ARP GALAXIES

[Mike JW]

Following Martin’s lead with the Arp-Madore thread. This thread can be used to post our Arp observations, to help keep our observations all in one place. Do not feel you have to post your Arp observation here. It seems worth giving the idea a go. All observations are worth posting to give folk an idea what can and cannot be achieved.

A few resources:

Website: https://www.mantrapskies.com/  is a superb resource for images and information

https://cseligman.com/text/arpatlas.htm - always enjoy visiting this site which is regularly updated

http://arpgalaxy.com/

http://ned.ipac.caltech.edu/level5/Arp/frames.html - comprehensive material with original images

Arp.csv

Arp.Catalogue.xlsx

Arps by type.xlsx

Arps sorted by constellation.xlsx

 

If anyone else has suitable resources, send them to me and I will post them here, whilst I can still edit this post.

If as this thread develops, folk can see a better way of keeping the Arp posts together and better organised - please make suggestions.

Thanks to folk for their enthusiasm to give this approach a go.

Good hunting as you hunt out these targets.

Mike

[Mike JW]

In a recent post David did a shot of Arp 104 and noted that he had not picked up the bridge. Nor have I in the past so last night I decided to get the 15 and ultrastar on the case.

Ignore the C11 details on the image below. I used the 15 at f4.5, 83 x 5sec. There is a hint of the bridge but it could just be noise in the right place. What my efforts do show is that even with a large aperture scope and almost 7 minutes of stacking the bridge is not obvious.

[Martin Meredith]

Arp 104 is a great place to start this thread. Yes, I can see a hint of the bridge in your shot.

I managed to capture the bridge a few years back but only with a lot of stretching... (and 12.5 minutes of exposure). Mike, perhaps you need to go longer than 5s with a CCD due to read noise?

There appears to be some kind of z-shaped galaxy cluster to the R too but I it isn't an Abell cluster as far as I can see.

Here's a nice paper describing Arp 104 https://arxiv.org/abs/1009.0219v1 with some great photos from the 0.9m and 3.5m scopes at Kitt Peak, Arizona.

Edited April 12, 2020 by Martin Meredith

[Mike JW]

Thanks Martin, When I use the 15, its tracking is so poor that going beyond 5 second gives me elongated stars.. I have improved the tracking so I should probably have a go at 10 second stacks with the 15. See below an annotated version. Thanks for the link.

[roelb]

Arp 104 with Evo8 @ f/5 and ZWO ASI290MM   10 x 10 s

 

[Mike JW]

Noting the posting in Hickson Galaxies - Hickson 40, it seems appropriate to post here Arp 321 which is also Hickson 40.

It amazes me just how well we do with the EEVA technique. Below is the original plate (200 inch Palomar scope) and my image from back in February. I have marked the galaxy Leda 82490 as it is at a similar distance to the main galaxy group and high resolution images reveal some distortion to it. This would suggest that at some point is may have interacted with the Arp group. The bottom three galaxies show signs of interaction, especially in high resolution images.

Mike

                                                                                                  

[Dragon_Astro]

On 12/04/2020 at 20:04, Martin Meredith said:

Arp 104 is a great place to start this thread. Yes, I can see a hint of the bridge in your shot.

I managed to capture the bridge a few years back but only with a lot of stretching... (and 12.5 minutes of exposure). Mike, perhaps you need to go longer than 5s with a CCD due to read noise?

There appears to be some kind of z-shaped galaxy cluster to the R too but I it isn't an Abell cluster as far as I can see.

Here's a nice paper describing Arp 104 https://arxiv.org/abs/1009.0219v1 with some great photos from the 0.9m and 3.5m scopes at Kitt Peak, Arizona.

A little fact about ARP 104, is that it’s also known as Keenan’s System, after Philip C. Keenan who first wrote a paper about the bridge in the 1935 😊.

[Mike JW]

Arp 268 in Ursa Major is a delight to view because the view is so unexpected. It is a dwarf galaxy, not far away, just a mere 10 million lyrs away. It is quite active with young blue stars. Arp classed it as a galaxy (not E or S) with irregular lumps.

I have also been trying out Jocular. First image is my normal SLL view. Second image is Jocular - zoomed in. The black lines coming out of the stars is a Ultrastar oddity when I use 2x2 bining mode - so annoying.

 

 

[Martin Meredith]

Nice shot. That's not one I've seen to date. Very irregular. I like the 'neck' of material curving out of the top. It would be interesting to find out more about what is going on here. And for a dwarf it must be quite bright to get such a detailed image in a short overall exposure. Worth a look in colour.

Any idea whether the Ultrastar issue can be fixed? It looks like some kind of weird inverted bleeding of charge from the bright stars. I assume it is always horizontal, flowing along the rows. Does it also occur when you expose in unbinned mode for a sufficiently long time?

Martin 

[Dragon_Astro]

The other night I thought I’d have a try at capturing the bridge on Arp 104/Ngc5216.

It was harder to capture it than I thought, with 6 x 5min subs only just catching a whiff of it.

I inverted my effort, as it was easier to see.

[Mike JW]

I too had another go at the Arp 104 bridge. Attached. In the original the bridge can be picked out amongst the noise. Below is a my attempt - what a mess!

Mike

[Mike JW]

 

9 hours ago, Martin Meredith said:

Any idea whether the Ultrastar issue can be fixed? It looks like some kind of weird inverted bleeding of charge from the bright stars. I assume it is always horizontal, flowing along the rows. Does it also occur when you expose in unbinned mode for a sufficiently long time?

Martin 

It only happens in 2x2 binned mode. So to loose it, I have to go for a black background which then looses detail in the DSO. It does not happen in unbinned mode even after 5 minutes. Yes it is always horizontal. No idea why it happens or if it could be fixed. Extremely annoying. Mike

[Martin Meredith]

Very nice shot DragonAstro! I personally love the inverted images. Now, 5m subs are something I could only dream of.... (my mount is capable of being used in EQ mode but I never have, preferring altaz for convenience). 

Likewise, Mike, the bridge is definitely visible in your 10s subs version. Have you considered using darks to handle the odd hot/warm pixel?

Martin

[Martin Meredith]

1 hour ago, Mike JW said:

 

It only happens in 2x2 binned mode. So to loose it, I have to go for a black background which then looses detail in the DSO. It does not happen in unbinned mode even after 5 minutes. Yes it is always horizontal. No idea why it happens or if it could be fixed. Extremely annoying. Mike

I would contact SX to see if there is something like a firmware update that might solve this. I'm no expert though... And just to clarify, this is using binned mode in SLL? I wonder if you could download full resolution images and find a way to do the binning in software (I mean, as a check). We can discuss by PM if you like. I may add a binning option to Jocular at some point.

[Dragon_Astro]

35 minutes ago, Martin Meredith said:

Very nice shot DragonAstro! I personally love the inverted images. Now, 5m subs are something I could only dream of.... (my mount is capable of being used in EQ mode but I never have, preferring altaz for convenience). 

Likewise, Mike, the bridge is definitely visible in your 10s subs version. Have you considered using darks to handle the odd hot/warm pixel?

Martin

Thanks Martin, that bridge was a bit of a tinker to tease out! Amazing what can be picked up with amateur kit

Hopefully clear tonight, so I’m planning on having a look at VV 678 to see how many I can tease out of that nest.

[Mike JW]

ARP 143 lurks in Lynx and here we have another galactic carve up. This is the mess as a result of two galaxies meeting each other. The elliptical/lenticular NGC 2444 is on the left and has stayed reasonably intact but its companion NGC 2445 (Im pec  designation, says it all) is having a hard time. The nucleus has stayed fairly central but four/five obvious star formation regions can be seen. In high resolution colour images much blue regions are seen. Not the place for a quiet life! Mike

[Bill S]

Some of the Arp galaxy objects are also Messier objects. Two examples in Virgo are Arp 134 (Messier 49) and Arp 152 (Messier 87).

M49 also has the designation NGC 4472. This elliptical galaxy has a magnitude of about 9 and it lies around 56 Mly away.

Arp 152 (M87, NGC 4486) is a very interesting object. It was the subject of the Event Horizon Telescope study imaging its supermassive black hole. It is a very big elliptical galaxy about 54 Mly away. The supermassive black hole is producing a relativistic jet shooting out about 5000 ly. It is a bit of a challenge to observe this but EEVA is a way of making this possible.

Zoomed in and stretched differently to show the jet.

This snapshot from last year shows the jet rather better.

 

Cheers

Bill

 

 

[Mike JW]

Hi Bill, Amazed you got the jet in M87, although I note the time needed to do it.

I too visited M87 again (last visit was a year ago) and this time I pointed the 15 at it - just 130 seconds. The jet is visible - just. If I play with the settings and exclude most of the galaxy it is more visible.  At the time of taking various shots I was able to pick up the jet in just 10 secs with the correct settings .

Recently on one of these exceptional nights we have had (minus the aircraft contrail effect), a mate spotted it visually (just) in a 24" scope.

 

Arp 134 - visited  a few days ago, with the C11. Bit of a messy shot.

[roelb]

Here are some M 87 shots I managed earlier:

ASI 224 MC   37x8s

 

Edited April 29, 2020 by roelb

[Mike JW]

ARP 120 - what a beauty this one is. NGC 4438 is the left hand one with its enormous thin cloud of stars surrounding it. Arp thought its neighbour was perturbing it but it turns out it is a line of sight pairing. This leads to the question as to which galaxy is messing with NGC 4438? Likely to be M86. There is very little dust in the surrounding star cloud. The shot also contains a galaxy at Q6.1, and several between 1 and 2 billion lyrs away. Mike

Here is M86, also from last night.

 

 

[Mike JW]

ARP 155. You get a lot for your money with this Arp and surrounds. Two galaxies have collided forming this mess, with a clearly visible, somewhat large dust lane. It looks like a spiral but it is possibly an irregular lenticular galaxy which may have a ring structure (caused by the collision).

What fascinated me about this shot is the other galaxies I imaged - see cropped image. The numbers are in billions light years.

Mike

 

 

 

[Mike JW]

ARP 269. I have visited this pairing before in CVn.  The light nights of our summer do not stop me being out there. When it is clear I will observe from about 11.30 pm to 1.30 am.

This shot was taken just after midnight.

The galaxy pair are in the process of merging which, is triggering much star formation? The big galaxy is a barred spiral (NGC 4490) and no doubt it will consume its small neighbour (NGC 4485), A connecting bridge of stars appears to be in the process of forming.

https://academic.oup.com/mnras/article/307/3/481/960844   In this article it concludes that NGC 4490 is a young galaxy and that its rate of star formation has in fact been constant. Further it has yet to be seriously affected by the merging process so the star formation knots that we see are nothing to do with the merging. The merging began about 10 million years ago. NGC 4485 being considerably smaller is being disrupted by the collision.

Definitely one to watch over the next few million years!!!!!!!

Mike

Edited June 11, 2020 by Mike JW
grammar

[Martin Meredith]

Very good detail in that capture Mike. It might be interesting to see some H-alpha superimposed on it. I do have an image of the Cocoon from years ago with my achromatic 80mm scope but the chromatic aberration makes it far too embarrassing to post... (I soon dumped that scope in favour of my Newtonian -- well, I still have the scope but it doesn't get much use).

Martin

 

[2STAR]

These are very interesting images and good information supplied thanks

eric

[Bill S]

Arp 104 again.

At the end of May I decided to revisit Arp 104 (Keenan's System) to see if I could pick out the bridge between NGC 5216 and NGC 5218. Left things stacking for a while and watched things build up. (Not strictly true. I nipped into the kitchen and then had a look at my list of targets for the night to decide what I was going to look at next.)

Anyway I reckon I saw the bridge (22000 light years long) to my satisfaction.

Not exactly near real time viewing (nearly 20 minutes stacking).

Best regards

Bill S