WASHINGTON (AP) - An exploding star that lighted up the southern sky in 1987 and then dimmed is starting to brighten again as its high-speed blast wave creates a ring of fire.

Though not visible from the ground, astronomers said Tuesday, the increasing brightness of the supernova remnant is clearly visible in images taken by the Hubble Space Telescope. They said light from the ring of fire should intensify over the next 10 years.

''This is the first spark of some stellar fireworks that will take place over the next few years,'' said Robert P. Kirshner, a Harvard astronomer.

The exploding star, known as Supernova 1987A, was first sighted on Feb. 23, 1987, in ground telescope photo images of the Large Magellanic Cloud, a small galaxy of stars 167,000 light years from Earth. The star is visible only from the Southern Hemisphere.

It's believed the star was a red supergiant, 20 times the mass of the sun, that reached the end of its lifetime and exploded, heating instantly to 10 billion degrees.

High speed particles, called neutrinos, raced out from the explosion and lighted up a disk of gas that is thought to have earlier formed a ring 100 billion miles around the star.