National Geographic : 1988 May
TELESCOPICSUNGLASSES were needed to protect even a small 16-inch instrument at CerroTololo, so brightwas the supernova's glare.At sunset, researchassistantMario Hamuy preparesto attach a screen to the telescope. hearing a familiar song sung in another lan guage: recognizable without being under standable. tim. Because the Large Magellanic Cloud is nearby and has been in tensively studied, we should have been able to tell what star exploded by looking at images taken before February 23. Accurate measurements of the supernova position showed that it was at exactly the same place as a hot blue star in an LMC catalog prepared in 1969 by Nick Sanduleak of Case Western Re serve University in Cleveland, Ohio. His list tabulated this prime suspect as number 202 in the group of stars 69 degrees south of the Equa tor. We call it Sanduleak -69°202. The Sanduleak star has a close neighbor, so close that the two stars blend together in pic tures of moderate quality. Following my re quest to NASA, George Sonneborn of the IUE Observatory had been watching SN 1987A. Because the supernova's ultraviolet radiation had plummeted a thousandfold, we were able to survey the scene of destruction. We expect ed to see only the neighbor star. We were shocked to find two stars still present! Could the Sanduleak star have survived? When I suggested this possibility, Stan Woosley, a supernova theorist from the Uni versity of California at Santa Cruz, was more than skeptical. "If the Sanduleak star didn't blow up, the supernova came from a star just like it!" In the end the theorist's confidence was jus tified: Subsequent scrutiny showed that the Sanduleak star had possessed not one but two companions, both bright enough in the ultra violet to be detected by the IUE satellite. Sanduleak -69°202, we knew now, had not survived. The catalog listed its vital statistics. Sandu leak -69°202 was a hot blue-white star resem bling Rigel, a bright, familiar star in the constellation Orion. It was about 20 times the mass of the sun, shining furiously with 100,000 times the sun's luminosity. Using its fuel in 630 Son of Supernova? AMYSTERYSPOT near the dying star was detected lastApril, baffling observers. The spot, seen beneath the supernovain the image below, was 8 percent as brightas its neighbor,was about two light-weeks away from it, and could not have existed earlier. The phenomenon was discovered by CostasPapaliolios (opposite, at left) of the Harvard-Smithsonian Centerfor Astrophysics.