APOD: Star Cluster R136 Breaks Out (2021 Jan 10)

[neufer]

" a small foreground galaxy " has a bar, doesn't it?

Victor, I wish I knew, but I don't!

I joined Galaxy Zoo for a while, where you were supposed to classify galaxies, but
I gave up quickly because they asked me if the little blobs they showed me had a bar.

How the heck would I know?

Three little blobs in a bar

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<<C, E-flat, and G go into a bar. The bartender says, "Sorry, but we don't serve minors." So E-flat leaves, and C and G have an open fifth between them. After a few drinks, the fifth is diminished, and G is out flat. F comes in and tries to augment the situation, but is not sharp enough. D comes in and heads for the bathroom, saying, "Excuse me; I'll just be a second." Then A comes in, but the bartender is not convinced that this relative of C is not a minor. Then the bartender notices B-flat hiding at the end of the bar and says, "Get out! You're the seventh minor I've found in this bar tonight."

E-flat comes back the next night in a three-piece suit with nicely shined shoes. The bartender says, "You're looking sharp tonight. Come on in, this could be a major development." Sure enough, E-flat soon takes off his suit and everything else, and is au natural. Eventually C sobers up and realizes in horror that he's under a rest. C is brought to trial, found guilty of contributing to the diminution of a minor, and is sentenced to 10 years of D.S. without Coda at an upscale correctional facility.>>

[VictorBorun]

What I find surprising about that secretive dusty outskirts beside the fact that it's huge and dwarfing the light-emitting part of the galaxy.
It's clearly non-planar. So the normal matter (can not call it light matter any more) part is overall not a disk but an R=200 kly thorus with an R=20 kly disk brane across the hole. The brane gets thinner at R=4 kly where its prone to form a stable bar ripple, and at R=1 kly there is a core super globular stellar cluster, and at R=1 ly there may be a tiny thorus and disk of accretion by the central black hole.

But how the dusty outskirts survive at such distance from the dark matter globe halo — which is of constant density at R<4 kly and rarefy to nothing at R=40 kly? The dusty skirt is so lose it should have been stripped at encounters with other galaxies.

Maybe they do things different at faraway galaxy clusters. In some each galaxy has a compact dark halo, in others each galaxy has a dusty outskirt.

[Ann]

What I find surprising about that secretive dusty outskirts beside the fact that it's huge and dwarfing the light-emitting part of the galaxy.
It's clearly non-planar. So the normal matter (can not call it light matter any more) part is overall not a disk but an R=200 kly thorus with an R=20 kly disk brane across the hole. The brane gets thinner at R=4 kly where its prone to form a stable bar ripple, and at R=1 kly there is a core super globular stellar cluster, and at R=1 ly there may be a tiny thorus and disk of accretion by the central black hole.

But how the dusty outskirts survive at such distance from the dark matter globe halo — which is of constant density at R<4 kly and rarefy to nothing at R=40 kly? The dusty skirt is so lose it should have been stripped at encounters with other galaxies.

Maybe they do things different at faraway galaxy clusters. In some each galaxy has a compact dark halo, in others each galaxy has a dusty outskirt.

NGC 3314, a pair of overlapping and non-interacting galaxies. NASA, ESA, the Hubble Heritage (STScI/AURA)-ESA/Hubble Collaboration, and W. Keel (University of Alabama).

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Victor, much of that is math-speak that you will have to ask someone else about. But I do want to show you another pair of overlapping galaxies.

NGC 3314 is a pair of overlapping but non-interacting galaxies, which is to say that they are so far separated that they don't affect one another gravitationally.

As you can see, the dust lanes of the foreground galaxy, NGC 3314B, look very dark when seen in silhouette against the bright disk of galaxy NGC 3314A. But when seen against the blackness of space, the dust of NGC 3314B almost "disappears". By contrast, the blue star clusters of the arms of NGC 3314B become very obvious against the black background of space, but when seen against the bright background of the disk of NGC 3314A, they almost disappear.

We have good reasons to think that there is more star formation in the extended arms of NGC 3314B than there is closer to the center of that galaxy. It seems likely, too, that there is more dark and concentrated dust closer to the center of NGC 3314B than in the outer parts of the arms.

Still, I think it is remarkable to see how NGC 3314B turns from "brown" when seen in silhouette against the bright disk of NGC 3314A, to "blue" when seen against the blackness of space.

Ann

[VictorBorun]

If the foreground galaxy, NGC 3314B, has outer dusty thorus we would not see it.
The hole or brane or disk central part occupies the whole backlight area.
Or may be there is no outer dusty thorus.

And yes, the brown/blue galaxy against backlight/black is amazing here