Talk:Planetary nebula

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Contents

[edit] Image

I worked on the project that produced this image (one of the et al. in Chu et al.) and the image processing was done at NASA. I believe, therefore, it's in the public domain and I have the right to give permission for its GDL release. Please contact me if there's a problem with either assumption! -- April

If the work is in the public domain, I have just as much right as you do to release it under a licence, ie none. Sorry. Taxpayers paid for Hubble, therefore we own any images coming out of it. -AC

I have a PhD in the abundances of heavy elements in planetary nebulae, so couldn't resist writing a bit on this page. Apologies to all if I've got too technical! Please edit ruthlessly if I have. (Worldtraveller)

==

"In other galaxies, planetary nebulae may be the only objects observable enough to yield useful abundance information." Apologies for removing the "abundance" part, I misunderstood it and thought of it as either bad grammar or a forgotten piece of an older sentence. -F. Delpierre

No probs - it made me realise that section could be a bit clearer so I've tweaked it a bit more. Hope that makes it clearer. Worldtraveller 01:35, 31 Dec 2004 (UTC)

Images from this article are in wikimedia commons now. --213.194.213.59 04:10, 1 Jan 2005 (UTC)

[edit] Plasma/Gas

I just changed 'plasma' to 'gas' in the intro., because although the majority of a planetary nebula will be plasma, there are often neutral species present so the more general description is better, I think. Worldtraveller 23:49, 2 Jan 2005 (UTC)

[edit] Slashdot News

This story was linked by Slashdot on Jan 5 2005. Coincidentally, the slashdot heading linked to this article as a reference on planetary nebula(e for plural?). Anyway, apparently the article contains some new findings apropos to the mystery of magnetic fields and why the nebulae aren't usually round. Unfortunately it's 3 in the morning here (too late to write articles by my clock) and I know nothing about the subject. I thought you all should know though.Matthewcieplak 21:20, 6 Jan 2005 (UTC)

This news had been added to the intro, with a statement that 'it is likely that magnetic fields are responsible' for diverse shapes of planetary nebulae. I thought that sounded a bit strong - this is just one paper, with 2/5 definite detections of magnetic fields and 2/5 probable detections. It's still just one of many competing theories, so I've removed the sentence from the intro and added a bit to the 'open questions' section. Worldtraveller 20:22, 23 Jan 2005 (UTC)

[edit] Recombination

In the lifetime section of the article, recombination is linked to a disambiguation page which doesn't seem to have anything to do with planetary nebulae. I don't know how to fix this right off the top of my head, which is why I'm mentioning it on this talk page. --Arkuat 09:14, 11 March 2006 (UTC)

Thanks for pointing that out - I've made it link to a more appropriate article. Worldtraveller 16:01, 11 March 2006 (UTC)

Ah, that makes much more sense now. Thanks for the fix. --Arkuat 07:35, 12 March 2006 (UTC)

[edit] Characteristics

Forgive me if i'm just being naive, but:

"with a density generally around 1000 particles per cm³ - which is about a million billion billion times less dense than the earth's atmosphere"

What is a million billion billion? That really does not seem like a real number to me. Is this an editing error where extra words were not deleted?

1,000,000,000,000,000,000,000,000 ?

Juniorrachel 20:11, 20 March 2006 (UTC)

Don't think there was an error, no! The figure you've written out is a million billion billion, and planetary nebulae really are a million billion billion times less dense than the earth's atmosphere. We could say 1024 times less dense, or write out the number, but I think using the commonly known words is probably the best way of communicating what is intended. Worldtraveller 18:40, 23 March 2006 (UTC)

Thanks for clearing that up.  :) Juniorrachel 13:43, 4 April 2006 (UTC)

Actually, Juniorrachel had a point. The Earth's atmosphere has a mean molar mass of 29 g/mol, so 1027 particles/cm3 would imply a density of 48 kg/cm3—clearly ridiculous. In fact, air contains just 2.5×1019 molecules/cm3. Dumbing this down, as seems to be required, makes a 1000 particles/cm3 planetary nebula just 25 million billion times less dense than this stuff we breathe.
—Herbee 00:12, 22 January 2007 (UTC)

Do you have a reference for these figures? —The preceding unsigned comment was added by 81.179.64.173 (talk) 08:50, 23 January 2007 (UTC).

[edit] Stingray nebula

the article Stingray Nebula is on the list of orphan articles because nothing links to it. It is certainly not up to the standards of other planetary nebulae articles and should also be listed in various lists and tables. Will someone adopt this article? Thatcher131 20:54, 24 May 2006 (UTC)

This article has been un-orphaned and expanded with citations. WilliamKF 01:08, 14 February 2007 (UTC)

[edit] Version 0.5

This article has been selected for release into Version 0.5 due to its importance and quality; however, is it possible to get the sparse bare links in the article converted to references? Also, the article uses footnotes, so it could benefit from the cite.php citation system. Titoxd(?!? - help us) 23:20, 31 May 2006 (UTC)

Hadn't noticed this post earlier - sorry about that. I've converted the refs to the cite.php format now. Worldtraveller 11:25, 12 June 2006 (UTC)

[edit] Affection on Earth?

Could planetary nebulas affect Earth like the supernova explotions or the Gamma-Ray Busts?--Spaceman 16:26, 10 July 2006 (UTC)

Err... gamma-ray busts? :-) I would think probably not, unless you mean a planetary nebula generated by an evolved Sun. — RJH (talk) 17:14, 11 January 2007 (UTC)

[edit] Wings of a Butterfly Nebula

Needs a home. I'm currently working on orphaned articles. Any suggestions? meatclerk 10:07, 13 September 2006 (UTC)

[edit] Links needed

AGB giants produce planetaries, as far as I believe I know. Thus some link from here to Asymptotic Giant Branch? Rursus 22:39, 8 January 2007 (UTC)

A link is in the See also section. WilliamKF 01:07, 14 February 2007 (UTC)

[edit] Thermal pulses from double-shell?

It was pointed out to me elsewhere that the thermal pulses may be produced due to instability of a double-shell (H-He) burning phase (during the post-AGB evolution of a <8 solar mass star).[1] I'm not sure that the text quite captures this detail. — RJH (talk) 17:33, 8 June 2007 (UTC)

[edit] Updated the information on the PNe numbers in the Galaxy

I have taken the liberty of updating the information on the PNe page due to the significant new Galactic PNe that have been reported in the literature and have also updated the references. I also included a reference to the recent high quality H-alpha survey which permitted these discoveries. Out of interest I attach the web link to this powerful on-line survey: http://www-wfau.roe.ac.uk/sss/halpha/ as the entire survey is available in digital form for dowload as fits images. Respectfully yours Quentin A Parker 31/07/07130.79.129.227 09:06, 29 July 2007 (UTC)

[edit] 1500 vs 3000?

The intro says there are 1500 nebula, while "Numbers and distribution" says 3000. Beast of traal T C _ 03:26, 3 March 2008 (UTC)Beast of traal

[edit] 30000K

The article says that: "When the exposed surface reaches a temperature of about 30,000K, there are enough ultraviolet photons being emitted to ionize the ejected atmosphere, making it glow. The cloud has then become a planetary nebula." But the rest of the article mentions temperatures as high as 100 million K. Is that 30,000K right? Because it would seem logical that the exposed surface of the star is VERY hot. Am I wrong? 195.50.206.252 (talk) 11:14, 26 April 2008 (UTC)