APOD: Spiral Galaxy NGC 1512: The Inner Rings (2022 May 08)

[APOD Robot]

Spiral Galaxy NGC 1512: The Inner Rings

Explanation: Most galaxies don't have any rings -- why does this galaxy have two? To begin, the bright band near NGC 1512's center is a nuclear ring, a ring that surrounds the galaxy center and glows brightly with recently formed stars. Most stars and accompanying gas and dust, however, orbit the galactic center in a ring much further out -- here seen near the image edge. This ring is called, counter-intuitively, the inner ring. If you look closely, you will see this the inner ring connects ends of a diffuse central bar that runs horizontally across the galaxy. These ring structures are thought to be caused by NGC 1512's own asymmetries in a drawn-out process called secular evolution. The gravity of these galaxy asymmetries, including the bar of stars, cause gas and dust to fall from the inner ring to the nuclear ring, enhancing this ring's rate of star formation. Some spiral galaxies also have a third ring -- an outer ring that circles the galaxy even further out.

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[bystander]

https://apod.nasa.gov/apod/ap170710.html
discuss_apod.php?date=170710

https://apod.nasa.gov/apod/ap170807.html
discuss_apod.php?date=170807

viewtopic.php?p=322504#p322504

[MoonRockMan]

I'm wondering if there are any phenomena on Earth that generate spiral objects with bars.

[heehaw]

That IS a beauty! Fantastic!

[JohnD]

A very similar galaxy, "Hoag's Object" has featured many times on APoD, most recently https://apod.nasa.gov/apod/ap191127.html

I've never seen a picture of Hoag with as much resolution as this one. Has Hubble ever imaged Hoag? The structures seen within NGC1512 and the blurb (which I have yet to follow up) has links that indicate how it has formed. So applicable to Hoag?

John

[Ann]

I'm wondering if there are any phenomena on Earth that generate spiral objects with bars.

Not to my knowledge, and I don't think it is possible. After all, a spiral galaxy with a bar and a ring is a tremendously huge and dynamical system, whereas the Earth is a (comparatively) tiny ball of rock, with a thin, thin layer of gas and liquid on its surface. I don't think that conditions on the Earth allows small spiral systems with bars and rings to arise spontaneously.

Ann

[Ann]

A very similar galaxy, "Hoag's Object" has featured many times on APoD, most recently https://apod.nasa.gov/apod/ap191127.html

I've never seen a picture of Hoag with as much resolution as this one. Has Hubble ever imaged Hoag? The structures seen within NGC1512 and the blurb (which I have yet to follow up) has links that indicate how it has formed. So applicable to Hoag?

John

In my opinion, Hoag's Object is not similar to NGC 1512. The main difference is that the ring in Hoag's Object appears to be completely detached from the yellow center of that object, as if the blue ring and the yellow elliptical component were completely separate from one another. That is certainly not the case with NGC 1512.

I'd say it is Hoag's Object that is the "odd man out" here, not NGC 1512.

Ann

[AVAO]

A very similar galaxy, "Hoag's Object" has featured many times on APoD, most recently https://apod.nasa.gov/apod/ap191127.html

I've never seen a picture of Hoag with as much resolution as this one. Has Hubble ever imaged Hoag? The structures seen within NGC1512 and the blurb (which I have yet to follow up) has links that indicate how it has formed. So applicable to Hoag?

John

In my opinion, Hoag's Object is not similar to NGC 1512. The main difference is that the ring in Hoag's Object appears to be completely detached from the yellow center of that object, as if the blue ring and the yellow elliptical component were completely separate from one another. That is certainly not the case with NGC 1512.

I'd say it is Hoag's Object that is the "odd man out" here, not NGC 1512.

Ann

In my opinion too. the core is very diffuse in Hoag's Object but highly structured in NGC 1512.


https://live.staticflickr.com/65535/520 ... cc52_h.jpg
Jac Berne (flickr)

[Ann]

Nuclear rings like the one in NGC 1512 are not common, but they are certainly not unheard of, either.

But first, let me show you my favorite image of NGC 1512 and its satellite galaxy NGC 1510 - and let's not forget all the ultraviolet-glowing tendrils of NGC 1512! According to the caption, these tendrils may be the remnants of another satellite galaxy, or just the remnants of a galaxy that blundered too close to NGC 1512. Yes, maybe so, but if that is the case, then these tendrils are certainly still forming hot new stars!

Ultraviolet image of NGC 1512 and smaller satellite galaxy NGC 1510, as well as the wide-ranging ultraviolet tendrils of NGC 1512. Photo: NASA/JPL-Caltech.

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Note the broad-looking blue outer ring of NGC 1512 in the ultraviolet GALEX image, signalling the presence of stars of spectral classes A, B and O. (I refuse to call it an inner ring.) The nuclear ring is lost in the overall glare of the central core of the galaxy.

Anyway, rings. Let's have a look at some other galactic rings (and bars)! Let's start with NGC 1097, because this galaxy is somewhat similar to NGC 1512. Like NGC 1512, it is interacting with a smaller companion galaxy, and like NGC 1512, it has a nuclear ring and and outer ring, as well as some blue outer tendrils:

NGC 1097, with an nuclear ring, a bar and an outer ring, interacting with satellite galaxy 1097A. Image: ESO.

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NGC 1097 and its satellite galaxy, along with ultraviolet tendrils. NASA/JPL-Caltech.

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This is the nuclear ring of NGC 1097. It is just so much brighter than the bar and the bulge of NGC 1097!

The nuclear ring of NGC 1097. Photo: ESO/TIMER survey.

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This Hubble image really brings home how much brighter the nuclear ring is than the bar. Image: ESA/Hubble and NASA.

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Got to show you two pictures of M77, one "normal" and one "enhanced". M77 is a barred spiral, but the bar is not easy to spot, and if there is a nuclear ring, it is not obvious. But I love the "enhanced" image! Note the outer ring, I mean, the really outer ring!

M77. NASA, ESA & A. van der Hoeven.

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"Enhanced" portrait of M77. Note the outer ring. ESO/Stuart Rankin.

Let's have a look at gorgeous barred spiral NGC 1398, too:

Barred spiral NGC 1398. Note the ring encircling the bar. Image: ESO.

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Enhanced portrait of NGC 1398. Image: ESO/Stuart Rankin.

Gorgeous spiral NGC 1398 has a ring encircling its bar, and then its "first set of spiral arms" seems to form yet another ring. You've got to admit that Stuart Rankin's enhanced version of this galaxy makes it even more gorgeous, and even more full of rings, than it already is!

Ann

[JohnD]

There IS a Hubble pic of Hoag: https://science.nasa.gov/hoags-object-n ... 76fabc8b1b

But it seems that it is 20 times further away than NGC 1512 (600 Miilion LY) so maybe even Hibble can't resolve it any better!
JOhn

[orin stepanek]

Almost a perfect ring! ! wonder why some galaxies spiral out;
and some can hold there arms in? Does the gravity on some galaxies
prove stronger? Yet there is some spiraling out of arms; though quite
dark! Also some dark spirals inside the ring!

[MoonRockMan]

I'm wondering if there are any phenomena on Earth that generate spiral objects with bars.

Not to my knowledge, and I don't think it is possible. After all, a spiral galaxy with a bar and a ring is a tremendously huge and dynamical system, whereas the Earth is a (comparatively) tiny ball of rock, with a thin, thin layer of gas and liquid on its surface. I don't think that conditions on the Earth allows small spiral systems with bars and rings to arise spontaneously.

Ann

Makes sense to me

[Chris Peterson]

I'm wondering if there are any phenomena on Earth that generate spiral objects with bars.

Not to my knowledge, and I don't think it is possible. After all, a spiral galaxy with a bar and a ring is a tremendously huge and dynamical system, whereas the Earth is a (comparatively) tiny ball of rock, with a thin, thin layer of gas and liquid on its surface. I don't think that conditions on the Earth allows small spiral systems with bars and rings to arise spontaneously.

Consider that a galaxy is basically a vacuum. Except in small areas where gas or dust density is high, almost all interactions are driven by gravity. The structures that we see (like arms and bars) aren't structural at all, but a consequence of gravitational resonances. No such thing exists on Earth. Whether in the air or in the water, particles interact through fluid dynamics- that is, by actual collisions.

Fluid dynamic processes easily create spirals, which we see all the time on Earth. And maybe they could come together in such a way as to create something that looked like a barred spiral galaxy. But the appearance would be purely coincidental, created by entirely different and unrelated mechanisms.

[AVAO]

Nuclear rings like the one in NGC 1512 are not common, but they are certainly not unheard of, either.
Ann

...Galaxies wrap their arms around and form ring-like structures all the time...

Geck's idea from the legendary APOD discussion to Hoag's Object (2019 Nov 27) convinces me. I think "intertwined spiral arms" would be more correct than the model of a continuously closed ring. This applies in my opinion to outer rings as in Hoag's Object or to inner rings as in NGC 1512.

sky.esa.int/?target=60.97586381880696%20-43.348700443782334&hips=HST+WFC3&fov=0.01260347509909621&cooframe=J2000&sci=true&lang=en

[johnnydeep]

Thanks for those other ring galaxy pics, Ann! They form quite a motley (and beautiful) menagerie!

[orin stepanek]

Just wanted to add: Nice job Judith!