Six Arps in Lynx

[Martin Meredith]

There are actually 9 Arps in Lynx (6, 55, 143, 195, 202, 215, 250, 283, 315), just the right number for a single observing session if all goes well.

Unfortunately, Arp 55 was just out of view during the time slot I was able to devote to it, but I managed to take a good look at the remaining 8. Here are 6 of them -- I posted about Arp 6, the Bear's Paw Galaxy, and Arp 143, the collisional ring galaxy, in other threads.

Arp 195 is classified as a "Galaxy with material ejected from nuclei". It is a triple galaxy system  with a very clear linear plume at the N. The lower galaxy has spiral arms that can be made out in the shot. I can't find much online about this specific galaxy group but one article refers to it an ultra-luminous infra red galaxy [1] resulting from galaxy merger.

 

 

 

Arp 202 (NGC 2719, 2719A) is classified in the same way as Arp 195. A 2018 paper [2] devoted entirely to Arp 202 is worth a look as it contains multi-spectral images of this pair but also because it explores the formation of a 'tidal dwarf galaxy' resulting from stars stripped from each galaxy during the interaction -- presumably in sufficient number to spawn a new dwarf galaxy from the two parent galaxies. There is nothing visible at the proposed location of the tidal dwarf in my image (some way off to the right of the pair). I wonder whether it would be possible to capture it with a longer overall exposure in H-alpha.

 

Arp 215 (NGC 2782) is well-described as a "galaxy with adjacent loops", very evident of to the left in this highly-stretched image. Apparently, this is the result of a minor merger and has tidal tails extending to both sides, only one of which is evident in my image (the other is very weak in the visible spectrum) [3]. Coincidentally, a tidal dwarf galaxy candidate was proposed in the brighter tail. A ripple structure referred to in the paper is clearly visible to the upper-right of the galaxy. These are very blue in the DSS2 image.

Arp 250 is a "galaxy with the appearance of fission" and is also quite hard to spot in this image! These galaxies have magnitudes 16.6 and 17.5 so it has to be one of the more challenging Arps. The faintness is made up for by the presence in the same shot of the face-on spiral NGC 2415 towards the bottom-left which looks like it makes a nice pair with the nearby star. This (NGC 2415) is a blue compact galaxy (like the Bear's Paw, Arp 6). 

 

Arp 283 is categorised as "galaxies with infall and attraction". It consists of the pair NGC 2798 and 2799. There is a clear bend to the edge-on member (NGC 2799) and a curving plume towards the top of the brighter member NGC 2798.

 

Lying almost at the 'four corners' point where Lynx meets Cancer, Leo and Leo Minor, Arp 315 is simply categorised as "groups of galaxies". In the central part is the triple making up the Arp group. But the field contains as many as 6 further NGC galaxies and is in fact the core part of Abell 779, a relatively nearby galaxy grouping.

Cheers

Martin

[1] https://iopscience.iop.org/article/10.1088/0004-637X/784/2/140/pdf
[2] https://arxiv.org/pdf/1712.04913
[3] https://arxiv.org/pdf/1712.00932.pdf

 

Edited March 4, 2020 by Martin Meredith

[Mike JW]

Hi Martin, Lynx is full of interesting DSOs.

Arp 195 - you did well picking up the arm on the southern galaxy. This grp are about 750 million lyrs away. I have have labelled some other galaxy distances on your image - below. To get 4 galaxies at 1 billion lyrs or more in the same image - nice one.

 

Arp215  - great shot and now eight distant galaxies (ringed)

Arp 315 - see below but I am fairly certain the smudge in the circle is a quasar at 9.9!!!!!!!!!! - it just gets better!!!!!!!

 

 

I was meant to be sorting some of my images on this very wet afternoon but closely inspecting your shots has been just as much fun. Can't wait to get to have another look at the Lynx Arps.  Mike

[Martin Meredith]

I'm glad you had some fun with them! I get as much pleasure during the observation as I do later reading about them and as much again looking afresh at the image. 

I did take a look myself for the quasar on the Arp 315 image and wasn't too sure, but checking again with the DSS image I can see it is there. The thing you've circled shows both a star and the quasar very close by at around 10 o'clock. Its interesting to compare the detail in the two images. Clearly the DSS2 has better resolution and goes deeper in some wavelengths, but it always surprises me how much one can obtain with a modest setup.

[Mike JW]

Thanks for the confirmation. Mike

[roelb]

Arp 315  with ASI290MM on a Evo 8 @ F/4.7 at Bortle 7

10 x 12 s

 

[Mike JW]

Hi Roelb,

Thanks for adding your shots into this post and others. It is good to compare and helps other folk to see what can be achieved with the different equipment and settings. Mike