Starship Asterisk*

In the information brought up through the 'nuclear fusion' link in the explanation it states "Like all stars, the sun is a huge fusion reactor, pumping out 100 million times as much energy in a single second as the entire population of Earth uses in a year!". Wow, that is amazing (well it is to me :ssmile:). That's a lot of energy waiting to be exploited. :wink:

[quote="Cousin Ricky"][quote="Can't make it up"]I thought that a planetary nebula was formed at the red giant phase during the transition from hydrogen fusion to helium fusion in the core, not when fusion stopped. I wasn't aware that main sequence core fusion stopped until a large iron core had been created. Nice, deep exposure though. I didn't even recognize it.[/quote]

I can never remember the sequence of events during the death throes of a star. However, in the medium-mass stars that create planetary nebulae, an iron core [i]never[/i] forms. Stars that are massive enough to form iron cores end with supernova explosions. I have heard the nebulae created by Wolf-Rayet stars (which [i]do[/i] generate iron cores) referred to as planetary nebulae, but M27 is not in that category.

Notwithstanding my first sentence, I do remember that the iron core doesn't develop until well after the star has left the main sequence.

Doctor: You've developed an iron core.
Type O/B/WR patient: OMG, how much time have I got?
Doctor: Ten...
Patient: Ten what? Months? Weeks?
Doctor: Nine...[/quote]
Nebulae created by Wolf Rayet stars are [b][size=110]NOT[/size][/b] planetary nebulae! They are either Wolf Rayet bubble nebulae like the Crescent Nebula or they are Wolf Rayet ring nebulae like RCW 58. There are three types, ejecta nebulae created by material ejected by a Wolf Rayet star, a windswept bubble of material in the surrounding interstellar medium created by the strong and fast winds of a Wolf Rayet star and finally there are some that are a combination of the two.

[quote="Can't make it up"]I thought that a planetary nebula was formed at the red giant phase during the transition from hydrogen fusion to helium fusion in the core, not when fusion stopped. I wasn't aware that main sequence core fusion stopped until a large iron core had been created. Nice, deep exposure though. I didn't even recognize it.[/quote]

I can never remember the sequence of events during the death throes of a star. However, in the medium-mass stars that create planetary nebulae, an iron core [i]never[/i] forms. Stars that are massive enough to form iron cores end with supernova explosions. I have heard the nebulae created by Wolf-Rayet stars (which [i]do[/i] generate iron cores) referred to as planetary nebulae, but M27 is not in that category.

Notwithstanding my first sentence, I do remember that the iron core doesn't develop until well after the star has left the main sequence.

Doctor: You've developed an iron core.
Type O/B/WR patient: OMG, how much time have I got?
Doctor: Ten...
Patient: Ten what? Months? Weeks?
Doctor: Nine...

Beautiful image!

I thought that a planetary nebula was formed at the red giant phase during the transition from hydrogen fusion to helium fusion in the core, not when fusion stopped. I wasn't aware that main sequence core fusion stopped until a large iron core had been created. Nice, deep exposure though. I didn't even recognize it.

Wow....That is awesome detail...

Looks more like a split open Seashell...

:---[===] *

Yay a planetary nebula! The only complaint I could make is that it is a popular one. The description should have mentioned its halo, something that is associated with a large majority of planetary nebulae. I'm fairly confident that even more will be discovered in the next few years! :D

Not sure why, but this picture reminded me of this scene:

https://www.youtube.com/embed/DOFgFAcGHQc?start=202&end=206

Definitely not a dumbbell anymore.

[url=http://apod.nasa.gov/apod/ap140914.html][img]http://apod.nasa.gov/apod/calendar/S_140914.jpg[/img] [size=150]M27: The Dumbbell Nebula[/size][/url]

[b] Explanation: [/b] The first hint of what will become of our [url=http://asterisk.apod.com/viewtopic.php?f=24&t=18012]Sun[/url] was discovered inadvertently in [url=http://en.wikipedia.org/wiki/1764]1764[/url]. At that time, [url=http://en.wikipedia.org/wiki/Charles_Messier]Charles Messier[/url] was compiling a list of diffuse objects not to be confused with comets. The 27th object on [url=http://www.seasky.org/astronomy/astronomy-messier.html]Messier's list[/url], now known as [url=http://apod.nasa.gov/apod/ap080626.html]M27[/url] or the Dumbbell Nebula, is a [url=http://apod.nasa.gov/apod/planetary_nebulae.html]planetary nebula[/url], the type of nebula our [url=http://apod.nasa.gov/apod/ap131002.html]Sun[/url] will produce when [url=http://fusedweb.pppl.gov/]nuclear fusion[/url] stops in its core. [url=http://apod.nasa.gov/apod/ap020302.html]M27[/url] is one of the brightest [url=http://en.wikipedia.org/wiki/Planetary_nebula]planetary nebulae[/url] on the sky, and can be seen toward the [url=http://www.astro.wisc.edu/~dolan/constellations/extra/constellations.html]constellation[/url] of the Fox ([url=http://en.wikipedia.org/wiki/Vulpecula]Vulpecula[/url]) with binoculars. It takes light about 1000 years to reach us from M27, [url=http://billsnyderastrophotography.com/?page_id=1767]shown above[/url] in colors emitted by [url=http://en.wikipedia.org/wiki/H-alpha]hydrogen[/url] and [url=http://periodic.lanl.gov/8.shtml]oxygen[/url]. Understanding the physics and significance of [url=http://apod.nasa.gov/apod/ap100826.html]M27[/url] was well beyond 18th century science. Even today, many things remain mysterious about [url=http://apod.nasa.gov/apod/ap130915.html]bipolar planetary nebula[/url] like M27, including the physical mechanism that expels a low-mass star's gaseous outer-envelope, leaving an [url=http://missionscience.nasa.gov/ems/11_xrays.html]X-ray[/url] hot [url=http://imagine.gsfc.nasa.gov/docs/science/know_l2/dwarfs.html]white dwarf[/url].

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