Upper Limits to the Prompt X-ray Flux from Supernova 1987a

Abstract

AbstractThe literature contains numerous predictions of an X-ray pulse associated with the emergence of the shock-wave at the surface of a star undergoing a supernova explosion. Applied to supernova 1987a, these suggest a small, solar-flare like event lasting about a minute with a terrestrial flux of order 1 μWm-2 and a black-body temperature between 106K and 107K occurring between 0900 and 1000 UT on February 23, 1987. Unfortunately, no direct X-ray observations appear to have been made. However, such an event would be expected to give rise to an observable enhancement of ionization in the upper D-region of the ionosphere. The absence of a detectable perturbation in VLF radio signals propagating in the earth-ionosphere waveguide sets upper limits to the X-ray flux and temperature below those predicted.