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APOD: The Helix Nebula from CFHT (2020 Nov 24)
Posted: Tue Nov 24, 2020 5:05 am
by APOD Robot
The Helix Nebula from CFHT
Explanation: Will our Sun look like this one day? The
Helix Nebula is one of brightest and closest examples of a
planetary nebula, a gas
cloud created at the end of the life of a Sun-like star. The outer gasses of the star
expelled into space appear from our vantage point as if we are looking down a
helix. The remnant central stellar core, destined to become a
white dwarf star, glows in light so
energetic it causes the previously expelled gas to
fluoresce. The
Helix Nebula, given a technical designation of
NGC 7293, lies about 700
light-years away towards the
constellation of the Water Bearer (
Aquarius) and spans about 2.5 light-years. The
featured picture was taken with the
Canada-France-Hawaii Telescope (CFHT) located atop a dormant volcano in
Hawaii,
USA. A
close-up of the
inner edge of the
Helix Nebula shows complex gas knots of
unknown origin.
Re: APOD: The Helix Nebula from CFHT (2020 Nov 24)
Posted: Tue Nov 24, 2020 6:20 am
by rdjay@xtra.co.nz
'...gasses...'? Did you mean 'gases'?
Re: APOD: The Helix Nebula from CFHT (2020 Nov 24)
Posted: Tue Nov 24, 2020 7:32 am
by WWW
Same nebula different eye shadow.
Re: APOD: The Helix Nebula from CFHT (2020 Nov 24)
Posted: Tue Nov 24, 2020 11:12 am
by wolfbear
It's like looking through the pupil of an eye. Which I am wondering about: if the explosion blasted the star to the extent that we could see right through its core, what will cause those gases to come back together to form a white dwarf? Is there something acting like a sheath of sorts preventing the core from dissipating? Or that will eventually pull the core back in to become a star?
Re: APOD: The Helix Nebula from CFHT (2020 Nov 24)
Posted: Tue Nov 24, 2020 11:30 am
by Sa Ji Tario
There seems to be confusion, the star DOES NOT explode, it only emitted 15% of its mass in the form of gas and dust and expanded due to temperature, it will cool down and will be a dwarf
Re: APOD: The Helix Nebula from CFHT (2020 Nov 24)
Posted: Tue Nov 24, 2020 11:34 am
by Sa Ji Tario
At the end of the life of stars that reach the red giant phase, the outer layers of the star are expelled by pulsations and intense stellar winds. After the expulsion of these layers, a small core of the star remains, which is at a high temperature and shines brightly. The ultraviolet radiation emitted by this core ionizes the outer layers that the star had expelled (Wikipedia)
Re: APOD: The Helix Nebula from CFHT (2020 Nov 24)
Posted: Tue Nov 24, 2020 1:07 pm
by orin stepanek
Reminds me of a miner with a spotlight on his helmet!
First time I saw the helix in pink!
Re: APOD: The Helix Nebula from CFHT (2020 Nov 24)
Posted: Tue Nov 24, 2020 2:44 pm
by Chris Peterson
rdjay@xtra.co.nz wrote: ↑Tue Nov 24, 2020 6:20 am
'...gasses...'? Did you mean 'gases'?
"Gases" is the more common plural form, but both are considered acceptable, and any English dictionary will offer "gasses" as an alternative plural.
Re: APOD: The Helix Nebula from CFHT (2020 Nov 24)
Posted: Tue Nov 24, 2020 2:48 pm
by Chris Peterson
wolfbear wrote: ↑Tue Nov 24, 2020 11:12 am
It's like looking through the pupil of an eye. Which I am wondering about: if the explosion blasted the star to the extent that we could see right through its core, what will cause those gases to come back together to form a white dwarf? Is there something acting like a sheath of sorts preventing the core from dissipating? Or that will eventually pull the core back in to become a star?
The star blew off its outer layers, leaving behind a denser central part (which still retains most of the mass of the original- 80% or more). Nothing falls back, and the use of "core" is just referring to a more interior part of the original, not to anything with a clear structural meaning.
Re: APOD: The Helix Nebula from CFHT (2020 Nov 24)
Posted: Tue Nov 24, 2020 4:12 pm
by neufer
Chris Peterson wrote: ↑Tue Nov 24, 2020 2:44 pm
rdjay@xtra.co.nz wrote: ↑Tue Nov 24, 2020 6:20 am
'...gasses...'? Did you mean 'gases'?
"Gases" is the more common plural form, but both are considered acceptable,
and any English dictionary will offer "gasses" as an alternative plural.
https://grammarist.com/usage/gases-gasses/ wrote:
<<In modern English, the plural of gas is usually gases, and gasses is the simple-present verb. For instance, we might say that the more Bill gasses up his car, the more greenhouse gases his car emits. This isn’t a rule, though, and the plural gasses survives, appearing a small percentage of the time.>>
Re: APOD: The Helix Nebula from CFHT (2020 Nov 24)
Posted: Tue Nov 24, 2020 4:53 pm
by Fred the Cat
That helix is powered by
wings.
In an ad for a new type of telescope, they used this image.
It looks like a
telescope for immediate gratification.
Re: APOD: The Helix Nebula from CFHT (2020 Nov 24)
Posted: Tue Nov 24, 2020 6:49 pm
by JohnD
"The outer gasses of the star"
maybe "The star's outgassing" was intended?
John
Re: APOD: The Helix Nebula from CFHT (2020 Nov 24)
Posted: Tue Nov 24, 2020 10:24 pm
by johnnydeep
JohnD wrote: ↑Tue Nov 24, 2020 6:49 pm
"The outer gasses of the star"
maybe "The star's outgassing" was intended?
John
I don't think so. "The outer gasses of the star expelled into space appear..." looks grammatical, clear, and non-ambiguous to me.
