Talk:SN 1885A

How do we know...
...that S Andromedae was really within the Andromeda galaxy and not part of the Milky Way?80.141.182.110 (talk) 09:40, 24 October 2010 (UTC)


 * It's a question worth asking. Parallax measurements? Rothorpe (talk) 15:20, 24 October 2010 (UTC)


 * These types of supernovae always have the same absolute magnitude. When you know that and you measure the apparent magnitude, you can then calculate the distance. The Andromeda galaxy is too far away to measure its parallax. 80.101.212.102 (talk) 18:13, 24 November 2010 (UTC)


 * Right, thanks! Rothorpe (talk) 18:24, 24 November 2010 (UTC)

No, I think it was mostly positional coincidence at the time, only 16 arcsec from the nucleus. Of course SN Ia were not recognized as a distinct type (with a standard absolute magnitude) until much later; in fact, the concept of supernova did not exist in 1885. Also, there were no photographic spectra or precision light curves available in 1885, so we really only think it was a Type IA today mostly because of its visual brightness then, now that we know its distance. It was at first believed to be an ordinary nova, which was argued to prove that the Andromeda galaxy could not be very far away, not an "island universe", as some people were beginning to suspect.

When ordinary stars were first resolved in photographs taken with the 100" telescope in the 1920s, it was realized that the Andromeda Galaxy had to be very distant (because those stars looked so faint), so that if S Andromedae was in the galaxy, it was far too bright to be an ordinary nova. Thus S Andromedae was the defining, "Type Object", of the whole supernova class, the first ever recognized as such.

All this should probably be made more clear in the article, but I have no time to do it now, with proper referencing, etc. Wwheaton (talk) 07:39, 19 March 2015 (UTC)

Wrong interpretation
The sentence "found (...) that M31 was not a gas or dust cloud, but an "island universe" or galaxy" seems to be utterly wrong. Simon Singh writes in his Book "Big Bang" just the opposite: when there was the debate whether M31 was a dust nebula inside our galaxy or far outside, the supernova was an argument in favor of the "near nebula" hypothesis. Otherwise the star would have to have a brightness that people believed to be impossible. — Preceding unsigned comment added by 93.192.67.214 (talk) 17:05, 3 October 2015 (UTC)


 * I support that assessment. They thought it was an ordinary nova. Only when Leavitt's and Hubble's observations proved it to be an extragalactic object, the "nova" became an enigma, and the basis for the "discovery" of supernovae. Rursus dixit. ( m bork3 !) 17:10, 30 March 2016 (UTC)

Andromeda galaxy or Andromeda constellation?
In the intro of the article it is stated that the supernova took place inside the Andromeda Galaxy. On the other hand, in the infobox it is stated that the event took place in the constellation Andromeda. Well, these two are not the same. It's true that Andromeda galaxy is inside the Andromeda constellation from the Earth perspective. But Andromeda constellation is inside the Milky Way galaxy itself (its brightest star is just 97 light years far from the Earth). So which is true to say? The supernova took place inside the Andromeda galaxy or inside the Andromeda constellation? Aminabzz (talk) 00:24, 12 May 2023 (UTC)
 * Where do you get the idea that the Andromeda constellation is "inside" the Milky Way? Constellations are merely an area of the sky as observed from the Earth; objects within that area may be at any distance and still be said to be "in" the constellation.  Hence the Andromeda Galaxy, and by extension everything in the Andromeda Galaxy, is in the Andromeda constellation.  How could it not be in the Andromeda constellation?  Lithopsian (talk) 14:06, 12 May 2023 (UTC)
 * I didn't say Andromeda Galaxy isn't in the Andromeda constellation. Aminabzz (talk) 15:10, 12 May 2023 (UTC)
 * You said "Andromeda constellation is inside the Milky Way galaxy itself". Wrong.  You then extrapolate from that mistake to say that the supernova is either in the galaxy or in the constellation, but not both.  Wrong.  Any further questions?  Lithopsian (talk) 15:23, 12 May 2023 (UTC)