IC1459 group of galaxies

[gregbradley]

Thanks to Robert for the tip about this group of galaxies.

I took this last night for a total of 6 hours and 5 minutes.
LRGB image.

There are some interesting galaxies in this shot. I don't know what the total
number of galaxies are in it but it would be something like 50 or more.

Planewave CDK17 F4.45, PME mount , FLI PL16803 camera, from my home observatory.

It looks best in large.

http://upload.pbase.com/gregbradley/image/137622671/large regular

http://upload.pbase.com/gregbradley/image/137622671/original large

Greg.

[RB]

Greg the two links take me to the same file size jpg.

:shrug:

[Paul Haese]

Nice Greg, great colour in the galaxies. Love the central one. Only negative (if I can call it that; I would be really looking though) I can see is that maybe you have a bung sub in there somewhere. All you stars have a slight bulge to the upper left. Other than that this is a lovely piece of work.

[gregbradley]

I just replaced the links. Try that now.

Greg.

[gregbradley]

Yeah I noticed that but it was slight. I think its worth tracking it down. As you say it'll be one sub in one of the colours where the tracking went off.
I get a few of these now I am using a guide scope. Not that often but something like a dragging cable. I need to get a proper power and USB hub to minimise cables.

A hitech astro sounds like the go.

Greg.

[RB]

They both still take me to the 'large' version, 800 x 797 px.
Anyway I had a look at the original size, lovely shot once again mate !

[gregbradley]

Sorry Andrew, not sure what I did wrong. I replaced the link again and this time tested it and it seems to be correct now.

Greg.

[Stevec35]

Hi Greg

Looks like you found a decent galaxy group. I don't think I've seen this one before and it's a very nice shot. BTW i forgot to mention that the Hickson compact galaxy groups are probably worth a look too.

Cheers

Steve

[richardo]

Very nice job on this one Greg... I like it a lot and looks like your seeing was quite reasonable for your local standard sky conditions.
The two bottom face on spirals are very reminiscent of M83.. especially the larger of the two.
Lovely flat smooth back ground as well as good saturation of colour without being over board.

Nice group.. can't say I've seen this one either!

Good stuff:thumbsup:

Rich

[rogerg]

Love the field of view. Great image, so increadably smooth, noise free, and detailed. Interesting collection of galaxies.

[Octane]

Oh, that's neat. Love that spirally one down towards the bottom.

Great work, Greg!

H

[desler]

The galaxy detail is just something else. Beautifully captured!

Darren

[madbadgalaxyman]

Thanks, Greg, for making an image of this group; hardly any images of it have been made before, though one or two of the member galaxies have had some study in the literature.
As a group dominated by an S0/elliptical galaxy, this one is quite rich and massive.

IC 1459 definitely looks like an S0 galaxy in your image.
It lacks the compactness of the type examples of elliptical galaxies that are found in the Carnegie Atlas of Galaxies.
Beyond the inner spheroidal component, which falls off rapidly in surface brightness, there is an outer more extended component which falls off more gently.
Thus, the image classification of the two dimensional image is definitely S0 rather than elliptical, as S0 galaxy images have at least two different components ("core + halo").

What this galaxy actually looks like in three dimensions is another matter altogether; some of these two component systems genuinely look like a galaxy having a spheroid plus a planar disk, when they are seen edge-on........ but others of them do not.

The falloff of surface brightness with increasing galactocentric radius has been graphed in the literature, and this "two component" model is consistent with the surface brightness distribution that is actually observed over the face of IC 1459.

There is an extant Extremely Deep image by David Malin, made from co-added Schmidt plates, that shows some very strange outermost structures in IC 1459 :

99786

In my experience, a few amateur images now do reach as deep as the co-added Malin plates.....but it isn't going to be an easy job to go this deep.
________________________________

Good images of many southern elliptical galaxies (and some S0 galaxies having a minimal disk) including IC 1459 can be found at:

http://www.astro.yale.edu/obey//galaxies.html

___________________________________ ______

[midnight]

I just love these types of images as one can spend a long time studying it. There is depth in this image.

Lovelly!

Darrin...

[Alchemy]

Yep, love seeing the not often imaged subjects..... Keep it up

[gregbradley]

Thanks Steve.

I'll check out the Hickson Group. Thanks for the tip. I started imaging NGC6872 last night. Its got a highly distorted S shaped galaxy that's had interaction from a nearby galaxy passing by. Interesting.



Thanks Rich. Yes the seeing here has been quite reasonable in the last few weeks. There was one night where it was extremely good about a week ago.



Thanks for that. 6 hours does smooth things out. The fast F ratio helps in getting the data quickly as well but comes at cost of vignetting. If I showed you the image before gradient handling you'd laugh your head off.



Thanks Humi. Yes that is a quite a photogenic one.



Thanks Darren. I intend doing a lot of these grouped galaxy shots. Its something this setup is well suited to.



Thanks for that. You know as I was processing it that extended distorted area around the big elliptical was quite clear at one point. I thought it may have been an artifact from processing. But obviously not! I will work on that to bring that out more as the data is there. I have already seen it. It takes delicate gradient handling to make sure the data isn't shifted. I might give it a go in Pix Insight with its background tool.



I'm glad you like them as there are more coming if the weather stays clear!



Thanks Clive. I have imaged just about everything several times so its good to get some new targets.

Greg.

[multiweb]

Very nicely done indeed. Some interesting structures and colors in the field. :thumbsup:

[strongmanmike]

Yeh a really nice galaxy group image there Greg, it is a good collection of classes and they actually form a nice chain, even more evident in a slightly wider field.

Incidentally, for some reason my version of this galaxy chain taken from Wiruna back in 08 is the most hit image on my web site :shrug: with some 28 000 hits by itself - must be a more popular group than we think :P.

Mike

[gregbradley]

Cheers Marc. These galaxy groups are quite interesting.



Galaxy groups do make an interesting image. There was a fabulous one by Tony Hallas with an AP206 that was NASA APOD recently and another good one the other day by Steve Leshin.

Greg.

[jase]

Top shelf material Greg! Composition A+. I'm wondering if the data could be stretched more however. Regardless, I thoroughly enjoyed it. Well done.

[gregbradley]

Thanks Jase.

I'll check it out. Perhaps it will. I think there is some material around the elliptical galaxy that can be enhanced more.

Greg.

[madbadgalaxyman]

That's a very good point, Mike;
the fact that, with a slightly larger field, this Galaxy Group does form a noticeably long chain.

Why this galaxy group should be so elongated is, in my view, a very interesting question. In general, one might expect gravity to form objects that are elongated, if they are rotating.
At a pinch, off the top of my head, I don't know what is the relative incidence (numbers) of the various shapes of the galaxy groups that are found in the universe. At the largest spatial scales (scales bigger than galaxy clusters) galaxies occupy structures shaped like filaments and sheets (or walls), with a cellular structure in which the walls of the cells are occupied by galaxies; I have never been entirely convinced that gravity alone can form these types of structures, as the theorists tend to believe.
____________________

On a different topic, I mentioned to Greg, in his recent post about the Grus Quartet, that NGC 7421 has a galaxy-scale arc of star formation on one side of it, and that there is not a corresponding feature on the other side of this galaxy. This "bow shock" effect may have to do with the passage of NGC 7421 through the hot (multi-million degrees) X-ray emitting gas that pervades this relatively massive Galaxy Group. It has been speculated, without much physical/mathematical modelling in evidence, that the interstellar medium of NGC 7421 is being compressed, as it passes through the inter-galaxy gas, leading to star formation at the leading edge of this galaxy.

This "bow shock" effect is not particularly obvious in Greg's shot, perhaps because CCDs are generally red sensitive and this feature is actually a blue feature. The blue channel of his image may show the feature more obviously.
The blue image from Sandage's "NASA Atlas" (in the Grus Quartet post) shows the "bow shock" quite well.

Here are the FUV and NUV images of NGC 7421 from the GALEX orbiting telescope, which tend to emphasize young blue Ultraviolet-emitting features:

99867

99868

[Ross G]

Hi Greg,

So many galaxies!

What a beautiful photo.

Great colour and detail.

I love the framing.

Thanks.

Ross.