32.png.4d2ae14b6de072e1f71e385dba4d2c81.png

 PGC 38265 in UMa  is tiny and faint. I have distance data and nothing else. It lies 745 million lyrs away. Many of the fuzz spots in the left hand shot are in fact mag 18/19 galaxies.

46923418_PGC3826515Mar21_14_50_05.png.d04a7c5b1c5d77b65dfba12978041baf.png532201853_PGC3826515Mar21_15_06_09.png.d01507d2e92f05bdfd93428e85cc6e2b.png

 

Mike

 

 

 

 

Edited by Mike JW
  • Like 6
Link to comment
Share on other sites

Some really remarkable galaxies there. UGC 6309 is so unusual -- very hard to get my head around that. I can't find what the ^ means and I have trawled through the entire N page table in the most recent galaxy classification I could find...You've really been able to pull a lot of detail out of Arp 336, with the helter-skelter trails and the bomb-shaped outer envelope -- wonderful shot. The 3 Arp ring galaxies I think I have visited (146-148). I'm looking forward to both observing some of these and seeing what other shots get posted in this thread.

Martin

Link to comment
Share on other sites

Posted (edited)

Arp 224 (NGC 3921) in UMA. This is thought to be a merger in process - the close up shot gives a hint of of two nucleus in close proximity. It lies about 275 million lyrs away. It has a starburst nucleus which is really no surprise as these two galaxies collide. Designation is (R') SA (s)O / pec. The R' indicating a pseudo ring - in however many millions of years it might well become a proper ring.

The Zwicky cluster - ZWCl 1148.6+5523 is centred on NGC 3921 and the various fuzz spots are galaxies at about 1 billion lyrs away. Down and to the left on the wider shot is another ZWCl (only the cluster edge in view) where the galaxies are a touch nearer at about 800 million lyrs away.

950184047_NGC392115Mar21_14_33_43.png.23afd9be451258409fb670d97ee76a93.png1863615836_NGC392115Mar21_14_34_13.png.386d029fa4400ee6a9dcbd3b9fe0a8f4.png

 

UGC 5055 (Markarian 114) in UMa.  One of those WOW moments as this galaxy appeared in the middle of its guardian stars . Designation (R') SBb (Sbrst) - not a true ring galaxy, just the appearance of one with those spiral arms turning back on themselves. 363 million lyrs away.

243081823_Markarian11415Mar21_14_16_41.png.17d8d379eae8b546f156b580c2c93fbb.png1366245980_Markarian11415Mar21_14_18_30.png.9a8de6ad1137cb9baa4d5db115b471bb.png

UGC  6334  in UMA.  This is a nice example of  a lenticular with no bar and an outside ring - hence (R) SO/a - now what does this mean? SO = lenticular where not sure if it has a bar or not (SAO=unbarred, SBO =barred), so I am assuming the /a might be indicating the preference for it lacking a bar?

868207527_UGC633415Mar21_15_15_56.png.deef4e9827a936a01c13e2f57d9be1b1.png878450620_UGC633415Mar21_15_16_22.png.f5676e2da2d06538b3c7de29fdd43120.png

PGC 31214 in UMa, is in the ring galaxy list as (R) Sab at a mere 919 million lyrs away! I was using the C11 for this shot so it was hard to pick up at mag 16.

614936306_PGC3121417Mar21_07_51_00.png.6595d186d7d1f80fd4fc66fd7208bf70.png

Arp 143 in Lynx is a glorious mess, made up of NGC 2444  - SO (Ring A), merging with NGC 2445 - Im (pec) (Ring B). So we have a lenticular merging with Magellanic type dwarf, irregular galaxy. Along with the mess we get star forming regions in 2445 and two rings for the price of one.

1671119879_Arp14315Mar21_09_50_59.png.6bf19c40274f9618ca96c2b853157a41.png

 

NGC 3945 is found in UMA. I was thrilled to see this one pop onto the screen. This is bigger than the Milky Way at about 120,000 lyrs diameter and 68 million lyrs away.

It is a 'Saturn' look a like. My first thought was just how many rings have we here?  - (R) SBO^ + (rs) + LINER

1964106854_NGC394515Mar21_13_59_06.png.2bf8ae162728fa229f346751c364da25.png

NGC 3945 in Bootes is SB(rs)ab - LINER. rs = spiral arms coming off the end of the bar and forming a ring, which my shot picked up. There is the extra halo fuzz but this is too diffuse to be considered a ring?

1283528513_NGC594515Mar21_15_21_38.png.6570fcfe67aa12a32350b93e040dadea.png

As always it is worth the cold, wrecked sleep patterns.... to 'see' such sights.

Mike

 

 

Edited by Mike JW
  • Like 1
Link to comment
Share on other sites

Fascinating objects. I can add Arps 145 and 146, plus my take on Arp 148. These come from the last few years.

Ignore some of the labelling of seeing etc; these come from a rogue version of Jocular.

Arp 145 consists of a very clear doughnut ring (PGC 9060; type S0), and the ingressor (?) UGC 1840, type S0-a. The interesting thing about these, observationally, is the presence of several foreground stars and the possibility that the fuzzier 'star-like' things are knots or a galactic nucleus in the case of the spherical object. The ring itself is not uniform, seemingly mottled in its Northern sector.

There is an intriguing tack-shaped vertically-oriented bit of fuzz just to the NW too. 

I probably mentioned before that I have a great fondness for this field as it is the one I used when testing the live stacking alignment algorithm. I couldn't get it to work for ages until I worked out I had the x and y coordinates reversed...

941477685_Arp14521Mar21_14_11_13.jpg.9a4a24f7a698bfcacf4730894bbf420d.jpg

 

Arp 146 in Cetus is a tiny smoke ring, about a third of the apparent size of Arp 145 but similar in many respects, including the non-uniform ring presumably left by the passage of the other galaxy. This is 1.1 billion light years away while Arp 145 is about 262 million LYs distant, so the actual sizes of these collisional pairs must be quite similar. Further away still is a z=2.1 redshift quasar which at mag 19.0 is quite bright.

1768098742_Arp14621Mar21_14_08_26.jpg.13acd6a67be567f1d0a1b21e54e8b62f.jpg

 

Finally, here is my take on Arp 148 -- certainly nothing added relative to Mike's as far as the ring pair is concerned but always fascinating to see the torpedo-like ingressor. Interestingly, these must be of a similar actual size as the earlier two Arps given the apparent size/distance=500 MLyrs relationship. All I can add are a couple of very distant quasars. The z=3.0 one corresponds to a light travel time of 9.5-11.5 billion years according to my 'go to' redshift calculator: http://astro.ucla.edu/~wright/CosmoCalc.html

1262702818_Arp14821Mar21_14_06_08.jpg.f74155aea20dc6e3797aa95e43e0ccaf.jpg

 

cheers

Martin

Link to comment
Share on other sites

Thanks Martin for adding in the Arps. I have checked my Arp 145 but it does not add any extra detail. Always a mystery how you get those extra spider spikes in this shot but I do rather like them - adds to the drama.

Mike

Link to comment
Share on other sites

Ah, those deliberate extra spikes... I have a misaligned secondary and this being EEVA I haven't done anything about it in the last 6.5 years since I bought the Quattro. That accounts for one set. I've no idea where the others come from. I would say they are second harmonics of the first set somehow. Perhaps it is time to disassemble everything and clean the mirror at the same time.

Martin

Link to comment
Share on other sites

  • 1 month later...

                                                                                         I have been going through my Ring Galaxy observations in Leo.

NGC 3821 is a lovely example of an outer ring - (R)SAB (s)ab                                             NGC 3646 is a beautiful  spiral galaxy to view, with star forming regions  - SA (r)bc pec

I have also seen this galaxy classified as SO. Off to the right is PGC 36293 - what a           The internal ring is partially hidden by a spiral arm from our perspective

lovely barred spiral, SABb

918188070_NGC382115Apr21_18_24_07.png.fb78ff3435c2e97f2b3e873dd7470505.png512570054_NGC364615Apr21_18_24_49.png.5a5ca627534ccecd0a36443bd362b542.png

Mike

  • Like 1
Link to comment
Share on other sites

Just checked my observations and I don't have either of those listed, but they're both real beauties. The 'far' arm in NGC 3646 appears to be rippled. It just shows that nearly every galaxy has something new and distinct to offer (except for most of the ellipticals 😉)

NGC 3821 is a great example of a ring, almost perfectly face on. And the galaxy partly obscured by the star to its right makes for an interesting field.

I hope I'll get a chance to look at these with the moon out of the way. 

Thanks for posting

Martin

Link to comment
Share on other sites

  • 1 month later...

June 1st 2021 - there was me pottering about in Serpens and looking at my lists I saw this bright galaxy - NGC 5921 (mag 10).

What a surprise when this ring galaxy appeared on the screen. Classified as SB(r)bc LINER (= bright nucleus). It lies 79 million lyrs away, has a strong bar and a slightly elliptical bulge. The two spiral arms have many H11 regions (I picked up a few of them). This inner ring galaxy was not even on my list of ring galaxies.

 

1321871104_NGC592102Jun21_18_17_40.png.6f9429d1d76f2fdc0cd71c1e57e663da.png

Mike

  • Like 2
Link to comment
Share on other sites

Lovely shot. I just looked this one up in the de Vaucouleurs atlas where it figures as a luminosity class I-II standard for Sb galaxies. The image shows an extensive and quite messy set of spiral arms extending 3-4 times the width of the central 'theta' part in your shot. I imagine this is one of those galaxies that just gets progressively more detailed with increasing overall exposure.

Martin

Link to comment
Share on other sites

I probably should go back to this one and run the camera for longer. I did actually run it for about 5 minutes and then deleted the poor subs (the unsteady ones). As usual, so much to see..

Mike

Link to comment
Share on other sites

Those extra spikes are due to things like mirror clips. The hints are how many, the orientation compared to the secondary vanes and whether any are masked by projections like the focuser tube. 

Link to comment
Share on other sites

  • 1 month later...

August 3rd - My first object after the summer break. A real cracker.

NGC 7217 (UGC 11914) has it all (well worth looking up Hubble images). Classified as (R)SA(r)ab, Sy LINER. In fact there is a nuclear ring as well. It lies about 30 million lyrs away, is mag 11 and as indicated is an unbarred spiral. The middle ring is weak and the outer ring is much stronger and has most of the H11 regions (very blue in Hubble images). Overall the galaxy is gas poor and strangely has stars in a counter rotation. This suggests a merger. One merger model indicates a Lenticular merging with two small high gas galaxies. The other theory suggests a merger of two galaxies  with the rings still developing. Surrounding the galaxy is a very large spherical halo (a spheroid) - again best seen in the Hubble images.

Below - same stack but stretched slightly differently.

Mike

 

322509721_NGC721704Aug21_06_48_35.png.d196e34e0956b25c407985ce6996461d.png566072540_NGC721704Aug21_07_29_57.png.7b98a4ccc47f524f58c81665b133f0d3.png

 

  • Like 3
Link to comment
Share on other sites

  • 1 month later...

I have been collecting Ring galaxies during September. Here is a feast of them.

Arp 145 in Pegasus - Martin posted this one further up the thread and had a collimation issue . I had not focused properly- so annoyed with myself at the poor focusing. I re-did it after this poor shot. Must be something about Arp 145?????

1405740097_Arp14516Sep21_08_19_26.png.d707cf63e291796c04aa16b43f18182a.png

NGC 7742 (Pegasus) is SA(r)b, LINER, H11 = unbarred spiral with active central black hole (Seyfert 2), inner ring, plenty star formation. Lies about 62Gyr away. It is known as the Fried Egg Galaxy - obvious in decent images.

1957885299_NGC774209Sep21_07_51_12.png.d9d4175e204352b9dc1717625602c498.png

 

IC 5285 in Pegasus - SO (but some say spiral) with an outer ring, 275Gyr away. A lovely sight. The outer ring is counter rotating and is thought to have been formed by the galaxy accreting gas.

705193897_IC528514Sep21_10_34_43.png.5d9898f32c4c7bfc7c6747cbcfe23e40.png

NGC 38 in Pisces (R)SAa is a tight spiral with an outer ring, 363Gyr away.

1853461724_NGC3816Sep21_08_23_59.png.2cde249e3fdc311e098fee6623e3852f.png

PGC 606 (Pisces) - this little guy really did it for me . Light travel time is 967Gyr - wow. This must be the furthest ring galaxy I have viewed and so clear despite being low down in the murk.

Its classification is R(N)3 - apart from the ring notation I have no idea what the rest means.

1808196644_PGC60616Sep21_08_26_55.png.1f6859bf4d9dec088225b15904f6a1dc.png

NGC 7428 (Pisces) gives you two rings for the price of one!! - (R)SAB(r)a pec. The peculiar designation probably refers to the long curving arm heading off to the north (up) and curving to the right - look carefully and you can just see a hint of it. This galaxy is always going to lie in the murk for me (Martin - any chance you could try for this?)

137646796_NGC742816Sep21_08_37_18.png.31de920ee85c7d82492d65c2cbd1e7f1.png

and finally a real wow shot - NGC 125 (Pisces). It is (R)SAO pec. At first I was not sure why it is peculiar - looks OK to me. High resolution images show an arm coming off from the right and curving upwards.  Now for those three galaxies to the left - (NGC 127/8/30). Two are obviously connected by a tidal stream of some sort. The core of NGC128 (the big one) seems to have a double bulge - a double peanut shell of stars - see https://astronomynow.com/2016/05/08/astronomers-detect-double-peanut-shell-galaxies/  These three galaxies , NGC125, the one bottom left and the other two galaxies in the shot (to the right)  all lie in the same region of space (188 - 202 Gyr away) so are likely to be a true group.

424163580_NGC12516Sep21_09_08_51.png.89e90717ef8f5890b69d4ce08630cc52.png

Mike

 

Edited by Mike JW
  • Like 3
Link to comment
Share on other sites

What a marvellous collection!

I'll have a go at NGC 7428 as soon as I get a clear night.

The one that stands out for pure interest is the last shot. The curve on NGC 128 looks like a gravitational lens (though obvs. isn't). Can't wait to take a closer look at this field myself -- so much to see here.

I've no idea what the N means either but will dig out the de Vaucouleurs Atlas later to see if I can spot anything. 

Thanks for posting such an interesting collection.

Martin

Link to comment
Share on other sites

The 'N' might mean 'nuclear ring' defined as a ring of intense star formation close to the nucleus. The image I'm looking at right now in de Vaucouleurs for NGC 1097 is somewhat similar to your PGC 606 in that it has a bright ring close in with several knots and gaps.

There are also images of other 'peanut' galaxies like NGC 128 but I have to say that your image beats them all! To better see the x-shape they use unsharp masking in the Atlas. Sounds like it might be worth implementing. The x-shape is also visible in some non-edge-on galaxies using this techique. The examples shown are for NGCs 7020, 1527, 4429 and IC 5240 which is pretty spectacular with unsharp masking.

Martin

Link to comment
Share on other sites

Hi Martin,

N for nucleus makes sense.  Below is a close up of NGC 128 - used a different stretch/settings and added a small amount of tweaking in Photoshop (not really sure what I am doing). I will investigate the other peanut galaxies

 

1878881007_NGC12517Sep21_06_22_22.thumb.png.c5dc76c146dedc9e9451c4a65227cac1.png

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Mike

  • Like 1
Link to comment
Share on other sites

  • 3 weeks later...

Mike, I tried to improve upon your shot of NGC 7428 but didn't get anything better. Its pretty murky for me in that direction too and until I trim the summer growth I was also observing through gaps in a philadelphus (or similar).... remarkable that one can get anything at all that way. My NGC 125/128 is also no improvement, but was very enjoyable to observe.

731407556_NGC12805Oct21_18_59_28.jpg.324f23ca376c9cb2c867a7a55d2aedb5.jpg

 

I also followed your lead and looked at IC 5285 with its remarkable ring. Here's a stretched shot to bring it out more clearly at the expense of background noise. Also in shot is NGC 7489 which is really ragged, with spiral arms splayed out all over the place to the N. This is type SABc or Sc and, like the ring galaxy, is at about 300 MLyrs distance. In the SDSS shot it looks quite blue, as does the ring in IC 5285.

638400172_IC528505Oct21_19_04_27.jpg.4b7c96daf3f14f553b0f0a714542a174.jpg

Here's my take on the wonderful NGC 7217

245835757_NGC721706Oct21_20_13_35.jpg.dd27e0b8663b074321d0ec18320e4bd2.jpg

 

Martin

 

Edited by Martin Meredith
added NGC 7217
Link to comment
Share on other sites

Hi Martin, always good to see other shots of a target - makes for an added interest/comparison. Re IC 5285 - I had totally failed to look at its interesting neighbour so here is a close up from my original stack of NGC  7489.  The brighter sections to the north would appear to coincide with star forming regions when I took a look at the Aladin image.

1829957294_IC528505Oct21_19_20_33.png.363dc96597b9064246dbde193f3bc7dd.png

Mike

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share

  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue. By using this site, you agree to our Terms of Use.