UCL Mathematical & Physical Sciences


Ashes of a dead star

SN 1987A seen by Hubble, ALMA and Chandra

13 January 2014

In 1987, a bright point of light appeared in the night sky. Training their telescopes on it, astronomers quickly realised that they were witnessing one of the most elusive events in astronomy: a supernova, the collapse and subsequent explosion of a giant star.

Supernovae are very rare, as stars live a long time and only the very largest end their lives as supernovae. None have been observed within our Milky Way galaxy since the invention of the telescope in the 16th century.

Supernova 1987A, as the 1987 event was quickly christened, exploded in the Large Magellanic Cloud, a satellite galaxy of the Milky Way located about 160 000 light years away. It is by far the closest supernova ever observed with a telescope.

In the quarter century that has followed, Supernova 1987A has been heavily studied. The bright flash of the exploding star has long since faded, but the shockwaves and expanding clouds gas are still extremely active.

In the last few years, the shockwaves have reached a shell of gas surrounding the dead star, and have made parts of it light up, creating a necklace of bright glowing pearls of gas.

Now, a new study by a team including Mike Barlow and Mikako Matsuura (both UCL Physics & Astronomy) has used the the Atacama Large Millimeter-submillimeter Array (ALMA, the world's most advanced radiotelescope) to study the cold dust at the centre of the supernova remnant, something which is impossible to see using visible light.

The picture above combines these two recent discoveries. The location of the cold dust (seen by ALMA at millimetre wavelengths) is shown in red, while the ring of glowing pearls observed by Hubble (optical) and Chandra (X-ray) is in green and blue respectively.

Credit: ALMA (ESO/NAOJ/NRAO)/A. Angelich, NASA/ESA Hubble Space Telescope, NASA Chandra X-Ray Observatory


High resolution image

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