Explanation: To some, it may look like a cat's eye. The alluring Cat's Eye nebula, however, lies three thousand light-years from Earth across interstellar space. A classic planetary nebula, the Cat's Eye (NGC 6543) represents a final, brief yet glorious phase in the life of a sun-like star. This nebula's dying central star may have produced the simple, outer pattern of dusty concentric shells by shrugging off outerlayers in a series of regular convulsions. But the formation of the beautiful, more complex inner structures is not well understood. Seen so clearly in this digitally sharpened Hubble Space Telescope image, the truly cosmic eye is over half a light-year across. Of course, gazing into this Cat's Eye, astronomers may well be seeing the fate of our sun, destined to enter its own planetary nebula phase of evolution ... in about 5 billion years.
Re: APOD: The Cat's Eye Nebula from Hubble (2014 Nov 09)
Posted: Sun Nov 09, 2014 6:21 am
by Boomer12k
Purrrrrrrrrrr.....Always an Awesome sight....I wonder at the gyrations of the star, that it threw its material off like that....maybe in small then larger stages over time?? So, if "flared" larger at times...Since you have these smaller globe like ends, and a larger middle, the you get a final billowing in the center...maybe it had the hiccups???
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Re: APOD: The Cat's Eye Nebula from Hubble (2014 Nov 09)
Posted: Sun Nov 09, 2014 8:30 am
by Startreader
Boomer12k wrote:...maybe it had the hiccups???
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Do felines even get hiccoughs?
Very beautiful. And I love the dead cat being swung by the upper arm. Highly symbolic.
Re: APOD: The Cat's Eye Nebula from Hubble (2014 Nov 09)
Posted: Sun Nov 09, 2014 10:14 am
by geckzilla
Startreader wrote:Very beautiful. And I love the dead cat being swung by the upper arm. Highly symbolic.
What are you talking about?
Re: APOD: The Cat's Eye Nebula from Hubble (2014 Nov 09)
Posted: Sun Nov 09, 2014 11:05 am
by ThePiper
Startreader wrote:
Boomer12k wrote:...maybe it had the hiccups???
:---[===] *
Do felines even get hiccoughs?
Very beautiful. And I love the dead cat being swung by the upper arm. Highly symbolic.
That's not a dead cat; it's a jumping brown panther with a flamy tail. Think positive!
Re: APOD: The Cat's Eye Nebula from Hubble (2014 Nov 09)
Posted: Sun Nov 09, 2014 12:06 pm
by Ann
It's the Ceiling Cat, looking at us with only one of its eyes open. (I couldn't find a good picture of the Ceiling Cat, so this one will have to suffice.)
Ann
Re: APOD: The Cat's Eye Nebula from Hubble (2014 Nov 09)
Posted: Sun Nov 09, 2014 3:34 pm
by tomatoherd
So the destiny of "a sun-like star". Well, if our system/star is already 5 billion years old, and it has another 5 billion to go, that makes sun-like star life times around 10 billion yrs. If we accept a Universe age of 13-14 billion yrs, and the Cat's Eye star has already completed its life of 10 billion, are they implying that system formed when the Universe was only 3 to 4 billion yrs old? Is the Cat's Eye spectrum low on heavy metals? If not, how could supernovas have formed and cycled metals into interstellar space and reused again, all in 3 billion yrs? Maybe astronomy needs some geologists to make realistic time-frames. For me, I think the universe is much older, and 13 billion is just the limit of our vision...
Re: APOD: The Cat's Eye Nebula from Hubble (2014 Nov 09)
Posted: Sun Nov 09, 2014 3:57 pm
by Chris Peterson
tomatoherd wrote:So the destiny of "a sun-like star". Well, if our system/star is already 5 billion years old, and it has another 5 billion to go, that makes sun-like star life times around 10 billion yrs.
In this context, "sun-like" just means not very massive. But otherwise, it wasn't all that sun-like. Its current mass is greater than a solar mass, and its original mass was several times that. So it would have entered the red giant phase after only a couple billion years. The progenitor star here is probably no older than the Sun.
Is the Cat's Eye spectrum low on heavy metals? If not, how could supernovas have formed and cycled metals into interstellar space and reused again, all in 3 billion yrs?
The nebula has the usual assortment of heavier elements observed in planetary nebulas. As noted above, the progenitor formed much later than your estimate. Nevertheless, by the time the Universe was 3 billion years old it was full of galaxies and there had been multiple generations of supernovas. The Universe was rich in heavy elements by that time.
Re: APOD: The Cat's Eye Nebula from Hubble (2014 Nov 09)
Posted: Sun Nov 09, 2014 7:52 pm
by geckzilla
If you want to see a PN generated by a low metallicity star, I found one in the Hubble archive. It's out there in the galactic halo with the other Population II stars and hardly any oxygen could be found in it. And there is a cool paper on it. Not the prettiest thing in the archive but it's quite interesting.
Re: APOD: The Cat's Eye Nebula from Hubble (2014 Nov 09)
Posted: Sun Nov 09, 2014 8:13 pm
by Chris Peterson
geckzilla wrote:If you want to see a PN generated by a low metallicity star, I found one in the Hubble archive. It's out there in the galactic halo with the other Population II stars and hardly any oxygen could be found in it. And there is a cool paper on it. Not the prettiest thing in the archive but it's quite interesting.
I took tomatoherd's question about heavier elements to refer to those produced in supernova explosions, and therefore part of the mix of later generation stars (like the Sun). Normally, you'd expect any planetary nebula to contain oxygen, since that's a product of ordinary stellar nucleosynthesis (as opposed to supernova nucleosynthesis), and therefore we'd find it in a planetary nebula produced by even a first generation star. I note that in the referenced paper, the explanation for the low oxygen ratio is linked to some nebulous (ha!) mixing process, and not the original ingredients. Since the progenitor is estimated at one solar mass, I assume that it was one of the earliest stars in the Milky Way (per tomatoherd's reasoning).
Re: APOD: The Cat's Eye Nebula from Hubble (2014 Nov 09)
Posted: Sun Nov 09, 2014 8:19 pm
by madtom1999
Its a bit hard to tell on a screen and I haven't got a printer available but aren't the 'concentric rings' in reality a spiral?
Re: APOD: The Cat's Eye Nebula from Hubble (2014 Nov 09)
Posted: Sun Nov 09, 2014 8:23 pm
by geckzilla
Chris Peterson wrote:I took tomatoherd's question about heavier elements to refer to those produced in supernova explosions, and therefore part of the mix of later generation stars (like the Sun). Normally, you'd expect any planetary nebula to contain oxygen, since that's a product of ordinary stellar nucleosynthesis (as opposed to supernova nucleosynthesis), and therefore we'd find it in a planetary nebula produced by even a first generation star. I note that in the referenced paper, the explanation for the low oxygen ratio is linked to some nebulous (ha!) mixing process, and not the original ingredients. Since the progenitor is estimated at one solar mass, I assume that it was one of the earliest stars in the Milky Way (per tomatoherd's reasoning).
Oh, ok. So it's not a Population II star or even a low metallicity star, then? I didn't quite catch that. In the proposal they were even speculating that it could have been a Population III star, which turned out to not be true.
Re: APOD: The Cat's Eye Nebula from Hubble (2014 Nov 09)
Posted: Sun Nov 09, 2014 8:27 pm
by Chris Peterson
geckzilla wrote:Oh, ok. So it's not a Population II star or even a low metallicity star, then? I didn't quite catch that. In the proposal they were even speculating that it could have been a Population III star, which turned out to not be true.
I don't know. I was just drawing a distinction between "low metallicity" and "low heavy elements", where the first is anything heavier than helium, and the latter might be taken as anything that is produced only by supernova nucleosynthesis.
Re: APOD: The Cat's Eye Nebula from Hubble (2014 Nov 09)
Posted: Sun Nov 09, 2014 8:29 pm
by geckzilla
madtom1999 wrote:Its a bit hard to tell on a screen and I haven't got a printer available but aren't the 'concentric rings' in reality a spiral?
They are not rings or spirals. They are roughly spherical shaped shells which you can only see the edges of where the material is relatively thicker, kind of like how you can most easily see the edge of a soap bubble against a white background. They're not perfect spheres, though, so it's difficult to follow them all the way around.
Re: APOD: The Cat's Eye Nebula from Hubble (2014 Nov 09)
Posted: Sun Nov 09, 2014 9:26 pm
by quigley
I am curious about the rays that appear to be emanating from the nebula. Are they incidental artifacts of the image, and if not, than what causes them?
Re: APOD: The Cat's Eye Nebula from Hubble (2014 Nov 09)
Posted: Sun Nov 09, 2014 10:46 pm
by geckzilla
quigley wrote:I am curious about the rays that appear to be emanating from the nebula. Are they incidental artifacts of the image, and if not, than what causes them?
I know for sure they are not artifacts but I don't know what causes them. Looks like some force emanating somewhat evenly out from the center. Maybe they are related to the concentric shells. I have noticed a strong leaning towards the hypothesis that complex structures of planetary nebulas are drastically affected by a companion star. Smaller perturbations may even be caused by orbiting planets.
Re: APOD: The Cat's Eye Nebula from Hubble (2014 Nov 09)
Posted: Sun Nov 09, 2014 10:55 pm
by hand-launched
The designations 'Population II" or "low metallicity" star really do not mean anything - these terms are contrivances meant to give academic popularity to mysterious and unfathomable celestial phenomenon. If anything, the population and classification of stars is a topic in which Mark Twain's diction about science and conjecture applies. However, the reference to the stellar mass, which can be calculated from empirical geometrics, is significant.
Before the star went nova, it must have been a chimney stack type of body laden with carbon or some other element which bore down on its interior. Going nova was the mechanism by which the star shed the burden and re-established equilibrium.
If, and when, Betelguese goes nova for similar reasons, a nebula similar to NGC 6543 or the Crab Nebula will probably be produced. It is erroneous to suggest that a star going nova is 'dying' or nearing the end of its life; a star going nova may mark a new beginning with mass shed during the nova event recombining around the central star to form a Sun-like planetary solar system.
The amazing images of the observable universe speak for themselves. The Hubble space telescope is truly the greatest instrument invented by man. Hope ESA and NASA continue to operate the telescope until every discernible celestial object is mapped.
Re: APOD: The Cat's Eye Nebula from Hubble (2014 Nov 09)
Posted: Sun Nov 09, 2014 11:05 pm
by Chris Peterson
hand-launched wrote:The designations 'Population II" or "low metallicity" star really do not mean anything...
They are observational classifications, and therefore useful for many purposes.
If, and when, Betelguese goes nova for similar reasons, a nebula similar to NGC 6543 or the Crab Nebula will probably be produced. It is erroneous to suggest that a star going nova is 'dying' or nearing the end of its life; a star going nova may mark a new beginning with mass shed during the nova event recombining around the central star to form a Sun-like planetary solar system.
You seem to be confusing novas and supernovas (Betelgeuse will almost certainly produce a type II supernova); NGC 6543 was never a supernova. Novas do not necessarily represent the end of life of a star (in the sense of it becoming a non-fusing object). Supernovas do. And the star in the center of most planetary nebulas is also at a dead end, no longer fusing and simply cooling very slowly.
Re: APOD: The Cat's Eye Nebula from Hubble (2014 Nov 09)
Posted: Mon Nov 10, 2014 12:33 am
by Ann
Chris wrote:
And the star in the center of most planetary nebulas is also at a dead end, no longer fusing and simply cooling very slowly.
Yes, but under certain circumstances, a white dwarf can start fusing again.
Astronomers recently discovered the rather memorably named SDSS J010657.39–100003.3, which is a binary star system composed of two white dwarfs, one of which is 17% the Sun's mass, while the other is about 43%. The two orbit each other at a distance of just 140,000 miles, which is even closer than the distance between the Earth and the Moon. The two rotate each other at about a million miles per hour.
That's where things start to get really crazy - at those speeds, the stars complete a full revolution every 39 minutes, which is by far the fastest orbital time ever seen in a binary system. In fact, they're so close to each other that they actually warp the fabric of space-time between them. These spatial warps create energy discharges, which in turn force the stars ever closer. These two white dwarfs will soon collide.
Of course, "soon" is a relative term, particularly in astronomy - the stars aren't due to collide for another 37 million years. When white dwarfs collide, one of two things can happen: if the combined masses is greater than 140% of the Sun, the collision creates a supernova. But in this case, the white dwarfs will actually reignite nuclear fusion, creating a brand new star just like our Sun that will, after another few billion years of renewed life, cool down into yet another white dwarf.
Ann
Re: APOD: The Cat's Eye Nebula from Hubble (2014 Nov 09)
Posted: Mon Nov 10, 2014 7:15 pm
by Ron-Astro Pharmacist
This planetary nebula and others almost appear to exhibit "jet-like" protuberances from their poles. If so, I wonder why they would occur? Google shows one mechanism but…
Click to play embedded YouTube video.
is this what looks to be occurring at the "Cat's Eye?" Could any large gas planet (or sun as in the video) supply the jet material?
Though cats don't like being messed with but this shows old cats "can" learn new tricks.
The Cat's Eye Nebula from Hubble
