Visual Observability of the Cassiopeia A Supernova

TL;DR

This paper investigates the historical and observational evidence for the Cassiopeia A supernova, suggesting it was a Type Ic event observed in 1680, with implications for understanding supernova progenitors and their visibility.

Contribution

It provides an analysis of historical records and observational data to support the classification of Cas A as a Type Ic supernova and discusses its visual observability in 1680.

Findings

Evidence suggests Cas A was a Type Ic supernova.

Historical observations align with the supernova's expected brightness.

The supernova's peak likely occurred in winter 1679-1680.

Abstract

It is generally believed that the explosion which gave birth to the Cassiopeia A supernova remmant resulted from core collapse of a hydrogen-deficient star. A progenitor that has lost all its hydrogen envelope and part of its helium envelope would lead to an explosion with the optical properties of a Type Ic supernova. There is evidence, if not general agreement, that Flamsteed observed the Cas A supernova as a sixth magnitude object in August, 1680. If an explosion with a typical SNIc light curve at the position and distance of Cas A attained maximum luminosity during the winter of 1679-1680, it would at that time have been poorly situated for visual observation, as its upper culmination would have taken place during daylight, while in August, between 170-200 days after peak luminosity, it would have been a sixth magnitude star.