APOD: NGC 4565: Galaxy on Edge (2011 Oct 15)

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Expand view Topic review: APOD: NGC 4565: Galaxy on Edge (2011 Oct 15)

Re: APOD: NGC 4565: Galaxy on Edge (2011 Oct 15)

by neufer » Wed Oct 19, 2011 12:02 am

neptunium wrote:
Messier missed it?! How!? :shock:
Messier's notes are messier than you might imagine.

Re: APOD: NGC 4565: Galaxy on Edge (2011 Oct 15)

by neptunium » Tue Oct 18, 2011 10:51 pm

Messier missed it?! How!? :shock:

Re: APOD: NGC 4565: Galaxy on Edge (2011 Oct 15)

by jackkessler » Sat Oct 15, 2011 11:15 pm

What I actually meant is, why are galactic disks so thin compared to their diameters?

Re: APOD: NGC 4565: Galaxy on Edge (2011 Oct 15)

by jackkessler » Sat Oct 15, 2011 11:14 pm

Why are galactic disks so flat?

Re: APOD: NGC 4565: Galaxy on Edge (2011 Oct 15)

by Ann » Sat Oct 15, 2011 8:37 pm

NGC 4565 is a very large and bright galaxy. According to the Principal Galaxy Catalog, NGC 4565 is intrinsically 5.4 times brighter than the Milky Way. That's a lot. Admittedly the Principal Galaxy Catalog may be overestimating the brightness of NGC 4565 somewhat, as the this catalog puts NGC 4565 at a distance of 46 million light-years, rather than 40 million light-years, as the caption of today's APOD tells us. It is still clearly a very bright galaxy.
Image
You can actually tell from the general appearance of NGC 4656 that it is probably a very bright galaxy.
Image
Let's compare it with NGC 891, which was one of today's links.

As it happens, both these images were made by Bob Franke!

According to the Principal Galaxy Catalog, NGC 891 is a much smaller galaxy than NGC 4565. While NGC 4565 was estimated to be five times brighter than the Milky Way, NGC 891 was estimated to be only about as bright as our own galaxy.

If you compare the two galaxies, you can see that NGC 4565 looks "cleaner", "straighter" and more "perfect" than its edge-on "cousin". The bulge of NGC 4565 is a bit more "rounded" and "puffed up" above the disk of the galaxy than the bulge of NGC 891, and it is also brighter than the bulge of NGC 891. The dust lane of NGC 4565 also seems straighter and thinner than the dust lane of NGC 891. The dust lane of NGC 891 is coarser, thicker and more uneven, and unlike the dust lane of NGC 4565, it extends almost to the edge of the visible disk of the galaxy. Close-ups of the two galaxies will show that the dust lane of NGC 891 has prominent "dust chimneys", where huge amounts of dust are blown in tremendous plumes for thousands of light-years above and below the plane of the galaxy. NGC 4565 has dust chimneys too, but much weaker ones.

Closeups will also show that NGC 891 has prominent star formation regions in parts of its dust lane. Such obvious star formation regions are missing from the dust lane of NGC 4565.

Importantly, the disk of NGC 4565 seems larger and more wide-ranging than the disk of NGC 891.

Conclusions? NGC 4565 has a larger disk and a brighter bulge than NGC 891. Its dust lane is thinner and straighter and shows few signs of active high-mass star formation. NGC 4565 therefore has a very large population of old yellow stars, but it is relatively poor in gas, dust and bright young stars.

NGC 4565 is relatively "quiet". It is quiet in that it isn't currently forming very many stars. Since star formation is a somewhat messy affair, the general lack of star formation in NGC 4565 contributes to its "clean" and majestic shape. It is, on the other hand, obvious that NGC 4565 has been forming stars very actively in the past, which is why it has so many old yellow stars.

NGC 4565 is a remarkable galaxy that would certainly have deserved to be in Messier's catalogue. Thanks to Bob Franke for the very fine image of it!

Ann

Re: APOD: NGC 4565: Galaxy on Edge (2011 Oct 15)

by bystander » Sat Oct 15, 2011 3:47 pm

alphachap wrote:Here's a close up from ESO VLT: (why image so small? the source I uploaded was much larger)
The images are reduced to 400 px width here, so they don't take up too much space. Click on the image to see the full size.
Also, it would be nice to get a view from the other side, for a change.
We sent some people out to take pictures. We should have the results back in about 150 to 200 million years. :wink:

Re: APOD: NGC 4565: Galaxy on Edge (2011 Oct 15)

by Psnarf » Sat Oct 15, 2011 3:11 pm

What is that greenish-blue smudge in the upper center of this amazing image, a dwarf galaxy?
http://www.noao.edu/outreach/aop/observ ... 65hugo.jpg

As always, I start my day by staggering my imagination with APODs and their links.
Sew! it takes a hundred thousand years for a photon emitted at one edge to reach the opposite edge? Of course that could never happen because of the warped spacetime near the galactic center where a vector representing the direction of future time points in the direction of the singularity from anywhere inside the event horizon.

[Aside: I'll go out on a limb here by suggesting that we are viewing the near edge of the galaxy. You can see the far edge, if you get your gravitational lenses lined up just right.]

Re: APOD: NGC 4565: Galaxy on Edge (2011 Oct 15)

by orin stepanek » Sat Oct 15, 2011 1:17 pm

Pretty much a perfectly shaped galaxy! 8-) Good background material! :D :wink:

Re: APOD: NGC 4565: Galaxy on Edge (2011 Oct 15)

by alphachap » Sat Oct 15, 2011 10:36 am

Here's a close up from ESO VLT: (why image so small? the source I uploaded was much larger) http://www.eso.org/public/images/eso0525a/

Also, it would be nice to get a view from the other side, for a change.

Re: APOD: NGC 4565: Galaxy on Edge (2011 Oct 15)

by sameer » Sat Oct 15, 2011 9:32 am

APOD: 2009 April 28 mentions that NGC4565 is 30 million light years away and today's APOD says its 40 million light years. Did we drift 10 million light years in 2 years....or were the old measurements incorrect ?

Re: APOD: NGC 4565: Galaxy on Edge (2011 Oct 15)

by bystander » Sat Oct 15, 2011 5:12 am

Re: APOD: NGC 4565: Galaxy on Edge (2011 Oct 15)

by Beyond » Sat Oct 15, 2011 4:34 am

Ok, that's at least twice now that this picture has been shown in the APOD thread, and i think they are just needling us, as no-one has yet said which edge of the galaxy we are viewing.

Re: APOD: NGC 4565: Galaxy on Edge (2011 Oct 15)

by zerro1 » Sat Oct 15, 2011 4:23 am

That is a beautiful shot! crisp details, nice color in the galaxies and the stars! congrats Bob!

APOD: NGC 4565: Galaxy on Edge (2011 Oct 15)

by APOD Robot » Sat Oct 15, 2011 4:05 am

Image NGC 4565: Galaxy on Edge

Explanation: Magnificent spiral galaxy NGC 4565 is viewed edge-on from planet Earth. Also known as the Needle Galaxy for its narrow profile, bright NGC 4565 is a stop on many telescopic tours of the northern sky, in the faint but well-groomed constellation Coma Berenices. This sharp, colorful image reveals the galaxy's bulging central core cut by obscuring dust lanes that lace NGC 4565's thin galactic plane. An assortment of other background galaxies is included in the pretty field of view, with neighboring galaxy NGC 4562 at the lower right. NGC 4565 itself lies about 40 million light-years distant and spans some 100,000 light-years. Easily spotted with small telescopes, sky enthusiasts consider NGC 4565 to be a prominent celestial masterpiece Messier missed.

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