Like we look down a well.
Which is almost perfectly round and cylinder (with ⌀=1 ly) and which we are looking down almost perfectly along the axis.
At its outskirts the well is widening, like a hole in a doughnut, to a few ly.
Is it a many years old pair of hollow and widening jets followed by new pair of more tightly collimated hollow jets and some blue filling-clogging in the center?
Can we differentiate between one wide part moving our way and the other wide part moving away from us?
Just beautiful; happy I wasn't on a planet of this ster when the star
gave up it;s life! It's like a flower that came into bloom! amazing.
So symmetrical!
orin stepanek wrote: ↑Wed Aug 18, 2021 11:40 am
Just beautiful; happy I wasn't on a planet of this ster when the star
gave up it;s life! It's like a flower that came into bloom! amazing.
So symmetrical!
Where have all the graveyards gone?
Long time passing.
Where have all the graveyards gone?
Long time ago.
Where have all the graveyards gone?
They're covered with flowers every one.
Oh, When will they ever learn?
Oh, When will they ever learn?
seems to me that the hollow jet moving towards us is narrower and faster than the counter-jet.
It makes sense if on our side there is less interstellar media to slow down the jet and to curve the magnetic field lines of the jet's tube further away from the axis, does it?
ems57fcva wrote: ↑Wed Aug 18, 2021 4:05 pm
The "central ring" link is wrong. It is linking to the 8/15/2021 APOD instead of the intended 8/17/2021 APOD.
Congratulations! You've passed the "click on every link" test. I had been wondering what an APOD about the Perseids had to do with a "ring" - central or otherwise - and was also going to post about the problem, but you beat me to it.
-- "To B̬̻̋̚o̞̮̚̚l̘̲̀᷾d̫͓᷅ͩḷ̯᷁ͮȳ͙᷊͠ Go......Beyond The F͇̤i̙̖e̤̟l̡͓d͈̹s̙͚ We Know."{ʲₒʰₙNYᵈₑᵉₚ}
Avalon wrote: ↑Wed Aug 18, 2021 6:45 pm
So do the concentric rings represent more than one event, a few episodes of the star expelling layers of its shell?
<<M57 is 2,570 light-years from Earth. Photographs taken over a period of 50 years show the rate of nebula expansion is roughly 1 arcsecond per century, which corresponds to spectroscopic observations as 20–30 km/s. M57 is illuminated by a central white dwarf or planetary nebula nucleus (PNN) of 15.75v visual magnitude.
All the interior parts of this nebula have a blue-green tinge that is caused by the doubly ionized oxygen emission lines at 495.7 and 500.7 nm. These observed so-called "forbidden lines" occur only in conditions of very low density containing a few atoms per cubic centimeter.
In the outer region of the ring, part of the reddish hue is caused by hydrogen emission at 656.3 nm, forming part of the Balmer series of lines.Forbidden lines of ionized nitrogen or N II contributes to the reddishness at 654.8 and 658.3 nm.>>
Avalon wrote: ↑Wed Aug 18, 2021 6:45 pm
So do the concentric rings represent more than one event, a few episodes of the star expelling layers of its shell?
That is certainly one model of how stars in this mass range eject their outer layers. Likely, and broadly accepted as likely. But not certain.
Chris
*****************************************
Chris L Peterson
Cloudbait Observatory https://www.cloudbait.com
Rings Around the Ring Nebula
It's like a flower that came into bloom! amazing. 
