ARP GALAXIES

[Mike JW]

ARP 273 - in Andromeda. The Hubble mages of this pair are stunning.  The big one (UGC 1810) is 200,000+ lyrs across and the data suggests its companion (UGC 1813) dived straight through it creating the ring effect as it did so.

 

ARP 145 in Andromeda. This pair share the designation UGC 1840. The lower galaxy (lenticular) dived straight through the upper one to create the ring. Just to the right of the ring is the fuzz of the galaxy core.

 

[Martin Meredith]

These are two of my favourite Arps.

Arp 145 is one of the few galaxies with a complete ring that is also large and bright enough for our scopes, and the field is enhanced tremendously by the stellar car headlights sitting just above it. The ring itself could easily be mistaken for a planetary nebula.

It also has special memories as I spent many hours looking at Arp 145 as it was my test image while I was working on the live stacking algorithm....

Martin

 

[Mike JW]

Agree that it is a lovely sight. Dead centre of your fov is Leda 2180614 = mag 18.8 (according to ST4),

Mike

[roelb]

Arp 273

Evolution 8 @ f/5

ASI290MM

 

[Mike JW]

Hi Roel,

You have nicely caught the detail.

Mike

[Mike JW]

Tonight I was keen to test out the new release of Jocular (version 3). As it was so windy I had to use the small scope and tucked in tight to the house.

Arp 135 - NGC 1023 and 1023A.

A year ago a coloured shot of this Arp was posted.

https://stargazerslounge.com/uploads/monthly_2019_10/1032841108_ARP135NGC1023GXPERSEUS15X25A32M0W0SES3-1RC8UVIR.jpg.c68b602c4f3591bb24fd83dc48dc410b.jpg

At first sight there is not a second galaxy to be seen. However at the left side of the galaxy is a faint extended patch of fuzz which is 1023A, classed as a dwarf irregular. Redshift data puts it at a different distance to 1023 so the two are unlikely to be interacting. NGC 1023 lies about 20 million lyrs away ( I have seen other figures) and is a member of our local galaxy group, which makes it a near neighbour!

The second image is from earlier this year using my C11.

In this image (below), NGC 1023A is more obvious (right hand side this time).  Image is with SLL.

 

 

 

 

 

 

 

 

 

 

 

 

Using Jocular 3 tonight - a superb piece of software making EEVA easy and straightforward. It means for the likes of myself who have little software knowledge I am able to concentrate on the observation of the DSO rather than get bogged down in software/processing. SLL tends to give noisy shots and regularly struggles to align. Whereas Jocular gives cleaner shots, aligns easily and Joc 3 is able to give cleaner images, faster.

Mike

Edited November 16, 2020 by Mike JW

[roelb]

Arp 135

NGC 1023 + 1023A

PGC 10123 + 10139

Evolution 8 @ f/5

ASI290MM

 

Edited November 16, 2020 by roelb
Wrong designation

[Mike JW]

Thanks Roel for adding your shot - so we now have a shot with a 7", a 8" and a 11" scope and two different cameras. Useful to be able to see what can be achieved. Mike

[Mike JW]

ARP 135.

To complete the results from different size scopes I was able to point the 15 at this Arp and to my delight I was able to also pick up NGC 1023B. You may well ask where is this galaxy?

Both shots were carried out using the same settings and show the advantage of increased subs - less noise. Also of course a large scope can get results quicker.

Left hand shot - is 4 x 8 secs (ignore the data that says 4 x 14) - no sign of NGC 1023B.            Right hand shot - is 31 x 8 secs. Look just below the bright star on left - faint fuzz

 Mike

[AKB]

Here'a another Arp 135 from a session last night (very windy, so horrible star shapes.). I've tried to orient and scale to match @Mike JW above.

• C9.25 with Hyperstar (f2.3)
• Atik 460-EX camera

Had to throw away a lot of subs to just get this, but you can see 1023A (or is it B?)

 

 

To try and redeem myself (just a bit) for the shoddy image, here's the full-field view (~1.3º) with a few other choice galaxies there.

(I would have identified them, but I am having trouble with permissions, again, in Pretty Deep Maps.)

Tony

 

[Mike JW]

Hi Tony, with your image using the C 9.25 we have a "full house", unless someone points a 20" at it. 

Very much like the hyperstar view to see the context, My understanding is NGC 1023 is the big galaxy. 1023A is the sticky out bit of fuzz at the left hand end. 1023B is a dwarf galaxy that is just beginning to show below the bright star on the left . It is called PGC 10169 and about mag 17.

Like you I had to throw away many subs to get the final image. I was determined to try pick up PGC 10169.

Pretty Deep Maps - every map I open I have to "allow" it before it will open  - no idea of the solution.

Thanks for posting.

Mike

[AKB]

38 minutes ago, Mike JW said:

My understanding is NGC 1023 is the big galaxy. 1023A is the sticky out bit of fuzz at the left hand end. 1023B is a dwarf galaxy that is just beginning to show below the bright star on the left

Ah.  Gotcha!  Thanks very much.

My PDM problem was entirely due to the fact that I forgot that I have to use Acrobat rather than Preview to get it to work on the Mac.

Here's a rotated and cropped bit of the above and the matching Pretty Deep Maps area showing (at least):

• FGC 41A
• U 2165
• P 10165
• P 2135955

all at about magnitude 15 to 16.

[Mike JW]

At last a break in the weather but at the very early hour of 4.30am this morning.

Arp 129 and Arp 63 are close to each other - "a two in one image" - found in Leo.

Arp 129 was classified as E and E like close to and perturbing spirals. In my shot it is the upper pairing and I was delighted to get hints of the spiral structure with star forming regions thrown in as well. The spiral has the feel of being a ring galaxy and is classified as such - SB(r)c pec. Its companion is classified as an intermediate spiral - SAB and feels as if it is behind. Indeed it is, about 10 million lyrs behind. So in all probability they are or did interreact resulting  in the messed up nearer of the two galaxies.  The pair are known as UGC 5146 and VV 83.

Arp 63 is the pairing at the bottom and known as NGC 2944 and are at a similar distance to Arp 129 - 320 million lyrs away.  The obvious and larger galaxy is SB pec and seems to have come worst in this interaction. Also known as VV 82. So what is happening with this pair. Well some folk actually suggest it is a triple, i.e NGC 2944 has two small bright companions, one at each end. 

Finally, you might be thinking why did Mike not make the two Arps central? - I just had to get the single galaxy (on the right near the edge) included - it lies a mere 1.11 billion lyrs away!!!

Mike

[Martin Meredith]

Kudos for being out at 4.30am! 

I've a shot of this from last year (end of March!) -- doesn't add anything except slightly lower resolution (which you can see in terms of the close pair mid-left). I'm assuming that its a star occluding the core of the larger galaxy and not the core itself? It looks very stellar.

Martin

[Mike JW]

11 hours ago, Martin Meredith said:

I'm assuming that its a star occluding the core of the larger galaxy and not the core itself? It looks very stellar.

Hi Martin - My first reaction it is the core but having called up Aladin it would appear to be a star -always something to learn (or observe in this case) . The core is slightly to the left of this star.

 https://de.wikipedia.org/wiki/UGC_5146#/media/Datei:Arp129_-_SDSS_DR14.jpg. This link also shows a detached blob of blue to the right (I got a hint of it).

Interesting to compare the resolution of the two scopes.

Mike

[Mike JW]

 

Arp 269 - 19/02/21. The Cocoon Galaxy in CVN. I have posted this Arp earlier in the thread but this shot is I think the best I can get with my set up. I so enjoy seeing all the star formation due to the close encounter of these two galaxies.

 

 

Next up is Arp 138 in Com.  NGC 4015 and PGC 37702 lie about 210 million lyrs away. Decent images seem to indicate that PGC 37702 lies in front of NGC 4015. There is no obvious signs that they are as yet interacting. Arp classified the pair as E and E like galaxies with material emanating from the galaxy. There certainly appears to a wide zone of material around this galaxy. To the left is a third galaxy.

 

Here is the third Arp I visited last night -ARP 305 (VV 1489). Arp classified them as a pair of galaxies. NGC 4016 at the top and NGC 4017 at the bottom. 4016 looks a bit messed up, does it have a double set of spiral arms? It would seem to have a bar (SBd or SBdm). It certainly looks messed up.

NGC 4017 at first glance looks OK but better images show bits of the galaxy are detaching - maybe a hint of this in my image. High resolution images show faint 'wind swept debris' heading in the direction of NGC 4016. Classified as SBbc. When I got the settings correct the bar showed up nicely. This pair lie about 170 million lyrs away. If you follow the upper arm from 4017 going towards 4016 about half way is a couple of small faint grey patches. High res images show them as part of the wind swept debris coming from 4017.

 

Mike

Edited February 19, 2021 by Mike JW
more info

[Martin Meredith]

This observation from earlier in the week is a case of 2-for-1 or even 3-in-1 as it contains Arp 313 and VV 523 just above and to the right, and the group is also known as WBL 366.

The Arp designation is simply 'galaxy group' -- what's so peculiar about that? The larger galaxy in the Arp pair is NGC 3995, and its companion is NGC 3994. Both are spirals: NGC 3995 is classed as SA(m)pec in the Arp Atlas and SABm by LEDA. I'm not sure what the m in parentheses refers to. Any ideas? NGC 3994 is SA(r)c pec, the 'r' indicating a ring-like structure, or just Sc by LEDA. Just above NGC 3995 is a bit of material that seems to me to be part of the disrupted upper spiral arm. Just to the right of the bright star is another dim slash of fuzz which is down as a mag 17.3 galaxy. The star is pretty bright, just about naked eye, at mag 6.4, and varies over a period of 17 hours, but nothing to get too excited about because the vairation is just 7 millimags.

The galaxies are worth looking at in detail. Here I've tried to bring out the series of knots that run down the crinkled 'leading edge' to both sides of the brighter nucleus in the main galaxy of the Arp pair. Is this the result of a recent interaction with its neighbour(s)? The three galaxies in this figure are at a similar distance of 155-160 million light years. 

To the upper right of the image is VV 523, identified as the galaxy NGC 3991,  classified as I-type (Irregular, I assume) but there may be 2 galaxies, the other being UGC 6933. The close up shows something quite unusual and it would be good to see if anyone can get a more detailed shot of this. Is is a pair of galaxies that are in the middle of an interaction but happen to be edge-on to our viewpoint?  Or is it a single galaxy with several prominent knots that are obscuring the rest? One might imagine it being similar to NGC 3995 but edge on except there is no clear central core.

So yes, a galaxy group, but quite satisfyingly peculiar!

 

 

[Mike JW]

Hi Martin,  (m) = irregular in appearance and with no bulge - I think. Good idea to bring out those knots down the edge.

VV 523 - certainly a pair of galaxies. Tadpole looking pair. Interestingly so in the tail you have picked up a double blob, then lower down a single faint blob (seems to coincide with a mag 18 galaxy) Also  at the bottom of the double blob - possibly the lower part of the double blob , NED shows a mag 17 galaxy. All very confusing. Many H11 region indicated by NED.

Arp 313 - NGC 3995, Looking at Aladin/Gaia data it would seem to indicate that in the tail there is indeed another galaxy - the final obvious bulge in my close up with a similar redshift, thus 3995 is two galaxies (which you picked up as well)

Below is my efforts from last year, using the C11 at f6.3 but if that is the case why have I got diffraction spikes? makes me think I must have been using the 15.

Edited March 7, 2021 by Mike JW

[Martin Meredith]

Thanks for posting. I read more of my de Vaucouleurs atlas to see if I could find the (m) in parentheses and so far no luck. There is a m subscript that signifies 'massive arms', and there is there is the m type that stands for Magellanic (as in, irregular but of the Magellanic Clouds variety -- I think this is what you are referring to?). However, this designation doesn't appear in parentheses but at the end e.g. SABm. Maybe it is just simply that the brackets were used to separate the m from the 'pec' part.  Looking at that galaxy again I can see that the presence of so many knots could lead to it being seen as Magellanic type, though I would have been hard-pushed to say so without seeing the class beforehand!

Martin

[Mike JW]

Hi Martin - I cannot find where I got my definition of  (m) from. I tend to agree with you that the brackets are there to separate out the 'm' from the 'pec' bit. I will keep looking. 

Below is what I have found out so far. (my brain aches!!!!)

Sm = LMC type spiral: no bulge and a single principle arm starting at one end of  a bar.

Sdm = has a main arm but there is a weaker/shorter second arm (e.g NGC 4207)

Im = highly irregular megellanic galaxies, no sign of a bar

IB(s)m = irregular megellanic galaxies with a bar

IAB(s)m = irregular intermediate spirals (megellanic type), with a bar

Mike

Edited March 8, 2021 by Mike JW

[Martin Meredith]

Thanks for digging these out. I certainly wouldn't like to live in a highy irregular Magellanic galaxy based on that description ...

I did a quick search in the Jocular planning tool and there are 155 galaxies whose type contains an 'm' out of the 12488 listed (basically just the M/NGC/IC/FGC), 112 of which are above dec -20, so plenty to look for. However, the classifications are all Sm, SBm or SABm (note no SAm), so I will see if I can find a list of more detailed classifications to include in the next version of the tool, because it would be fun to contruct an observing programme around finding good exemplars of each type.

Martin

[Mike JW]

Martin - that would be fun - yet another list to pursue.

Mike

[Bill S]

Arp 220 The Nearest ULIRG

I watched an interesting talk by Prof. Dimitra Rigopoulou on the BAA YouTube channel about Ultraluminous Infrared Galaxies (ULIRGs). These are amazing bright objects but only known in any detail thanks to the availability of infrared telescopes. See:

 

The nearest of these is Arp 220 so I thought I'll have a look at that. It's not the most photogenic DSO but knowing about the object when you look at it adds to its beauty. It's 250 million light years away. Not 250,000 as shown on the Powerpoint slide above.

 

 

 

This isn't the first Jocular observation of this remarkable object. I looked about a year ago too.

 

 

 

The object is also IC 4553 and VV 540.

Cheers.

Edited April 8, 2021 by Bill S
Substituted better snapshots

[Mike JW]

Hi Bill, I too enjoyed that talk, very informative. What a great idea of yours to take another look based on the information from the talk. I last looked at ARP 220 about a year ago with the C11.

Below is the close up  to show the two galaxies of this pair and the surrounding mess of stars as they interact. Then it was thought it was just one galaxy with the gap being a dust lane. Latest radio observations show that it  is two galaxies and the two cores will merge in about 1 billion years. It is given LINER and Seyfert 1 designations.  Arp classified it as a galaxy with a loop, which shows better in my wider fov shot (not posted). It has an AGN and plenty of star formation as well. So not the most photogenic DSO as you say but so much going on.

Mike

[roelb]

ARP 220 imaged at June 2019

Evolution 8 @ F/5   ASI290MM   

Full moon (some dew at corrector)

6 x 15 s

cropped