# Talk:Type Ia supernova

This article was the subject of a Wiki Education Foundation-supported course assignment, between 30 March 2020 and 5 June 2020. Further details are available on the course page. Student editor(s): ThomasDKennedy.
Above undated message substituted from Template:Dashboard.wikiedu.org assignment by PrimeBOT (talk) 11:52, 17 January 2022 (UTC)

The seed for this article came from the FA'd supernova page. The later had reached 88 Kb, so material needed to be split off. The Type Ia section on the supernova article will be written summary-style. — RJH (talk) 19:39, 1 May 2007 (UTC)

Summary-style rewrite completed. — RJH (talk) 18:47, 25 May 2007 (UTC)

In the "Consensus model" page it first stated that the star is unbound. But a subsequent addition said that:

As a general rule, the system will remain bound if the remnant is heavier than one half of the original total system mass. If not, the companion will evolve into a runaway star.
So this is contradictory to me. This reference states that the most favored scenario is the "complete disintegration of a CO white dwarf". Was this a confusion with core-collapse supernovae? — RJH (talk) 15:54, 24 May 2007 (UTC)

I have reviewed this article according to the GA criteria and have put the article on hold at this time until the following issues are addressed.

"The current view is that this limit is never actually attained, however, so that collapse is never initiated." What is the current view? From a particular group? Generally accepted by all astronomers? Specify a little here.
I specified that this is the viewpoint among astronomers who model these explosions. Also I added in an approximate mass and another reference.
"Regardless of the exact details of nuclear burning, it is generally accepted that a substantial fraction of the carbon and oxygen in the white dwarf is burned into heavier elements within a period of only a few seconds,[7] raising the internal temperature to billions of degrees." Either expand on this or incorporate it into another paragraph. Single sentences shouldn't stand alone.
Merged.
"A second possible, but much less likely, mechanism for triggering a Type Ia supernova is the merger of two white dwarfs, with the combined mass exceding the Chandrasekhar limit." Exceeding is spelled wrong.
Fixed.
"The white dwarf companion could also accrete matter from other types of companions, including a main sequence star (if the orbit is sufficiently close)." Again, expand or incorporate into another paragraph.
Done.
Somewhere in the article, maybe in its own section, include the differences between a Ia supernova and a Type II supernova. Also add Type II supernova to the See Also section.
I added a sentence about core-collapse supernovae, but really the supernova article is where the two are compared.
See if there are any other external links that are relevant and informative that could be added. Make sure they comply with WP:EL.
Seems a bit of a stretch, but I added two more. :-)
This isn't too much to fix, and I'll leave the article on hold for up to seven days. If you have any questions or when you are done addressing the above issues, let me know on my talk page and I'll get back to you as soon as I can. --Nehrams2020 18:41, 23 May 2007 (UTC)

Thank you for the review. I've attempted to address the outstanding issues. — RJH (talk) 18:40, 25 May 2007 (UTC) 

I have reviewed this article according to the GA criteria and have passed this article. Good work on addressing the above issues so quickly. The article is very informative and it was interesting read. I'll probably let another editor review Type II supernova just so there is a difference of opinion in the reviews. Make sure that the article maintains its high quality, and ensure than all new information is properly sourced. As a side note, are there any WikiProjects that this article falls under? If so, please add them to the top, as I'm sure they want to keep track of their GA articles. If you get the chance, please consider helping with the current drive to remove the backlog at GAC. Even if you review just one or two articles, the review waiting time will be reduced for new candidates. Keep up the good work, and I hope you continue to improve the quality of articles on Wikipedia! --Nehrams2020 18:50, 25 May 2007 (UTC)

Thanks again. — RJH (talk) 16:09, 26 May 2007 (UTC)

The following article discusses an unusual mechanism for igniting Type 1a supernovae through tidal disruption by an IMBH in a globular cluster.

Stephens, Tim (January 30, 2008). "Unusual Supernovae May Reveal Intermediate-Mass Black Holes In Globular Clusters". Space Daily. Retrieved 2008-01-30. {{cite web}}: Check date values in: |date= (help)
It should be interesting to see if this is observationally confirmed.—RJH (talk) 19:47, 30 January 2008 (UTC)

Under "Light curve", the text says that "Near the time of maximum luminosity, the spectrum contains lines of intermediate-mass elements from oxygen to calcium" while "The radioactive decay of nickel-56 through cobalt-56 to iron-56 produces high-energy photons which dominate the energy output of the ejecta at intermediate to late times." However the picture says "The peak is primarily due to the decay of Nickel (Ni), while the later stage is powered by Cobalt (Co)." This seems contradictory to me regarding the role of Nickel---or at least confusing enough to warrant clarification. -- Spireguy (talk) 14:20, 30 April 2008 (UTC)

Are you confused about how the "intermediate to late times" statement relates to the graph curve? Otherwise, the first statement shows that the Ni-56 decay produces Co-56, which then decays. Hence they are consistent chronologically.—RJH (talk) 16:21, 30 April 2008 (UTC)
I'll clarify: the confusion is about what generates the peak energy. The text seems to say that elements from Oxygen to Calcium are responsible for the emissions near the peak. The picture says that the peak is due to Nickel. That would be contradictory. Perhaps the Oxygen through Calcium lines are absorption lines, due to the outer layers filtering the Nickel-generated emissions? Or maybe they are emission lines, so that they are contributing to the output, but the Nickel-generated emissions are still predominant? Either would make sense logically, but whatever is going on, I think it needs to be spelled out. -- Spireguy (talk) 03:09, 1 May 2008 (UTC)

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 I passed it 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) 02:17, 3 March 2009 (UTC)

Thanks for checking on this article.—RJH (talk) 19:49, 3 March 2009 (UTC)

Wang, B.; Meng, X.; Chen, X.; Han, Z. "The helium star donor channel for the progenitors of Type Ia supernovae". Monthly Notices of the Royal Astronomical Society. doi:10.1111/j.1365-2966.2009.14545.x.{{cite journal}}:  CS1 maint: multiple names: authors list (link)
No issue information yet.—RJH (talk) 15:06, 15 April 2009 (UTC)

The first two paragraphs state the same thing that is covered perfectly well in the first two sections of Type_Ia_supernova.  The third paragraph paraphrases the "instability", but the link should suffice, or similar paraphrasing can be added to the Supernova article.  The only thing that would be missed if this article were deleted would be some of the links.
Długosz (talk) 20:11, 2 July 2009 (UTC)

Ah, I see... You want to merge Carbon detonation to here. Looks like it might be a good idea. --Falcorian (talk) 23:07, 2 July 2009 (UTC)

This has been cluttering up the article for months. I'm moving it here for aesthetics reasons.
—RJH (talk) 17:35, 23 February 2010 (UTC)

http://www.nytimes.com/2010/02/23/science/space/23star.html
This may also change the accuracy of the standard candle method according to the article  —Preceding unsigned comment added by 98.232.150.32 (talk) 18:04, 23 February 2010 (UTC) 

The type Ia's formed by collisions are already mentioned in this article, so I think we're okay. The NYT article also mentions that this shouldn't change the dark energy result.—RJH (talk) 20:52, 23 February 2010 (UTC)

Just posting this link as it might be useful/interesting for editors of this article.
Astronomers Hunt for Ticking Time Bombs
Jedikaiti (talk) 18:52, 20 July 2010 (UTC)

Thanks. It would probably be best to wait for the primary source to get published.—RJH (talk) 19:45, 20 July 2010 (UTC)

Good article but there is a glaring omission: the frequency with which this type of supernova occurs. I am not competent to answer this question and have no familiarity with the literature so I won't attempt to make the edit myself. But I'm sure there's someone out there who is competent to make the edit.154.5.45.119 (talk) 19:04, 5 September 2011 (UTC)

Do you mean the cosmic Type 1a supernova rate? Here is a possible source, but it estimates the local rate. RJH (talk) 15:41, 6 September 2011 (UTC)

I'm glad to see a light curve in this article, but the curve presented doesn't say how many days to the peak, or how long the peak lasts.  This interests me because SN 2011fe is in the news, and I'd like to know how long this particular supernova will be visible with small, portable telescopes.  Perhaps other readers have the same question.  Oaklandguy (talk) 18:15, 8 September 2011 (UTC)

We could list the half life of the radioactive elements that dominate the later stages of the light curve: 6.1 days for 56Ni and 77.1 days for 56Co.[1] Regards, RJH (talk) 15:53, 9 September 2011 (UTC)
The light curve is usually referenced to the peak and the time of the start is often poorly known. The timescale and curve are shown in figure 1 (f) of Goldhaber's key paper Timescale Stretch Parameterization of Type Ia Supernova B-band Light Curves. Perhaps some experienced author could extract that in a Wiki-friendly format and include it. George Dishman (talk) 08:37, 7 February 2014 (UTC)

Interesting information:

Francis, Matthew (February 27, 2012), "Explaining the explosion: rate of white dwarf mergers matches frequency of type Ia supernova", Ars Technica, retrieved 2012-02-28
Badenes, Carles; Maoz, Dan, The Merger Rate of Binary White Dwarfs in the Galactic Disk, arXiv.org, arXiv:1202.5472
Not yet published in a peer reviewed journal though. Regards, RJH (talk) 20:25, 28 February 2012 (UTC)
Published in The Astrophysical Journal Letters, 22 March 2012 as "The merger rate of binary white dwarfs in the galactic disk"--Gmacks (talk) 10:50, 19 January 2020 (UTC)

I was curious about the observation of Ia supernova's as evidence for an accelerating expansion. I have been reading up on the subject, and my understanding is that the reason we can use his particular type of supernova as a standard candle is due to the chandrasakar limit. In a binary system, the dense white dwarf pulls on matter from the other star. As matter 'rains' on the white dwarf, the white dwarf can potentially grow to a mass of 1.4 solar masses. At this mass, the star will collapse and supernova. Because of this particular mass of near 1.4 solar masses at collapse, we may infer distance through the observed luminosity of the event. Because mass and distance will determine a stars luminosity, we can infer distance through the intensity of the supernova- (a more intense nova would be nearer to us, a dimmer one would be further). So, the distance to the from observer to the supernova could be calculated through the inverse square law. 

Mass doesn't determine anything.  Type Ia supernovae are brighter than the much more massive type II supernovae.  What matters is primarily the amount of radioactive material (mostly Nickel) that can be ejected into space because that is what powers the light curve.  To some extent the kinetic eneregy of ejecta, not only radioactive material, is also relevant since that can be converted into visible light in some conditions. Some of the most massive supernovae, possibly including some white dwarf progrenitors, result in dim supernovae or even none at all as the radioactive and other ejecta are sucked into a black hole. Lithopsian (talk) 15:07, 5 July 2012 (UTC)
The section on light curves stated: "The similarity in the absolute luminosity profiles of nearly all known Type Ia supernovae has led to their use as a secondary[35] standard candle in extragalactic astronomy.[36] The cause of this uniformity in the luminosity curve is still an open question." 
The last sentence in particular confuses me. I will research light curves further, but i understood 'this uniformity' as a result of the similar masses of the white dwarves at the point of supernova. 

Like many things in astrophysics, the basic idea is fairly solid but the details elude us.  Most type Ia supernovae are produced from a highly uniform starting point and the highly uniform outcome is not surprising, but it still isn't entirely clear how we get from "too heavy" to "massive explosion destroys star".  There is already an established (small) variation in peak brightness which correlates with the width of the light curve and can't be modelled fully, while it is even less clear how the small percentage of substantially over or under luminous type Ia events are caused. Lithopsian (talk) 15:07, 5 July 2012 (UTC)
I have also had trouble in wiki research understanding how this particularly proves an accelerating universe. does the supernova spectra redden over time following the spectra? any answers or clarifications would be much appreciated!--Baleensample (talk) 01:31, 5 July 2012 (UTC)

The redshift of a type Ia supernova is an indicator of how much the universe has expanded since the explosion. The brightness gives an accurate distance. Comparing both for a large enough sample over a long enough period of time will show the rate of expansion and any changes in that rate over time. Wayne (talk) 11:25, 17 January 2013 (UTC)
The whole point of standard candles is the ability to determine the distance of something *independently* of its redshift, so then you know how fast things at different distances are moving away from eachother. Being that more distant objects are being observed as they were at progressively longer times in the past, we can tell whether the expansion of the universe is getting faster or slower.  Apparently it is faster, which was quite a surprise when first noticed and still the subject of great interest and refinement.  One obvious difficulty is whether the standard candle itself has a different brightness at different distances (ie different ages of the universe), and it almost inevitably is but the trick is to determine exactly how. Lithopsian (talk) 15:07, 5 July 2012 (UTC)

Why is angular momentum lost? Thanks.76.218.104.120 (talk) 22:53, 4 April 2013 (UTC)

Production of gravity waves. SkoreKeep (talk) 02:25, 20 May 2014 (UTC)

Hubble breaks record for furthest supernova.
Cheers! Josh, linguist (talk) 13:19, 6 April 2013 (UTC)

The article states ".. as the white dwarf approaches about 1% of the limit,[11] a period of convection ensues .." but the mass is already over 1.38 Msun and approaching 1.44 Msun. Should this say ".. approaches within about 1% of the limit ..", i.e. ".. approaches about 99% of the limit .."?  — Preceding unsigned comment added by GeorgeDishman (talk • contribs) 08:30, 7 February 2014 (UTC) 

What happens to the binary partner?

At the end of the observation section it reads "However, later analysis revealed that the CSM is too massive for the single-degenerate scenario, and fits better the core-degenerate scenario".
What is the "CSM"?

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The final section seems to be entirely devoted to uncritically advertising a controversial paper (ref. 57) and a media article describing it (ref. 56), both of which have been criticized by some of the leading experts (see e.g. https://blogs.scientificamerican.com/guest-blog/no-astronomers-haven-t-decided-dark-energy-is-nonexistent/).  This section either needs to be deleted, or to be rewritten to be NPOV.  — Preceding unsigned comment added by 2601:184:407F:A350:9DC1:78BB:FE19:498F (talk) 03:15, 25 February 2020 (UTC) 

"Type Ia supernova differ from Type II supernova ..." should either be "Type Ia supernovae differ from Type II supernovae ..." or "Type Ia supernovas differ from Type II supernovas ..." or "A Type Ia supernova differs from a Type II supernova ...".
I won't change it due to the risk of a vandalism ban.
--Felix Tritschler (talk) 11:55, 29 March 2021 (UTC)

Hi,
I found the wikilinking in this article perplexing. I think too many rather common words are linkified; and not enough unexplained 'terms of art' are linkified. 
For an example illustrating both problems, I was curious to learn more about "carbon-oxygen white dwarfs", which are not explained in the article. Helpfully, the term looks like a link - but it's two links, pointing to Carbon and Oxygen respectively. Anyone who's got this far in this article isn't going to be looking up chemical elements.
So I intend to tighten up the linkification. I'll tread gently. I'm not an expert at all. But there's a lot of outgoing links in the article, ranging from some which are directly helpful and supportive of the article, to others which seem only be useful for students of English as a foreign language (excuse the hyperbole).  
[Edit] Hmmm - I wonder if I've stumbled into "religious" territory? I hope not. I read the other day that some people think everything, every word, should be a hyperlink.
MrDemeanour (talk) 12:49, 11 September 2022 (UTC)