Starship Asterisk*

Hello All

Planetary Nebulae

http://antwrp.gsfc.nasa.gov/apod/ap050311.html
http://antwrp.gsfc.nasa.gov/apod/ap031101.html

More explanation on planetary nebulae to clear the definition. With a few examples.

http://www.noao.edu/jacoby/pn_gallery.html
[quote]A planetary nebula forms when a star can no longer support itself by fusion reactions in its center. The gravity from the material in the outer part of the star takes its inevitable toll on the structure of the star, and forces the inner parts to condense and heat up. The high temperature central regions drive the outer half of the star away in a brisk stellar wind, lasting a few thousand years. When the process is complete, the remaining core remnant is uncovered and heats the now distant gases and causes them to glow.


but there's more info and examples

http://www.aao.gov.au/images/general/planetary_frames.html

Sorry for giving so many links,,,,,,,,,,,bad habit

I think i will have a scotch and ice.

Thanks Qev! I was always under the impression that planetary nebulae were the result of novae. I stand corrected.
Orin

[quote="orin stepanek"]I found this.
http://observe.arc.nasa.gov/nasa/space/stellardeath/stellardeath_4a.html
So I think nova was the right description. I understand how the companion star contributes to the white dwarfs outbursts now.
Orin[/quote]
A nova is actually a case where an already-dead star, ie. a white dwarf, is accumulating matter from a nearby companion star. Once enough of this material accumulates, flash-fusion occurs across the surface of the white dwarf, producing a brief but intense increase in luminosity.

In this particular instance, the two stars are most likely [b]not[/b] companions, and the cloud one is seeing is a planetary nebula. It is even labelled as such in the APOD article.

I found this.
http://observe.arc.nasa.gov/nasa/space/stellardeath/stellardeath_4a.html
So I think nova was the right description. I understand how the companion star contributes to the white dwarfs outbursts now.
Orin

That's actually a planetary nebula, not a nova or supernova remnant. As star death events go, these are very 'gentle'; the dying star ejects its outer layers over time, forming an expanding shell of gas and dust around the core of the star, now collapsed into a white dwarf. These events would have very little effect on a companion star, unless they were extremely close together. The 'binary' stars in this case may in fact only be visual binaries, ie. laying close together on our line-of-sight, and not actually physically near each other.

Hello All

I agree with you starnut. It has ejected a shell and it is going through a phase in the life of a star.

NGC 246 and the Dying Star but I would not agree that this star is dying.

The other thing i would add is that we see the image front face to the hour glass image.


Some people do get supa nova and nova confused.

Not wanting to squabble, but the term "nova" usually refers to a sudden brightening of a star, usually a white dwarf or a neutron star in a binary system like this one, caused by an explosion on the surface of the star due to accumulation of material drawn from the larger companion. This explosion does not destroy the star, unlike a supernova which would be the final death throe of either the white dwarf (Type Ia supernova) or a massive star (Type II supernova). This star often goes "nova" at a regular interval as new material accumulates again on its surface. What we see in this APOD is the outer envelope of the white dwarf having been blown off by the hot wind of the white dwarf at the end of the precursor star's red giant phase. This ejection was not violent and powerful like a supernova, so it has no effect on the companion star.

http://antwrp.gsfc.nasa.gov/apod/ap060418.html
The larger member of the binary star seems to be intact. Why didn't the nova of its companion cause this star to also nova? Maybe not a bright [?]; but you would think the nova star would cause some havoc to its binary companion.
Orin