Starship Asterisk*

Christian G. wrote: ↑Sun Apr 28, 2024 11:39 am Had Messier discovered this planetary nebula with the same fine details seen here, I'm sure he would have ditched the term "planetary" nebula right away! We read over and over that it's a misnomer; what would be a better term? Red giant remnant?

Sa Ji Tario wrote: ↑Sun Apr 28, 2024 2:27 pm The instruments of the observers of the 16th and 17th centuries were less precise than the 150 mm amateur telescopes, but with the desire to discover they solved it. When the Ring Nebula is observed with an amateur telescope, a milky circle appears to the eye with a dark center and nothing more resolution, but since we know that is what we are looking at...

Roy wrote: ↑Sun Apr 28, 2024 2:48 pm Interesting adjective "elongated". Implies ovoid, but outermost wisps are almost perfectly circular. We do not know the viewing aspect. Could be looking down the barrel of somethig like the butterfly nebula.

Planetary Nebulae
Planetary nebulae (PN) represent the last stages of evolution for low- and intermediate-mass stars whose Main Sequence mass was less than about 8 solar masses. After evolving through the Asymptotic Giant Branch (AGB) on the Hertzsprung-Russell diagram, a phase characterised by shell burning resulting in radial pulsations that drive prodigious mass-loss, these stars possess thick, dusty, molecular circumstellar envelopes. In the rapid (few x 1000 yr) post-AGB or proto-planetary nebula (PPN) phase, the mass loss drops dramatically and the circumstellar envelope detaches from the star. The ejection of the envelope exposes the evolving progenitor star which is increasing in temperature and on its way to becoming a white dwarf. Once the central star temperature reaches ~30,000 K, it emits most of its radiation in the ultraviolet region. This radiation ionises the remnant circumstellar envelope, producing the optically-visible planetary nebula. The planetary nebula is still expanding however, and eventually its material will disperse into space, leaving the exposed white dwarf.

johnnydeep wrote: ↑Sun Apr 28, 2024 4:07 pm So, something similar will likely be the fate of our own Sun, correct? From the link -

Planetary Nebulae
Planetary nebulae (PN) represent the last stages of evolution for low- and intermediate-mass stars whose Main Sequence mass was less than about 8 solar masses. After evolving through the Asymptotic Giant Branch (AGB) on the Hertzsprung-Russell diagram, a phase characterised by shell burning resulting in radial pulsations that drive prodigious mass-loss, these stars possess thick, dusty, molecular circumstellar envelopes. In the rapid (few x 1000 yr) post-AGB or proto-planetary nebula (PPN) phase, the mass loss drops dramatically and the circumstellar envelope detaches from the star. The ejection of the envelope exposes the evolving progenitor star which is increasing in temperature and on its way to becoming a white dwarf. Once the central star temperature reaches ~30,000 K, it emits most of its radiation in the ultraviolet region. This radiation ionises the remnant circumstellar envelope, producing the optically-visible planetary nebula. The planetary nebula is still expanding however, and eventually its material will disperse into space, leaving the exposed white dwarf.

Chris Peterson wrote: ↑Sun Apr 28, 2024 4:09 pm

johnnydeep wrote: ↑Sun Apr 28, 2024 4:07 pm So, something similar will likely be the fate of our own Sun, correct? From the link -

Planetary Nebulae
Planetary nebulae (PN) represent the last stages of evolution for low- and intermediate-mass stars whose Main Sequence mass was less than about 8 solar masses. After evolving through the Asymptotic Giant Branch (AGB) on the Hertzsprung-Russell diagram, a phase characterised by shell burning resulting in radial pulsations that drive prodigious mass-loss, these stars possess thick, dusty, molecular circumstellar envelopes. In the rapid (few x 1000 yr) post-AGB or proto-planetary nebula (PPN) phase, the mass loss drops dramatically and the circumstellar envelope detaches from the star. The ejection of the envelope exposes the evolving progenitor star which is increasing in temperature and on its way to becoming a white dwarf. Once the central star temperature reaches ~30,000 K, it emits most of its radiation in the ultraviolet region. This radiation ionises the remnant circumstellar envelope, producing the optically-visible planetary nebula. The planetary nebula is still expanding however, and eventually its material will disperse into space, leaving the exposed white dwarf.

I would not say "fate". But this will be a step in the evolution of the Sun into a white dwarf.

johnnydeep wrote: ↑Sun Apr 28, 2024 4:14 pm

Chris Peterson wrote: ↑Sun Apr 28, 2024 4:09 pm

johnnydeep wrote: ↑Sun Apr 28, 2024 4:07 pm So, something similar will likely be the fate of our own Sun, correct? From the link -

I would not say "fate". But this will be a step in the evolution of the Sun into a white dwarf.

Ok, agreed. The Sun would be merely senescent, but not yet entirely dead!

zendae wrote: ↑Mon Apr 29, 2024 3:27 am

johnnydeep wrote: ↑Sun Apr 28, 2024 4:14 pm

Chris Peterson wrote: ↑Sun Apr 28, 2024 4:09 pm
I would not say "fate". But this will be a step in the evolution of the Sun into a white dwarf.

Ok, agreed. The Sun would be merely senescent, but not yet entirely dead!

Maybe these stars are quite comfortable in anticipation; a ripening chrysalis perhaps.

Bird_Man wrote: ↑Mon Apr 29, 2024 1:37 pm Are the different "rings" shown in this image from successive shedding events when it "evolves to throw off it's outer atmosphere"?

Christian G. wrote: ↑Mon Apr 29, 2024 12:05 pm

zendae wrote: ↑Mon Apr 29, 2024 3:27 am

johnnydeep wrote: ↑Sun Apr 28, 2024 4:14 pm

Ok, agreed. The Sun would be merely senescent, but not yet entirely dead!

Maybe these stars are quite comfortable in anticipation; a ripening chrysalis perhaps.

The ripening is only beginning, give them a quadrillion years and white dwarfs apparently turn into giant diamonds! Which of course are forever.

diamond star.png
https://www.livescience.com/space/cosmo ... e-our-eyes

https://pubs.aip.org/physicstoday/article/72/3/14/916006/White-dwarfs-crystallize-as-they-coolA-new-star wrote:Devoid of nuclear burning, a white dwarf is thought to exist as a homogeneous mixture of carbon and oxygen whose nuclei are liquid. (In the star’s ionized-plasma state, the electrons remain a Fermi gas and the nuclei are either liquid or solid.) When the nuclei freeze, the elements start segregating. Oxygen nuclei carry a higher charge than carbon, so they are the first to solidify—into a body-centered-cubic metal, according to calculations. Oxygen also has a higher density than carbon, and after nucleating, it “snows out” of the liquid and sinks to the core.

https://en.wikipedia.org/wiki/Timeline_of_the_far_future#:~:text=(1%20nonillion)-,The%20estimated%20time,-until%20most%20or wrote:
10³⁰ (1 nonillion) years from now
The estimated time until most or all of the remaining 1–10% of stellar remnants not ejected from galaxies fall into their galaxies' central supermassive black holes. By this point, with binary stars having fallen into each other, and planets into their stars, via emission of gravitational radiation, only solitary objects (stellar remnants, brown dwarfs, ejected planetary-mass objects, black holes) will remain in the universe.[9]

2×10³⁶ (2 undecillion) years from now
The estimated time for all nucleons in the observable universe to decay, if the hypothesized proton half-life takes its smallest possible value (8.2 × 10³³ years).[142][143][note 4]

10³⁶–10³⁸ (1–100 undecillion) years from now
Estimated time for all remaining planets and stellar-mass objects, including the Sun, to disintegrate if proton decay can occur.[9]