APOD: In the Center of Spiral Galaxy M61 (2014 May 20)

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APOD: In the Center of Spiral Galaxy M61 (2014 May 20)

Postby APOD Robot » Tue May 20, 2014 4:05 am

Image In the Center of Spiral Galaxy M61

Explanation: M61 is a barred spiral galaxy located in the nearby Virgo Cluster of Galaxies. Visible in M61 are a host of features common to spiral galaxies: bright spiral arms, a central bar, dust lanes, and bright knots of stars. M61, also known as NGC 4303, in similar to our own Milky Way Galaxy. M61 was discovered by telescope in 1779 twice on the same day, but one observer initially mistook the galaxy for a comet. Light from M61 takes about 55 million years to reach us. The above image of the central regions of M61 was taken with the Hubble Space Telescope and adapted for release as part of the Hubble's Hidden Treasures image processing competition.

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Re: APOD: In the Center of Spiral Galaxy M61 (2014 May 20)

Postby Ann » Tue May 20, 2014 5:13 am

It is not surprising that M61 has a starburst near its nucleus. That sort of thing is common among barred spirals. M100, which only has an incipient bar, has a large and bright starburst near its nucleus.

As for the starburst near the nucleus of M61, it had already been revealed by Rob Gendler when he processed Hubble data.

But it is nice to see a new take on this fascinating galaxy.

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Re: APOD: In the Center of Spiral Galaxy M61 (2014 May 20)

Postby starsurfer » Tue May 20, 2014 11:40 am

Shouldn't the description say that it was discovered on the same night instead of day? The starburst activity is really noticeable with Ha exposures, which reveal a lot of emission nebulae and HII regions.
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Re: APOD: In the Center of Spiral Galaxy M61 (2014 May 20)

Postby BDanielMayfield » Tue May 20, 2014 12:29 pm

starsurfer wrote:Shouldn't the description say that it was discovered on the same night instead of day?


The word "day" has meanings other that just when the Sun's up, such as 'In my grandfather's day', or 'back in the day ...'. In this case I'd think that 'in the same 24 hr period' is what was intended. Or that two careful observers reported their previous independant discoveries of what we now call M61 on the same calendar date in history.
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Re: APOD: In the Center of Spiral Galaxy M61 (2014 May 20)

Postby LocalColor » Tue May 20, 2014 3:25 pm

Oh my - stare at the center for a while and you feel like you are falling into the galaxy. Thank you for sharing the awesome wonders of our universe!
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Re: APOD: In the Center of Spiral Galaxy M61 (2014 May 20)

Postby Boomer12k » Tue May 20, 2014 5:56 pm

What detail...looks like you could just fall in....

"And away go troubles, down the drain...."

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Re: APOD: In the Center of Spiral Galaxy M61 (2014 May 20)

Postby MarkBour » Tue May 20, 2014 7:29 pm

Boomer12k wrote:What detail...looks like you could just fall in ...
"And away go troubles, down the drain...."
:---[===]*


I believe it is correct to view spiral galaxies as behaving much like a drain. The material is falling in as well as orbiting. And yet how different this is from our earth-bound human-size experience of drains! These drains, I speculate, are the engines that produce life in the universe. Indeed, I can think of no other place it would seem profitable to look for life of our kind. But perhaps I'm being closed-minded in that way.
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Re: APOD: In the Center of Spiral Galaxy M61 (2014 May 20)

Postby BDanielMayfield » Tue May 20, 2014 9:25 pm

MarkBour wrote:
Boomer12k wrote:What detail...looks like you could just fall in ...
"And away go troubles, down the drain...."
:---[===]*


I believe it is correct to view spiral galaxies as behaving much like a drain. The material is falling in as well as orbiting. And yet how different this is from our earth-bound human-size experience of drains! These drains, I speculate, are the engines that produce life in the universe. Indeed, I can think of no other place it would seem profitable to look for life of our kind. But perhaps I'm being closed-minded in that way.


But, very little on a percentage basis ever really goes down the "drain", that is the supermassive black holes at the centers of large galaxies. The great majority of material will orbit perpetually, never coming close enough to be affected adversely by the black hole. Also, much of what comes close to black holes doesn't 'go down the drain' either, because it gets shot out the accretion disk's polar jets.
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Re: APOD: In the Center of Spiral Galaxy M61 (2014 May 20)

Postby geckzilla » Tue May 20, 2014 9:56 pm

It is not useful at all to think of a black hole as a central drain. The presence of the black hole at the center of the galaxy is a correlation. The black hole does not cause the galaxy to be shaped in a certain way. It takes massive amounts of matter to make massive stars and the conditions which give rise to black holes so if most of the matter tends to congregate at a nucleus then naturally black holes should appear more frequently at these points. It doesn't even mean that the black hole even defines the very center of a galaxy, though I do wonder about that. It would make sense for a single, supermassive black hole to essentially be at or very near the center. Several black holes could be in mutual orbits around one another just like stars. Are they destined to merge due to the chaotic nature of galactic nuclei or is this more conducive to ejection?
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Re: APOD: In the Center of Spiral Galaxy M61 (2014 May 20)

Postby BDanielMayfield » Tue May 20, 2014 10:44 pm

geckzilla wrote:It is not useful at all to think of a black hole as a central drain.

I would agree with that, in the same way we wouldn't view the Sun as the "drain" of our solar system.

Are they destined to merge due to the chaotic nature of galactic nuclei or is this more conducive to ejection?

With three or more bodies in an orbital configuration the least massive can be ejected, with the two more massive drawing closer. In the real nature of galactic mergers, merger of supermassive black holes would have to be inevitable, given enough time, I would think.
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Re: APOD: In the Center of Spiral Galaxy M61 (2014 May 20)

Postby Boomer12k » Wed May 21, 2014 3:01 am

My allusion to a "drain" was purely visual observation. Maybe an Eddy Pool is more likely.

I might still have my HYPNO DISCS from the 70's. These were little "hypnotic" coins. They were like the 3 dimensional pictures that you move and you see a different angle, so it "swirled" some. And you held it up and gazed into it....deeper....and deeper....the swirls...pulling you in...deeper and deeper.....you feel like you are falling....falling a sleep....just close your eyes.....sleep.....sleep.....slee.....ZZZZZZZZZZZZ

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Re: APOD: In the Center of Spiral Galaxy M61 (2014 May 20)

Postby starsurfer » Wed May 21, 2014 10:46 am

BDanielMayfield wrote:
starsurfer wrote:Shouldn't the description say that it was discovered on the same night instead of day?


The word "day" has meanings other that just when the Sun's up, such as 'In my grandfather's day', or 'back in the day ...'. In this case I'd think that 'in the same 24 hr period' is what was intended. Or that two careful observers reported their previous independant discoveries of what we now call M61 on the same calendar date in history.

I couldn't resist being pedantic! :) :lol2:
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Re: APOD: In the Center of Spiral Galaxy M61 (2014 May 20)

Postby BDanielMayfield » Wed May 21, 2014 12:03 pm

starsurfer wrote:I couldn't resist being pedantic! :) :lol2:


I couldn't resist being explicative. I'm glad you made your comment. :ssmile:
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Re: APOD: In the Center of Spiral Galaxy M61 (2014 May 20)

Postby Beyond » Wed May 21, 2014 12:29 pm

Once again at the Asterisk*, we find that 'resistance' is futile!
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Re: APOD: In the Center of Spiral Galaxy M61 (2014 May 20)

Postby BillBixby » Wed May 21, 2014 11:27 pm

starsurfer wrote:
BDanielMayfield wrote:
starsurfer wrote:Shouldn't the description say that it was discovered on the same night instead of day?


The word "day" has meanings other that just when the Sun's up, such as 'In my grandfather's day', or 'back in the day ...'. In this case I'd think that 'in the same 24 hr period' is what was intended. Or that two careful observers reported their previous independant discoveries of what we now call M61 on the same calendar date in history.

I couldn't resist being pedantic! :) :lol2:


Ouch! Pedantic is a new word for me. I had to look it up. I hope you are not unimaginative and dull as defined in the merriam-webster dictionary usage 3. I find your comments enlightening.
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Re: APOD: In the Center of Spiral Galaxy M61 (2014 May 20)

Postby BDanielMayfield » Thu May 22, 2014 3:59 am

Boomer12k wrote:My allusion to a "drain" was purely visual observation. Maybe an Eddy Pool is more likely.

:---[===] *


Comparisons of spiral galaxies to rotating fluidic systems like whirlpools and cyclones is very understandable due to similar looking shapes, but unlike in whirlpools and cyclones, material in galaxies is not always in motion toward the center. Due to the nature of orbits, at any given time just about as much matter (stars, gas and dust, etc.) will be moving away from the center as what is falling toward it. Much material will also be in circular or very nearly circular orbits with no or very slight motion toward or away from the center.

I can imagine though that many people when seeing a photo of a spiral galaxy might think that everything in a spiral's arms might be "flowing" along the arms down toward the core region of the galaxy, like water circling a drain, which would be a misconception.

Bruce, Don't bring me down the drain Mayfield :ssmile:
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Re: APOD: In the Center of Spiral Galaxy M61 (2014 May 20)

Postby MarkBour » Fri May 23, 2014 6:01 pm

Sure, no analogy should be expected to be perfect.
But some process has created and organized those dust lanes, although I agree the material in them is not necessarily "flowing in" toward the center. And some process has amassed 5 million solar masses in a compact region in the center, and the center is an active galactic center. So I think that "drain" is an analogy that can help understand some of the forces at play.
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Re: APOD: In the Center of Spiral Galaxy M61 (2014 May 20)

Postby geckzilla » Fri May 23, 2014 9:42 pm

MarkBour wrote:Sure, no analogy should be expected to be perfect.
But some process has created and organized those dust lanes, although I agree the material in them is not necessarily "flowing in" toward the center. And some process has amassed 5 million solar masses in a compact region in the center, and the center is an active galactic center. So I think that "drain" is an analogy that can help understand some of the forces at play.

It is worse than imperfect because it reinforces the false notion that material is flowing toward the center so it is necessary to avoid and correct any instances when such an analogy is used. We do it at Asterisk quite frequently. It's important for people to realize that the forces involved are dramatically different from a flowing drain no matter how similar the pattern is.
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Re: APOD: In the Center of Spiral Galaxy M61 (2014 May 20)

Postby BDanielMayfield » Sat May 24, 2014 12:32 am

geckzilla wrote:
MarkBour wrote:Sure, no analogy should be expected to be perfect.
But some process has created and organized those dust lanes, although I agree the material in them is not necessarily "flowing in" toward the center. And some process has amassed 5 million solar masses in a compact region in the center, and the center is an active galactic center. So I think that "drain" is an analogy that can help understand some of the forces at play.

It is worse than imperfect because it reinforces the false notion that material is flowing toward the center so it is necessary to avoid and correct any instances when such an analogy is used. We do it at Asterisk quite frequently. It's important for people to realize that the forces involved are dramatically different from a flowing drain no matter how similar the pattern is.

But don't feel too bad Mark. It's part of the scientific method; throw an idea out there, but beware, 'cuze ifin' ya ain't got 'nough evidence your beloved idea is a gona get hashed, thrashed and trashed.

I've had to watch a few of my ideas go down the drain too. But you need to be able to let go of an incorrect idea so that you don't go down the drain with it. :lol2:
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Re: APOD: In the Center of Spiral Galaxy M61 (2014 May 20)

Postby starsurfer » Sun May 25, 2014 1:00 pm

BillBixby wrote:
starsurfer wrote:
BDanielMayfield wrote:
The word "day" has meanings other that just when the Sun's up, such as 'In my grandfather's day', or 'back in the day ...'. In this case I'd think that 'in the same 24 hr period' is what was intended. Or that two careful observers reported their previous independant discoveries of what we now call M61 on the same calendar date in history.

I couldn't resist being pedantic! :) :lol2:


Ouch! Pedantic is a new word for me. I had to look it up. I hope you are not unimaginative and dull as defined in the merriam-webster dictionary usage 3. I find your comments enlightening.

No I'm not "unimaginative and dull" but I was only referring to the moment, not my overall personality. Also it depends on what dictionary you use. :)
Also thanks for liking my comments!
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