{{Short description|Nova in the constellation Centaurus seen in 1986}} {{Starbox begin | name = V842 Centauri }} {{Starbox image | image= {{Location mark |image=V842CenLocation.png|alt=|width=280 }} |caption=Location of V842 Centauri (circled in red) }} {{starbox observe | epoch=[[J2000.0]] | constell=[[Centaurus]] | ra= {{RA|14|35|52.568}}<ref name="Gaia DR2"/> | dec= {{DEC|-57|37|35.39}}<ref name="Gaia DR2"/> | appmag_v= 18.5 (pre-nova)<ref name=Sion2010/><br>4.6 (max during nova)<ref name=Whitelock1987/><br>16.5 (2010)<ref name=Sion2010/> }} {{starbox character | class= | b-v = | u-b = | variable = [[nova]]<ref name=Whitelock1987/> }} {{starbox astrometry | radial_v= | prop_mo_ra= | prop_mo_dec= | parallax= | p_error= | parallax_footnote = | dist_ly = {{val|4498|391|254}}<ref name="Schaefer2018"/> | dist_pc = {{val|1379|120|78}}<ref name="Schaefer2018"/> | absmag_v = −7.5 (max during nova)<ref name=Whitelock1987/> }} {{Starbox detail | source = | mass = 0.88<ref name=Luna2012/> | radius = | luminosity = | temperature = | gravity = | metal_fe = | rotational_velocity = | age_myr = }} {{starbox catalog | names=Nova Centauri 1986, [[AAVSO]] 1428-57, Gaia DR2 5891405647833287296 }}{{Starbox reference | Simbad = V842+Centauri }}{{starbox end}}
[[File:V842CenLightCurve.png|thumb|left|The [[light curve]] of V842 Centauri, plotted from [[AAVSO]] data]] '''V842 Centauri''', also known as '''Nova Centauri 1986''', was a [[nova]] which occurred in 1986 in the constellation [[Centaurus]]. It was discovered by [[Robert H. McNaught]] of [[Siding Spring Observatory]] in Australia, on 22 November 1986. At the time of its discovery, it had an [[apparent magnitude]] of 5.6. It reached a peak magnitude of 4.6 one and a half days later, making it easily visible to the [[naked eye]].<ref name="whit"/>
V842 Centauri is considered a moderately fast nova, having faded by 3 magnitudes after 48 days.<ref name=Whitelock1987/> Near the end of 1986, and early in 1987, its light curve showed a sharp drop in brightness, caused by the formation of dust. This dramatic fading lasted only about 50 days, before the nova brightened by about 2.5 magnitudes.<ref name="smit"/> By 2010, it had faded to magnitude 16.5, but was still 2 magnitudes brighter than before the nova eruption.<ref name=Sion2010/>
From its shell's expansion velocity, it is estimated to be at a distance of 1.5 [[parsec|kpc]] (4900 light-years) from Earth.<ref name=Tomov2015/> Another method, based on the system's [[extinction (astronomy)|extinction]] rate, gives a similar distance of 1.65 ± 0.54 kpc.<ref name=Özdönmez2016/> It was observed by the [[Gaia (spacecraft)|Gaia spacecraft]], which measured a distance of 1.38 (+0.120, -0.078) kpc.<ref name="Schaefer2018"/>
The mass of the white dwarf in V842 Centauri is estimated at 0.88 [[solar mass]]es. The system is likely seem from a low [[inclination]].<ref name=Luna2012/> An expanding [[nebula]] has been detected around V842 Centauri, formed by material ejected during the nova. It has two components, with diameters of 3.6" and 10.6", corresponding to material with different densities and expansion velocities.<ref name=Tomov2015/>
A 2009 [[Photometry (astronomy)|photometric]] study of V842 Centauri found a possible 57 seconds period in the system's [[light curve]], which was interpreted as the white dwarf's rotation period. An [[orbital period]] of 3.94 hours was calculated from variations of this period. V842 Centauri was then classified as an [[intermediate polar]], with the third fastest rotation period for a cataclismic system.<ref name=Woudt2009/> However, two later studies revealed problems with this classification.<ref name=Luna2012/><ref name=Sion2010/>
In 1995, observations with the 3.9 meter [[Anglo-Australian Telescope]] detected a very small (~1.5 arc second diameter) [[nova remnant]] shell surrounding V842 Centauri.<ref name="gill"/> By March 1998 the shell had expanded to 5.6 × 6.0 arc seconds.<ref name="down"/>
==References== <references> <ref name="Gaia DR2">{{Cite Gaia DR2|5891405647833287296}}</ref>
<ref name="whit">{{cite journal |last1=Whitelock |first1=P.A. |title=Nova Cen 1986 |journal=Monthly Notes of the Astronomical Society of South Africa |date=January 1987 |volume=46 |page=72 |bibcode=1987MNSSA..46...72W |url=https://ui.adsabs.harvard.edu/abs/1987MNSSA..46...72W |access-date=1 January 2021}}</ref>
<ref name=Sion2010>{{cite journal|display-authors=4 |first1=Edward M. |last1=Sion |first2=Paula |last2=Szkody |first3=Anjum |last3=Mukadam |first4=Brian |last4=Warner |first5=Patrick |last5=Woudt |first6=Frederic |last6=Walter |first7=Arne |last7=Henden |first8=Patrick |last8=Godon6 |title=Multiwavelength Photometry and ''Hubble Space Telescope'' Spectroscopy of the Old Nova V842 Centaurus |journal=The Astrophysical Journal |volume=772 |issue=2 |pages=116 |id=Article 116 |date=August 2013 |bibcode=2013ApJ...772..116S |doi=10.1088/0004-637X/772/2/116 |arxiv=1305.4564 |s2cid=119202671 }}</ref>
<ref name=Woudt2009>{{cite journal|author=Woudt, Patrick A. |author2=Warner, Brian |author3=Osborne, Julian |author4=Page, Kim |title=57-second oscillations in Nova Centauri 1986 (V842 Cen)|journal=Monthly Notices of the Royal Astronomical Society|volume=395|issue=4|pages=2177–2182|date=June 2009|bibcode=2009MNRAS.395.2177W|doi=10.1111/j.1365-2966.2009.14668.x|doi-access=free |arxiv=0902.4826|s2cid=18517574 }}</ref>
<ref name=Luna2012>{{cite journal|author=Luna, G. J. M. |author2=Diaz, M. P. |author3=Brickhouse, N. S. |author4=Moraes, M. |title=XMM-Newton EPIC and OM observation of Nova Centauri 1986 (V842 Cen)|journal=Monthly Notices of the Royal Astronomical Society: Letters|volume=423|issue=1|pages=L75–L78|date=June 2012|bibcode=2012MNRAS.423L..75L|doi=10.1111/j.1745-3933.2012.01260.x|doi-access=free |arxiv=1203.4804|s2cid=85526864 }}</ref>
<ref name=Whitelock1987>{{cite journal|author=Whitelock, P. A.|title=Nova Cen 1986|journal=Monthly Notes of the Astron. Soc. Southern Africa|volume=46|page=72|date=1987|bibcode=1987MNSSA..46...72W}}</ref>
<ref name=Özdönmez2016>{{cite journal|author=Özdönmez, Aykut |author2=Güver, Tolga |author3=Cabrera-Lavers, Antonio |author4=Ak, Tansel |title=The distances of the Galactic novae|journal=Monthly Notices of the Royal Astronomical Society |volume=461|issue=2|pages=1177–1201|date=September 2016|bibcode=2016MNRAS.461.1177O|doi=10.1093/mnras/stw1362|doi-access=free |arxiv=1606.01907|s2cid=118589678 }}</ref>
<ref name=Tomov2015>{{cite journal|author=Tomov, T. |author2=Swierczynski, E. |author3=Mikolajewski, M. |author4=Ilkiewicz, K. |title=SALT observations of southern post-novae|journal=Astronomy & Astrophysics |volume=576|pages=A119 |id=A119|date=April 2015|bibcode=2015A&A...576A.119T|doi=10.1051/0004-6361/201424709|arxiv=1502.03462|s2cid=54741051 }}</ref>
<ref name="Schaefer2018">{{cite journal | title=The distances to Novae as seen by Gaia | last1=Schaefer | first1=Bradley E. | journal=Monthly Notices of the Royal Astronomical Society | volume=481 | issue=3 | year=2018 | pages=3033–3051 | arxiv=1809.00180 | bibcode=2018MNRAS.481.3033S | doi=10.1093/mnras/sty2388 | doi-access=free | s2cid=118925493 }}</ref>
<ref name="smit">{{cite journal |last1=Smith |first1=Craig H. |last2=Aitken |first2=David K. |last3=Roche |first3=Patrick F. |title=The mid-infrared spectral development of nova CEN 1986 |journal=Monthly Notices of the Royal Astronomical Society |date=March 1994 |volume=267 |issue=2 |pages=225–230 |doi=10.1093/mnras/267.2.225 |bibcode=1994MNRAS.267..225S |doi-access=free }}</ref>
<ref name="gill">{{cite journal |last1=Gill |first1=C.D. |last2=O'Brien |first2=T.J. |title=Deep optical imaging of nova remnants: a southern sky sample |journal=Monthly Notices of the Royal Astronomical Society |date=October 1998 |volume=300 |issue=1 |pages=221–232 |doi=10.1046/j.1365-8711.1998.01899.x |arxiv=astro-ph/9806076 |bibcode=1998MNRAS.300..221G |doi-access=free }}</ref>
<ref name="down">{{cite journal |last1=Downes |first1=Ronald A. |last2=Duerbeck |first2=Hilmar W. |title=Optical Imaging of Nova Shells and the Maximum Magnitude-Rate of Decline Relationship |journal=The Astronomical Journal |year=2000 |volume=120 |issue=4 |pages=2007–2037 |doi=10.1086/301551 |bibcode=2000AJ....120.2007D |s2cid=119431018 |url=https://ui.adsabs.harvard.edu/abs/2000AJ....120.2007D |access-date=1 January 2021|arxiv=astro-ph/0006458 }}</ref> </references>
==External links== * [http://www.citebase.org/fulltext?format=application%2Fpdf&identifier=oai%3AarXiv.org%3Aastro-ph%2F0411198 V842 Centauri] {{Webarchive|url=https://web.archive.org/web/20120214150910/http://www.citebase.org/fulltext?format=application%2Fpdf&identifier=oai:arXiv.org:astro-ph%2F0411198 |date=2012-02-14 }} * [http://simbad.u-strasbg.fr/simbad/sim-id?protocol=html&Ident=V+842+Cen&NbIdent=1&Radius=2&Radius.unit=arcmin&submit=submit+id V 842 Cen] * https://web.archive.org/web/20050907140444/http://www.tsm.toyama.toyama.jp/curators/aroom/var/nova/1980.htm
{{Stars of Centaurus}}
[[Category:Novae]] [[Category:Centaurus]] [[Category:Astronomical objects discovered in 1986]] [[Category:Objects with variable star designations|Centauri, V842]] [[Category:Discoveries by Robert H. McNaught]]