ARP106

Arp 106 is an interacting pair of galaxies in Coma Berenices about 315 million light-years away. Arp put it in his category of elliptical and elliptical-like galaxies connected to spirals. He made no comment on this entry.

The two galaxies are known as NGC 4211. While some catalogs give only one number to both a few do have separate numbers. MGC +5-29-042 is the northern member and MGC +5-29-043 is the southern to give one example. NED classes both as S0/a pec. I would say the southern one is likely S0 but the upper appears to be a distorted Sa or possibly Sb spiral to me. In any case, both have been severely disrupted by their interaction. They have somewhat different redshifts. I don't know if that will be enough to prevent them from merging in the future or not. I rather suspect they will merge eventually becoming an elliptical galaxy. Note that there appears to be a faint plume east of the southern well-defined plume. I see hints of it in the Sloan image as well. NGC 4211 was discovered by Édouard Stephan on April 30, 1881. I don't know if he saw the companion or not. I suspect he didn't.

Just west of the pair is LEDA 1828543 (SDSS J121521.05+281048.0), a spiral galaxy that is likely a member of the same group as Arp 106 as its redshift is practically the same.

Toward the southwest (lower right) corner is an object that NED shows as being a quasar in some catalogs, an IR source only in the 2MASX catalog, a star in the Sloan survey and a galaxy at a slightly different position (0.1" different in declination). NED shows two redshifts, one is z=0.692000, the other is z = 4.88922! Now that's a discrepancy. The distance I used on the annotated image is based on the lower z value which puts it 6.3 billion light-years away. The other value would put it over 12.4 billion light years which would mean it is brighter than any quasar I ever heard of. The lower value is even surprising considering its magnitude of 17.8.

An interesting galaxy at 670 million light years is SDSS J121522.43+280406.9 south-southwest of Arp 106. It seems to have one heavy arm on the south. It would fit in either Arp's one arm category or heavy arm category.

Arp's image
http://ned.ipac.caltech.edu/level5/Arp/Figures/big_arp106.jpeg

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

Related Designations for ARP106

ARP107

Arp 107 is a pair of colliding galaxies also known as UGC 05984. Arp classed them under "Elliptical or Elliptical like galaxy: Connected to a spiral." That would certainly be what you see in my image. I sometimes wonder about his classifications but this one is quite accurate. He described it saying "...double arm leads to E(astern) galaxy, diffuse material out either side of E(lliptical) galaxy." Other than there being some out the top of the elliptical as well (not seen well in his too short exposure with the 200" telescope) his descriptions seem fairly accurate.

This galaxy was the subject of a rather "famous" photo on the net taken in infrared light by the orbiting Spitzer telescope. They used two wavelengths, one that they colored blue shows old stars much better than new ones and one was taken in a wavelength that shows young hot stars much more strongly than older cool ones. They colored these red. Here's the image:
http://www.etsu.edu/physics/bsmith/arp107/arp107_press.html

Not being in orbit and not having a supply of liquid helium (needed for earth based IR work as well as most space based IR work) I have to use visible light. But as I've mentioned many times before, regions of young stars often show up very blue while regions of old stars show up red. This isn't as accurate method as Spitzer used but close. Compare the blue regions in my photo to the red ones in Spitzer's and my yellowish red regions to Spitzer's blue and you'll see they agree rather closely.

This pair is located about 463 million light-years away in the constellation of Leo Minor. Most folks realize there's a big and small bear in the sky, many know of the big and small dogs but for some reason, I find few know of the small lion. Maybe it's because the big one is just Leo rather than Leo Major, unlike the other two animals.

Most of the other galaxies of any size (and not red) in my image are at about the same distance as Arp 107. Oddly, NED shows a distance to Arp 107 of the 460 million light years I mentioned but shows the individual galaxies at about 480 million light years. I don't understand the difference. It classes the obvious elliptical as just that, elliptical and the spiral as an Sc spiral of the Seyfert 2 class meaning it has an active nucleus. This is common in interacting galaxies as the interaction throws material into the black hole at the galaxy's center causing it to be quite active.

There's a quasar at 7.7 billion light years and several galaxies ranging out to over 3 billion light years that I could find redshift data on and likely some of the fainter ones are even farther away. There is a Zwicky galaxy cluster with some 130 members centered just off the lower right corner but its 35 minutes across so many of the galaxies in the lower left region are likely members. NED gives no distance for this cluster though another with only 22 members centered only about 3 minutes of arc away shows a distance of 1.55 billion light years and must be part of the Zwicky cluster.

Arp's image of this group is at:
http://ned.ipac.caltech.edu/level5/Arp/Figures/arp107.gif

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

Related Designations for ARP107

ARP109

Arp 109 is in Arp's class for "E and E-like galaxies repelling spiral arms", a class that never has made sense to me. If it has spiral arms isn't it a spiral galaxy? What is a "repelling spiral arm?" In any case, it includes two galaxies, one a true elliptical to the east and a very strange disturbed spiral to the west. It seems to have two plumes both curving to the west. Were these plumes created by interaction with its large companion? The companion shows no sign of distortion. Could the outer plume be due to the remains of a small galaxy the western member is digesting? I found nothing to help with this issue.

The pair are about a half billion light-years away in the constellation of Draco, just below the bowl of the little dipper. The pair have almost identical redshifts so it's highly likely they are really about this close to each other as they appear to be. The eastern member is classed as E:. The western member is classed as S?. The pair is UGC 10053 and VV291. The VV says of them: "Hard core 0.15 x 0.15 surrounded by thin bright spiral arc, 2 diffuse spiral arcs is unequal bending in northwest". The CGPG says: "Irregular blue spiral, compact elliptical core, two spiral arms to the west". The VV does say it has been probably perturbed by the companion. Arp had no comment on this one. The spiral is classified as S? by NED and Sab? by Seligman. The elliptical is E: at NED and e3: by Seligman.

The rest of the field for which redshift information is available is rather sparse, with only 5 in NED. To the west is a LEDA 2730634 also at a half billion light-years so probably related to the pair in Arp 109. The others are all closer to us. MCG +12-15-020, a lenticular galaxy at about 350 million light-years is to the southeast. Further south is IC 1146 at a redshift 360 million light-years. Likely the two are related. NED shows no classification for it though Seligman says S. Looks like Sa to me. Near the top is CGCG 338-022 at nearly 460 million light-years. NED classes it as spherical. Looks like a disk galaxy to me with a hint of a bar and an arm. The remaining galaxy is IC 1147 to the far east and a bit north. It is quite red for a barred spiral though NED makes no attempt to classify it for some reason. Seligman says S but I'd say SB(r)a as it has a ring structure from arms coming from a bar. It is listed at about 470 million light years so about the same distance as CGCG 338-022. IC 1146 and IC 1147 were discovered on July 13, 1887 by Edward Swift.

Arp's image is at:
http://ned.ipac.caltech.edu/level5/Arp/Figures/big_arp109.jpeg

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

Related Designations for ARP109

ARP110

Arp 110 falls under Arp's classification of an elliptical galaxy repelling a spiral galaxy's arms. It is in Aquarius and just below my normal -15 degree limit. It is about 415 million light-years away. Arp 110 is also known as MGC-3-58-011. The "companion" is the IR source 2MASX J22540664-1514125/PGC 913872. Arp's comment on this one says; "Arm bent at root." A note at NED dating back to 1968 says "Interacting? Perturbed by nearby MCG -03-58-010 (PGC 69950), or maybe by companion (unless it is a star) 16 mag at 0.6 arcmin west." The companion is obviously a galaxy in Arp's image which was taken a few years before the comment so I find it odd. NED classes it as Sab with HII emission lines. No peculiar designation which I find, well, peculiar. They seem to consider it a M51 type galaxy pair.

Arp 110 seems to have two tight, short, rather red arms coming from each end of its core. These end in oddities. On the west end, a blue "arm" suddenly bends back that is far larger than the red arm at its base. Is it really the same arm or some star stream due to an interaction with the companion? The red east arm that runs to the east side of the galaxy ends in a huge blue amorphous region that includes a couple star clouds. Again the same question applies. Makes me wonder if much of the blue is due to stripping of dust and gas from the companion leaving only its core coupled with a similar stripping of Arp 110 as well. Only a guess on my part. I find nothing useful either way in the literature. This one hasn't been studied much or I didn't find it.

It does appear the two may be interacting. There's a faint spray of stars all around the companion extending out past the two stars on the western side of it. Dick Miller's web page on this one suggests the knot at the east end of the galaxy could be a barred spiral. http://www.338arps.com/arp_110.htm He didn't have the advantage of a color image. It appears to be a blue knot in what passes for a arm. I hadn't seen his comment but looking at my raw data as it came in I thought it likely a separate galaxy but once the color data was assembled it turned into a star cloud in the arm.

This area is not covered by the Sloan survey so we don't have help from that source. NED lists mostly APMUKS galaxies, the result of an automated plate survey which picks up only obvious galaxies and says nothing about the blue object. In fact, few galaxies in my image have much useful data at all. There is no distance data for the probable companion since a plate survey can't collect the needed information.

The galaxy southwest of Arp 110 is MCG-03-58-010/PGC 69950. Its redshift puts it at about the same distance as Arp 110. I find no classification for it. It is the only other galaxy in the image with distance data. There are a few very faint asteroids in the image the eagle eye's out there might spot. I make an annotated image to help you find them.

This one is just below my -15 degree cut off which reduces my transparency. I should have put more time into it to compensate but the following nights had too poor seeing that low. I never did get the needed time.

Arp's image
http://ned.ipac.caltech.edu/level5/Arp/Figures/big_arp110.jpeg

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

Related Designations for ARP110

ARP111

Arp 111/NGC 5421 is a pair or trio of galaxies in eastern Canes Venatici about 360 million light-years away. Arp put it in his category of elliptical or elliptical-like galaxies repelling spiral arm of a companion spiral. Since gravity can't repel (or at least we have no evidence it can be a repelling force) I don't understand what Arp means. Apparently, this is meant to describe what appears to be happening rather than be what is really happening. In the time of Arp's atlas that was about all we could do. The arm of the spiral does seem to bend away from the elliptical like galaxy. Arp's comment "E galaxy apparently bending arm at root." This is likely just a descriptive comment. I hope he didn't think it was pushing the arm back, just positioned to look like that was happening. Though years later his strange physics allowed for some odd things but don't think that was one of them.

This is quite a confusing area with so many cross-linked names trying to sort it all out is a nightmare. The main galaxies, the odd spiral and the elliptical like galaxy are known collectively as NGC 5421. The little blue galaxy is apparently made up of two galaxies but is collectively known as MGC+6-31-46. All of these are collectively known as VV 120. NED refers to the two parts of MGC+6-31-46 as Arp 111 NED 02/VV 120e and Arp 111 NED 03/VV 120d. To me, VV 120d is just a blue star cloud in the galaxy. The big spiral is Arp 111 NED 01/NGC 5421 NED01 and the elliptical like galaxy Arp 111 NED 04/NGC 5421 NED 02. Now that I have you totally confused (me too) I think I have it straight on the annotated image. Not all have redshift distances but I've included those when available. Then when you just about think you have it figured out you wonder; "What happened to VV 120b?" It is just a part of the turned back spiral arm. Why it gets its own designation is one of the mysteries of the universe.

With similar redshifts, all appear to be related. What caused the turned back arm? Wish I knew. Actually, it isn't all that "turned back" Just that it ends in a huge plume that goes in a different direction than the arm. The two arms, ignoring the plume are pretty much in agreement though the plume has stripped most of the stars from its arm. Probably due to an interaction with the elliptical like galaxy.

NED classes the spiral as Sc, NGC Project says SB? and Seligman says SBbc? So they can't even agree if it is a barred spiral or ordinary spiral. NGC 5421 was discovered by Édouard Stephan on June 9, 1880.

Arp's image
http://ned.ipac.caltech.edu/level5/Arp/Figures/big_arp111.jpeg

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

Related Designations for ARP111

ARP112

Arp 112 is a triple galaxy group classed by Arp as "Elliptical and elliptical-like galaxies with repelling arms." How that applies to this weird group I don't know. Maybe it is due to the near vertical spike coming from the northeastern galaxy. I placed Arp 112 well to the right of center to pick up another rather odd galaxy at the left hiding behind a star. It is PGC 000190 and is classed as an S0? galaxy. This seems very wrong. S0 galaxies have no or very weak spiral structure and usually appear as round spheres or spindle-like depending on our viewing angle. This looks like a rather nice face on Sb spiral with rather well-defined arms. I don't understand the discrepancy.

Arp 112's trio of galaxies from left to right is KUG 2359+311/PGC 111 with no redshift data. KUG stands for Kiso Ultraviolet Galaxy Catalogue indicating it is a strong emitter of ultraviolet light. Usually a sign of massive star formation. It looks like an arc but is classed simply as a spiral galaxy, not even a peculiar one. Sure looks peculiar to me. The center galaxy is NGC 7806 with a redshift distance of 200 million light years and is classed as SA(rs)bc? Pec. While tidally distorted it doesn't appear as peculiar as its companion to the east. The class indicates it has structures of both a standard spiral and a ring galaxy. Apparently, the ring refers to the outer football shaped bright edge around a portion of the galaxy. The rightmost galaxy is NGC 7805 also at about 200 million light years per its redshift. It is classed as SAB0 pec but has no ring designation yet one is quite prominent in my image. That I do find as peculiar. Its class would indicate it has elements of a standard spiral and a barred spiral with little dust or arm structure. Hence Arp's elliptical like reference. It also has the color of an elliptical as well.

NGC 7805 and 7806 were discovered by William Herschel on October 9, 1790. Neither are in either of the two Herschel 400 observing programs, however.

Nearly all the other galaxies are either anonymous or have little data. The only one worth mentioning is the blue galaxy southwest of Arp 112. It has the rather rare designation NPM1G +31.0507. This comes from the Lick "Northern Proper Motion program 1st list of Galaxies. Don't ask, I never heard of it either. Arp 112 is located in Pegasus not far from Arp 98 and 2.75 degrees northwest of Alpha Andromedae, Alphoratz, the lower left corner star of the "Great Square of Pegasus".

Arp's photo of it is at http://ned.ipac.caltech.edu/level5/Arp/Figures/big_arp112.jpeg

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

Related Designations for ARP112

ARP113

Arp 113 is in the Arp class "Elliptical or Elliptical-like Galaxies close to perturbing spirals". In fact, it's the first entry in that class. There are so many galaxies in this grouping I don't know which are the perturbed spirals and who is doing the perturbing! Arp made no comment on this group to help with this question. The entire group is larger than my field though Arp only was concerned with the dense core. It is known as the VV166 group with 15 members. VV stands for; Vorontsov-Velyaminov Interacting Galaxies. The group's average distance is just under 300 million light-years by redshift value. Many of the members are NGC galaxies. I've attached an annotated small image of the core to help identify this region. The galaxies, their classification (when known, "n/a" when not available) and their redshift distance are in the table below in millions of light-years.

NGC 67 E 290 Discovered October 7, 1855 by R. J. Mitchell
NGC 67A E 270 Discovered October 7, 1855 by R. J. Mitchell
NGC 68 SA0 240 Discovered September 11, 1784 by W. Herschel
NGC 69 SB(s)0 290 Discovered October 7, 1855 by R. J. Mitchell
NGC 70 SB(s)0 310 Discovered October 7, 1855 by R. J. Mitchell
NGC 71 SA0- pec 290 Discovered October 7, 1855 by R. J. Mitchell
NGC 72 SB(rs)ab 320 Discovered October 7, 1855 by R. J. Mitchell
NGC 72A E3 290
NGC 74 (R)SB0(rs)a? 310 Discovered October 7, 1855 by R. J. Mitchell
SRGb 062.050 n/a 330

Other galaxies in the image with red shift data:
CGCG 499-103 below SRGb 062.050 n/a 260 million light-years
CGCG 499-101 by bright yellow star upper right n/a 280 million light-years
CGCG 499-100 blue galaxy beyond CGCG 449-101 at upper edge Scd 210 MLY probably not a member
CGCG 499-099 blue spiral upper right corner S? 270 million light-years
NGC 76 Lower left edge S? 310 MLY Discovered September 22, 1884 by Guillaume bigourdan


Arp's image:
http://ned.ipac.caltech.edu/level5/Arp/Figures/big_arp113.jpeg

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

Related Designations for ARP113

ARP114

Arp 25/NGC 2276 is an interesting, many armed face on spiral. Arp put it in his category for spiral galaxies with one heavy arm. The most famous member of this category is M101. The galaxy is located in Cepheus. The distance is a bit vague. Redshift puts it at 110 million light-years. A single Tully Fisher measurement at NED says 120 million light years and a post at the HST website says 150 million light-years. Quite a difference. Arp's comment on this one under Arp 25's entry reads: "See also 114. Tubular arm, straight at first, then bent. Secondary arm from straight portion." Obviously, this refers to the southern arm that is somewhat separated from the rest of the galaxy and points in the general direction of NGC 2300. It's hard to write about Arp 25 without including nearby NGC 2300. So hard in fact that Arp made a second entry for NGC 2276 to include NGC 2300. Arp 25 was discovered by August Winnecke on June 26, 1876. Hubble image of part of NGC 2276 including the arm is at http://upload.wikimedia.org/wikipedia/commons/2/25/NGC_2276_Hubble_WikiSky.jpg

Arp 114 consists of NGC 2276 (Arp 25) and NGC 2300 and is in his category for elliptical and elliptical-like galaxies close to and perturbing spirals. Here Arp's comment concerns only NGC 2276 and ignores NGC 2300! It reads: "Spiral somewhat pec., may be perturbed. See No 25." While it is in a category assuming it is perturbed the comment says only it may be perturbed. For once I agree, it may be but that isn't all that certain. I see arguments either way. The big one that they aren't related is their redshift. By that measurement, NGC 2300 is some 24 million light-years closer than NGC 2276. But there are many non-redshift measurements of its distance that range from 101 to 134 million light-years and average out to about 115 million light-years. Then there's the above-mentioned 150 million light-year distance at the HST website. These would make them more likely to be true companions. But look at the redshift distances on the annotated image. They seem to fall into two groups. One that fits NGC 2276 at about 110 million light years and one that matches NGC 2300 much closer distance. But with a sample size of 2 and 3, this is far from deciding the issue!

The HST site argues strongly for interaction with this post: http://www.spacetelescope.org/images/opo9305a/ This shows a huge enveloping cloud of hot gas seen in in X-rays around NGC 2300. It extends to NGC 2276. One possible explanation is an interaction between the two. But it certainly isn't required for this to occur.

NED classes NGC 2276 as SAB(rs)c, the NGC Project says simply Sc I. NED says of NGC 2300 it is SA0^0^ while the NGC Project says simply that it is an elliptical. Few sources I found agree with the elliptical classification. Most consider it a S0 type galaxy as NED suggests. This because some structure is seen in the outer halo of the galaxy. I am puzzled by the strong red color I got. While I found few color images of NGC 2300 on the net, the few I did find have it as nearly white. It was discovered by Alphonse Borrelly in 1871. I can't pin down the exact date.

Arp's image of Arp 25:
http://ned.ipac.caltech.edu/level5/Arp/Figures/big_arp25.jpeg

Arp's image of Arp 114 (including Arp 25)
http://ned.ipac.caltech.edu/level5/Arp/Figures/big_arp114.jpeg

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

Related Designations for ARP114

ARP116

Arp 116 belongs in Arp's class for elliptical and elliptical-like galaxies close to and perturbing spirals. In this case, it is M 60 that is the elliptical and NGC 4647 that is the spiral. It is slightly sloshed with the core off center toward M60 as if pulled there by its gravity. Is that really the case? Redshift puts NGC 4647 at about 80 million light-years and M 60 at 66. But non-redshift measurements have a median value of 55 million light-years for both. These are part of the Virgo cluster which is well known to for galaxies having a wide difference in redshift due to the strong gravity well created by so many galaxies in a small area. Redshift is not considered very reliable both because the cluster is rather close (averaging about 60 million light-years) and due to the wide variance of their widely varying speeds unrelated to distance. One study shows that the spiral must be behind M60 since none of its absorption features can be seen against M 60 as would be expected if it were in front. Since M60 has virtually no such features their lack against the spiral is expected even if it is in front of the spiral. How far they are apart is still unknown. With their difference in redshift, any passage by each other would be brief hardly giving time for any interaction to show. While it might distort a spiral arm slightly I doubt it could be the cause of the sloshing of NGC 4647's core. But this is only my surmise. It could be that since the side toward M 60 is bright due to being seen through M60 the fainter parts of NGC 4647 are hidden and it really isn't sloshed at all.

Measuring the size of an elliptical galaxy like M 60 is difficult as the edges just fade away meaning the longer the exposure the larger the size will be. I measure it somewhat larger than NED's value and get a size of about 145,000 light-years assuming a distance of 55 million light-years. While #60 in Messier's list it was first discovered by Johann Koehler on April 11, 1779. The next day Barnaba Oriani saw it. Messier saw and recorded it on April 15, 4 days after Koehler saw it. It could be so many saw it about the same time as a comet was known to be in the area at the time.

I measure NGC 4647 at a bit under 40 million light-years. It was discovered by William Herschel on March 15, 1784. It is in the Hershel 2 400 observing list.

There are no other major galaxies in the frame. Most of the galaxies lie far beyond the Virgo Cluster or are very small dwarf galaxies. Telling them apart visually is often difficult so I did prepare an annotated image showing red-shift distances. I'm writing this years after taking this image and I have no idea why Arp 116 is so low in my frame. If centered, NGC 4637 an S0- galaxy, would be visible. Instead only its very northern part ekes into the lower right corner. It was discovered by R. J. Mitchell on March 1, 1854. Also, due to my leaving no notes about taking this one I have no idea why I used only one 10 minute frame for each color.
Arp's image: http://ned.ipac.caltech.edu/level5/Arp/Figures/big_arp116.jpeg

14" LX200R @ f/10, L=6x10' RGB=1x10', STL-11000XM, Paramount ME

Related Designations for ARP116

ARP117

This is a reprocess of an image taken back in 2009. My processing toolkit was limited as was my ability to use what tools I had. So it was time to redo it after I looked at it and got an instant yuck reaction in my stomach. I cheated by starting with a partly processed TIFF luminance image and since the color data looked good but for color balance I used it as I had processed it the first time except to adjust color balance some, mainly to remove airglow that tends to be strong at my latitude. Also, I wasn't doing annotated images back then. There was enough else going on I needed to go into that I had skipped in the original post 6 years ago.

This is a two for one Arp image that contains both Arp 79 and Arp 117. Arp 79 is listed by Arp under the category for spiral galaxies with high surface brightness companions. But there's no such companion. Arp's only comment on the object refers to the two star knots in the southern arm saying; "Small separation between two knots in arm." There is an orange field star in the other arm but I don't see how that looks anything like a companion galaxy either. Some have said he is referring to the brightening of the arm where those two star knots are located but since he refers to them and the brightening looks nothing like a companion I can't imagine that was his intent. It does have a strange feature, a straight bar of blue stars that appears separate from the galaxy seen below the two star knots. It's far from being of high surface brightness but could be considered a companion I suppose. I find nothing on it.

The right of two star knots in the arm is SDSS J141007.08+173647.6 which NED does call a galaxy rather than part of a galaxy but I've seen many such star knots listed this way so I don't put a lot of credence into that classification. The other star knot isn't listed at NED at all nor is the bar. Seems there's lots of mystery to this one. While it looks like a small spiral it is actually pretty normal sized at 70,000 light-years. It's just its distance that makes it seem small. It is sometimes known as NGC 5490C (NGC 5490 is at the bottom of my image) and is classified as SB(s)bc.

Arp 117 is listed by Arp under his classification for elliptical-like galaxies close to and perturbing spirals. Thus by his classification, the small galaxy is perturbing the big one. Arp apparently sees this as a warping of the spiral for which he notes: "Flattening of spiral's nucleus appears to be in a different plane than the arms." I'm not so sure I see what he is talking about. The core is very bright with a bright but short bar. Does he see this as a spiral seen edge on inside a face on set of arms? Other than this I don't see what he is talking about. While both galaxies have the same redshift and thus likely about the same distance from us it also could be their relative motions are actually quite different but their distance difference covers this up. I'd think there'd be distortions in the smaller companion as well as the spiral. I don't see that the companion is anything but very normal looking. It is IC 982, a SA0+ galaxy and the spiral is IC 983 an SB(r)bc galaxy. Note that except for the pseudo ring structure its classification is the same as that of Arp 79 even though they appear very different.

Arp 117 (both galaxies) was discovered by Stephane Javelle on May 27, 1891. IC 982 is about 80,000 light-years across while the spiral IC 983 is absolutely huge at over 325,000 light-years dwarfing everything around it.

Note in the annotated image there are many dwarf galaxies with a redshift indicating they are part of the same group. Many having almost exactly the same redshift in fact.

The other major galaxy in the image is NGC 5490 that for some reason I didn't get entirely on the frame. It is listed simply as an Elliptical galaxy and has a very similar redshift to the two Arp systems. Indicating it is likely part of the same group. It was discovered by William Herschel on March 14, 1784. It is in the second Herschel 400 observing program. I can't directly measure its size on my image since it is partly out of the frame. Using NED's diameter it would be about 125,000 light years in size using a distance of 250,000 million light-years determined by mostly type 1A supernova measurements though redshift places it a bit closer and thus smaller. It may be its own group as there are other galaxies around it with redshifts a bit less than that of the two Arp systems.

Arp's image of #79
http://ned.ipac.caltech.edu/level5/Arp/Figures/big_arp79.jpeg

Arp's image of #117
http://ned.ipac.caltech.edu/level5/Arp/Figures/big_arp117.jpeg

14" LX200R @ f/10, L=4x10' RGB=2x10' binned 3x3, STL-11000XM, Paramount ME

Related Designations for ARP117