In February 1987 a blue supergiant star in the Large Magellanic Cloud (LMC)
underwent a catastrophic explosion. Neutrinos, gamma-rays
produced by radioactive decay, and hard X-rays were subsequently observed.
The soft X-rays postulated to originate from the interaction of the exlosion
blast wave with circumstellar matter were missing until 1991,
when they were discovered for the first time by ROSAT.
Since then the luminosity increased steadily (c.f. the lightcurve), indicating
that the shock wave is propagating into the tail of the red supergiant wind,
which the progenitor star blew at an earlier phase of its evolution.
The upper-right figure shows the ROSAT PSPC imgage of an LMC field centered
on SN 1987A (c.f. the arrow), as it showed up in February 1997,
ten years after its birth or ten years after the death of the progenitor star.
G. Hasinger, B. Aschenbach, and J. Trümper
The X-ray lightcurve of SN 1987A, Astron. & Astrophs. 312, L9-L12 (1996)
from ADS service.
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