A thermonuclear explosion on a dead star has resulted in
an expanding space bubble shaped like a peanut.
The unusual
sight arose from an unstable pairing of two aged stars: a white dwarf and a
red giant in the constellation of Ophiuchus, known collectively as RS Oph.
Astronomers imaged the double-lobed peanut structure's material expanding
outwards at between 621 and 1,864 miles per second (1,000 and 3,000 kps).
"There are some astronomers who believe systems like
this will ultimately explode
as supernovae," said Valerio Ribeiro, an astrophysics researcher at
Liverpool John Moores University in the UK.
The white dwarf represents an Earth-sized dead star that
pulls hydrogen-rich gas from the red giant's outer layers. Every 20 years or so,
that buildup of gas eventually causes a cataclysmic explosion similar to that
created by a hydrogen bomb's uncontrolled fusion
reaction.
Energy output from RS Oph reaches 100,000 times that of
the sun during such events, and the eruption ejects an amount of material
equivalent to Earth's mass at hundreds of miles per second.
The red giant is a bloated, late-stage star whose days
are numbered. Researchers point to the red
giant's wind as the culprit behind the unusual shaping of the expanding
nebula. That wind usually forces surrounding material to gather near the stars'
orbital plane and leaves less near the poles.
When an outburst occurs, high-speed material from the
eruption hits the dense gas in the orbital plane and slows down, but it
continues moving outward at high speed in the polar areas to form the
double-lobed peanut shape.
Japanese amateur astronomers first spotted the system's latest
brightening on Feb. 12, 2006, which prompted scientists to turn to more
powerful ground-based radio telescopes and NASA's Hubble Space Telescope.
The research was to be presented April 22 at the European
Week of Astronomy and Space Science conference at the University of
Hertfordshire.
advertisement
