Astronomers have spotted a new object emerging from the ashes of a recently deceased star. The stellar post-mortem, which is recounted in two new videos, may also solve a mystery surrounding the unexpected shape of the star's explosive remains, scientists say.
In February 1987, astronomers saw a new point of light appear in the sky: a supernova explosion, roughly 150,000 light-years from Earth. A massive star had reached the end of its fuel supply and gone down in a blaze of glory. Since then, scientists have studied the corpse of Supernova 1987A extensively, including visualizing the supernova's dissection in a new video.
"It's like doing a forensic investigation into the death of a star," said Giovanna Zanardo, a Ph.D. candidate at the University of Western Australia, in a statement. [Supernova Photos: Great Images of Star Explosions]
Zanardo and a group of collaborators from the International Centre for Radio Astronomy Research (ICRAR) in Perth, Western Australia, have highlighted some of their most recent findings about 1987A in two videos. In them, the researchers "dissect" the supernova remains with observations, and attempt to recreate the event using computer models.
The ICRAR scientists believe they have identified a pulsar or neutron star in the supernova debris. When massive stars die, the leftover material may collapse down into an incredibly dense object called a neutron star. Pulsars are rapidly spinning neutron stars that radiate bright beams of light that appear to pulse on and off, like a lighthouse.
Images featured in one supernova video show what the ICRAR scientists say is light from the new object.
The challenge in identifying this object, said the researchers, is detecting its faint light in the bright chaos of the debris field. In order to disentangle the different light sources, the researchers combined observations from two telescopes: the Atacama Large Millimetre/submillimeter Array (ALMA) in Chile's Atacama Desert and the Australia Telescope Compact Array (ATCA) in New South Wales.
The combined observations allowed the ICRAR researchers to see different wavelengths of light emitted by the stellar remains: waves, microwaves and infrared light. Analyzing each of these wavelengths alone enabled the researchers to look for different objects that radiate different kinds of light.
In the second supernova video, the ICRAR scientists show how they may have also solved a long-standing mystery about the shock wave that is still expanding away from the supernova remnant.
Scientists have observed that one side of the supernova explosion appears brighter than the other. To figure out why, researchers at ICRAR developed a 3D simulation of the stellar death. They found that tweaking things in the simulation, like the asymmetry of the explosion and the composition of the gas surrounding the supernova, changed the outcome and eventually created models that agree with the new observations.
"The fact that the model matches the observations so well means that we now have a good handle on the physics of the expanding remnant, and are beginning to understand the composition of the environment surrounding the supernova," said Toby Potter, a UWA researcher at ICRAR, said in the statement. This understanding, he said, "is a big piece of the puzzle solved in terms of how the remnant of SN1987A formed."