Unwinding spiral galaxies

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Unwinding spiral galaxies

Post by MoreInput » Sun Jun 23, 2019 2:13 pm

Are you also annoyed of these winded spiral galaxies? Every spiral arm just warps around the center and it is difficulty to follow or compare the spiral arms. :D So I just to try to unwind them and I think the results are worth to be looked at.

Let's have a look here at M74: This is the original picture: https://commons.wikimedia.org/wiki/File ... by_HST.jpg
It is difficult to follow the spiral arms here.

Now I did a inverse polar coordinates mapping, and scaled it a little vertically (all with Gimp). Here is the result:
https://drive.google.com/file/d/1jDkBws ... 4RC7L/view
The winded and wrapped spiral arms are now just diagonal lines, and you can follow them easily.

I wanted to find out where the blueish star formation regions are lying with respect to the dust lanes of the spiral arm. I think that the star formation regions are lying in direction to the outside to the edge of the galaxy, but that's only my impression.
I'm also interested in if we could see here the density waves which induce the spiral arms.

I did inverse the colours you can see the wonderful pattern of the dust lanes more clearly: https://drive.google.com/file/d/1-cCEDB ... MaIi5/view

Or have a look at NGC 4921, which was the APOD picture of 15th May 2019: https://drive.google.com/file/d/1IM9WMi ... iQClC/view
Here is the original: https://apod.nasa.gov/apod/ap190515.html

Here is my collection of all transformed galaxies: https://drive.google.com/drive/folders/ ... eyR4r6f9Ej

As you see I made experiments also with planetary nebula, like the Cat's eye nebula:
https://drive.google.com/file/d/13p6R4K ... TMGeK/view
Here is the original: https://en.wikipedia.org/wiki/File:Catseye-big.jpg


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Re: Unwinding spiral galaxies

Post by geckzilla » Tue Jun 25, 2019 1:57 pm

kind of a different way of looking at things!
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Re: Unwinding spiral galaxies

Post by Ann » Wed Jun 26, 2019 5:23 am

Interesting! :D
M51. Jon and Bryan Rolfe/Adam Block/NOAO/AURA/NSF

As for where star formation typically takes place in spiral galaxies, I think you are right that it is mostly found on the outer edge of dust lanes. Your own picture of NGC 4921 is a case in point. The picture of M51 at right also suggests that star formation is mostly found on the outside of dust lanes.

However, I believe that star formation is mostly a product of local conditions, and I don't think we can be sure that the outer parts of dust lanes is always the "natural" place for new stars to form.

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Re: Unwinding spiral galaxies

Post by THX1138 » Mon Jul 08, 2019 4:07 am

Bottom line, Sure looks to be the case can you run that (Gimp) program on infra red images to perhaps catch more stars in the process of forming and if this is the case (at least where this galaxy is concerned) why is there so much star formation going on on the outside of dust lanes tidal forces?
Interesting and nice pictures MoreInput
inverse polar coordinates mapping, and scaled it a little vertically (all with Gimp) Took quite awhile to do this or was it as easy as one click I'm not familiar with (Gimp) to say the very least
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