APOD: Spiral Galaxy NGC 6744 (2014 Aug 08)

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APOD: Spiral Galaxy NGC 6744 (2014 Aug 08)

Post by APOD Robot » Fri Aug 08, 2014 4:10 am

Image Spiral Galaxy NGC 6744

Explanation: Big, beautiful spiral galaxy NGC 6744 is nearly 175,000 light-years across, larger than our own Milky Way. It lies some 30 million light-years distant in the southern constellation Pavo. We see the disk of the nearby island universe tilted towards our line of sight. Orientation and composition give a strong sense of depth to this colorful galaxy portrait that covers an area about the angular size of the full moon. This giant galaxy's yellowish core is dominated by the light from old, cool stars. Beyond the core, spiral arms filled with young blue star clusters and pinkish star forming regions sweep past a smaller satellite galaxy at the lower left, reminiscent of the Milky Way's satellite galaxy the Large Magellanic Cloud.

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Ann
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Re: APOD: Spiral Galaxy NGC 6744 (2014 Aug 08)

Post by Ann » Fri Aug 08, 2014 7:25 am

I'm so glad to see this fine picture of a very fascinating galaxy! NGC 6744 is very interesting because it is so large, much bigger than the Milky Way. For myself, I'm also fascinated by the appearance of it. For such a large galaxy, it is interestingly "fuzzy". Many other large galaxies have sharp features - consider the following Adam Block pictures of NGC 4535, NGC 5364, NGC 1530 and NGC 613. In the Adam Block galaxy pictures, you can see sharp bar features, striking rings and long sweeping spiral arms. By contrast, the bar of NGC 6744 is broad and fuzzy, the ring is only just there, and most of the spiral arm segments are short, making NGC 6744 resembling a flocculent galaxy.

Note that the blue disk of NGC 6744 is impressively large, but it is rather faint. That is why the integrated colors of NGC 6744 are rather red, in spite of the impressive size of blue disk.

I love seeing all those pink emission nebulas in the inner part of the starforming disk! :D

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Re: APOD: Spiral Galaxy NGC 6744 (2014 Aug 08)

Post by starsurfer » Fri Aug 08, 2014 10:06 am

I'm very glad to see this fabulous image by Don on APOD and I can't believe this is the first time NGC 6744 has been featured! This is also one of the very few images of this galaxy to show its nebulae clearly. Considering it is only LRGB, I imagine Ha would show a lot more!

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Re: APOD: Spiral Galaxy NGC 6744 (2014 Aug 08)

Post by Boomer12k » Fri Aug 08, 2014 11:18 am

Oooooooo....Pretty!

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Re: APOD: Spiral Galaxy NGC 6744 (2014 Aug 08)

Post by NGC3314 » Fri Aug 08, 2014 1:26 pm

starsurfer wrote: I imagine Ha would show a lot more!
Indeed. I once did this narrowband image (not particularly cleaned up yet) for some filter tests, bringing out hundreds of emission regions.
NGC6744haraw.jpg
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Re: APOD: Spiral Galaxy NGC 6744 (2014 Aug 08)

Post by Boomer12k » Fri Aug 08, 2014 4:50 pm

It looks like there are allot of sections from Mergers...and then there are distant patches, that look like star streams that are coming into the disc area...but are not connected....

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Re: APOD: Spiral Galaxy NGC 6744 (2014 Aug 08)

Post by sunlight » Fri Aug 08, 2014 7:47 pm

could someone tell me what are the black spots near some of the stars? For example near the two yellow stars "east" of NGC6744. And there are more somewhere else. Thanks

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Re: APOD: Spiral Galaxy NGC 6744 (2014 Aug 08)

Post by ta152h0 » Fri Aug 08, 2014 8:01 pm

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Re: APOD: Spiral Galaxy NGC 6744 (2014 Aug 08)

Post by JollyCrackers » Fri Aug 08, 2014 10:07 pm

For NGC 6744 the text info says 175,000 light years across. Well, which way is "across" and where does this "across begin and end since the outer fringes of this spiral galaxy are not well defined.
Maybe you can post photos that show data info when one moves the cursor over the photo.

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Re: APOD: Spiral Galaxy NGC 6744 (2014 Aug 08)

Post by rstevenson » Sat Aug 09, 2014 1:09 am

JollyCrackers wrote:For NGC 6744 the text info says 175,000 light years across. Well, which way is "across" and where does this "across begin and end since the outer fringes of this spiral galaxy are not well defined.
Maybe you can post photos that show data info when one moves the cursor over the photo.
NGC 6744 is likely fairly close to circular, as most spiral galaxies are. It appears elongated to us because it's tilted to our line of sight. So "across" in this case would refer to the apparent long axis of the galaxy.

And yes, the edges are fuzzy. There will be a point where the stars thin out too much to be counted in the measured width. Those astronomers who measure these sorts of things will use multiple images taken in different parts of the elctromagnetic spectrum to determine just where that point lies. Such an edge may not be particularly evident in this image.

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Re: APOD: Spiral Galaxy NGC 6744 (2014 Aug 08)

Post by starsurfer » Sat Aug 09, 2014 2:50 pm

sunlight wrote:could someone tell me what are the black spots near some of the stars? For example near the two yellow stars "east" of NGC6744. And there are more somewhere else. Thanks
These are imaging artifacts, I have no idea what causes them.