APOD: The Ring Nebula from Webb (2023 Aug 14)

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APOD: The Ring Nebula from Webb (2023 Aug 14)

Post by APOD Robot » Mon Aug 14, 2023 4:06 am

Image The Ring Nebula from Webb

Explanation: The Ring Nebula (M57), is more complicated than it appears through a small telescope. The easily visible central ring is about one light-year across, but this remarkable exposure by the James Webb Space Telescope explores this popular nebula with a deep exposure in infrared light. Strings of gas, like eyelashes around a cosmic eye, become evident around the Ring in this digitally enhanced featured image in assigned colors. These long filaments may be caused by shadowing of knots of dense gas in the ring from energetic light emitted within. The Ring Nebula is an elongated planetary nebula, a type of gas cloud created when a Sun-like star evolves to throw off its outer atmosphere to become a white dwarf star. The central oval in the Ring Nebula lies about 2,500 light-years away toward the musical constellation Lyra.

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Re: APOD: The Ring Nebula from Webb (2023 Aug 14)

Post by mister T » Mon Aug 14, 2023 9:34 am

:shock: Are you sure that is not Great Prismatic spring in Yellowstone?
8-)

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Re: APOD: The Ring Nebula from Webb (2023 Aug 14)

Post by AVAO » Mon Aug 14, 2023 11:52 am


tairving

Re: APOD: The Ring Nebula from Webb (2023 Aug 14)

Post by tairving » Mon Aug 14, 2023 12:29 pm

Why is the center of the nebula colored bright blue?

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Re: APOD: The Ring Nebula from Webb (2023 Aug 14)

Post by Chris Peterson » Mon Aug 14, 2023 1:27 pm

tairving wrote: Mon Aug 14, 2023 12:29 pm Why is the center of the nebula colored bright blue?
Because whichever IR filter passed the most light from this part of the image is assigned to the blue output channel.
Chris

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Re: APOD: The Ring Nebula from Webb (2023 Aug 14)

Post by johnnydeep » Mon Aug 14, 2023 1:30 pm

Wow! It's like we're look up from the depths of hell through a hole torn in a fiery roof, to behold a bright blue sky speckled with assorted clouds, and a bunch of "daytime stars". It almost makes me optimistic for the future!
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Re: APOD: The Ring Nebula from Webb (2023 Aug 14)

Post by Chris Peterson » Mon Aug 14, 2023 1:32 pm

johnnydeep wrote: Mon Aug 14, 2023 1:30 pm Wow! It's like we're look up from the depths of hell through a hole torn in a fiery roof, to behold a bright blue sky speckled with assorted clouds, and a bunch of "daytime stars". It almost makes me optimistic for the future!
Well, we are seeing the future of our own solar system here...
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Re: APOD: The Ring Nebula from Webb (2023 Aug 14)

Post by johnnydeep » Mon Aug 14, 2023 1:43 pm

Chris Peterson wrote: Mon Aug 14, 2023 1:32 pm
johnnydeep wrote: Mon Aug 14, 2023 1:30 pm Wow! It's like we're look up from the depths of hell through a hole torn in a fiery roof, to behold a bright blue sky speckled with assorted clouds, and a bunch of "daytime stars". It almost makes me optimistic for the future!
Well, we are seeing the future of our own solar system here...
May the atoms of my makeup find a worthy new home in the body of a new species of life in some far future world orbiting a yet-to-be-born star!
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Re: APOD: The Ring Nebula from Webb (2023 Aug 14)

Post by Rauf » Mon Aug 14, 2023 2:41 pm

johnnydeep wrote: Mon Aug 14, 2023 1:43 pm
Chris Peterson wrote: Mon Aug 14, 2023 1:32 pm
johnnydeep wrote: Mon Aug 14, 2023 1:30 pm Wow! It's like we're look up from the depths of hell through a hole torn in a fiery roof, to behold a bright blue sky speckled with assorted clouds, and a bunch of "daytime stars". It almost makes me optimistic for the future!
Well, we are seeing the future of our own solar system here...
May the atoms of my makeup find a worthy new home in the body of a new species of life in some far future world orbiting a yet-to-be-born star!
I wonder where those atoms were before the creation of solar system, and us. Maybe some other species used it too? That sounds extremely unlikely though! :?

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Re: APOD: The Ring Nebula from Webb (2023 Aug 14)

Post by Tekija » Mon Aug 14, 2023 6:09 pm

Chris Peterson wrote: Mon Aug 14, 2023 1:27 pm
tairving wrote: Mon Aug 14, 2023 12:29 pm Why is the center of the nebula colored bright blue?
Because whichever IR filter passed the most light from this part of the image is assigned to the blue output channel.
Indeed, these are assigned colors, but citing Neufer (remember him?) who pointed it out, there is a ring of truth in the colors including central blue:

http://asterisk.apod.com/viewtopic.php?t=41868#p315917

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Re: APOD: The Ring Nebula from Webb (2023 Aug 14)

Post by orin stepanek » Mon Aug 14, 2023 6:11 pm

M57_JwstKong_960.jpg
If everything came from the big bang; then maybe our atoms weren't
created yet! But who knows! :mrgreen:
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Re: APOD: The Ring Nebula from Webb (2023 Aug 14)

Post by Chris Peterson » Mon Aug 14, 2023 6:15 pm

Tekija wrote: Mon Aug 14, 2023 6:09 pm
Chris Peterson wrote: Mon Aug 14, 2023 1:27 pm
tairving wrote: Mon Aug 14, 2023 12:29 pm Why is the center of the nebula colored bright blue?
Because whichever IR filter passed the most light from this part of the image is assigned to the blue output channel.
Indeed, these are assigned colors, but citing Neufer (remember him?) who pointed it out, there is a ring of truth in the colors including central blue:

http://asterisk.apod.com/viewtopic.php?t=41868#p315917
But not in this case. The camera being used can't see blue light. At all. So if the center is blue in the image, it's because somebody made a deliberate choice to map it that way. In visible light we see the center strongly illuminated by ionized oxygen, which is why "true color" presents a green or cyan center. But there is no visible light captured here.
Chris

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Re: APOD: The Ring Nebula from Webb (2023 Aug 14)

Post by Tekija » Mon Aug 14, 2023 7:21 pm

Chris Peterson wrote: Mon Aug 14, 2023 6:15 pm
Tekija wrote: Mon Aug 14, 2023 6:09 pm
Chris Peterson wrote: Mon Aug 14, 2023 1:27 pm

Because whichever IR filter passed the most light from this part of the image is assigned to the blue output channel.
Indeed, these are assigned colors, but citing Neufer (remember him?) who pointed it out, there is a ring of truth in the colors including central blue:

http://asterisk.apod.com/viewtopic.php?t=41868#p315917
But not in this case. The camera being used can't see blue light. At all. So if the center is blue in the image, it's because somebody made a deliberate choice to map it that way. In visible light we see the center strongly illuminated by ionized oxygen, which is why "true color" presents a green or cyan center. But there is no visible light captured here.
Indeed, to avoid misunderstanding I began my post by acknowledging these are assigned colors. My point was, it was logical to assign them as they were.

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Re: APOD: The Ring Nebula from Webb (2023 Aug 14)

Post by Chris Peterson » Mon Aug 14, 2023 7:23 pm

Tekija wrote: Mon Aug 14, 2023 7:21 pm
Chris Peterson wrote: Mon Aug 14, 2023 6:15 pm
Tekija wrote: Mon Aug 14, 2023 6:09 pm

Indeed, these are assigned colors, but citing Neufer (remember him?) who pointed it out, there is a ring of truth in the colors including central blue:

http://asterisk.apod.com/viewtopic.php?t=41868#p315917
But not in this case. The camera being used can't see blue light. At all. So if the center is blue in the image, it's because somebody made a deliberate choice to map it that way. In visible light we see the center strongly illuminated by ionized oxygen, which is why "true color" presents a green or cyan center. But there is no visible light captured here.
Indeed, to avoid misunderstanding I began my post by acknowledging these are assigned colors. My point was, it was logical to assign them as they were.
Maybe. Or maybe a mistake, given the possible misinterpretation of data that means something quite different at these long wavelengths.
Chris

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Re: APOD: The Ring Nebula from Webb (2023 Aug 14)

Post by AVAO » Mon Aug 14, 2023 9:10 pm

Chris Peterson wrote: Mon Aug 14, 2023 7:23 pm
Tekija wrote: Mon Aug 14, 2023 7:21 pm
Chris Peterson wrote: Mon Aug 14, 2023 6:15 pm
But not in this case. The camera being used can't see blue light. At all. So if the center is blue in the image, it's because somebody made a deliberate choice to map it that way. In visible light we see the center strongly illuminated by ionized oxygen, which is why "true color" presents a green or cyan center. But there is no visible light captured here.
Indeed, to avoid misunderstanding I began my post by acknowledging these are assigned colors. My point was, it was logical to assign them as they were.
Maybe. Or maybe a mistake, given the possible misinterpretation of data that means something quite different at these long wavelengths.
Well. I don't want to come off as forensic after yesterday.
But this APOD is also a mixture, today of a Webb AND a Hubble image, I call them WEBBLE.
The original can probably be found at https://www.flickr.com/photos/196439708 ... tostream/ and is protected by copyright. At the highest resolution, this is pixel-perfect identical to today's APOD image.
(If you look at the two images in the blue channel, you will also notice the difference ;-)

In the future I would appreciate it if at least one link by the author or in the APOD text would lead to a source where the technical data for the published image would also be correctly disclosed...

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Re: APOD: The Ring Nebula from Webb (2023 Aug 14)

Post by Chris Peterson » Mon Aug 14, 2023 10:49 pm

AVAO wrote: Mon Aug 14, 2023 9:10 pm
Chris Peterson wrote: Mon Aug 14, 2023 7:23 pm
Tekija wrote: Mon Aug 14, 2023 7:21 pm

Indeed, to avoid misunderstanding I began my post by acknowledging these are assigned colors. My point was, it was logical to assign them as they were.
Maybe. Or maybe a mistake, given the possible misinterpretation of data that means something quite different at these long wavelengths.
Well. I don't want to come off as forensic after yesterday.
But this APOD is also a mixture, today of a Webb AND a Hubble image, I call them WEBBLE.
The original can probably be found at https://www.flickr.com/photos/196439708 ... tostream/ and is protected by copyright. At the highest resolution, this is pixel-perfect identical to today's APOD image.
(If you look at the two images in the blue channel, you will also notice the difference ;-)

In the future I would appreciate it if at least one link by the author or in the APOD text would lead to a source where the technical data for the published image would also be correctly disclosed...
I've been complaining for years about APODs that lack technical details. Will likely be complaining for years to come.
Chris

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Re: APOD: The Ring Nebula from Webb (2023 Aug 14)

Post by MarkBour » Tue Aug 15, 2023 12:22 am

If someone were to attempt to estimate the mass of the Ring Nebula from the Hubble image in the year 2010, and then to do the same with the new JWST image now available, wouldn't they now get a significantly higher figure, now that they (we) can see a lot more stuff?
Mark Goldfain

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Re: APOD: The Ring Nebula from Webb (2023 Aug 14)

Post by Chris Peterson » Tue Aug 15, 2023 12:24 am

MarkBour wrote: Tue Aug 15, 2023 12:22 am If someone were to attempt to estimate the mass of the Ring Nebula from the Hubble image in the year 2010, and then to do the same with the new JWST image now available, wouldn't they now get a significantly higher figure, now that they (we) can see a lot more stuff?
Depends on the model they're using to convert luminosity to mass.
Chris

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Re: APOD: The Ring Nebula from Webb (2023 Aug 14)

Post by alter-ego » Tue Aug 15, 2023 2:32 am

AVAO wrote: Mon Aug 14, 2023 9:10 pm ...

Well. I don't want to come off as forensic after yesterday.
But this APOD is also a mixture, today of a Webb AND a Hubble image, I call them WEBBLE.
The original can probably be found at https://www.flickr.com/photos/196439708 ... tostream/ and is protected by copyright. At the highest resolution, this is pixel-perfect identical to today's APOD image.
(If you look at the two images in the blue channel, you will also notice the difference ;-)

In the future I would appreciate it if at least one link by the author or in the APOD text would lead to a source where the technical data for the published image would also be correctly disclosed...
I like the gif comparison of the two images. The brightest star shows one of the Hubble diffraction spikes which also shows up in the composite.
https://live.staticflickr.com/65535/530 ... 511f_o.gif Because it's new, I tend to like Webb image the best.
A pessimist is nothing more than an experienced optimist

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Re: APOD: The Ring Nebula from Webb (2023 Aug 14)

Post by Ann » Tue Aug 15, 2023 4:02 am

AVAO wrote: Mon Aug 14, 2023 9:10 pm
Chris Peterson wrote: Mon Aug 14, 2023 7:23 pm
Tekija wrote: Mon Aug 14, 2023 7:21 pm

Indeed, to avoid misunderstanding I began my post by acknowledging these are assigned colors. My point was, it was logical to assign them as they were.
Maybe. Or maybe a mistake, given the possible misinterpretation of data that means something quite different at these long wavelengths.
Well. I don't want to come off as forensic after yesterday.
But this APOD is also a mixture, today of a Webb AND a Hubble image, I call them WEBBLE.
The original can probably be found at https://www.flickr.com/photos/196439708 ... tostream/ and is protected by copyright. At the highest resolution, this is pixel-perfect identical to today's APOD image.
(If you look at the two images in the blue channel, you will also notice the difference ;-)

In the future I would appreciate it if at least one link by the author or in the APOD text would lead to a source where the technical data for the published image would also be correctly disclosed...
Thanks, AVAO, that really explains why the picture looks the way it looks! :shock:

That said, the WEBBLE picture does look impressive. Everything seems to rush away from the scorchingly hot white dwarf in the center at a furious rate. The image does make you feel that this glorious planetary nebula can't last long when it is being blasted by ultraviolet light from the ultra-hot white dwarf like that - and it can't, either! A planetary nebula lasts for a couple of thousand years. Maybe twenty thousand, maybe more, but hardly a hundred thousand (I'm too lazy to google, so I'm just guessing). And that's nothing in the lifetime of a star.

Anyway. I like the picture. But thank you, AVAO, for explaining it to us.

Ann
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Re: APOD: The Ring Nebula from Webb (2023 Aug 14)

Post by AVAO » Tue Aug 15, 2023 5:38 am

Ann wrote: Tue Aug 15, 2023 4:02 am
AVAO wrote: Mon Aug 14, 2023 9:10 pm
Chris Peterson wrote: Mon Aug 14, 2023 7:23 pm
Maybe. Or maybe a mistake, given the possible misinterpretation of data that means something quite different at these long wavelengths.
Well. I don't want to come off as forensic after yesterday.
But this APOD is also a mixture, today of a Webb AND a Hubble image, I call them WEBBLE.
The original can probably be found at https://www.flickr.com/photos/196439708 ... tostream/ and is protected by copyright. At the highest resolution, this is pixel-perfect identical to today's APOD image.
(If you look at the two images in the blue channel, you will also notice the difference ;-)

In the future I would appreciate it if at least one link by the author or in the APOD text would lead to a source where the technical data for the published image would also be correctly disclosed...
Thanks, AVAO, that really explains why the picture looks the way it looks! :shock:

That said, the WEBBLE picture does look impressive. Everything seems to rush away from the scorchingly hot white dwarf in the center at a furious rate. The image does make you feel that this glorious planetary nebula can't last long when it is being blasted by ultraviolet light from the ultra-hot white dwarf like that - and it can't, either! A planetary nebula lasts for a couple of thousand years. Maybe twenty thousand, maybe more, but hardly a hundred thousand (I'm too lazy to google, so I'm just guessing). And that's nothing in the lifetime of a star.

Anyway. I like the picture. But thank you, AVAO, for explaining it to us.

Ann
ThanX Ann

I am also always very happy when I see APOD images from the JWST and also appreciate especially the work that Yuval Harpaz an d others are doing on the subject.

https://yuval-harpaz.github.io/astro/ngc_thumb.html
https://nerdculture.de/@yuvharpaz
https://www.flickr.com/photos/196439708@N03/
Source: Yuval Harpaz https://nerdculture.de/@yuvharpaz/110833782872564579

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Re: APOD: The Ring Nebula from Webb (2023 Aug 14)

Post by Hopalong » Wed Aug 16, 2023 1:25 pm

Is the "scorchingly hot white dwarf in the centre" your assumption, Ann, or is that fact? If the latter, what are the other white spots against the blue?

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Re: APOD: The Ring Nebula from Webb (2023 Aug 14)

Post by Ann » Wed Aug 16, 2023 7:00 pm

Hopalong wrote: Wed Aug 16, 2023 1:25 pm Is the "scorchingly hot white dwarf in the centre" your assumption, Ann, or is that fact? If the latter, what are the other white spots against the blue?
The "scorchingly hot white dwarf in the centre" is not my assumption. It is a fact.
Wikipedia wrote about the central star of the Ring Nebula:

The central star now consists primarily of carbon and oxygen with a thin outer envelope composed of lighter elements. Its mass is about 0.61–0.62 M☉, with a surface temperature of 125,000±5,000 K.
The Sun, for comparison, is 5778 K. So if we assume that the central star of the Ring Nebula is 125,000 K, then the central star of the Ring Nebula is some 21 or 22 times hotter than the Sun.

As for the color of the central star of the Ring Nebula, this series of images is revealing:

The Ring Nebula through different filters NOAO AURA NSF.png
The Ring Nebula through different filters.
Credit: NOAO/AURA/NSF

Okay. Let's have a look at what colors these wavelengths represent. The longest wavelength, 6300 Å or 630 nm, is very close to this color: ███. As you can see, the central star is not visible at all at this wavelength.

The second longest wavelength, 5007 Å or 500.7 nm, is (about) this color: ███. As you can see, the star is still not visible.

Moving towards shorter wavelengths, the next wavelength is 4861 Å or 468.1 nm, which is almost exactly this color: ███. The star is just beginning to become visible at this wavelength.

The shortest wavelength is this series is 4686 Å, or 468.6 nm. This is very close to this color: ███. This is the bluest wavelength so far, and as you can see, the central star is clearly visible.

If we had moved to still shorter and shorter wavelengths, the central star of the Ring Nebula would have been ever brighter and brighter.

So the central star of the Ring Nebula is indeed scorchingly hot and very blue, but above all, it is very very ultraviolet.

Ann
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Re: APOD: The Ring Nebula from Webb (2023 Aug 14)

Post by Hopalong » Fri Aug 18, 2023 3:38 am

Many thanks, Ann. Earth is 150 million km from the sun, and there are days when it's scorchingly hot here (even in the shade) ... so if the white dwarf in the Ring nebula is 22 times hotter, humans had better keep at least 3300 million km from it - but who's going to hold the end of the tape at the white dwarf? :wink:
My second question was: what are the other white spots? Are they also other white dwarf stars, possibly further away? (If so, who'd want to think about going there?)

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Re: APOD: The Ring Nebula from Webb (2023 Aug 14)

Post by Ann » Fri Aug 18, 2023 4:58 am

Hopalong wrote: Fri Aug 18, 2023 3:38 am Many thanks, Ann. Earth is 150 million km from the sun, and there are days when it's scorchingly hot here (even in the shade) ... so if the white dwarf in the Ring nebula is 22 times hotter, humans had better keep at least 3300 million km from it - but who's going to hold the end of the tape at the white dwarf? :wink:
My second question was: what are the other white spots? Are they also other white dwarf stars, possibly further away? (If so, who'd want to think about going there?)
The other stars are just stars, ordinary stars.

Take a look at the four exposures through different filters of the Ring Nebula again:



Note the star to the left of the Ring Nebula. It shows up well in all of the exposures except the 5007 Å, where it appears to be invisible. Actually it is not, though. If you look at the full size of the picture, you can see it, although very faintly.

The likely reason why the star looks so faint at 5007 Å is that the 5007 Å wavelength corresponds to doubly ionized oxygen, where the Ring Nebula is very bright indeed. If you ask me, I'd say that the 5007 Å image may be "underexposed" so as not to be too bright. The star became "underexposed" and faint as well.

Correspondingly, the 4686 Å image may be overexposed, and the star may be overexposed and "too bright" as well.

Let's look at a Hubble image of the Ring Nebula where some of the other stars can be seen:


As you can see, the star to the left of the Ring Nebula shows up well in the Hubble image. It looks white, maybe a little bit reddish. One star to the upper right of the Ring Nebula is also visible, and it also looks white. In the "four series exposures", both stars show up in the orange 6300 Å exposure as well as in the blue 4685 one. These two stars are not hot and blue.

Note however that we can see several stars in the inner blue center of the Ring Nebula. The white dwarf is seen in the center of it, but there is a fairly bright star to the upper right of it. If you look at the series of four exposures of the Ring Nebula through different filters, you can indeed spot this star in the 4686 Å image. You can actually also see another star here, namely right at the lower right edge of the "inner nebula", at the 5 o'clock position.

You can see this star, the one to the upper right of the central white dwarf, in the 5861 Å exposure as well. This star could be a background star that is indeed hot and blue, although nowhere near as hot and blue as the white dwarf! Because normal stars are never as hot as white dwarfs.

The reason why white dwarfs are so hot and blue (when they are young) is that they are the exposed cores of dead stars. Remember that if the temperature of the white dwarf inside the Ring Nebula is 125,000 K, that is actually not nearly as hot as it was when the now-white dwarf was a stellar core wrapped in thick layers of hydrogen and helium. After all, the core of our own Sun is 15 million K! Compared with that, 125,000 K is nothing! Yes, but the photosphere of the Sun, the "visible apparent surface" of the Sun, is barely 6,000 K!

Young white dwarfs are the exposed naked cores of dead stars which have shed their "wrapping" of gases surrounding them. In planetary nebulas, it is these "wrappings" that are ionized by the blasts of ultraviolet light from the scorchingly hot core. The "wrappings" are quickly dispersed by the brutal onslaught of ultraviolet photons and stellar wind from the white dwarf, destroying the planetary nebula and leaving only the cooling white dwarf behind.

Let's take a look at some white dwarfs inside globular cluster M4:



The circled little dots in the picture at right are white dwarfs in globular cluster M4. You can see how tiny and faint they are, but you can also see that they are bluish. Their blue color means that they are hotter than the other stars in the picture. However, white dwarfs keep radiating their heat into space, and since they can't produce any new energy, they keep getting cooler and cooler. After a sufficient number of billion years they won't be blue any more, and in the end they will become burnt-out black cinders.

M4 is a very old globular cluster, some 12 to 13 billion years old. So the oldest white dwarfs in M4 may be almost 12 to13 billion years old, too. These very oldest white dwarfs must have cooled so that they are not blue at all any more, but they are far from being stone cold black dwarfs.

But this is my point: We have very good reasons to believe that all the other stars that we can see in the direction of the Ring Nebula are ordinary stars and not white dwarfs. Yes, there are lots of white dwarfs in the Milky Way, but unless they are so young that they are surrounded by a planetary nebula they are very faint indeed, and they would have to be far in the foreground to show up in a picture of the Ring Nebula.


Ann
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