Editing Nova (section)

== Recurrent novae<!--'Recurrent nova', 'Recurrent novae', 'Recurrent Nova', and 'Recurrent Novae' redirect here--> ==
A '''recurrent nova'''<!--boldface per WP:R#PLA--> ('''RN''')<!--boldface per MOS:BOLDSYN--> is an object that has been seen to experience repeated nova eruptions. The recurrent nova typically brightens by about 9 magnitudes, whereas a classical nova may brighten by more than 12 magnitudes.<ref name=Schaefer2009>
{{cite journal
 |last=Schaefer |first=Bradley E.
 |year=2010
 |title=Comprehensive Photometric Histories of All Known Galactic Recurrent Novae
 |arxiv=0912.4426
 |doi=10.1088/0067-0049/187/2/275
 |volume=187
 |issue=2
 |journal=The Astrophysical Journal Supplement Series
 |pages=275–373
 |bibcode = 2010ApJS..187..275S |s2cid=119294221
 }}</ref>

Although it is estimated that as many as a quarter of nova systems experience multiple eruptions, only ten recurrent novae (listed below) have been observed in the Milky Way.<ref>{{cite journal |bibcode=2014ApJ...788..164P |title=Identifying and Quantifying Recurrent Novae Masquerading as Classical Novae |last1=Pagnotta |first1=Ashley |last2=Schaefer |first2=Bradley E. |journal=The Astrophysical Journal |year=2014 |volume=788 |issue=2 |page=164 |doi=10.1088/0004-637X/788/2/164 |arxiv=1405.0246 |s2cid=118448146 }}</ref>

Several [[Extragalactic astronomy|extragalactic]] recurrent novae have been observed in the [[Andromeda Galaxy]] (M31) and the [[Large Magellanic Cloud]]. One of these extragalactic novae, [[M31N 2008-12a]], erupts as frequently as once every 12 months.

On 20 April 2016, the ''[[Sky & Telescope]]'' website reported a sustained brightening of [[T Coronae Borealis]] from magnitude 10.5 to about 9.2 starting in February 2015. A similar event had been reported in 1938, followed by another outburst in 1946.<ref name=sandt>{{cite web |url=http://www.skyandtelescope.com/observing/whats-up-with-t-crb04202016 |publisher=Sky & Telescope website |title=Is T CrB About to Blow its Top?|date=20 April 2016 |accessdate=2017-08-06}}</ref> By June 2018, the star had dimmed slightly but still remained at an unusually high level of activity. In March or April 2023, it dimmed to magnitude 12.3.<ref>{{cite web |last1=Schaefer |first1=B.E. |last2=Kloppenborg |first2=B. |last3=Waagen |first3=E.O. |title=Announcing T CrB pre-eruption dip |url=https://www.aavso.org/news/t-crb-pre-eruption-dip |website=AAVSO |publisher=American Association of Variable Star Observers |access-date=18 January 2024}}</ref> A similar dimming occurred in the year before the 1945 outburst, indicating that it would likely erupt between March and September 2024.<ref>{{cite web |last1=Todd |first1=Ian |title=T Coronae Borealis nova event guide and how to prepare |url=https://www.skyatnightmagazine.com/space-science/t-coronae-borealis-nova |website=Sky at Night Magazine |publisher=BBC |access-date=18 March 2024}}</ref> {{As of|2025|2|10|post=,}} this predicted outburst has not yet occurred.

{{Clear|left}}

{| class="wikitable sortable" text-align:center;"
|-----
! Full name
! Discoverer
! Distance ([[light-year|ly]])
! [[Apparent magnitude|Magnitude]]<br/> range
! Days to drop<br/> 3&nbsp;magnitudes<br/> from peak
! Known eruption years
! Interval (years)
! Years since latest eruption
|-----
| [[CI Aquilae]]
| [[Karl Wilhelm Reinmuth|K. Reinmuth]]
| {{val|8590|830}}
| 8.6–16.3
| 40
| 1917, 1941, 2000
| 24–59
|bgcolor=#84CF65|{{age in years|2000|04|30}}
|-----
| [[V394 Coronae Australis]]
| [[Luis Enrique Erro|L. E. Erro]]
| {{val|17000|3000}}<ref>{{cite journal |last1=Hachisu |first1=Izumi |last2=Kato |first2=Mariko |title=A Theoretical Light-Curve Model for the Recurrent Nova V394 Coronae Australis |journal=The Astrophysical Journal |date=September 2000 |volume=540 |issue=1 |pages=447–451 |doi=10.1086/309338 |arxiv=astro-ph/0003471 |bibcode=2000ApJ...540..447H |url=https://iopscience.iop.org/article/10.1086/309338 |access-date=3 May 2024}}</ref>
| 7.2–19.7
| 6
| 1949, 1987
| 38
|bgcolor=#E2EB20|{{age in years|1987|07|30}}
|-----
| [[T Coronae Borealis]]
| [[John Birmingham (astronomer)|J. Birmingham]]
| {{val|2987|75}}
| 2.5–10.8
| 6
| 1217, 1787, 1866, 1946
| 80
|bgcolor=#E2EB20|{{age in years|1946|02|09}}
|-----
| [[IM Normae]]
| [[Ida E. Woods|I. E. Woods]]
| {{val|9800|1600}}<ref>{{cite journal |last1=Patterson |first1=Joseph |last2=Kemp |first2=Jonathan |last3=Monard |first3=Berto |last4=Myers |first4=Gordon |last5=de Miguel |first5=Enrique |last6=Hambsch |first6=Franz-Josef |last7=Warhurst |first7=Paul |last8=Rea |first8=Robert |last9=Dvorak |first9=Shawn |last10=Menzies |first10=Kenneth |last11=Vanmunster |first11=Tonny |last12=Roberts |first12=George |last13=Campbell |first13=Tut |last14=Starkey |first14=Donn |last15=Ulowetz |first15=Joseph |last16=Rock |first16=John |last17=Seargeant |first17=Jim |last18=Boardman |first18=James |last19=Lemay |first19=Damien |last20=Cejudo |first20=David |last21=Knigge |first21=Christian |title=IM Normae: The Death Spiral of a Cataclysmic Variable? |journal=The Astrophysical Journal |date=1 January 2022 |volume=924 |issue=1 |pages=27 |doi=10.3847/1538-4357/abec87 |doi-access=free |bibcode=2022ApJ...924...27P |arxiv=2010.07812 }}</ref>
| 8.5–18.5
| 70
| 1920, 2002
| ≤82
|bgcolor=#84CF65|{{age in years|2002|01|14}}
|-----
| [[RS Ophiuchi]]
| [[Williamina Fleming|W. Fleming]]
| {{val|8740|850}}
| 4.8–11
| 14
| 1898, 1907, 1933, 1958, 1967, 1985, 2006, 2021
| 9–26
|bgcolor=#84CF65|{{age in years|2021|08|08}}
|-----
| [[V2487 Ophiuchi]]
| [[Kesao Takamizawa|K. Takamizawa]] (1998)
| {{val|20900|5200}}<ref>{{cite journal |last1=Rodríguez-Gil |first1=Pablo |last2=Corral-Santana |first2=Jesús M |last3=Elías-Rosa |first3=N |last4=Gänsicke |first4=Boris T |last5=Hernanz |first5=Margarita |last6=Sala |first6=Gloria |title=The orbital period of the recurrent nova V2487 Oph revealed |journal=Monthly Notices of the Royal Astronomical Society |date=20 October 2023 |volume=526 |issue=4 |pages=4961–4975 |doi=10.1093/mnras/stad3124 |doi-access=free |url=https://academic.oup.com/mnras/article/526/4/4961/7310889 |access-date=3 May 2024|arxiv=2310.05877 }}</ref>
| 9.5–17.5
| 9
| 1900, 1998
| 98
|bgcolor=#84CF65|{{age in years|1998|06|19}}
|-----
| [[T Pyxidis]]
| [[Henrietta Swan Leavitt|H. Leavitt]]
| {{val|9410|780}}
| 6.4–15.5
| 62
| 1890, 1902, 1920, 1944, 1967, 2011
| 12–44
|bgcolor=#E2EB20|{{age in years|2011|04|14}}
|-----
| [[V3890 Sagittarii]]
| [[Harriet Dinerstein|H. Dinerstein]]
| {{val|16000}}<ref>{{cite journal |last1=Anupama |first1=G. C. |last2=Sethi |first2=S. |title=Spectroscopy of the recurrent nova V3890 Sagittarii 18 d after the 1990 outburst |journal=Monthly Notices of the Royal Astronomical Society |date=1 July 1994 |volume=269 |issue=1 |pages=105–109 |doi=10.1093/mnras/269.1.105 |doi-access=free |url=https://academic.oup.com/mnras/article/269/1/105/1004643 |access-date=3 May 2024}}</ref>
| 8.1–18.4
| 14
| 1962, 1990, 2019
| 28–29
|bgcolor=#84CF65|{{age in years|2019|08|27}}
|-----
| [[U Scorpii]]
| [[N. R. Pogson]]
| {{val|31300|2000}}<ref name="Hachisu2017">{{Cite journal |last=Hachisu |first=Izumi |last2=Kato |first2=Mariko |date=1 April 2016 |title=The UBV Color Evolution of Classical Novae. II. Color-Magnitude Diagram |journal=[[The Astrophysical Journal Supplement Series]] |volume=223 |issue=2 |pages=21 |arxiv=1602.01195 |bibcode=2016ApJS..223...21H |doi=10.3847/0067-0049/223/2/21 |doi-access=free}}</ref>
| 7.5–17.6
| 2.6
| 1863, 1906, 1917, 1936, 1979, 1987, 1999, 2010, 2022, 
| 8–43
|bgcolor=#84CF65|{{age in years|2022|06|05}}
|-----
| [[V745 Scorpii]]
| [[Lukas Plaut|L. Plaut]]
| {{val|25400|2600}}<ref name="Hachisu2017" />
| 9.4–19.3
| 7
| 1937, 1989, 2014
| 25–52
|bgcolor=#84CF65|{{age in years|2014|02|06}}
|}