Back in 2007, a science team under Eric Mamajek of the University of Rochester announced something unusual – a giant world, orbiting the star 1SWASP J140747.93-394542.6 with a ring system so immense it makes Saturn’s look like a kiddie toy.
This world – officially known as 1SWASP J140747.93-394542.6b to differentiate it from its star 1SWASP J140747.93-394542.6, is thought to have a mass maybe 13-26 times that of Jupiter, which makes it a pretty big giant world, but not a star.
The ring system has a radius of 0.6 astronomical units – sixty percent the distance of Earth from the Sun or around 90 million kilometres. Its total diameter is 180,000,000 kilometres. A gap in the system some 61,000,000 km from the planet suggests an exomoon, which has been calculated to have up to 0.8 Earth masses.
The rings were picked up because the planet was detected by means of the transit method – in which a planet passes directly between the star and Earth. A suitable telescope can pick up the ‘light wobble’ as the planet partially shields the light of the star. In this case, the wobble was a curious curve, which was best explained as this gigantic ring system.
That’s also how the star and planet got their names: they were discovered by the Super Wide Angle Search for Planets programme, run from two observatories at La Palma and Sutherland. Hence WASP. The rest of the name is the internal database coding used by the programme. I suppose eventually the more important discoveries will be given sensible names by the IAU, like Roger or Jacinta, meanwhile we have to put up with long codes.
The 1SWASP telescopes, incidentally, use eight 200-mm Canon lenses, ganged up – which sounds an awful lot like the one I own. The 1SWASP J140747.93-394542.6 system is about 420 light years from Earth, in the constellation Centaurus, which gives you an idea of the sensitivity of the setup.
Pretty cool. And who knows what else might be out there.
Copyright © Matthew Wright 2015