Skip to main content
News_

Faintest hisses from space reveal famous star’s past life

2 August 2016
Astronomers 'see' millions of years into the past life of a star that collapsed spectacularly 29 years ago.

Research led by a PhD student investigating the cosmic ruins of a famous star has resulted in the piecing together of its past dating back millions of years. The star's spectacular explosion 29 years ago was the closest seen from Earth; the findings about supernova remnant 1987A will help astrophysicists' understanding of supernovas generally. 

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.
Mr Joseph Callingham.
Supernova flare seen in the Large Magellanic Cloud on 23 February 1987. Image at the top of this page: Murchison Widefield Array radio image of a part of the Large Magellanic Cloud, our neighbouring galaxy.   Source: CAASTRO.

Artist's impression of the supernova flare seen in 1987 in the Large Magellanic Cloud, our neighbouring galaxy. Top of this page: Murchison Widefield Array radio image depicting the location of the supernova remnant in the Large Magellanic Cloud. Source: CAASTRO. More images below.

Astronomers have managed to peer into the past of a nearby star millions of years before its famous explosion, using a telescope in remote outback Australia at a site free from FM radio interference.

Research led by a student at the University of Sydney and including an international team of astronomers observing the region at the lowest-ever radio frequencies has helped fine-tune our understanding of stellar explosions.

The research paints a picture of the star’s life long before its death in what was the closest and brightest supernova seen from Earth, now known as supernova remnant 1987A, which collapsed spectacularly almost 30 years ago.

Much had been known about the immediate past of this star through studying the cosmic ruins resulting from the star’s collapse on 23 February 1987, which occurred in neighbouring galaxy, the Large Magellanic Cloud. However it was the detection of the very faintest of hisses through low-frequency radio astronomy that has provided the latest insights.

Previously, only the final fraction of the dead star’s multi-million-year-long life, about 0.1% or 20,000 years, had been observable.

This latest research – which has enabled astrophysicists to probe the supernova’s past life millions of years further back than was previously possible – was led by Joseph Callingham, a PhD candidate with the University of Sydney and the ARC Centre of Excellence for All-Sky Astrophysics (CAASTRO), under supervision from former Young Australian of the Year Bryan Gaensler, now at the University of Toronto.

The findings are published today in the Monthly Notices of the Royal Astronomical Society, Oxford University Press.

Operating the Murchison Widefield Array in the West Australian desert, the radio astronomers were able to ‘see’ right back to when the star was in its long-lasting red supergiant phase. Mr Callingham explained previous studies focused on material that was ejected into space when the star was in its final blue supergiant phase.

“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,” Mr Callingham said.

Researchers found the red supergiant lost its matter at a slower rate and generated slower winds that pushed into its surrounding environment than was previously assumed.

“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 supernova explosions,” Mr Callingham said.

Professor Gaensler explained that key to gaining these new insights was the quiet environment in which the radio telescope is located.

“Nobody knew what was happening at low radio frequencies, because the signals from our own earthbound FM radio drown out the faint signals from space. Now, by studying the strength of the radio signal, astronomers for the first time can calculate how dense the surrounding gas is, and thus understand the environment of the star before it died.” Professor Gaensler said.

Vivienne Reiner

Media and PR Adviser (Science, Veterinary Science, Agriculture)
Address
  • Room 192, Level 1 Carslaw F07

Related articles

24 September 2020

University of Sydney to advance COVID-19 DNA vaccine to human trials

The University of Sydney is testing a novel DNA-based COVID-19 vaccine with the goal of being administered using a needle-free system.
23 September 2020

When does a second COVID surge end? Look at the maths

Mathematicians have analysed COVID-19 infection rates from all US states. The results suggest public health officials shouldn't relax restrictions until surge periods are demonstrably over. They also used the method to look at Australian infection rates.
16 September 2020

Australia unprepared for over-the-counter medical cannabis sales

Professor Iain McGregor from the Lambert Initiative says it is time for Australia to have a mature approach to consumer access to safe and effective cannabinoid products without a prescription.
10 September 2020

How the Milky Way stole an enormous gas halo from our dwarf neighbours

A stream of gas from the Magellanic Clouds the mass of more than a billion Suns fills our skies in UV and x-ray light. But why does it remain so massive and not evaporate into its enormous neighbour, the Milky Way? Professor Joss Bland-Hawthorn was part of the team that found out.
09 September 2020

University and Health Infrastructure unveil emergency ventilator

The University of Sydney has joined with Health Infrastructure and Vestech Medical to celebrate the success of the NSW government's Ventilator Innovation Project and unveil the completed "CoVida", an emergency ventilator.
08 September 2020

Gen Z not ready to eat lab-grown meat, survey reveals

New research by the University of Sydney and Curtin University has found that, despite having a great concern for the environment and animal welfare, Generation Z is not ready to eat lab-grown meat.