View source for SN 1885A

{{Short description|1885 supernova in the Andromeda Galaxy}}
{{Infobox supernova |
| name = Supernova 1885
| image = File:SAndLightCurve.png
| caption = The [[Photometric_system#Photometric_letters|visual band]] [[light curve]] of S Andromedae, adapted from Patchett ''et al.'' (1985)<ref name="Patchett">{{cite journal |last1=Patchett |first1=B. E. |last2=Stickland |first2=D. J. |last3=Crilly |first3=D. |last4=Wood |first4=R. |title=A revised light curve for the 1885 supernova in M 31 |journal=The Observatory |date=December 1985 |volume=105 |pages=232–238 |bibcode=1985Obs...105..232P }}</ref>
| epoch = [[J2000.0]]
| type = I pec
| SNRtype = Unknown
| host = [[Andromeda Galaxy]]
| constellation = [[Andromeda (constellation)|Andromeda]]
| ra = 00<sup>h</sup> 42<sup>m</sup> 43.11<sup>s</sup>
| dec = +41° 16′ 04.2′′
| gal = 121.1702 -21.5741
| discovery = 20 August 1885 [[UTC]]
| iauc =
| distance = 2.6 [[Light-year|Mly]]
| mag_v  = +6
| progenitor = Unknown
| progenitor_type = Unknown
| b-v = +1.3 ~ +0.6<ref name="devau"/>
| notes = First and only supernova observed in [[Andromeda Galaxy|Andromeda]]; <br/>first extragalactic supernova observed; <br/> closest type Ia observed
|predecessor = [[SN 1604]] (observed), [[Cassiopeia A]] (unobserved, {{circa|1680}}), [[G1.9+0.3]] (unobserved, {{circa|1868}})
|successor = [[SN 1895B]]
}}

'''SN 1885A''' (also '''S Andromedae''') was a [[supernova]] in the [[Andromeda Galaxy]], the only one seen in that [[galaxy]] so far by astronomers. It was the first supernova ever seen outside the [[Milky Way]],<ref>{{cite web |url=http://messier.seds.org/more/m031_sAnd.html |title=S Andromedae: Supernova 1885 in M31 |last1=Frommert |first1=Hartmut |last2=Kronberg |first2=Christine |website=SEDS Messier Database |access-date=2017-01-22}}</ref> though it was not appreciated at the time due to how far away it was. It is also known as "Supernova 1885".

==Discovery==
[[Image:Isaac Ward.gif|125px|thumb|left|Isaac Ward]]
The supernova appears to have been seen first on August 17, 1885, by French astronomer [[Ludovic Gully]] during a public stargazing event.<ref>{{cite journal |title=Ueber den neuen Stern im grossen Andromeda-Nebel |journal=Astronomische Nachrichten |volume=113 |issue=3 |pages=45–46 |date=1885 |bibcode=  1885AN....113...45.|doi=10.1002/asna.18861130306 }}</ref> Gully thought it was scattered moonlight in his telescope and did not follow up on this observation. Irish amateur astronomer [[Isaac Ward (astronomer)|Isaac Ward]] in [[Belfast]] claimed to have seen the object on August 19, 1885, but did not immediately publish its existence.<ref>{{cite journal |last=Beesley |first=D. E. |date=September 1985 |title=Isaac Ward and S Andromedae |journal=[[Irish Astronomical Journal]] |volume=17 |issue=2 |page=98 |bibcode=1985IrAJ...17...98B}}</ref><ref>{{cite journal |last=Ward |first=Isaac |date=1885 |title=New Star in Andromeda |journal=[[Astronomical Register]] |volume=23 |page=242 |bibcode=1885AReg...23..242W}}</ref>

The independent detection of the supernova by [[Ernst Hartwig]] at [[Tartu Observatory|Dorpat (Tartu) Observatory]] in [[Estonia]] on August 20, 1885, however, was communicated in a telegram on August 31, 1885, once Hartwig had verified in more ideal circumstances that the feature was not caused by reflected moonlight.<ref>{{cite journal |title=Ueber den neuen Stern im grossen Andromeda-Nebel |last=Hartwig |first=Ernst |journal=Astronomische Nachrichten |volume=112 |issue=24 |page=355 |date=1885 |bibcode=1885AN....112..355H |doi=10.1002/asna.18851122408 }}</ref><ref>{{cite journal |last=Copeland |first=Ralph |date=September 1885 |title=Dun Echt Circulars, No. 97 and No. 98 |journal=Dun Echt Circular |volume=23 |pages=248 |bibcode=1885AReg...23..248C |number=97}}</ref> The telegram prompted widespread observations of the event,<ref>{{cite journal |last=Vogel |first=H.C. |date=1885 |title=Ueber den neuen Stern im grossen Andromeda-Nebel |journal=[[Astronomische Nachrichten]] |volume=112 |issue=16–17 |pages=283–288 |bibcode=1885AN....112..283V |doi=10.1002/asna.18851121604}}</ref> and prompted Isaac Ward, Ludovic Gully, and several others to publish their earlier observations (the first reports on S Andromedae appeared before Hartwig's discovery letter which followed his telegram, since the letter was initially lost by Astronomische Nachrichten and only reprinted in a later issue). The history of the discovery is summarized by K.G. Jones<ref>{{cite journal |title=S Andromedae, 1885: An Analysis of Contemporary Reports and a Reconstruction |last=Jones |first=Kenneth Glyn |journal=Journal for the History of Astronomy |volume=7 |page=27 |date=1976 |bibcode=1976JHA.....7...27J|doi=10.1177/002182867600700103 |s2cid=125433348 }}</ref> and [[Gérard de Vaucouleurs|de Vaucouleurs]] and [[H. G. Corwin Jr.]]<ref name="devau">{{cite journal |title=S Andromedae 1885 - A centennial review |last1=de Vaucouleurs |first1= G. |last2=Corwin Jr. |first2=H. G. |journal=Astrophysical Journal |volume=295 |date=1985 |pages=287 |bibcode=1985ApJ...295..287D|doi = 10.1086/163374 |doi-access=free }}</ref> Both studies doubt that Ward really saw the event since his estimated magnitude is significantly off from the later reconstructed [[light curve]],<ref name="devau"/> and conclude that Hartwig should be considered as the discoverer of the supernova.

==Features==
[[File:SN 1885A remnant Hubble.jpg|thumb|left|Hubble image of the remnant in absorption.]]
SN 1885A reached magnitude 5.85 on 21 August 1885, and faded to magnitude 14 six months later.<ref name="devau"/> It was reddish in color and declined rapidly in brightness, which is unusual for [[Type Ia supernova|type Ia supernovae]]. Some astronomers observed the [[stellar spectrum|spectrum]] of the star visually (no photographic spectral observations were made in that time). These observations were made at the limit of visibility, but they were considered to be in good agreement with each other and with modern data on typical supernovae of type Ia; SN 1885A has thus been assigned to this type.<ref name=devau/> Studies led by [[Dovi Poznanski]] and by [[Hagai Perets]] suggest that SN 1885A belongs to a new subclass of Type I supernovae, along with [[SN 2002bj]] and [[Messier_59#Supernova|SN 1939B]].<ref name="jpost">{{cite news |last=Siegel-Itzkovich |first=Judy |date=November 5, 2009 |title=US-Israeli team's speedily evolving supernova seems to be a new class of exploding star |url=https://www.jpost.com/health-and-sci-tech/us-israeli-teams-speedily-evolving-supernova-seems-to-be-a-new-class-of-exploding-star |access-date=2009-11-06 |work=[[The Jerusalem Post]]}}</ref><ref>{{cite news | first=Christine | last=Pulliam | date=April 26, 2011 | work=Smithsonian Insider | title=New Type of Exploding Star Discovered | url=http://insider.si.edu/2011/04/new-type-of-exploding-star-discovered/ | access-date=2017-01-22 }}</ref>

The supernova occurred at an [[angular separation]] of {{val|16|ul=arcsec}} from the relatively bright nucleus of the galaxy. This made detection of its remnant difficult – early attempts were unsuccessful. In 1988, R. A. Fesen and others used the [[Nicholas U. Mayall Telescope|4-meter Mayall telescope]] at [[Kitt Peak]] to discover the iron-rich remnant of the explosion.<ref>{{Cite journal |last=Fesen |first=Robert A. |last2=Saken |first2=Jon M. |last3=Hamilton |first3=Andrew J. S. |date=June 1989 |title=Discovery of the remnant of S Andromedae (SN 1885) in M31 |journal=[[The Astrophysical Journal]] |language=en |volume=341 |pages=L55 |bibcode=1989ApJ...341L..55F |doi=10.1086/185456 |issn=0004-637X}}</ref> Further observations were made with the [[Hubble Space Telescope]] in 1999.<ref>{{Cite journal |last=Hamilton |first=Andrew J. S. |last2=Fesen |first2=Robert A. |date=2000-10-20 |title=An Ultraviolet Fe ii Image of SN 1885 in M31 |journal=[[The Astrophysical Journal]] |language=en |volume=542 |issue=2 |pages=779–784 |arxiv=astro-ph/9907102 |bibcode=2000ApJ...542..779H |doi=10.1086/317014 |issn=0004-637X |s2cid=14856435}}</ref> The spectrum of the remnant shows the presence of [[iron]], [[calcium]] and [[manganese]], which were likely created during the explosion. There is some evidence for spherical symmetry in the explosion; this would mean that this type Ia supernova was not triggered by merging.<ref name=Fesen2017>{{cite journal | title=Optical and UV Spectra of the Remnant of SN 1885 (S And) in M31 | last1=Fesen | first1=R. A. | last2=Weil | first2=K. E. | last3=Hamilton | first3=A. J. S. | last4=Höflich | first4=P. A. | display-authors=1 | journal=The Astrophysical Journal | volume=848 | issue=2 | pages=130 | date=October 2017 | bibcode=2017ApJ...848..130F | doi=10.3847/1538-4357/aa8b11| arxiv=1603.04895 | s2cid=119232746 | doi-access=free }}</ref>

{{Portal |Astronomy}}

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==References==
{{Reflist |2}}

==External links==
* [https://sne.space/sne/SN1885A/ Light curve] {{Webarchive|url=https://web.archive.org/web/20171022142836/https://sne.space/sne/SN1885A/ |date=2017-10-22 }} on the [https://sne.space Open Supernova Catalog] {{Webarchive|url=https://web.archive.org/web/20160303230459/https://sne.space/ |date=2016-03-03 }}
* {{cite web |title=S Andromedae: Supernova 1885 in M31 |work=Students for the Exploration and Developments of Space |url=http://messier.seds.org/more/m031_sAnd.html  |access-date=2005-08-12 }}
* {{cite web |title=Supernova 1885A - S Andromedae  |url=http://casa.colorado.edu/~mcl/sand.html| access-date=August 12, 2005 |archive-url=https://web.archive.org/web/20010219002215/http://casa.colorado.edu/~mcl/sand.html |archive-date=February 19, 2001}}
* {{cite simbad | title=S And | access-date=October 9, 2018 }}

{{Stars of Andromeda}}
{{Andromeda Galaxy}}

{{DEFAULTSORT:SN 1885A}}
[[Category:Andromeda (constellation)]]
[[Category:Supernovae]]
[[Category:Andromeda Galaxy]]
[[Category:Objects with variable star designations|Andromedae, S]]
[[Category:Bright Star Catalogue objects|0182]]
[[Category:Astronomical objects discovered in 1885|18850817]]
[[Category:Durchmusterung objects]]