News in Science

Missing supernova mystery solved

Dust busting A large number of dying stars called core-collapse supernovae are not detected because they are obscured by galactic dust, say astronomers.

The discovery, reported in Astrophysical Journal explains why astronomers are see far more of these high mass stars being born, compared to the numbers they see reaching the end of their lives.

"This has kept us awake at nights," says Dr Stuart Ryder from the Australian Astronomical Observatory, who is one of the paper's authors.

"Our new study indicates between 15 and 20 per cent of these core-collapse supernovae are being missed by obscuring dust in nearby galaxies, and about 40 per cent in more distant galaxies," says Ryder.

"We know massive stars are being born at a certain rate."

"They live fast and die young, going out in a blaze of glory as core-collapse supernovae."

"But we weren't seeing this, so we wanted to close the gap," says Ryder.

Key to success

Ryder and colleagues used the Gemini North telescope in Hawaii to peer through the obscuring dust, looking for the missing supernovae at infrared wavelengths, which penetrates dust better than optical light.

By combining the infrared with adaptive optics (which removes the haze caused by the Earth's atmosphere), astronomers obtained highly detailed images exposing previously hidden core-collapse supernovae.

"Adaptive optics has been the key breakthrough which has allowed us to see into the dense and clumpy cores of galaxies and discover many of the supernovae that were undetected by previous surveys," says Ryder.

"We imaged galaxies six months apart looking for new points of light which signal a new supernovae."

"But we only covered a handful, about eight galaxies."

The study will expand next year when a new infrared adaptive optics camera built by the Australian National University is installed on the Gemini South Telescope in Chile.

"It will have a much bigger field of view than the one we've been using in the north," says Ryder.

"This will allow us to dramatically expand our search and capture a much broader and representative sample of supernovae."