Image caption SN 1987A: The inner ring of pearls is about one light-year across

The Hubble space telescope has returned to view one of its favourite subjects - a giant stellar explosion that was first seen on Earth in 1987.

The new observations allow us to accurately measure the velocity and composition of the ejected 'star guts' Kevin France, University of Colorado, Boulder

The famous supernova is one of the most studied objects in the southern sky.

The new image of SN 1987A is the observatory's first picture of the explosion since its systems were repaired and upgraded last year.

It has given astronomers the chance to catch up on the progress of all the material blasted into space.

Their research is reported in a paper published in the journal Science.

SN 1987A is sited in the nearby Large Magellanic Cloud, a dwarf galaxy adjacent to our own Milky Way Galaxy.

Being just 168,000 light-years from Earth, the supernova has given scientists a detailed view of what happens when big stars end their days.

The explosion spewed out colossal amounts of gas and dust, including many of the heavy elements like sulphur, silicon and iron expected to be forged in supernovas.

This debris is now crashing into matter shed by the dying star just prior to its collapse and heating it, causing it to glow.

Scientists have calculated that the inner ring, which looks like a pearl necklace, was probably puffed out some 20,000 years before the main explosion.

The shock waves rushing out through the ring will continue to brighten the pearls, which will probably grow and merge together in the coming years to form a continuous, expanding circle, researchers say.

"The new observations allow us to accurately measure the velocity and composition of the ejected 'star guts', which tell us about the deposition of energy and heavy elements into the host galaxy," said Kevin France from the University of Colorado, Boulder, US.

"The new observations not only tell us what elements are being recycled into the Large Magellanic Cloud, but how it changes its environment on human time scales."

SN 1987A was the closest observed supernova since one seen in 1604, which occurred within the Milky Way itself.

Jonathan.Amos-INTERNET@bbc.co.uk