APOD: NGC 4565: Galaxy on Edge (2017 May 24)

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APOD: NGC 4565: Galaxy on Edge (2017 May 24)

Post by APOD Robot » Wed May 24, 2017 4:05 am

Image NGC 4565: Galaxy on Edge

Explanation: Is our Galaxy this thin? We believe so. 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 upper left. 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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Re: APOD: NGC 4565: Galaxy on Edge (2017 May 24)

Post by Boomer12k » Wed May 24, 2017 4:08 am

Great Image... Reminds me.. I have to post my M104 I got last night in the cafe... 8-)

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Re: APOD: NGC 4565: Galaxy on Edge (2017 May 24)

Post by Ann » Wed May 24, 2017 4:26 am

Boomer12k wrote:Great Image... Reminds me.. I have to post my M104 I got last night in the cafe... 8-)

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You got a picture of M104 last night in the cafe? :shock:

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Re: APOD: NGC 4565: Galaxy on Edge (2017 May 24)

Post by Ann » Wed May 24, 2017 5:54 am

Back to the subject of NGC 4565, a most interesting galaxy. (Aren't they all?)

I can't resist showing you two small and poorly resolved images of two edge-on galaxies, NGC 4565 and NGC 891:
Image
NGC 4565. Photo:
Peter Bresseler.
Image
NGC 891. Photo: Jimmy Walker.















Okay! Now we'll be looking at Hubble closeups of parts of their disks. Which disk is which?



















Why, the closeup of NGC 4565 is at left, and the closeup of NGC 891 is at right. That wasn't so hard, was it?

Note the following:

1) NGC 4565 has a thinner and more elongated profile than NGC 891. You can actually see that the thick disk of NGC 891 - the disk that can be seen above and below the dust lane - is more puffed up in NGC 891 than it is in NGC 4565.

2) Note that in the picture of NGC 891, we can see huge columns of dust rising above and below the central dust lane in the lower right part of the picture. Note that there are bright blue star clusters in the dust lane where we see the tall "chimneys" of smoke. The columns of dust are undoubtedly remnants of violent supernovas.

3) Note that there are no such "chimneys" in the dust lane of NGC 4565. And while there are some small clusters of young blue stars in the disk, they are not prominent at all, and they don't seem to be associated with supernovas. Indeed, if a galaxy is going to be as flat as NGC 4565, there can't be much star formation in the disk. And in NGC 4565, there isn't.
NGC 4565 in ultraviolet.
Photo: GALEX.
That doesn't mean that there are no young stars at all in NGC 4565. We can actually see small numbers of blue stars scattered in the dust lane of the galaxy in the Hubble closeup of NGC 4565. Almost certainly, star formation is going on slowly and steadily in NGC 4565, leading to the continuous, slow creation of a massive star here and a massive star there. In the low-resolution picture of NGC 4565 in ultraviolet light at left, the entire dust lane glows blue from hot stars scattered there.

NGC 4565 is a huge galaxy. You can actually see from the enormously extended disk of it that it is much larger than NGC 891. According to freestarcharts.com, the radius of NGC 4565 is 70,000 light-years, which would make the size of NGC 4565 140,000 light-years in diameter. That would make it much bigger than the Milky Way, whose optical disk is supposed to be some 100,000 light-years in diameter. freestarcharts.com also says that there are a trillion stars in NGC 4565. Well, I can believe it. Because not only is NGC 4565 huge, but it is yellow too, meaning that it must contain enormous numbers of small red and yellow stars. The B-V index of NGC 4565 is 0.840, which is relatively, although not tremendously, red.

(Okay... today's caption says that the disk of NGC 4565 is "only" 100,000 light-years in diameter. Whatever.)
Image
M101.
Photo: Oriol Lehmkuhl and Ivette Rodríguez.
We can compare NGC 4565 with M101, which was the APOD just a few days ago. According to Wikipedia, the disk of M101 is 170,000 light-years in diameter, much larger than NGC 4565. Yes, but the color index of M101 is 0.450, which is tremendously blue. M101 contains astonishing numbers of bright blue OB stars, but how many small red stars it contains is an open question.

M101 and NGC 4565 are two very large galaxies. But while one is in the throes of tidal forces causing huge distortions of its disk, NGC 4565 sails through peaceful skies like a perfect needle of the heavens.

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heehaw

Re: APOD: NGC 4565: Galaxy on Edge (2017 May 24)

Post by heehaw » Wed May 24, 2017 8:46 am

I like 4565 because we see it almost exactly like we see our OWN galaxy - edge on! We are far from the center of our galaxy and very close to the galactic plane. I wish we could make contact with one of those advanced civilizations in the Andromeda galaxy because we could get from them pictures of our own galaxy taken from a very different perspective. It is very hard, since we are limited to measurements from a single point near the plane, to get an unambiguous picture of the full 3D structure of our own galaxy.

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Re: APOD: NGC 4565: Galaxy on Edge (2017 May 24)

Post by Indigo_Sunrise » Wed May 24, 2017 10:46 am

... with neighboring galaxy NGC 4562 at the upper left.
Would someone please point out where exactly this galaxy is? (in a screen-shot, maybe?) I've looked and looked, and am just not seeing it... :(
TIA

NM: Found it. Just have to click on the 'included in the pretty field of view' link. :ssmile:
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Re: APOD: NGC 4565: Galaxy on Edge (2017 May 24)

Post by leon.l7027@gmail.com » Wed May 24, 2017 1:03 pm

NGC 4562 got cropped! the line of stars is there, but not the galaxy! :(

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Re: APOD: NGC 4565: Galaxy on Edge (2017 May 24)

Post by sillyworm » Wed May 24, 2017 1:51 pm

Once again,Thanks Ann,for all the info & pictures.

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Re: APOD: NGC 4565: Galaxy on Edge (2017 May 24)

Post by Chris Peterson » Wed May 24, 2017 1:59 pm

heehaw wrote:I like 4565 because we see it almost exactly like we see our OWN galaxy - edge on! We are far from the center of our galaxy and very close to the galactic plane.
In an undisturbed spiral, being far from the center almost guarantees being close to the galactic plane. ;)
I wish we could make contact with one of those advanced civilizations in the Andromeda galaxy because we could get from them pictures of our own galaxy taken from a very different perspective.
Maybe somebody in Andromeda took a picture a couple of million years ago and sent it this way, and one of our radio telescopes will pick it up at any moment. Well, it's possible.
It is very hard, since we are limited to measurements from a single point near the plane, to get an unambiguous picture of the full 3D structure of our own galaxy.
True. But between IR telescopes and instruments like Gaia, we're getting a better picture all the time.
Chris

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Re: APOD: NGC 4565: Galaxy on Edge (2017 May 24)

Post by Ann » Wed May 24, 2017 5:51 pm

heehaw wrote:I like 4565 because we see it almost exactly like we see our OWN galaxy - edge on! We are far from the center of our galaxy and very close to the galactic plane. I wish we could make contact with one of those advanced civilizations in the Andromeda galaxy because we could get from them pictures of our own galaxy taken from a very different perspective. It is very hard, since we are limited to measurements from a single point near the plane, to get an unambiguous picture of the full 3D structure of our own galaxy.
Your post reminded me of the time when I was fifteen, and, armed with my parents' binoculars, I went outside to try to find the Andromeda galaxy. I had never looked at the sky with binoculars before, and soon I had to lie down on the snow-covered ground to keep my arms from shaking, and in that supine position I kept searching for Andromeda. I became acutely aware of the entire Earth curving away below me as I lay on the ground, staring up into the heavens.

And there it was! Andromeda! A faintly yellow patch of fuzz! It was so incredibly different from the icy, sharp points of light from individual stars. Heehaw, I must tell you, at that moment I felt sure that there was someone inside that yellow fuzz, a member of an advanced civilization, looking back at me from their own alien yet (I felt sure at that moment) Earth-like world!
NGC 253. Anyone there?
Have you seen our splendid Milky Way galaxy?
Photo: Steve Mazlin, Jack Harvey, Rick Gilbert, and Daniel Verschatse
Anyway, your post made me remember something I have read somewhere (in David Malin's A View of the Universe, perhaps?), that any intelligent beings in NGC 253 would have a grand face-on view of the Milky Way, provided they were able to see anything at all out of their own very dusty galaxy!

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Re: APOD: NGC 4565: Galaxy on Edge (2017 May 24)

Post by Ann » Wed May 24, 2017 6:13 pm

[c]NGC 6814, a face-on version of NGC 4565?
Source: https://cgs.obs.carnegiescience.edu/CGS ... C6814.html[/c]
And heehaw, you made me think of another thing, too. What would NGC 4565 look like face on? It would have to be very regular, with very few kinks.

So I searched the web for face-on, large-looking spiral galaxies. It was quite frustrating. It is surprisingly hard to find information about the true size of galaxies, and I wanted a picture of a large-looking, face-on, undisturbed spiral galaxy.

So I settled on NGC 6814 in the picture at left, but I'm really just guessing. I don't claim to know that NGC 6814 is anything like a face-on version of NGC 4565 at all! I just thought it might be, and that it sort of looks like it. Interestingly, NGC 6814 has exactly the same B-V as NGC 4565: 0.840.
M100. Photo: Philipp Keller and Christian Fuchs.










I think I've read somewhere that NGC 4565 might look similar to M100 if we could see it face on. Yes, maybe. I just think that M100 looks like it is forming more stars than NGC 4565 (although admittedly that's hard to know, considering NGC 4565's very edge-on position). I also think that M100 somehow looks more irregular than NGC 4565, but what do I know?

And one more thing. I've found a really beautiful picture of NGC 4565 by Bob Franke. It is too big for me to post here, either as a picture or as a link, but I'm posting the link anyway. The picture is 513.29 KB, so open it at your own risk!

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Re: APOD: NGC 4565: Galaxy on Edge (2017 May 24)

Post by danie » Wed May 24, 2017 7:34 pm

Chris Peterson wrote: Maybe somebody in Andromeda took a picture a couple of million years ago and sent it this way, and one of our radio telescopes will pick it up at any moment. Well, it's possible.
We will miss it if its a hologram encoded in cubits with gravity waves as the transport medium...

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Re: APOD: NGC 4565: Galaxy on Edge (2017 May 24)

Post by Ann » Wed May 24, 2017 7:40 pm

Chris Peterson wrote: Maybe somebody in Andromeda took a picture a couple of million years ago and sent it this way, and one of our radio telescopes will pick it up at any moment. Well, it's possible.
It would require very collimated beams.

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Re: APOD: NGC 4565: Galaxy on Edge (2017 May 24)

Post by Chris Peterson » Wed May 24, 2017 11:23 pm

Ann wrote:
Chris Peterson wrote: Maybe somebody in Andromeda took a picture a couple of million years ago and sent it this way, and one of our radio telescopes will pick it up at any moment. Well, it's possible.
It would require very collimated beams.
Or a very powerful transmitter.
Chris

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Re: APOD: NGC 4565: Galaxy on Edge (2017 May 24)

Post by Nitpicker » Wed May 24, 2017 11:54 pm

Ann wrote:Anyway, your post made me remember something I have read somewhere (in David Malin's A View of the Universe, perhaps?), that any intelligent beings in NGC 253 would have a grand face-on view of the Milky Way, provided they were able to see anything at all out of their own very dusty galaxy!
Funny that you should mention NGC 253, as it just happens to be very much like NGC 4565 (of this APOD) in this regard. The former is close to the Galactic South Pole and the latter is close to the Galactic North Pole (of the Milky Way). It is this closeness to the galactic poles that gives these galaxies the ability to see the Milky Way face-on. NGC 4565 would see us the "correct" way, looking "down" on us from "above". Interestingly enough, almost all people on Earth can see both galactic poles in their sky for some portion of every day (though not at the same time).

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Re: APOD: NGC 4565: Galaxy on Edge (2017 May 24)

Post by Ann » Thu May 25, 2017 5:47 am

Nitpicker wrote:
Ann wrote:Anyway, your post made me remember something I have read somewhere (in David Malin's A View of the Universe, perhaps?), that any intelligent beings in NGC 253 would have a grand face-on view of the Milky Way, provided they were able to see anything at all out of their own very dusty galaxy!
Funny that you should mention NGC 253, as it just happens to be very much like NGC 4565 (of this APOD) in this regard. The former is close to the Galactic South Pole and the latter is close to the Galactic North Pole (of the Milky Way). It is this closeness to the galactic poles that gives these galaxies the ability to see the Milky Way face-on. NGC 4565 would see us the "correct" way, looking "down" on us from "above". Interestingly enough, almost all people on Earth can see both galactic poles in their sky for some portion of every day (though not at the same time).
The sculptor Henry Moore.
Photo: Henry Moore Foundation Archive.
Embroiderer in a Landscape of Chateauneuf.
Painting: Paul Serusier.


















What a good point! I didn't think of that! So maybe we shouldn't just ask the sculptors of the Sculptor Galaxy if they have seen our splendid galaxy, but we should as the needleworkers of the Needle Galaxy, too!

But to the needleworkers of the Needle Galaxy, our Milky Way would present a smaller spiral in the sky than it would to the sculptors of the Sculptor Galaxy. The distance to NGC 253 is 10-13 million light-years, but the distance to NGC 4565 is about 40 million light-years.

Ann

And just to clarify: NGC 253 is found in the direction of the Sculptor constellation, so it is known as the Sculptor Galaxy. NGC 4565, of course, is the Needle Galaxy!
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