Astronomers in Australia have created a ‘unique view’ of the Milky Way by taking information from a radio telescope and producing an image of what our galaxy would look like if humans could see radio waves.
The image from the Murchison Widefield Array telescope shows low-frequency radio emissions from the centre of the galaxy in yellow and gold, with flecks of blue and green.
‘Our images are looking directly at the middle of the Milky Way, towards a region astronomers call the Galactic Centre’, says Astrophysicist Dr Natasha Hurley-Walker.
The team from Curtin University used the massive image to discover the remnants of 27 massive stars that exploded in supernovae, one of which happened 9,000 year ago and would have been visible in the Earth sky.
This image from the Murchison Widefield Array telescope shows low-frequency radio emissions from the centre of the galaxy presented in a way humans can see
The images are taking using the GaLactic and Extragalactic All-sky MWA survey (pictured here). It is also know asr GLEAM for short
These giant star explosions visible in the image would have been eight or more times more massive than the sun before their dramatic destruction.
Dr Hurley-Walker says younger supernova remnants are easier to spot than the older ones seen in the image and 295 are already known.
She said one of the newly-discovered supernova remnants lies in an empty region of space, far out of the plane of our galaxy.
‘It’s the remains of a star that died less than 9,000 years ago, meaning the explosion could have been visible to Indigenous people across Australia at that time.’
The team from Australia uncovered the remnants of 27 supernova explosions and this image shows the location of where one would have been visible set against the Guilderton Lighthouse in Western Australia
Anthropologists from Australia hope to be able to examine the traditional records of the aboriginal people to see if there is any cultural memory of these events.
Some Aboriginal traditions do describe bright new stars appearing in the sky, but we don’t know of any definitive traditions that describe this particular event’, said Duane Hamacher from the University of Melbourne, an expert in cultural astronomy.
‘Now that we know when and where this supernova appeared in the sky, we can collaborate with Indigenous elders to see if any of their traditions describe this cosmic event. If any exist, it would be extremely exciting,’ he said.
Of the 27 supernova explosions spotted within the image, some were found in areas of the sky that had no other big stars
The images are taking using the GaLactic and Extragalactic All-sky MWA survey – or GLEAM for short.
The system has a resolution of two arcminutes (about the same as the human eye) and maps the sky using radio waves at frequencies between 72 and 231 MHz (FM radio is near 100 MHz).
‘It’s the power of this wide frequency range that makes it possible for us to disentangle different overlapping objects as we look toward the complexity of the Galactic Centre,’ Dr Hurley-Walker said.
‘Essentially, different objects have different radio colours, so we can use them to work out what kind of physics is at play.’
This image shows the galactic centre using radio waves. The red areas are low frequency, middle frequencies are in green and high frequencies in blue. The bright white spot in the centre is the super massive black hole Sagittarius A*
Aboriginal residents of Australia would have seen one of the supernova explosions as it happened 9,000 years ago. This image shows what it would have looked like amongst the Milky Way from the Pinnacles Desert in Western Australia
There were several ‘surprises’ found within the data, according to Dr Hurley-Walker and her team from Australia.
Two of the supernova remnants discovered in the image were ‘orphans’ – that means they were found in a region of sky where there are no massive stars.
Other supernova remnants discovered in the research are very old.
‘This is really exciting for us, because it’s hard to find supernova remnants in this phase of life–they allow us to look further back in time in the Milky Way’, she said.
These are the 27 newly-discovered supernova remnants of stars that ended their lives in huge stellar explosions thousands to hundreds of thousands of years ago
The team hope to be able to discover much more in future, as the next generation of radio telescopes come online.
The Square Kilometre Array, which is due to be built in Australia and South Africa from 2021 will be much more sensitive than the one used to create this image.
“The low-frequency part of the Square Kilometre Array will be thousands of times more sensitive and have much better resolution.
‘It should find the thousands of supernova remnants that formed in the last 100,000 years, even on the other side of the Milky Way.”
The research has been published by the International Centre for Radio Astronomy Research.
The milky way looks very different when viewed through radio waves (right) than when seen using the naked eye (left)
WHAT IS A SUPERNOVA AND HOW DOES IT FORM?
A supernova occurs when a star explodes, shooting debris and particles into space.
A supernova burns for only a short period of time, but it can tell scientists a lot about how the universe began.
One kind of supernova has shown scientists that we live in an expanding universe, one that is growing at an ever increasing rate.
Scientists have also determined that supernovas play a key role in distributing elements throughout the universe.
In 1987, astronomers spotted a ‘titanic supernova’ in a nearby galaxy blazing with the power of over 100 million suns (pictured)
There are two known types of supernova.
The first type occurs in binary star systems when one of the two stars, a carbon-oxygen white dwarf, steals matter from its companion star.
Eventually, the white dwarf accumulates too much matter, causing the star to explode, resulting in a supernova.
The second type of supernova occurs at the end of a single star’s lifetime.
As the star runs out of nuclear fuel, some of its mass flows into its core.
Eventually, the core is so heavy it can’t stand its own gravitational force and the core collapses, resulting in another giant explosion.
Many elements found on Earth are made in the core of stars and these elements travel on to form new stars, planets and everything else in the universe.