APOD: Arp 159 and NGC 4725 (2015 Sep 03)

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APOD Robot
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APOD: Arp 159 and NGC 4725 (2015 Sep 03)

Postby APOD Robot » Thu Sep 03, 2015 4:10 am

Image Arp 159 and NGC 4725

Explanation: Pointy stars and peculiar galaxies span this cosmic snapshot, a telescopic view toward the well-groomed constellation Coma Berenices. Bright enough to show off diffraction spikes, the stars are in the foreground of the scene, well within our own Milky Way. But the two prominent galaxies lie far beyond our own, some 41 million light-years distant. Also known as NGC 4747, the smaller distorted galaxy at left is the 159th entry in the Arp Atlas of Peculiar Galaxies, with extensive tidal tails indicative of strong gravitational interactions in its past. At about a 100,000 light-years across, its likely companion on the right is the much larger NGC 4725. At first glance NGC 4725 appears to be a normal spiral galaxy, its central region dominated by the yellowish light of cool, older stars giving way to younger hot blue star clusters along dusty spiral outskirts. Still, NGC 4725 does look a little odd with only one main spiral arm.

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Ann
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Re: APOD: Arp 159 and NGC 4725 (2015 Sep 03)

Postby Ann » Thu Sep 03, 2015 4:47 am

Nice picture! :D

APOD Robot wrote:

At first glance NGC 4725 appears to be a normal spiral galaxy, its central region dominated by the yellowish light of cool, older stars giving way to younger hot blue star clusters along dusty spiral outskirts. Still, NGC 4725 does look a little odd with only one main spiral arm.


Yes, NGC 4725 is known as a one-armed spiral. But Stephen Lehsin's picture shows us that it does have not just another arm, but in fact two more arms. A dust lane of another arm can be seen emanating from the blue "spiral ring" at about 4 o'clock. One of the "other arms" consists of very faint, "old red stars only" and seems to be superimposed on an orange star at about 2 o'clock (in reality the orange star must be a foreground object). Another arm lies just outside the main blue arm of NGC 4725 and closely follows it, and contains some blue stars itself.

Ann
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Re: APOD: Arp 159 and NGC 4725 (2015 Sep 03)

Postby Wee liam » Thu Sep 03, 2015 6:16 am

Exactly. You beat me to it.

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Re: APOD: Arp 159 and NGC 4725 (2015 Sep 03)

Postby Ron-Astro Pharmacist » Thu Sep 03, 2015 3:45 pm

I wish we could depict galaxies (like the one on the right) as a giant gravity well ending in some strange object at the bottom. Maybe we could call it a" Black Drain"? No, that's not quite right… And since it developed over a long time I wish we could show it that way too. We could call that the "Time Space" view. Hmmm, that's not quite right either…

Guess we will just have to settle for looking at it in two dimensions and use our imagination for the other two. I really wish our view of the universe wasn't as flat as it's said to be physically.
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Re: APOD: Arp 159 and NGC 4725 (2015 Sep 03)

Postby LocalColor » Thu Sep 03, 2015 4:21 pm

Ron-Astro Pharmacist wrote:I wish we could depict galaxies (like the one on the right) as a giant gravity well ending in some strange object at the bottom. Maybe we could call it a" Black Drain"? No, that's not quite right… And since it developed over a long time I wish we could show it that way too. We could call that the "Time Space" view. Hmmm, that's not quite right either…

Guess we will just have to settle for looking at it in two dimensions and use our imagination for the other two. I really wish our view of the universe wasn't as flat as it's said to be physically.

I like the way you think. 8-)

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Ron-Astro Pharmacist
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Re: APOD: Arp 159 and NGC 4725 (2015 Sep 03)

Postby Ron-Astro Pharmacist » Thu Sep 03, 2015 5:38 pm

LocalColor wrote:
Ron-Astro Pharmacist wrote:I wish we could depict galaxies (like the one on the right) as a giant gravity well ending in some strange object at the bottom. Maybe we could call it a" Black Drain"? No, that's not quite right… And since it developed over a long time I wish we could show it that way too. We could call that the "Time Space" view. Hmmm, that's not quite right either…

Guess we will just have to settle for looking at it in two dimensions and use our imagination for the other two. I really wish our view of the universe wasn't as flat as it's said to be physically.

I like the way you think. 8-)


As my wife likes to tell friends who respond to my jokes or comments, "Don't encourage him!" But Thanks!! I would like to able to see the universe as we think it really is. :)
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Re: APOD: Arp 159 and NGC 4725 (2015 Sep 03)

Postby saturno2 » Thu Sep 03, 2015 9:57 pm

NGC 4725 has a very blue blue zone of
young stars . Interesting.


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