[RightWhale]

In the theory, when a red giant collapses to a white dwarf, is it sudden or is there an associated nova event? If there were a nova would ancient records show it, or is it possible such an event would pass without record such as during the Dark Ages?

[ngc6656]

If there were a nova would ancient records show it, or is it possible such an event would pass without record such as during the Dark Ages?

Although European records were sparse during the Dark Ages, skywatchers in the Far East recorded transient objects they observed in the sky during that era. There is a list of transient objects in the General Catalog of Variable Stars, Volume III, (Moscow, 1973). The list covers sightings recorded between 2296 BC and 1690 AD.

The list is in places ambiguous because of difficulty in determining the precise location in the sky of some of the objects recorded; however, when the subject is Sirius, the brightest star in the sky, one is tempted to believe those ancient stargazers would have had no difficulty in pinpointing it for us.

Bear that in mind as I reveal that my review of the list turns up no reports of the brightening of Sirius or of the appearance of a "guest star" in its immediate vicinity.

Still, it is possible that a brightening of Sirius or the Pup could have been missed, if for example it occurred during a time when Sirius was lost in the sun's glare (Dog Days) and for a duration measured in days, not weeks or months.