APOD: M64: The Black Eye Galaxy (2015 Jun 18)

[APOD Robot]

M64: The Black Eye Galaxy

Explanation: This big, bright, beautiful spiral galaxy is Messier 64, often called the Black Eye Galaxy or the Sleeping Beauty Galaxy for its heavy-lidded appearance in telescopic views. M64 is about 17 million light-years distant in the otherwise well-groomed northern constellation Coma Berenices. In fact, the Red Eye Galaxy might also be an appropriate moniker in this colorful composition. The enormous dust clouds obscuring the near-side of M64's central region are laced with the telltale reddish glow of hydrogen associated with star forming regions. But they are not this galaxy's only peculiar feature. Observations show that M64 is actually composed of two concentric, counter-rotating systems. While all the stars in M64 rotate in the same direction as the interstellar gas in the galaxy's central region, gas in the outer regions, extending to about 40,000 light-years, rotates in the opposite direction. The dusty eye and bizarre rotation is likely the result of a billion year old merger of two different galaxies.

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[Ann]

The Black Eye Galaxy is a lady indeed. It looks as if she is flirting with us.

But this is a lady in distress. She is choking on her own diminishing gas supply. Long ago, she almost certainly didn't have a black eye, but she was a full-fledged spiral galaxy forming stars all over her glittering arms. But that was then. Now, she has used up almost all of her gas, and her formerly sparkling arms are anemic and satiated. They wobble faintly, as an echo of their former glory, looking slightly like a worn but still elegant ballroom dress without its trimmings.

And in a billion years or so, even her black eye might be gone, leaving her staring eyelid-less into the blackness of space, forever.

Ann

[Boomer12k]

Except for the dust in the middle, you don't see anything well defined... the Hubble shot is much different as it shows a close up of the center, which looks more "spiral-y"...but is very dusty, and tightly woven...

:---[===] *

[starsurfer]

Except for the dust in the middle, you don't see anything well defined... the Hubble shot is much different as it shows a close up of the center, which looks more "spiral-y"...but is very dusty, and tightly woven...

:---[===] *

Another one that is similar is Centaurus A. This also has structured dust lanes near the centre but diffuse featureless parts on the outside. However that isn't the case with deep images!

[Tszabeau]

The fact that the outer dust lanes are spinning in opposition to the inner disk of the galaxy because of the merger of opposing galaxies makes me wonder if galaxies have poles. If so, does the polarity determine which way a galaxy spins? What kind of effect does opposing spin have on the polarity? Does the outer spin tend to slow the inner spin over time or vice versa? Will the opposing spinning unify at some point?

[ThePiper]

The Black Eye Galaxy is a lady indeed. It looks as if she is flirting with us.

But this is a lady in distress. She is choking on her own diminishing gas supply. Long ago, she almost certainly didn't have a black eye, but she was a full-fledged spiral galaxy forming stars all over her glittering arms. But that was then. Now, she has used up almost all of her gas, and her formerly sparkling arms are anemic and satiated. They wobble faintly, as an echo of their former glory, looking slightly like a worn but still elegant ballroom dress without its trimmings.

And in a billion years or so, even her black eye might be gone, leaving her staring eyelid-less into the blackness of space, forever.

Ann

A sad story - but in another billion years a little frog king will appear and they begin a wild dance of love...

[Chris Peterson]

The fact that the outer dust lanes are spinning in opposition to the inner disk of the galaxy because of the merger of opposing galaxies makes me wonder if galaxies have poles. If so, does the polarity determine which way a galaxy spins? What kind of effect does opposing spin have on the polarity? Does the outer spin tend to slow the inner spin over time or vice versa? Will the opposing spinning unify at some point?

What do you mean by "pole"? A galaxy has a center of mass, and a net angular momentum about that center, a vector whose direction can be seen as defining the polar axis. The magnitude of the angular momentum can be high, as with a spiral galaxy, or low, as with an elliptical. Spin direction is merely a matter of viewpoint.

Dynamically, there is no problem with material orbiting in different directions. Each particle is in its own orbit. Perturbations between particles can exchange (orbital) angular momentum between them whether they rotate in the same direction or different directions.

[Tszabeau]

The fact that the outer dust lanes are spinning in opposition to the inner disk of the galaxy because of the merger of opposing galaxies makes me wonder if galaxies have poles. If so, does the polarity determine which way a galaxy spins? What kind of effect does opposing spin have on the polarity? Does the outer spin tend to slow the inner spin over time or vice versa? Will the opposing spinning unify at some point?

What do you mean by "pole"?

Magnetic pole... as opposed to an axis.

[Chris Peterson]

The fact that the outer dust lanes are spinning in opposition to the inner disk of the galaxy because of the merger of opposing galaxies makes me wonder if galaxies have poles. If so, does the polarity determine which way a galaxy spins? What kind of effect does opposing spin have on the polarity? Does the outer spin tend to slow the inner spin over time or vice versa? Will the opposing spinning unify at some point?

What do you mean by "pole"?

Magnetic pole... as opposed to an axis.

Galaxies have diffuse magnetic fields running through them supported by the interstellar medium. They can also have global magnetic fields. This means that galaxies also have magnetic poles.

Galactic magnetic fields influence galactic structure such as spiral arms. Although the fields are weak, they can support the ISM against gravitational forces.

Although one mechanism proposed for galactic magnetism involves dynamo processes, I doubt that the different directions of material in galaxies like this one has much impact on the global magnetic field.

[ta152h0]

Great name for a band