APOD: M27: The Dumbbell Nebula (2011 Dec 27)

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APOD: M27: The Dumbbell Nebula (2011 Dec 27)

Post by APOD Robot » Tue Dec 27, 2011 5:06 am

Image M27: The Dumbbell Nebula

Explanation: The first hint of what will become of our Sun was discovered inadvertently in 1764. At that time, Charles Messier was compiling a list of diffuse objects not to be confused with comets. The 27th object on Messier's list, now known as M27 or the Dumbbell Nebula, is a planetary nebula, the type of nebula our Sun will produce when nuclear fusion stops in its core. M27 is one of the brightest planetary nebulae on the sky, and can be seen toward the constellation of the Fox (Vulpecula) with binoculars. It takes light about 1000 years to reach us from M27, shown above in colors emitted by hydrogen and oxygen. Understanding the physics and significance of M27 was well beyond 18th century science. Even today, many things remain mysterious about bipolar planetary nebula like M27, including the physical mechanism that expels a low-mass star's gaseous outer-envelope, leaving an X-ray hot white dwarf.

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Re: APOD: M27: The Dumbbell Nebula (2011 Dec 27)

Post by owlice » Tue Dec 27, 2011 5:18 am

That's a great image of this nebula!
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Re: APOD: M27: The Dumbbell Nebula (2011 Dec 27)

Post by islader2 » Tue Dec 27, 2011 5:44 am

Lookee thar! I see Jimmy Durante's face and trademark schozz in M27. :D :lol:

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Re: APOD: M27: The Dumbbell Nebula (2011 Dec 27)

Post by neptunium » Tue Dec 27, 2011 6:15 am

I wonder why it's called the Dumbbell nebula if it doesn't look like a dumbbell. :?

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Re: APOD: M27: The Dumbbell Nebula (2011 Dec 27)

Post by Boomer12k » Tue Dec 27, 2011 6:47 am

If you look closely, some of the center "clouds" have faces, and heads.


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Re: APOD: M27: The Dumbbell Nebula (2011 Dec 27)

Post by biddie67 » Tue Dec 27, 2011 12:24 pm

APOD Robot wrote: M27: The Dumbbell Nebula

The first hint of what will become of our Sun was discovered inadvertently in 1764. ........ M27 or the Dumbbell Nebula, is a planetary nebula, the type of nebula our Sun will produce when nuclear fusion stops in its core.
It just amazes me that there is such a certainy about the future of our sun. And, in extension, such certainys about many of the dynamics in this universe ((not to ignore the many dynamics that aren't understood or even recognized yet)).

We, this species that we are, have been observing for such a brief period of time albeit with instrumentation and mathematical models that have become more informative but the vastness out there is such, it is hard to understand how we can feel so certain of some things like the mere future of our sun.

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Re: APOD: M27: The Dumbbell Nebula (2011 Dec 27)

Post by Tszabeau » Tue Dec 27, 2011 12:53 pm

I would name this nebula "the Birth Quartering Nebula", if I was a namer of stuff.

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Re: APOD: M27: The Dumbbell Nebula (2011 Dec 27)

Post by orin stepanek » Tue Dec 27, 2011 1:30 pm

It doesn't look much like a dumbbell to me either! :?
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Re: APOD: M27: The Dumbbell Nebula (2011 Dec 27)

Post by Chris Peterson » Tue Dec 27, 2011 2:55 pm

neptunium wrote:I wonder why it's called the Dumbbell nebula if it doesn't look like a dumbbell. :?
m27vis.jpg
Visually, it does resemble a dumbbell, and most of these famous objects were named based on their appearance through the eyepiece of a telescope. This image is one I made, but knocked back in brightness and contrast to approximate its appearance in a telescope. It shows a couple of fuzzy blobs that appear joined in the middle- which more or less describes a dumbbell.
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Re: APOD: M27: The Dumbbell Nebula (2011 Dec 27)

Post by Chris Peterson » Tue Dec 27, 2011 3:00 pm

biddie67 wrote:It just amazes me that there is such a certainy about the future of our sun. And, in extension, such certainys about many of the dynamics in this universe ((not to ignore the many dynamics that aren't understood or even recognized yet)).

We, this species that we are, have been observing for such a brief period of time albeit with instrumentation and mathematical models that have become more informative but the vastness out there is such, it is hard to understand how we can feel so certain of some things like the mere future of our sun.
It's not really that amazing when you consider the wide sample of stars we have available for study. Our understanding of the Sun comes not just from the Sun, but from observing stars similar to it that range from newly formed to no longer fusing.

It's rather like the fact that a young adult has a good idea what they were like from the moment of conception, and what they will be like until they die of old age, even though they have no memory of much, nor any experience of the future. But they have lots of examples of these things in other human beings.
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Re: APOD: M27: The Dumbbell Nebula (2011 Dec 27)

Post by TNT » Tue Dec 27, 2011 4:48 pm

I'm not seeing it, either. To me, it's the nebula version of NGC 7600.
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Re: APOD: M27: The Dumbbell Nebula (2011 Dec 27)

Post by nstahl » Tue Dec 27, 2011 6:06 pm

I got Google's image page for "Dumbbell nebula" and looked for a dumbbell. This one looks pretty dumbbelly to me.

Image

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Re: APOD: M27: The Dumbbell Nebula (2011 Dec 27)

Post by ems57fcva » Tue Dec 27, 2011 7:15 pm

[T]he Dumbbell Nebula, is a planetary nebula, the type of nebula our Sun will produce when nuclear fusion stops in its core.
I find this to be a very odd statement, since it takes added energy coming from the stellar core for the outer layers to be expelled in the first place. If the core is out nuclear fuel, then where is the energy needed to expel the outer layers coming from?

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Re: APOD: M27: The Dumbbell Nebula (2011 Dec 27)

Post by Ann » Tue Dec 27, 2011 8:17 pm

ems57fcva wrote:
[T]he Dumbbell Nebula, is a planetary nebula, the type of nebula our Sun will produce when nuclear fusion stops in its core.
I find this to be a very odd statement, since it takes added energy coming from the stellar core for the outer layers to be expelled in the first place. If the core is out nuclear fuel, then where is the energy needed to expel the outer layers coming from?
Image
The core is out of nuclear fuel, that's true. But a shell around the nucleus is still fusing hydrogen into helium.

The "energy generator" has moved closer to the surface of the star, puffing it up. Also, it could be that a larger volume of the star is undergoing fusion when the fusion has moved into a shell around the nucleus than when the fusion was confined to the nucleus. That could be the reason why red giants are brighter than the main sequence stars they evolved from.

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guest12

Re: APOD: M27: The Dumbbell Nebula (2011 Dec 27)

Post by guest12 » Tue Dec 27, 2011 9:01 pm

The image shows what is to become of the sun.

It would be very nice if the image could show the orbits of our planets so there is a sense of size/scale for the nebula.

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Re: APOD: M27: The Dumbbell Nebula (2011 Dec 27)

Post by nstahl » Tue Dec 27, 2011 9:44 pm

This is from 2008 but likely it's still operative. It says earth might be in the sun or not, but our present orbit will be, and any descendants we leave will be toast unless they've left town.
guest12 wrote: It would be very nice if the image could show the orbits of our planets so there is a sense of size/scale for the nebula.
Of course a lot of problems are a lot more immediate, like run-away global warming just for instance.

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Re: APOD: M27: The Dumbbell Nebula (2011 Dec 27)

Post by ems57fcva » Tue Dec 27, 2011 11:02 pm

Ann wrote:
ems57fcva wrote:
[T]he Dumbbell Nebula, is a planetary nebula, the type of nebula our Sun will produce when nuclear fusion stops in its core.
I find this to be a very odd statement, since it takes added energy coming from the stellar core for the outer layers to be expelled in the first place. If the core is out nuclear fuel, then where is the energy needed to expel the outer layers coming from?
Image
The core is out of nuclear fuel, that's true. But a shell around the nucleus is still fusing hydrogen into helium.

The "energy generator" has moved closer to the surface of the star, puffing it up. Also, it could be that a larger volume of the star is undergoing fusion when the fusion has moved into a shell around the nucleus than when the fusion was confined to the nucleus. That could be the reason why red giants are brighter than the main sequence stars they evolved from.

Ann
This is only partially helpful, since we are dealing with the next stage on: The core is now carbon/oxygen, not helium. So what I am infering is that as the core runs out of helium, it triggers helium burning in a shell around and that is also surrounded by a shell of hydrogen burning. So I'm guessing that enough of the star gets so involved with fusion that it finally starts pushing off the outermost layers, and the reduced gravity makes it even easier for the next layers to come off. Eventually, all that is left is the degenerate (or at least dengenerating) core. I still suspect that this must be going on while there still is helium being burned up in the core, and the core is therefore at or near its maximum temperature. Once the nuclear reactions stop, the energy that encourages shell burning must also start to dissapate.

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Re: APOD: M27: The Dumbbell Nebula (2011 Dec 27)

Post by Chris Peterson » Tue Dec 27, 2011 11:52 pm

ems57fcva wrote:This is only partially helpful, since we are dealing with the next stage on: The core is now carbon/oxygen, not helium. So what I am infering is that as the core runs out of helium, it triggers helium burning in a shell around and that is also surrounded by a shell of hydrogen burning.
Exactly. And of course, fusion isn't what powers a star in any case; the energy source is gravity. Once the core is inert (carbon and oxygen), you still have a shell of helium (you also have hydrogen, but that isn't the important reaction) outside that. And the tricky thing with helium fusion is that it's exquisitely sensitive to temperature, so just a few degrees of temperature rise (as from convective processes in the outer envelope) can cause a massive burst of energy output, which blows away some of the outer layers. And that process will continue until the helium fusion ends (which is still long after the core fusion ended)- throwing out shells of material in successive waves of activity. And there you have a planetary nebula.
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Re: APOD: M27: The Dumbbell Nebula (2011 Dec 27)

Post by ems57fcva » Wed Dec 28, 2011 5:26 am

Chris Peterson wrote:
fusion isn't what powers a star in any case; the energy source is gravity
That I will politely take issue with. While the release of gravitational potential energy can act as an energy source, what powers the stars very much is nuclear fusion, with E=mc2 showing up as the difference in mass between the atoms that were fused and the fusion product.
Once the core is inert (carbon and oxygen), you still have a shell of helium (you also have hydrogen, but that isn't the important reaction) outside that. And the tricky thing with helium fusion is that it's exquisitely sensitive to temperature, so just a few degrees of temperature rise (as from convective processes in the outer envelope) can cause a massive burst of energy output, which blows away some of the outer layers.
I can quibble about how inert the core is as helium shell burning sets in, but the literature that I am able to find and recall does back up your main point: That this is an unstable configuration that lends itself to massive energy outbursts. Also, I can see that nuclear fusion may be brought to an end by the loss of the outer layers and the pressure that they once exerted on the core.
And that process will continue ... throwing out shells of material in successive waves of activity. And there you have a planetary nebula.
You can actually see shells of material in that picture, but then are the polar outflows that give the Dumbbell Nebula its name. I take that as some evidence that the central star is still quite active. This is not like the Ring Nebula, which I suspect is quite complete and fading as its now-inert central star cools down. This planetary nebula looks to me like a work in progress.

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Re: APOD: M27: The Dumbbell Nebula (2011 Dec 27)

Post by Chris Peterson » Wed Dec 28, 2011 3:42 pm

ems57fcva wrote:That I will politely take issue with. While the release of gravitational potential energy can act as an energy source, what powers the stars very much is nuclear fusion, with E=mc2 showing up as the difference in mass between the atoms that were fused and the fusion product.
In the absence of a gravitational gradient, there would be no fusion. Fusion in stars is simply the conversion of gravitational energy to a different form. I think it is quite correct to point out that gravitational energy is the ultimate source of energy for all stars.
You can actually see shells of material in that picture, but then are the polar outflows that give the Dumbbell Nebula its name. I take that as some evidence that the central star is still quite active.
I agree. Unlike a supernova, the process of "star death" that leads to a planetary nebula is not an instantaneous event, but something that happens over thousands of years. So we can see planetary nebulas in different stages of formation.

Polar outflows are common, and presumably related to the rotation of the progenitor star, and not to any specific fusion activity. We see planetary nebulas with polar structure, such as the Ring Nebula, where there is no longer any active outflow. I think the key to identifying planetary nebulas still being formed is as simple as seeing dense material very near the central star.
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