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View Full Version : ever been a supernova in M31?



peteshimmon
2012-Feb-01, 01:25 PM
This object has been recognised as an
external galaxy for a hundred years or
so but any new bright stars there would
surely have been seen in previous centuries.
Never read of any though. Is one due? A type
2 would have a neutrino signal that should be
detected withs the facilities today. And any
other effects perhaps.

ngc3314
2012-Feb-01, 01:30 PM
Sure, SN 1885 (=S Andromedae) near the nucleus. Fesen and colleagues recovered the remnant a few years ago via absorption in an iron line, and a more recent project (http://adsabs.harvard.edu/abs/2007ApJ...658..396F) mapped iron and calcium absorption from the remant against the bright bulge starlight. .

Hornblower
2012-Feb-01, 01:49 PM
This object has been recognised as an
external galaxy for a hundred years or
so but any new bright stars there would
surely have been seen in previous centuries.
Never read of any though. Is one due? A type
2 would have a neutrino signal that should be
detected withs the facilities today. And any
other effects perhaps.

The author of the following paper concludes that S And was an anomalous Type Ia.
http://iopscience.iop.org/1538-3881/123/4/2045/pdf/201505.web.pdf

This star only reached 6th magnitude. Similar ones in previous centuries would not have been eye catching.

As for when another supernova is "due", we can deal only with probabilities. Another one could blow at any time.

peteshimmon
2012-Feb-01, 02:02 PM
Ahh thanks! I read in Constellations that the
Pinwheel galaxy was known for supernovae and
there was one last August so why not the good
old Andromeda galaxy. At ten times closer they
would be more noticeable.

ngc3314
2012-Feb-01, 05:12 PM
Andromeda might well be "deficient" in Type IIs, since its star-formation rate is really on the quiescent side for luminous spirals. Dunno where its Type Ias all hide, though - although statistics of really small numbers don't tell much at all. An unreddened one should have V~5 or a bit brighter seen in M31. I don't know how far back we could count on nondetections at that level to be helpful, probably not too much earlier than 1885 (especially since sitting in the galaxy light, the extra light would change the galaxy's naked-eye appearance only in a pretty subtle way).