Taking 290 million years to reach Earth, last month that light from a supernova explosion was spotted by an Irish amateur astronomer in his backyard observatory.
David Grennan’s backyard observatory
David Grennan was just about to go to bed on September 17 when he spotted the exploding star through his 36 cm (14-inch) Schmidt Cassegrain Telescope at his home observatory in Raheny in north Dublin.
He beat professional astronomers across the globe with his discovery, which was officially confirmed by international astronomy authorities earlier this week.
It is the first supernova to be discovered from Ireland.
The explosion happened long before dinosaurs roamed the Earth.
Grennan discovered the supernova by comparing images taken of the same area in the sky in August and September.
He noticed a black spot in the later images that had not been there previously. He said the force of the supernova would be equivalent to 100 million Earths exploding at the same time.
Supernovae are categorised by the elements in their spectra and precisely how they brighten to a peak and decline. Type II supernova are easiest to describe, occurring when a vast star dies, with its core collapsing in upon itself to form a neutron star or even a black hole. A Type Ia supernova is believed to be caused by a white dwarf star in a compact binary system accumulating matter from its companion star until the density threshold for nuclear fusion occurs, resulting a titanic nuclear explosion. Types Ib and c would seen better considered as a subtype of Type II as their mechanisms are identical. Again they are believed to be triggered by the cores of huge stars imploding just like Type II but in their cases the the star has previous lost its outer layers either to a nearby companion star or through ferocious stellar winds making them deficient in hydrogen.
Although Grennan’s discovery was made during a search undertaken on September 17th, it is required that detailed confirmation must follow before being officially announced. Prof. Stephen Smartt and his team at Queen’s University Belfast analysed the light coming from the explosion using the 2.5metre Nordic Optical Telescope at La Palma in the Canaries. Prof. Smartt and his team confirmed the discovery as a “Type 1b/c” supernova meaning that the explosion was caused by one star ripping material from another. Prof. Smartt concluded that his analysis of this event shows it has peculiarities which mean this discovery may be of great interest to the scientific community.
Cosmic cataclysm: the distant supernova (location marked in red) appears as a speck against the faint smudge of its galaxy in this negative image.
Every century a couple of supernovae ought to occur in our own galaxy, the Milky Way, but are usually obscured by the great lanes of dust which thread their way through the spiral arms. The last confirmed supernova in the Milky Way to be observed was in 1604 (known to history as Kepler‘s Star; it was bright enough to be seen in the daytime sky). Ever since then all supernovae examined by astronomers have been denizens of other galaxies. Grennan’s supernova lies in a galaxy estimated to be 290 million light years (89 Mpc) away.
Grennan bought his first hand-held telescope in 1991 and gradually upgraded his equipment over the years, building his home observatory in 2005.
There’s nothing particularly sophisticated about the observatory – he said he bought most of the equipment in a DIY store and made it single-handedly over a couple of months (he seems to have done a better job than I did with my observatory back in 1999!).
It includes a retractable roof so he can keep the protect the telescope and other equipment from the elements.
‘Unfortunately, the Irish weather doesn’t afford me much time to observe the skies but I try to devote about two nights a week to it.’
‘I couldn’t really do it without my wife Carol,’ he added, ‘because she helps me look at the images and spot anything interesting.
‘Naturally I’m very excited at having made this discovery, especially since it’s a first for Ireland. I find myself wondering if there were some poor souls living on planets surrounding the star when it exploded. one thing is for sure: we’ll never know.’
He added: ‘I would really love to see younger kids getting interested in science and astrophysics because it’s amazing what you discover.
‘I firmly believe that science is a key to the way out of our economic difficulties, which will drive the knowledge based economy they are trying to promote.’
Two years ago, Mr Grennan discovered an asteroid just three metres wide and named it after his mother Catherine Griffin, who had encouraged his interest in the stars when he was a boy.
The supernova is expected to remain visible with a telescope for about two or three months before it fades.
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Filed under: Astronomy News • Deep Space
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