APOD: Spiral Galaxy NGC 1512: The Nuclear Ring (2017 Jul 10)

Comments and questions about the APOD on the main view screen.
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Ann
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Re: APOD: Spiral Galaxy NGC 1512: The Nuclear Ring (2017 Jul 10)

Postby Ann » Mon Jul 10, 2017 6:47 pm

JohnD wrote:I share Guest's confusion!

The blurb just doesn't match the image shown as today's APOD, or the galaxies that the blurb links to!
It just doesn't look like a barred galaxy - no bar! - and nothing like the example NGC 1672.
The Wiki entry for NGC 1512, given to show it "Seen in total", looks exactly like the APOD - no outer rings at all.
And a Google for other images of 1512 find it as an oval, angulated as seen from Earth, with a distinct bar, no dust lanes and wide spiral arms, not an outer ring. See: http://www.billionsandbillions.com/ngc_1512.html

Shurley shome osher Galashie?
John


The nuclear ring of barred spiral NGC 1512.
NASA, ESA, Hubble, LEGUS, Judy Schmidt.
Barred spiral NGC 1097, with inner and outer rings and dust lanes.
Photo: ESO/Rob Gendler.






















It can be confusing to spot a barred spiral, I know.

A typical feature of barred spirals is that they have two dust lanes running along the bar. In the picture at right of NGC 1097, you can clearly see the two dust lanes in the bar, one running from the inner ring to the lower left until it meets the outer ring, the other dust lane running from the inner ring to the upper right to the outer ring.

If you take a look at today's APOD, you can see two dust lanes running from the inner ring, one to the upper left, the other to the lower right. These two dust lanes strongly suggest that the nuclear ring is connected to a bar.

Here is a 549 KB image of galaxy NGC 1512. I recommend it, and you can clearly see both the inner and the outer ring and the connecting bar. One nuclear dust lane is obvious, while the other one is harder to spot. Please note that the inner ring is very tiny compared with the outer one, but also brighter than the outer one, which is typical.

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Re: APOD: Spiral Galaxy NGC 1512: The Nuclear Ring (2017 Jul 10)

Postby Ann » Mon Jul 10, 2017 7:07 pm



Thanks for posting that image, bystander, and great processing of that NASA/ESA/LEGUS picture, Geck!

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Re: APOD: Spiral Galaxy NGC 1512: The Nuclear Ring (2017 Jul 10)

Postby JohnD » Mon Jul 10, 2017 7:13 pm

Art, I come from the haunts of hoot and cern...

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Re: APOD: Spiral Galaxy NGC 1512: The Nuclear Ring (2017 Jul 10)

Postby chuckster » Mon Jul 10, 2017 7:26 pm

As a regular guy who's addicted to APOD, if the blurb sez there's a bar there, I figure the spectrum that the photo was taken in just doesn't feature it, and the blurb is pointing out other aspects of the galaxy. Since Andromeda has such 'low surface brightness' so as to keep it small in our sky at optical wavelengths, I've learned to take Hubble's (and APOD's) word for it on these things. This APOD is a Dust thing, not a Bar thing.

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Re: APOD: Spiral Galaxy NGC 1512: The Nuclear Ring (2017 Jul 10)

Postby BDanielMayfield » Mon Jul 10, 2017 7:43 pm

neufer wrote:
When two comparably sized galaxies (e.g., Andromeda & the Milky Way) collide
what prevents their dark matter from elastically escaping into space
and leave their disturbed in-elastically colliding gases behind :?:


Nothing.

We baryonic beings and things,
attracted to dark matter we are.

But baryons don't matter,
to the darkest of matter,
no matter how dense or diffuse.
For us DM has absolutely no use.

Dark Matter just ain't into us,
'tho it's passing right through us.



Bad original poetry by Bruce
Last edited by BDanielMayfield on Mon Jul 10, 2017 7:52 pm, edited 1 time in total.
"Happy are the peaceable ... "

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Re: APOD: Spiral Galaxy NGC 1512: The Nuclear Ring (2017 Jul 10)

Postby danhammang » Mon Jul 10, 2017 7:50 pm

Congratulations and thanks to Judy Schmidt for capturing one of the wonders and sharing her work with us.

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Re: APOD: Spiral Galaxy NGC 1512: The Nuclear Ring (2017 Jul 10)

Postby Ann » Mon Jul 10, 2017 8:05 pm

BDanielMayfield wrote:
We baryonic beings and things,
attracted to dark matter we are.

But baryons don't matter,
to the darkest of matter,
no matter how dense or diffuse.
For us DM has absolutely no use.

Dark Matter just ain't into us,
'tho it's passing right through us.



Bad original poetry by Bruce



Hey, I like it, Bruce! Except, I would say,

Dark Matter just ain't us.
tho it's passing right through us.
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Re: APOD: Spiral Galaxy NGC 1512: The Nuclear Ring (2017 Jul 10)

Postby Ann » Tue Jul 11, 2017 4:53 am

Ann wrote:
A typical feature of barred spirals is that they have two dust lanes running along the bar. In the picture at right of NGC 1097, you can clearly see the two dust lanes in the bar, one running from the inner ring to the lower left until it meets the outer ring, the other dust lane running from the inner ring to the upper right to the outer ring.

If you take a look at today's APOD, you can see two dust lanes running from the inner ring, one to the upper left, the other to the lower right.


Sorry about quoting myself, but I was wrong here. The dust lanes are channeling gas into the inner ring, which is why there is enhanced star formation there.

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Re: APOD: Spiral Galaxy NGC 1512: The Nuclear Ring (2017 Jul 10)

Postby JohnD » Tue Jul 11, 2017 8:40 am

It seems that compared with this arm of the Milky Way, things are a lot more "exciting" in a lot more places in the Galaxy. Exciting, as in "lethal".

Jobn

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Re: APOD: Spiral Galaxy NGC 1512: The Nuclear Ring (2017 Jul 10)

Postby BDanielMayfield » Tue Jul 11, 2017 8:57 am

Ann wrote:
BDanielMayfield wrote:
We baryonic beings and things,
attracted to dark matter we are.

But baryons don't matter,
to the darkest of matter,
no matter how dense or diffuse.
For us DM has absolutely no use.

Dark Matter just ain't into us,
'tho it's passing right through us.



Bad original poetry by Bruce



Hey, I like it, Bruce! Except, I would say,

Dark Matter just ain't us.
tho it's passing right through us.


Thanks Ann. Both ways work.

Bruce
"Happy are the peaceable ... "

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Re: APOD: Spiral Galaxy NGC 1512: The Nuclear Ring (2017 Jul 10)

Postby Ann » Tue Jul 11, 2017 8:59 am

BDanielMayfield wrote:
Thanks Ann. Both ways work.

Bruce


They do! :D

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Re: APOD: Spiral Galaxy NGC 1512: The Nuclear Ring (2017 Jul 10)

Postby MarkBour » Tue Jul 11, 2017 3:39 pm

Now that line of Tennyson's keeps popping back into my head:
I hope to see my Pilot face to face
When I have crost the bar.

I have come up with about 7 interpretations,
1. The literal was a reference to a ship crossing over a sand-bar
2. The original was meant metaphorically to refer to human death (as a passage) and is now sometimes used in the military for that.
More punnish-ly ...
3. I noted that it could refer to a star circling a galactic central bar
4. Surely lawyers like using it concerning their exams
5. Runners in a relay race, possibly, perhaps a better fit would be for high-jumpers and pole vaulters
6. In a cowboy movie, sometimes it is a major feat to get crost the bar
7. Wilderness hikers don't like to come across a bar (old word for "bear")
Got any more?

But, back to this APOD, both inside and outside of the featured bright ring, the dark tendrils are seen in regions that appear generally luminous and cream-colored. This is all part of the bar of NGC 1512, so the glow here is the diffuse light of many, many stars in those regions, right? In which case, although the ring stands as uniquely productive in young, bright star formation, this is actually occurring within a part of the galaxy that is well-populated with stars, probably more mature and average. I don't think there is an inherent conflict between a region having star formation and star populations on a large scale, although they tend to conflict on smaller scales (as stellar winds remove clouds locally). But I find it interesting to consider what dynamics could produce such a ring. Actually stellar winds would not eliminate gas, even though the term evaporation is sometimes misleadingly used. All they really do is push the stuff around. I guess it has to collect somewhere in the end. There may be a reason it can become concentrated into a ring-shaped region.
Mark Goldfain

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Re: APOD: Spiral Galaxy NGC 1512: The Nuclear Ring (2017 Jul 10)

Postby JohnD » Tue Jul 11, 2017 5:00 pm

Undoubtedly, Tennyson was reffering to death. He wrote the Bar three years before his own death, and previous works - Ulysses, Tithonius are similarly melancholy, as are The Idylls of the King, mosly concerned with Arthur's funeral as his boat disappears over the horizon. If you are an LoR fan its influence on Tolkien is extreme, even to the "one black dot" as Boromir vanishes of the Falls.

JOhn


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