Astronomers peer further into supernova’s past

Researchers have peered into the unknown past of a star millions of years before its explosion was seen in 1987.

This was achieved by an international team of researchers with the aid of the Murchinson Widefield Array (MWA) - a telescope comprised of more than 2,000 antennas arranged in 128 ‘tiles’. The researchers, at the International Centre of Radio Astronomy Research (ICRAR), focused on supernova remnant 1987A, the closest and brightest supernova seen from Earth.

Joseph Callingham, from the University of Sydney and first author, said: “Just like excavating and studying ancient ruins that teach us about the life of a past civilisation, my colleagues and I have used low-frequency radio observations as a window into the star's life.”

Previously, scientists had only been able to observe approximately 20,000 years of the star’s life before it exploded. The astronomers used the telescope to see when the star was in its red supergiant phase, in contrast to previous studies that had focused on material ejected into space during its final blue supergiant phase. They found that the red supergiant lost matter at a slower rate and generated slower winds that were pushed into the surrounding environment than was previously thought.

Callingham said: “Our new data improves our knowledge of the composition of space in the region of supernova 1987A; we can now go back to our simulations and tweak them, to better reconstruct the physics of supernovae.” The scientists used the MWA as it one of the most radio quiet places on Earth.

Professor Lister Staveley Smith, co-author from the ICRAR, said: “Low-frequency radio waves are very sensitive to the presence of intervening plasma, so tell us a great deal about the density of matter immediately in front of the supernova remnant. Their presence also tells us about the in-situ acceleration of very high-energy particles called cosmic rays, many of which are believed to be created in young remnants such as this.”

Supernova 1987 is located in the Large Magellanic Cloud, and erupted more than 160,000 years ago. The research was published in the Monthly Notices of the Royal Astronomical Society.