Talk:Nebula

Goal?

"The main goal in this stage is to achieve equilibrium."

Stars and nebulosa don't have goals... —Preceding unsigned comment added by 129.123.248.44 (talk) 07:12, 25 April 2009 (UTC)

 But it'll eventually reach equilibrium so its "goal" is to reach equilibrium.  —Preceding unsigned comment added by 68.200.110.9 (talk) 21:27, 25 May 2010 (UTC) 

Dark Nebula under Diffuse Nebula

the dark nebula is listed within the category "Diffuse Nebula", even though it says that dark nebulae arent a type of diffuse nebulae —Preceding unsigned comment added by 216.232.237.84 (talk) 02:17, 13 December 2007 (UTC)

Possible Misinformation

The following material is not accurate, so I put it here until I (or someone else) corrects it and reincorporates it into the main text. AN

Stars emanate gas during novae and supernovae, giving rise to planetary nebulae and supernova remnants, respectively. In a nova, the star sloughs off its outer layers of gas as it collapses into a dwarf, and these clouds are propelled outward by the remaining star's stellar windand glow from the heat of the star. In a supernova, the star collapses violently on itself and explodes with an enormous shock wave which lights up all the interstellar gas in the region, and the remaining neutron star or black hole emits highly charged radiation as it sucks up everything around it, keeping the center of the cloud brightly lit

At this point the star may die or move on, and the cloud may disperse and merge with other clouds. But when the dust is dense enough, gravity will turn the inevitable knots and perturbances into new stars. These new stars may reflect light off the gas, creating a reflection nebula, or excite the gas with their radiation, creating an emission nebula. Many nebulae display both characteristics, and are referred to as diffuse nebulae. In addition, the lit parts of this kind of nebula may be blocked by unlit gas on the nebula's periphery, creating a dark nebula.

--Unknown Editor from an early version of the talkpage

I also removed some rather obvious inaccuracies from the article. Specifically, 66.178.172.98 had made an edit claiming that the Eagle Nebula was now considered a galaxy, which sounds laughably implausible to me. Hope I wasn't out of line, as I am kind of new around here. --Cecilkorik 02:33, 15 May 2007 (UTC)

Merging Types of Nebulae

I don't know who proposed the merge, but I agree with it. When I first came to the Nebula article, I was actually looking for more information about the different types of nebula. I would never have thought to look under 'Types of Nebula' to find that information. Most other articles seem to provide a fairly comprehensive discussion of types in the main article, only branching off into a separate article if the information becomes extremely detailed, which is not the case here. In any case, there should be at least some discussion of the various types of nebulae in the main article, as currently there is none. Cecilkorik 18:16, 24 May 2007 (UTC)

This article now needlessly repeats itself now that Types of nebula has been merged. It needs a bit of re-writing. Rip-Saw 12:42, 23 August 2007 (UTC)

Molten planets

I would like to see an explanation of why the planets were initially in a molten form if they formed from nebulae. 71.102.74.156 (talk) 02:45, 9 December 2007 (UTC)

did you know that the star forbidden galaxy of nebularmeland contains 6 billion million geeknebulars, thats 40 000 000 nebulars all together... in just one galaxy —Preceding unsigned comment added by 86.141.48.0 (talk) 20:21, 4 September 2008 (UTC)

I would also like to see that but also i would like to just have a understandable explanation, or just a simple definition. Like :

nebula- a large amount of clouds of gas or dust in space.

I need something that would be understandable to a small child. Or for someone doing homework and has no clue what a certian word is. Otherwise, they, as i, will go to some other page to find the information i need —Preceding unsigned comment added by 72.177.4.236 (talk) 17:38, 7 December 2008 (UTC)

Merger proposal

This merge tag has been left here for about 4 months as far as I can tell...Creating a place for discussion. From what I can see, the two are syonymous (??) but I will defer to someone who knows more. Casliber (talk · contribs) 19:29, 16 February 2009 (UTC)

• Oppose. They are not exactly synonymous. Interstellar cloud is just a cloud of gas regardless of its external appearance. Some gas clouds are invisible. Nebula refers to a luminous extended object. Initially this definition included galaxies and star clusters as well. Another difference is their origin. For instance, planetary nebulas are technically gas clouds, although they are never called such. Interstellar cloud commonly refers to a cloud that formed naturally from the interstellar medium, and was not ejected from a star. Ruslik (talk) 19:54, 16 February 2009 (UTC)

Cool. Not sure who placed the merge tag in the first place....Casliber (talk · contribs) 20:00, 16 February 2009 (UTC)

I found this message at WP:PM:

Merge Interstellar cloud with Nebula those are two articles about the same subject. Carsrac (talk) 18:13, 10 December 2007 (UTC)

76.66.196.229 (talk) 08:07, 18 February 2009 (UTC)

To make a good encyclopedia (and avoid future merger proposals) the articles should reflect the abovementioned differences between the 2 terms, preferably in the article lead section. Debresser (talk) 17:17, 19 February 2009 (UTC)

As there appears to be no support for the proposed merge, I've removed the tags from the articles. Euryalus (talk) 10:45, 28 March 2009 (UTC)

also the nebula was formed by a gigantic cow living on the surface of pluto. this information is completely correct as i studied this theory for 15 years at oxford university, along with the theory that uranus is 3 times larger than the cow. —Preceding unsigned comment added by 81.154.251.147 (talk) 11:16, 18 April 2011 (UTC)

Headline text

more information would be good. —Preceding unsigned comment added by 99.140.74.186 (talk) 22:43, 1 April 2009 (UTC)

Top Right Picture

Cough Cough, is it supposed to be called "Testical Emission Garren Nebula"? (or am I just being childish) 91.105.64.59 (talk) 14:15, 11 June 2009 (UTC)

Types of nebulae

After watching the History Channel, they said that there are 4 types of nebulae.

• Diffuse (which encompasses Bright and Reflection)
• Planetary Nebula
• Supernova Remnant
• Dark Nebula

But is also mentions that other items, by right, are also really nebulae.

• Herbig Haro

They do not mention Protoplanetary Nebulae. Thanks, Marasama (talk) 15:56, 31 July 2009 (UTC)

BTW, Protoplanetary Nebulae are in fact proto-(Planetary Nebulae), i.e. very new Planetary Nebulae. ... said: Rursus (^mbork³) 16:31, 19 August 2009 (UTC)

There are lots of types not mentioned. I would group diffuse and dark nebulae together into a bigger interstellar cloud nebula group (mostly hydrogen, carbon, oxygen and compounds thereof), the development sequence of interstellar cloud nebulae use to be:

1. a dark nebula slowly compresses, often under the star wind pressure from bright young stars of O and B types, other times by gravitational instabilities caused by nearby supernova explosions. The dark nebulae tend to "fracture" and develop to protostars.

2. The protostars attain high temperatures and infalling gas create spectacular brightness variation and nebulosities, so called YSO nebulosities (young star object) , the smaller protostars constituting T Tauri objects, the brighter ones so called Herbig-Haro object nebulae, f.ex. Hind's variable nebula is a nebulosity near a T Tauri star.

3. After a time (~10-100 ma) the central fusion of the Proton–proton chain reaction (or CNO cycle for heavier stars) starts and most dark nebulosity is dispersed, often to reveal a newly formed planetary system. If the star is very luminous, of stellar classification types O and B, the stellar wind might excite hydrogen in the surrounding more "dilute" nebulosity, making it glow red from the Balmer H_α excitation (the Balmer series represented by HII - H-roman-2), a kind of bright nebulosities, among others Orion Nebula (M42), Rosette Nebula, Eagle Nebula and such.

4. After some more time, the excited HII are removed from the neighborhood of the stars, either by the star wind, later star creation, supernova explosions or the stars simply moving away from those clouds, and for a while afterwards the removal of most surrounding hydrogen, dust particles remain around the stars, constituting reflection nebulae for example the reflection nebulae around the stars in Pleiades. I think that dust is very much carbon and other solid goo.

I'll be back in half'n'hour but before that, the other types are old stars' ejecta: among others planetary nebulae (PN:s), supernova remnants, wolf-rayet ejecta, and other spectacular thingies... ... said: Rursus (^mbork³) 16:30, 19 August 2009 (UTC)

Next: the old stars' ejecta doesn't exhibit any developmental sequence like the one above. Old stars are stars nearing the end of their "lives", the fusion is about to stop because the fuel is running out.

A. A planetary nebula is a normal mass star, sun sized that have run out of hydrogen and grown a red giant, started helium fusion that have also begun to run out and so become a asymptotic giant branch giant, that besides being red and swollen also undergoes thermal pulses, and slowly enrich the carbon in the atmosphere to become a carbon star. One final thermal pulse occurs and thereafter the star throws it's envelope (atmosphere and thick layers underneath) into space. That's the protoplanetary nebula (PPN). Underneath reveals a hot blue core star, that emits a strong star wind, that blows away the envelope in a ring or a bipolar structure, the PPN soon becomes a regular planetary nebula and the central star becomes bluer and bluer by compression. Planetary nebulae spectra contains forbidden green lines of oxygen and neon, indicating extremely attenuated gas excited by the stellar wind. The outermost parts of the nebula exhibit spectra as an atenuated stellar atmosphere.

B. A heavy star, say class early B or O emits a very strong stellar wind, and the star wind driven ejection of material from the star seem to accelerate so that later in the life, the star accretes a nebulosity of larger and larger parts of the atmosphere, while lower and lower layers of the star is laid bare, this is a Wolf-Rayet star. Many Wolf-Rayets also seems to have originated in binary star systems where one component removes the envelope of the other star. The final fate of this class of stars is not known but it is likely some of them go supernovae. Wolf-Rayet nebulae exhibit spectra as atenuated stellar atmospheres.

C. An extraordinarily heavy star, belonging to the rare hypergiant and the rare luminous blue variable (LBV) groups, seems to get rid of its own atmosphere quickly. Eta Carinae belongs to this group. Their ejecta often obscure the star themselves, so that Eta Carinae slowly developed to magnitude -0.8 in 1843 then declined to mag 8 in 1900—1940, and now has mag about 5, believed to increase once again. LBV ejecta have no unique name that I know of... It is generally believed Eta Carinae will blang supernova shortly (where short is 1000:ths of years).

D. Supernovae. Heavy stars that run out of fuel, first hydrogen, then helium, then carbon, then neon and oxygen and then the fusion modes becomes complicated with lots of alpha particles merging with whatever it hits. This occur in a few days and then all possible fusion modes run out of fuel and the star core collapses, or so. The details are still under discussion, but at the same time the star explodes violently and ejects all atmospheric and envelope stuff, including the radioactive supernova signature Nickel-56, that under some months steadily decliningly decays to Cobalt-56 and then Iron-56. The supernova remnants exhibit spectra of this or that chemical element, among others silicon and other alpha process elements characteristic of the late life stages of the star.

There are certainly more types, f.ex. symbiotic stars and such, but I think these are the most commonly known. ... said: Rursus (^mbork³) 17:46, 19 August 2009 (UTC)

Listing types

Moving the list here.

Diffuse (encompass Bright & Reflection) (HII region) Planetary Nebula (PN) Protoplanetary Nebula (PPN) Super Planetary Nebula (from intermediate sized stars) Supernova Remnant (SNR) Hypernova Remnant (theory) Dark Nebula Pinwheel Nebula (dated, are now determined to be galaxies) Pinwheel Nebula (occurring around WR stars)

Herbig Haro object (HH) Hot Corino (heated gas around PMS stars) Materials around shell stars? Dust and tail around the Mira stars? Infrared Cirrus Hypervelocity Cloud (HVC) Intermediate Velocity Cloud (IVC) Low Velocity Cloud (LVC) Intergalactic Cloud (ie. Smith's Cloud) X-ray Nebula (XRN) Pulsar Wind Nebula (PWN) Bok globule Cometary globule

Thanks, Marasama (talk) 23:11, 23 August 2009 (UTC)

(I made it multicolumn for the sake of overview ... said: Rursus (^mbork³) 10:47, 27 August 2009 (UTC))

Cool, thanks, Marasama (talk) 20:45, 29 August 2009 (UTC)

Just adding reference to prepare

Basic info. on nebula. Not the detail items.

• http://www.haystack.mit.edu/edu/pcr/resources/astronomyhistory.htm
• http://www.noao.edu/image_gallery/nebulae.html
• http://seds.lpl.arizona.edu/Messier/nebula.html

Still trying to find the history on it and the first nebula discovered. Thanks, Marasama (talk) 18:00, 20 October 2009 (UTC)

History to-do list

This is just a working list of information that could be added to the History section:

• The General Catalogue of Nebulae and Clusters of John Herschel, which later became the NGC. John Herschel postulated that that there was sparse matter throughout space that did not glow.
• Lord Rosse discovers that many of the nebulae have a spiral structure. He and John Herschel were at odds over the nature of nebulae, with Rosse believing they were unresolved clusters of stars. (The contention was related to the theory of evolution, with Rosse not believing that new stars were still forming.)
• In 1900, Cornelius Easton argued that the Milky Way had a spiral structure and that many of the nebulae formed part of this structure.[1] (This had first been suggested in the middle of the 19th century.)[2]
• The observations of E. E. Barnard lent weight to the idea that the dark regions of the sky were actually obscuring matter (rather than tunnel-like holes suggested by John Herschel).[3][4]
• The 1920 Shapley–Curtis Debate that would lead to the categorization of many nebulae as Island Universes (or galaxies) per Edwin Hubble.
• Max Wolf was the first person to estimate the distance to interstellar clouds. His approximation compared the number of stars per square degree (and their magnitudes) in a cloud region to elsewhere.
• In 1927, Herman Zanstra determined how the neutral hydrogen in H II regions became excited.
• The 1927 explanation by Ira Sprague Bowen of the forbidden lines in the O III spectrum within nebula. (Previously attributed to "nebulium".)
• The 1953 suggestion of Iosif Shklovsky that the continuum radiation from the Crab Nebula is actually synchrotron radiation.

If you can add some of these in to the article, it would be appreciated. Thanks.—RJH (talk) 19:38, 1 November 2009 (UTC)

Question on other types of Nebulae and/or Clouds

What the difference between Nebula and Molecular cloud?
Also there are types of Nebulae/Clouds. Talk:Nebula#Listing_types Thanks, Marasama (talk) 15:53, 28 December 2011 (UTC)