Interesting galaxies thread

[Martin Meredith]

I also looked at this one a while back. It isn't as clear as in mono but NGC 4302 does show some interesting reddening in the central region. Thanks for the link Bill -- I'll check to see if any of this colour is meaningful!

[Mike JW]

Here are few more galaxies of interest, simply because they are in the IC catalogue and are around the 1 billion distance and all visible with a large Dob. 2881 and 3848 are both galaxy pairs and 2860 fov has PCG galaxies in view which are 2 billion lyrs or more. The quasar just below it lurks around the 8 billion lyr distance.

Mike

Edited April 6, 2022 by Mike JW

[Martin Meredith]

Going back through some recent captures I came across M77 in Cetus.

This is how it looks on the 'normal' settings I use for LRGB captures (gamma stretch), showing an extremely bright core region within which it is hard to discern any structure (even on a single blue sub it is bright and stellar). The spiral arms show what appear to be star-forming region (blue), all bathed in the yellow glow of a halo? of stars

But it turns out that the galaxy is much more extended than this. Switching to hyper stretch and applying some sharpening produces a result that is not 'pretty' but which reveals a clear outer structure with what look to be a pair of additional spiral arms but which could well be continuations of the ones visible in the above shot. 

Something I've started to explore is subtracting the responses of different filters. This is early days but here's an example of using the difference between the red and blue filter as the luminance component. There is no finesse to this at present, hence the horrible artefact on the bright star to the left, but the process does hint at a double structure of some kind at the core (again, this might be an artefact).

Edited April 15, 2022 by Martin Meredith

[Mike JW]

Always good to experiment.

Mike

[PatG]

It would be remis not to include M87 on this thread.

Whilst the capture is not much to look at, the satisfaction of being able to observe this behemoth of a galaxy with its relativistic jet of synchrotron radiation blasting out (at about 2 o'clock) from the super-massive blackhole at the galaxies core - and all with a modest telescope and camera in just a few seconds.

What's not to love!

Pat

 

[Mike JW]

EEVA has certainly caught your imagination.

Mike

[catburglar]

I too couldn't let a clear night pass without snapping a shot of the M87 jet...When I first saw posts (probably 12 months ago) showing this I was amazed at how easy it was to capture...It was plainly visible in a single 10 second exposure. Apparently there's also a jet in the opposite direction, but this is more difficult to capture. I let my capture run for 5 minutes in the vain hope of being able to get a glimpse of it, but I guess it's not going to happen. Maybe next time 😉 .

[Martin Meredith]

Here's a quick snap of a pair of mag 7-ish yellow-orange stars (both have B-V colour indices of ~ 0.9) in Bootes, close to the border with Corona Borealis. Gliese 593 is also known as Otto Struve 298, a very close double (sep 1.2"). 

However, since this is the interesting galaxies thread, using a more aggressive stretch reveals the main point of the operation, a pair of NGC/IC galaxies, plus a third galaxy, the triplet curving gently through the stellar pair. 

 

Distance-wise, the stellar pair are both listed at 73 light years (so presumably not just an optical pairing), while IC 4563 and NGC 5966 are about 30000 times further out at around 215 million light years. The middle galaxy, mag 16.4, is nearly a billion light years away.

 

Martin

Edited May 9, 2022 by Martin Meredith

[Mike JW]

For a moment  Martin, I thought you had lost the plot (although as you know I do like doubles)!!!! and then all was revealed - a delightful capture - excellent to have hunted this one out.

Mike

Edited May 9, 2022 by Mike JW

[Martin Meredith]

Well, it wouldn't be the first time I've lost the plot... Anyway, last night with it being clear but accompanied by a bright moon overhead, and there being few open clusters on offer towards the south, I did check out some doubles (may post elsewhere) purely for their aesthetic value. 

But with Virgo so well-placed the call of the galaxies was too strong to ignore, and the highlight of the night for me in spite of the moon was NGC 4762 in Virgo. This is a member of VV 1573 but the way my ASI 290 sensor was oriented was such that the pair only just squeezed on to the sensor, so I focused more on NGC 4762.

This is a perfectly edge-on galaxy and as such shows a clear core.

Below is what I tend to think of as a  'colourised' capture: that is, I started off in luminance-only, then added some RGB at the end to capture the pale peachy glow of the "arms" and the brighter yellow core.

Just as with my previous post, no one stretch shows it all, and there is much more to this galaxy than its clean-cut central region. Barely visible in the gamma-stretched image are very faint curved extensions to the central streak of light. These are better seen using a hyper stretch on a negative image:

The reason I put "arms" in quotes above is that this version makes me wonder if what we're seeing in the gamma-stretched image is the core plus an extensive bar, with the spiral arms only showing up in the stretched form. At any rate, there is a clear asymmetry in the outer parts and what to me is a surprisingly abrupt cutoff between the linear bar(?) and the rest. Time for some reading I think...

Martin

 

 

[Mike JW]

One classification describes NGC 4762 as SB(r)0^0^ sp LINER - Ok it has a bar, is likely to be a spiral but how do they get to work out that it has an inner ring and what does the  0^0^ mean??

 

[Martin Meredith]

The de Vaucouleurs Atlas describes it as "one of the most remarkable S0 galaxies in the sky" with a "very well defined inner disk zone flanked by a noticeably warped thicker disk". They cite a 1984 article by Wakamatsu & Hamabe that suggests that "the innermost hump represents the ends of a bar oriented at an intermediate angle to the line of sight" and that the very sharp edge that we see is an edge on view of a lens.

[Bill S]

NGC 660 a polar ring galaxy.

Came across this when I was rambling around this part of the sky (Pisces).

Polar ring galaxies have an outer ring of dust and stars that is rotating around the main body of the galaxy. Quite probably the result of a galactic gravitational  interactions or stripping material from a passing galaxy. This one is 45 million ly away.

When I finished collecting subs I noticed that some cloud had come in, so perhaps it would be worth another look.

 

It may be worth looking for other examples of this type of peculiar galaxy.

And it was quite cosy around 15 degC.

Bill S

 

[Mike JW]

Bill, really interesting galaxy. There is a catalogue of Polar Ring Galaxies - Sloan Polar Ring Catalogue  but I have no idea how many have NGC numbers.  We do of course already have the Ring Galaxy Thread for ring galaxy observations. Polar ring galaxies are so called because the ring of orbiting stars/dust is very inclined to the ecliptic of the galaxy.

I shall certainly take a look at this galaxy.

Mike

[Martin Meredith]

Beautiful galaxy with unusual dust lanes that I find hard to get my head around.

I observed NGC 660 last year and rather than posting the main galaxy, which is also taken with a Lodestar and 200mm scope and quite similar to yours, I noted that in the lower left of your shot there is a curving chain of fainter galaxies that nevertheless show some interesting structure. 

The left hand pair appear to be interacting but the distance estimates are very different. The leftmost one is supposedly at 1.88 billion light years distance (mag 18.3) while its visual companion is mag 17.2 and at a 'mere' 782 million LYs. It is more likely to be part of a group with the obvious near face-on spiral (mag 16.3, 779 MLy). Finally, the rightmost galaxy is mag 17.7 but closest to us, at 642 MLyrs. Assuming all these to be correct, we're not looking at a group at all but an orderly progression in distance from right to left.

There are other fuzzy spots in the general area that I don't have data for.

[Mike JW]

Martin, this has really whetted my appetite to pay the area a visit. Just checked out these galaxies in Sky Tools 4. By the way NGC 660 is VV 979.

Mike

[Bill S]

Ooh yes, Martin. I see what you mean. I had another look at this early this morning and here's a snapshot labelled up with the ones you drew attention to. As you say, various other objects around too.

[Mike JW]

Hi Bill/Martin,

At last, I have got around to taking a look at this wonderful galaxy. Not the most transparent conditions last night. However, a little more detail picked up, but not sufficient to make anyone rush out and get a scope bigger than the 8" scopes that you use. (Although as usual it only took 5 mins of subs).

 

Mike

[Martin Meredith]

I found this photogenic configuration by accident earlier tonight. IC 239 is a delicate face on spiral surrounded by a lovely asterism of mag 10-12 stars (not part of a cluster as far as I can tell -- very different parallaxes but they happen to glow at a similar apparent magnitude).

The galaxy is of type Scd, hence the evident far-flung arms.

 

 

 

[Mike JW]

It also has a very active nucleus.  A very fine member of our local galaxy group.

Mike

[Martin Meredith]

I was intending to focus on Arps last night but as usual when browsing the charts I got distracted by this very thin sliver of a galaxy in Coma that stands out not just for its fine linear appearance but also for its relative isolation. Not surprisingly, it is a member of the Flat Galaxy Catalogue and also denoted UGC 7321. We're seeing this galaxy very nearly edge-on. There is some clear mottling visible along its length.  

 

According to Simbad it is a well-studied galaxy as its edge-on nature allows a good estimation of the luminosity profile which in turn feeds theories of galaxy evolution

https://simbad.u-strasbg.fr/simbad/sim-basic?Ident=fgc+1403&submit=SIMBAD+search