You might have heard already that looking into space is like looking back into the past. The light from distant stars and galaxies has taken eons to reach our eyes and telescopes.
But there’s a flaw in this time machine: The light comes from a specific moment. You can’t look further back in time for a specific object. An international team of astronomers, however, has found an intriguing way around the issue.
The research, led by student Joseph Callingham of the University of Sydney, used very low-frequency radio waves to observe the region around a famous supernova, and thanks to this stellar hiss, the scientists were able to figure out the last few million years in the life of the star.
“Just like excavating and studying ancient ruins that teach us about the life of a past civilization, my colleagues and I have used low-frequency radio observations as a window into the star’s life,” Callingham said in a statement.
The supernova in question is called 1987A, the brightest and closest supernova since the invention of the telescope. It is located in the Large Magellanic Cloud, one of the satellite galaxies that orbits the Milky Way.
Thanks to decades of multi-wavelength observations of the Large Magellanic Cloud, astronomers have known that the progenitor star of 1987A was a blue supergiant star, an unstable type of star with a typical lifespan of 20,000 years.
Stars rarely get to the blue supergiant phase, normally exploding while they are still red supergiants. During this time, the red star spews material into space, and while this was already expected, the research published in the Monthly Notices of the Royal Astronomical Society shows that the red supergiant phase of 1987A lost matter at a slower rate and had slower stellar winds than 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,” Callingham said.
So far, low-frequency radio observations have been difficult due to interference from FM radio. The researchers instead used a telescope in the Australian outback to be out of range from other stations, and in doing so, have shown that low-frequency radio observations are worth pursuing.
Speaking to IFLScience, Mr Callingham said that the most exciting use for low-frequency radio waves "would be to observe young galaxies as you can use them to predict their evolutionary path. So you can predict how many would become just like the Milky Way!"