SN 1885A (also S Andromedae) was a
supernova in the
Andromeda Galaxy
The Andromeda Galaxy (IPA: ), also known as Messier 31, M31, or NGC 224 and originally the Andromeda Nebula, is a barred spiral galaxy with the diameter of about approximately from Earth and the nearest large galaxy to the Milky Way. The gal ...
, the only one seen in that
galaxy so far by astronomers. It was the first supernova ever seen outside the
Milky Way
The Milky Way is the galaxy that includes our Solar System, with the name describing the galaxy's appearance from Earth: a hazy band of light seen in the night sky formed from stars that cannot be individually distinguished by the naked eye. ...
, though it was not appreciated at the time how far away it was. It is also known as "Supernova 1885".
Discovery
The supernova appears to have been seen first on August 17, 1885, by French astronomer
Ludovic Gully during a public stargazing event. Gully thought it was scattered moonlight in his telescope and did not follow up on this observation. Irish amateur astronomer
Isaac Ward in
Belfast
Belfast ( , ; from ga, Béal Feirste , meaning 'mouth of the sand-bank ford') is the capital and largest city of Northern Ireland, standing on the banks of the River Lagan on the east coast. It is the 12th-largest city in the United Kingdom ...
claimed to have seen the object on August 19, 1885, but did not immediately publish its existence.
The independent detection of the supernova by
Ernst Hartwig
Carl Ernst Albrecht Hartwig (14 January 1851 in Frankfurt – 3 May 1923 in Bamberg) was a German astronomer.
On 20 August 1885, Hartwig discovered a new star, SN 1885A (S Andromedae), in the Andromeda Galaxy, which was the first supernov ...
at
Dorpat (Tartu) Observatory in
Estonia
Estonia, formally the Republic of Estonia, is a country by the Baltic Sea in Northern Europe. It is bordered to the north by the Gulf of Finland across from Finland, to the west by the sea across from Sweden, to the south by Latvia, a ...
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. The telegram prompted widespread observations of the event, 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 and
de Vaucouleurs and Corwin.
Both studies doubt that Ward really saw the event since his estimated magnitude is significantly off from the later reconstructed
light curve
In astronomy, a light curve is a graph of light intensity of a celestial object or region as a function of time, typically with the magnitude of light received on the y axis and with time on the x axis. The light is usually in a particular frequ ...
,
and conclude that Hartwig should be considered as the discoverer of the supernova.
Features
SN 1885A reached magnitude 5.85 on 21 August 1885, and faded to magnitude 14 six months later.
It was reddish in color and declined rapidly in brightness, which is unusual for
type Ia supernovae. Some astronomers observed the
spectrum
A spectrum (plural ''spectra'' or ''spectrums'') is a condition that is not limited to a specific set of values but can vary, without gaps, across a continuum. The word was first used scientifically in optics to describe the rainbow of colors ...
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.
[ Studies led by ]Dovi Poznanski
Dovi is an arrondissement in the Zou department of Benin. It is an administrative division under the jurisdiction of the commune of Zagnanado. According to the population census conducted by the Institut National de la Statistique Benin
An in ...
and by Hagai Perets
Haggai (; he, חַגַּי – ''Ḥaggay''; Koine Greek: Ἀγγαῖος; la, Aggaeus) was a Hebrew prophet during the building of the Second Temple in Jerusalem, and one of the twelve minor prophets in the Hebrew Bible and the author of ...
suggest that SN 1885A belongs to a new subclass of Type I supernovae, along with SN 2002bj
SN 2002bj was the explosion of a star in the galaxy NGC 1821, located in the constellation
Lepus. The explosion was discovered by Jack Newton in scans of images produced by Tim Puckett. (It was independently discovered by the Lick/Tenagra Observa ...
and SN 1939B.
The supernova occurred 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 4-meter Mayall telescope at Kitt Peak
Kitt Peak ( ood, Ioligam) is a mountain in the U.S. state of Arizona, and at is the highest point in the Quinlan Mountains. It is the location of the Kitt Peak National Observatory. The radio telescope at the observatory is one of ten dishes co ...
to discover the iron-rich remnant of the explosion. Further observations were made with the Hubble Space Telescope
The Hubble Space Telescope (often referred to as HST or Hubble) is a space telescope that was launched into low Earth orbit in 1990 and remains in operation. It was not the first space telescope, but it is one of the largest and most vers ...
in 1999. The spectrum of the remnant shows the presence of iron
Iron () is a chemical element with Symbol (chemistry), symbol Fe (from la, Wikt:ferrum, ferrum) and atomic number 26. It is a metal that belongs to the first transition series and group 8 element, group 8 of the periodic table. It is, Abundanc ...
, calcium
Calcium is a chemical element with the symbol Ca and atomic number 20. As an alkaline earth metal, calcium is a reactive metal that forms a dark oxide-nitride layer when exposed to air. Its physical and chemical properties are most similar t ...
and manganese
Manganese is a chemical element with the symbol Mn and atomic number 25. It is a hard, brittle, silvery metal, often found in minerals in combination with iron. Manganese is a transition metal with a multifaceted array of industrial alloy use ...
, 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.
References
External links
Light curve
on th
Open Supernova Catalog
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{{DEFAULTSORT:SN 1885A
Andromeda (constellation)
Supernovae
Andromeda Galaxy
Andromedae, S
0182
18850817
Durchmusterung objects