Editing Supernova (section)

====Non-standard type Ia====
Abnormally bright type Ia supernovae occur when the white dwarf already has a mass higher than the Chandrasekhar limit,<ref>
{{Cite journal
 |last1=Howell |first1=D. A.
 |last2=Sullivan |first2=M.
 |last3=Nugent |first3=P. E.
 |last4=Ellis |first4=R. S.
 |last5=Conley |first5=A. J.
 |last6=Le Borgne |first6=D.
 |last7=Carlberg |first7=R. G.
 |last8=Guy |first8=J.
 |last9=Balam |first9=D.
 |last10=Basa |first10=S.
 |last11=Fouchez |first11=D.
 |last12=Hook |first12=I. M.
 |last13=Hsiao |first13=E. Y.
 |last14=Neill |first14=J. D.
 |last15=Pain |first15=R.
 |last16=Perrett |first16=K. M.
 |last17=Pritchet |first17=C. J.
 |year=2006
 |title=The type Ia supernova SNLS-03D3bb from a super-Chandrasekhar-mass white dwarf star
 |journal=[[Nature (journal)|Nature]]
 |volume=443 |issue=7109 |pages=308–311
 |arxiv=astro-ph/0609616
 |bibcode=2006Natur.443..308H
 |doi=10.1038/nature05103
 |pmid=16988705
|s2cid=4419069
 }}</ref> possibly enhanced further by asymmetry,<ref>
{{Cite journal
 |last1=Tanaka |first1=M.
 |last2=Kawabata |first2=K. S.
 |last3=Yamanaka |first3=M.
 |last4=Maeda |first4=K.
 |last5=Hattori |first5=T.
 |last6=Aoki |first6=K.
 |last7=Nomoto |first7=K. I.
 |last8=Iye |first8=M.
 |last9=Sasaki |first9=T.
 |last10=Mazzali |first10=P. A.
 |last11=Pian |first11=E.
 |year=2010
 |title=Spectropolarimetry of Extremely Luminous Type Ia Supernova 2009dc: Nearly Spherical Explosion of Super-Chandrasekhar Mass White Dwarf
 |journal=[[The Astrophysical Journal]]
 |volume=714 |issue=2 |pages=1209
 |arxiv=0908.2057
 |bibcode=2010ApJ...714.1209T
 |doi=10.1088/0004-637X/714/2/1209
|s2cid=13990681
 }}</ref> but the ejected material will have less than normal kinetic energy. This super-Chandrasekhar-mass scenario can occur, for example, when the extra mass is supported by [[differential rotation]].<ref>{{cite journal | title=Thermonuclear explosions of rapidly differentially rotating white dwarfs: Candidates for superluminous Type Ia supernovae? | last1=Fink | first1=M. | last2=Kromer | first2=M. | last3=Hillebrandt | first3=W. | last4=Röpke | first4=F. K. | last5=Pakmor | first5=R. | last6=Seitenzahl | first6=I. R. | last7=Sim | first7=S. A. | journal=Astronomy & Astrophysics | volume=618 | id=A124 | date=October 2018 | pages=A124 | doi=10.1051/0004-6361/201833475 | arxiv=1807.10199 | bibcode=2018A&A...618A.124F | s2cid=118965737 }}</ref>

There is no formal sub-classification for non-standard type Ia supernovae. It has been proposed that a group of sub-luminous supernovae that occur when helium accretes onto a white dwarf should be classified as '''type Iax'''.<ref name=wang>
{{cite journal
 |last1=Wang |first1=B.
 |last2=Liu |first2=D.
 |last3=Jia |first3=S.
 |last4=Han |first4=Z.
 |year=2014
 |title=Helium double-detonation explosions for the progenitors of type Ia supernovae
 |journal=[[Proceedings of the International Astronomical Union]]
 |volume=9 |issue=S298 |pages=442
 |arxiv=1301.1047
 |bibcode=2014IAUS..298..442W
 |doi=10.1017/S1743921313007072
|s2cid=118612081
 }}</ref><ref name=foley>
{{cite journal
 |last1=Foley |first1=R. J.
 |last2=Challis |first2=P. J.
 |last3=Chornock |first3=R.
 |last4=Ganeshalingam |first4=M.
 |last5=Li |first5=W.
 |last6=Marion |first6=G. H.
 |last7=Morrell |first7=N. I.
 |last8=Pignata |first8=G.
 |last9=Stritzinger |first9=M. D.
 |last10=Silverman |first10=J. M.
 |last11=Wang |first11=X.
 |last12=Anderson |first12=J. P.
 |last13=Filippenko |first13=A. V.
 |last14=Freedman |first14=W. L.
 |last15=Hamuy |first15=M.
 |last16=Jha |first16=S. W.
 |last17=Kirshner |first17=R. P.
 |last18=McCully |first18=C.
 |last19=Persson |first19=S. E.
 |last20=Phillips |first20=M. M.
 |last21=Reichart |first21=D. E.
 |last22=Soderberg |first22=A. M.
 |year=2013
 |title=Type Iax Supernovae: A New Class of Stellar Explosion
 |journal=[[The Astrophysical Journal]]
 |volume=767 |issue=1|pages=57
 |arxiv=1212.2209
 |bibcode=2013ApJ...767...57F
 |doi=10.1088/0004-637X/767/1/57
|s2cid=118603977
 }}</ref> This type of supernova may not always completely destroy the white dwarf progenitor and could leave behind a [[zombie star]].<ref name="mccully">
{{Cite journal
 |last1=McCully |first1=C.
 |last2=Jha |first2=S. W.
 |last3=Foley |first3=R. J.
 |last4=Bildsten |first4=L.
 |last5=Fong |first5=W.-F.
 |last6=Kirshner |first6=R. P.
 |last7=Marion |first7=G. H.
 |last8=Riess |first8=A. G.
 |last9=Stritzinger |first9=M. D.
 |year=2014
 |title=A luminous, blue progenitor system for the type Iax supernova 2012Z
 |journal=[[Nature (journal)|Nature]]
 |volume=512 |issue=7512 |pages=54–56
 |arxiv=1408.1089
 |bibcode=2014Natur.512...54M
 |doi=10.1038/nature13615
 |pmid=25100479
|s2cid=4464556
 }}</ref>

One specific type of supernova originates from exploding white dwarfs, like type Ia, but contains hydrogen lines in their spectra, possibly because the white dwarf is surrounded by an envelope of hydrogen-rich [[Circumstellar disc|circumstellar material]]. These supernovae have been dubbed '''type Ia/IIn''', '''type Ian''', '''type IIa''' and '''type IIan'''.<ref>
{{cite journal
 |last1=Silverman |first1=J. M.
 |last2=Nugent |first2=P. E.
 |last3=Gal-Yam |first3=A.
 |last4=Sullivan |first4=M.
 |last5=Howell |first5=D. A.
 |last6=Filippenko |first6=A. V.
 |last7=Arcavi |first7=I.
 |last8=Ben-Ami |first8=S.
 |last9=Bloom |first9=J. S.
 |last10=Cenko |first10=S. B.
 |last11=Cao |first11=Y.
 |last12=Chornock |first12=R.
 |last13=Clubb |first13=K. I.
 |last14=Coil |first14=A. L.|author4-link=Alison Coil
 |last15=Foley |first15=R. J.
 |last16=Graham |first16=M. L.
 |last17=Griffith |first17=C. V.
 |last18=Horesh |first18=A.
 |last19=Kasliwal |first19=M. M.
 |last20=Kulkarni |first20=S. R.
 |last21=Leonard |first21=D. C.
 |last22=Li |first22=W.
 |last23=Matheson |first23=T.
 |last24=Miller |first24=A. A.
 |last25=Modjaz |first25=M.
 |last26=Ofek |first26=E. O.
 |last27=Pan |first27=Y.-C.
 |last28=Perley |first28=D. A.
 |last29=Poznanski |first29=D.
 |last30=Quimby |first30=R. M.
 |year=2013
 |title=Type Ia Supernovae strongly interaction with their circumstellar medium
 |journal=[[The Astrophysical Journal Supplement Series]]
 |volume=207 |issue=1 |pages=3
 |arxiv=1304.0763
 |bibcode=2013ApJS..207....3S
 |doi=10.1088/0067-0049/207/1/3
|s2cid=51415846
 }}</ref>

The quadruple star [[HD 74438]], belonging to the open cluster [[IC 2391]] the [[Vela constellation]], has been predicted to become a non-standard type Ia supernova.<ref name="GIAISURVEY">{{cite journal |last1=Gilmore |first1=Gerry |last2=Randich |first2=Sofia |title=The Gaia-ESO Public Spectroscopic Survey |journal=The Messenger |date=March 2012 |volume=147 |issue=147 |pages=25–31 |publisher=European Southern Observatory |location=Garching, Germany |language=en |bibcode=2012Msngr.147...25G}}</ref><ref name="supernova">{{cite journal |last1=Merle |first1=Thibault |last2=Hamers |first2=Adrian S. |last3=Van Eck |first3=Sophie |last4=Jorissen |first4=Alain |last5=Van der Swaelmen |first5=Mathieu |last6=Pollard |first6=Karen |last7=Smiljanic |first7=Rodolfo |last8=Pourbaix |first8=Dimitri |last9=Zwitter |first9=Tomaž |last10=Traven |first10=Gregor |last11=Gilmore |first11=Gerry |last12=Randich |first12=Sofia |last13=Gonneau |first13=Anaïs |last14=Hourihane |first14=Anna |last15=Sacco |first15=Germano |last16=Worley |first16=C. Clare |title=A spectroscopic quadruple as a possible progenitor of sub-Chandrasekhar type Ia supernovae |journal=Nature Astronomy |date=12 May 2022 |volume=6 |issue=6 |pages=681–688 |doi=10.1038/s41550-022-01664-5|arxiv=2205.05045 |bibcode=2022NatAs...6..681M |s2cid=248665714 }}</ref>