Talk:Type II supernova

message: The body of this article was formed from a section of the FA'd supernova page. The material was copied here primarily to reduce the length of the supernova article. This should allow for expansion of the content. — RJH (talk) 21:42, 1 May 2007 (UTC)
replies: text: Nice work! ··coelacan 18:58, 6 May 2007 (UTC)
thread_title: Supernova article

message: This article was just started? Nice work! Trevor GH5 21:28, 6 May 2007 (UTC)
replies: text: I was "blown away" by this too ... seems it was split off from an existing FA, but it's still a great article.  Kudos to those who wrote it! Antandrus  (talk) 21:30, 6 May 2007 (UTC)
thread_title: New article?

message: I am glad to say that this article which was nominated for good article status has succeeded. This is how the article, as of June 3, 2007, compares against the  six good article criteria:
:1. Well written?: All the potentially obscure jargon has been explained. In the future perhaps some edit could be usefull to "lighten" the lead" (it's just my point of view on the lead, but it pass WP:LEAD) the rest of the article is just great.
:2. Factually accurate?: There is no problem everything is well sourced
:3. Broad in coverage?: This article give all the important information on the matter, personnaly I found reading that article great for my knowledge (particulary the Core collapse section)
:4. Neutral point of view?: No problem of point of view.
:5. Article stability? It's stable, no edit war.
:6. Images?: Picture are appropriate, all free license.
If you feel that this review is in error, feel free to take it to a GA review. Thank you to all of the editors who worked hard to bring it to this status. 
— Esurnir 19:44, 3 June 2007 (UTC)
replies: text: Thank you. — RJH (talk) 14:47, 4 June 2007 (UTC)
thread_title: Successful [[Wikipedia:Good articles|good article]] nomination

message: Article says: "When the core's size exceeds the Chandrasekhar limit, degeneracy pressure can no longer support it, and catastrophic collapse ensues."
From my understanding, electron degeneracy pressure rises with density. New electrons crammed into each cubic meter get higher and higher speeds just because lower energy levels are all taken by electrons which were already there. This fails when new electron's energy is so high that it can fuse with proton (ordinarily it is not possible, e + p weigh less than n). Such electron "disappears", it no longer contributes to degeneracy pressure.
Density starts to rise fast, more electrons fuse.
That's how degeneracy pressure fails. If this description is correct, can it be added to the article?—Preceding unsigned comment added by 89.102.207.196 (talk • contribs) 
:Well, first it would need a reference. I think it also needs some modifications to comply with the Wikipedia:MoS, such as avoiding unnecessary vagueness. But yes I think something like this would make a nice addition.—RJH (talk) 16:15, 12 May 2008 (UTC)
thread_title: How exactly degeneracy pressure fails?

message: The middle C humming model for patching the missing link between core collapse and explosion HERE. Use or dismiss at your option, while I dig into other matters. Said: Rursus (☻) 20:46, 3 November 2008 (UTC)
thread_title: Humming core autodestruct

message: The onion star picture seems to be incorrect. Oxigen inside Neon? I don't think so. Dauto (talk) 19:56, 21 February 2009 (UTC)
replies: text: Actually I believe that is correct. See: http://commons.wikimedia.org/wiki/File_talk:Evolved_star_fusion_shells.png Yes it is contrary to intuition.—RJH (talk) 19:51, 22 February 2009 (UTC)

text: It is correct. Neon burning occurs at lower temperatures than Oxygen burning. ... said: Rursus (bork²) 20:47, 10 May 2009 (UTC)
thread_title:  The onion 

message: As part of the WikiProject Good Articles, we're doing sweeps to go over all of the current GAs and see if they still meet the GA criteria. I'm specifically going over all of the "Stars, constellations, and clusters" articles. I believe the article currently meets the criteria and should remain listed as a Good article. I have made several minor corrections throughout the article. Altogether the article is well-written and is still in great shape after its passing in 2007. Continue to improve the article making sure all new information is properly sourced and neutral. I would recommend going through all of the citations and updating the access dates and fixing any dead links. If you have any questions, let me know on my talk page and I'll get back to you as soon as I can. I have updated the article history to reflect this review. Happy editing! --Nehrams2020 (talk) 02:21, 3 March 2009 (UTC)
replies: text: Thanks for checking on this article.—RJH (talk) 19:46, 3 March 2009 (UTC)
thread_title: GA Sweeps Review: Pass

message: Why doesn't this article say anything about how bright a type II supernova can be?  We see a nice luminosity curve, but nothing about how bright the darn things tend to be.  I came here hoping for some information on that.  John Baez (talk)
:Yes you're right, we should include some information about that, even though the absolute magnitude varies quite a bit for a Type II.—RJH (talk)
::All the more reason to provide the info.  The quantity of data now available on supernova luminosity, ranging from "faint" to "hypernova", deserves to be expressed here. Lithopsian (talk) 10:45, 1 June 2012 (UTC)
thread_title: Luminosity?

message: Until I read this article I thought I had understood the Chandrasekhar limit as being about 1.4 times the mass of the Sun. This article, however, says that the Chandrasekhar limit relates to the mass of the iron core within a star, and the star itself must be about 9 solar masses to obtain an iron core of 1.44 solar masses.  Glad I read it!!
And I guess it must be so.
:You might also want to read the Type 1a supernova article.—RJH (talk) 15:11, 31 July 2009 (UTC)
thread_title: Comment?

message: The first sentence of this article is misleading. A type II supernova is *not* a subtype of a cataclysmic variable.   —Preceding unsigned comment added by Alexanderd (talk • contribs) 18:30, 17 October 2009 (UTC)
replies: text: The cdsweb web site, which is based on the General Catalogue of Variable stars, categorizes Supernovae under cataclysmic variables.—RJH (talk) 17:14, 19 October 2009 (UTC)
thread_title: First Sentence

message: Just curious if anyone thinks this too, but it looks like a face in the center of the supernovae remnant! Does anyone else see this? Syntheticalconnections (talk) 02:19, 10 March 2010 (UTC)
replies: text: Nope.—RJH (talk) 19:20, 10 March 2010 (UTC)
thread_title:  Supernova 1987 A Image 

message: "Eventually, as the hydrogen at the core is exhausted, fusion starts to slow down and gravity causes the core to contract."
Actually burning hydrogen into helium causes the core to heat up because it is more dense.  This is why old Sol is getting brighter all the time.  Hcobb (talk) 23:41, 13 November 2010 (UTC)
replies: text: The significant word there is "exhausted".—RJH (talk) 20:30, 15 November 2010 (UTC)
thread_title:  Core evolution 

message: article says  very roughly 4 solar masses;
here are a few references, all NASA, saying 1.3-2.5, or 1.4-3.2
http://www.nasa.gov/mission_pages/GLAST/science/neutron_stars.html
http://heasarc.gsfc.nasa.gov/docs/xte/learning_center/ASM/journey/neutron_star.html
http://www.nasa.gov/centers/goddard/news/topstory/2007/millisecond_pulsar.html
http://imagine.gsfc.nasa.gov/docs/ask_astro/answers/010607a.html  — Preceding unsigned comment added by 91.201.80.240 (talk) 13:08, 22 March 2012 (UTC)
replies: text: Yes, unless I am misreading it, the cited Bombaci (1996) paper also says 1.5–3.0 solar masses. Possibly somebody just made a typo, or they were being extremely conservative, so I changed the article to match. Thanks for the catch. Regards, RJH (talk) 15:35, 22 March 2012 (UTC)
thread_title:  I thought the upper limit for a neutron star was 3 solar masses, not 4 

message: As discussed at times on this page and elsewhere, type Ib/c and type II supernovae are only slight variants of the same thing: a core collapse supernova.  Most of the things that could be said about one apply to the other.  So here is a proposal to merge the two pages. Lithopsian (talk) 19:18, 4 June 2012 (UTC)
replies: text: I removed the merge tags based on this from the article "A supernova is first categorized as either a Type I or Type II, then sub-categorized based on more specific traits. Supernovae belonging to the general category Type I lack hydrogen lines in their spectra; in contrast to Type II supernovae which do display lines of hydrogen. The Type I category is sub-divided into Type Ia, Type Ib and Type Ic supernovae." It didn't make sense to merge Type 1's into a Type 2 article. Maybe a merge into Type 1. AIRcorn (talk) 11:35, 18 October 2012 (UTC)
replies: text: The type I/II classification is an early attempt to classify supernovae based on the gross appearance of their spectra.  As discussed in the artcles, it does not reflect the true nature of the explosions or the progenitors.  This has resulted in the split into type Ia and Ib/c which are entirely different objects, while type Ib/c and type II supernovae differ only in fairly superficial ways, essentially just the quantity of hydrogen remaining in their atmospheres.  It absolutely would not be acceptable to merge the type Ia supernova article with any of the others.  I have extensively revised the top level supernova article to reflect both the spectral classification system and the actual nature of the different types, but the sub-articles desperately need revision.  My thought was to create sub-articles covering white dwarf supernovae (type Ia) and core collapse supernovae (everything else), but I would welcome other options.  The status quo is not an option as the articles are badly out of date and misleading, and the content of the articles on type Ib/c and type II overlap heavily. Lithopsian (talk) 11:43, 18 October 2012 (UTC)
replies: text:  I think you're on the right track. Two articles - white dwarf supernovae and core collapse supernovae. Then have the type Ia redirect to the first article and type Ib/Ic and type II redirect to the second. If the first-paragraph summary includes mention of the specific numbered types it covers, that probably does the job. Tarl.Neustaedter (talk) 06:30, 19 October 2012 (UTC)
replies: text:  I think that merging it would be too broad. When I did some research for Science Olympiad some time, I found that the presence of different articles was helpful to keep the two concepts organised and away from each other, as merging them painted the subject too broadly and too generally. I think that supernovae should be separated by the general class (I, or II), as it keeps the topics different and away. Ifly6 (talk) 16:17, 8 May 2013 (UTC)

text: You're just making stuff up.  Did you read the articles, or even the proposal?  They are very much treated in the groupings I describe my modern researchers, with type Ib/c and type II generally considered together, and type Ia separately.  Just because astronomers of the last century categorised them in a confusing way before they knew better, doesn't mean we can't describe them in a more helpful way for people.  Lithopsian (talk) 12:34, 11 November 2013 (UTC)
thread_title:  Merge Type II and Type Ib/c? 

message: This article states that silicon burning process of a star with 25\begin{smallmatrix}M_\odot\end{smallmatrix} lasts about 5 days. Silicon burning process article states that silicon-burning process of (mass of the star not defined) lasts less than a day. Can someone find out which one of it is true and how much does the duration of silicon-burning process differ from stars of 10 \begin{smallmatrix}M_\odot\end{smallmatrix} to 120 \begin{smallmatrix}M_\odot\end{smallmatrix}? --Artman40 (talk) 11:58, 25 June 2012 (UTC)
replies: text: It depends.  Asking how long without specifying in exactly what conditions is like asking how long a star lives for without specifying which star.  Also "Silicon burning" is not an entirely well-defined event.  It starts gradually as the core temperature increases, and may end before all Silicon is consumed, or it may build up to a substantial core largely depleted of elements lighter than the iron group, and may continue further in a shell.  With some standard definitions about how the duration is defined, a typical 10 solar mass star (about 15 before mass loss) will burn silicon for 5-10 days, while a 15 solar mass star (initially around 60) will burn silicon for a day or less.  If you want a real contrast, consider that in the conditions of a white dwarf supernova, complete silicon burning takes place in seconds. Lithopsian (talk) 13:48, 25 June 2012 (UTC)
replies: text:  Another thing is about the period after the silicon-burning process is finished. Does the star collapse start straight away after or does the majority of nickel-56 and cobalt-56 have to decay into iron-56 for a collapse to start? If the core is still composed mainly of nickel-56 and cobalt-56, should we replace some of the images of a star illustrating pre-supernova state by replacing iron in the core with nickel and cobalt as not a lot of iron-56 hasn't been created yet from the radioactive decay? --Artman40 (talk) 00:32, 26 June 2012 (UTC)
replies: text:  Absolutely not.  The core does not consist mainly of Ni and Co.  It consists mainly of Fe, that's why it is called an iron core :)  Ni and Co are not energetically favoured (and are radioactive so they decay to iron anyway) and are only produced in large quantities when the supernova explosion occurs.  The collapse itself does not occur until the core is too large to be supported by electron degeneracy, so silicon shell burning will continue adding iron to the core until it reaches about 1.4 solar masses. Lithopsian (talk) 10:39, 26 June 2012 (UTC)
replies: text:  Perhaps even more detail.  The explosion produces mainly nickel-56 which then decays to cobalt-56 which then decays to iron-56, all the while powering the visible light curve.  Details of the core formation are complex, and there is considerable mixing and convection.  Because of this, the inner core may not form as near-pure iron and it may have a mass considerably larger than 1.4. But the basic idea is an iron core forms, it is degenerate because there is no further source of energy from fusion, it grows, it collapses, the energy forms masses of nickel and a big explosion.Lithopsian (talk) 11:16, 26 June 2012 (UTC)
thread_title: Silicon burning process duration discrepancy

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thread_title:  Malware Link Removal 

message: Before this article was split from Supernova, this edit added a ref, which came with it in the split. So far as I can tell, it does not support the statement for which it is cited. Could someone please double-check? LeadSongDog come howl! 16:08, 10 October 2017 (UTC)
replies: text: Agreed.  Just looks like two random supernova papers not directly relevant to the claims in the article.  The claims are not unreasonable, just not cited.  Lithopsian (talk) 16:29, 10 October 2017 (UTC)
thread_title:  Failed verification 

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thread_title:  External links modified (January 2018) 

message: Regarding:
: "The IIb class was first introduced (as a theoretical concept) by Woosley et al. in 1987,[39] and the class was soon applied to SN 1987K"
But that source has SN 1987 in its title. How can it then be a theoretical concept first (that is at least how it can be read - complete separation of the theoretical concept and the application of the theoretical concept)?
If the theoretical concept was inspired by SN 1987, isn't it misleading?
--Mortense (talk) 19:59, 20 June 2021 (UTC)
replies: text: SN 1987A ≠ SN 1987K.  Lithopsian (talk) 19:02, 21 June 2021 (UTC)
thread_title:  Wrong causality? 

message: The known energy source is not sufficient (Liebendorfer et al. 2008). Aldebarium does not allow to cite them, nor the known additional energy sources (my version of 00:25, 28 May 2022‎) because "much of the content was based on non-notable source material." Earlier Woosley & Heger (2007), which is a notable source of material cited 700+ times, noted that the energy source is not known, but Lithopsian does not allow it either because the energy source is known (correct! See sources in (not allowed) references in my version of 00:25, 28 May 2022‎). What is left after the combined forbiddings seem to me "Catch 22" and "Eyes Wide Shut" together: Ignoring the problem. Netsivi (talk) 20:50, 11 July 2022 (UTC)
thread_title:  Energy source