In May 2010, a South African astronomer discovered what he thought was a supernova in NGC 300. A supernova is a massive dying star spending its last remaining time in blazing at its finest. Most supernovae are only visible for only a few weeks before fading away from view.
When the dying star finally explodes, it leaves a residue that is what we call a black hole or a neutron star. None of these supernova residues should be seen from Earth. However, the supernova impostor called SN 2010da remained visible.
A supernova impostor is often mistaken for a supernova because of its massive light emission. Later on, it is found to be an enormous star with an intense flare. Many of them are actually two massive stars that orbit each other, and scientists believe that the irregular flares could be the result of distress from each companion.
In September 2010, SN 2010da was confirmed a fake when a postdoctoral researcher from the University of Washington's (UW) Department of Astronomy Breanna Binder looked at NGC 300 using NASA's Chandra X-ray Observatory. However, the UW Bothell's School of STEM lecturer found something else.
"There was just this massive amount of X-rays coming from SN 2010da, which you should not see coming from a supernova impostor," said Binder, who found that SN 2010da's X-ray intensity is the same as those coming from a neutron star. This type of star is the dense, broken core residue of a supernova. Binder found it surprising since it was previously determined that SN 2010da is a supernova impostor.
The research team analyzed SN 2010da once more in 2014 using Chandra, but this time, they brought in the big guns – Hubble Space Telescope. They found that SN 2010da wasn't alone; it had a companion like other impostors of its kind. However, SN 2010da is special because, unlike other impostors in a binary system, this one most likely had a neutron star as a companion once upon a time. This new data makes SN 2010da an even more impressive impostor to have survived when its real supernova companion exploded.
"The fact that this supernova event didn't expel the other star, which is 20 to 25 times the mass of our sun, makes this an incredibly rare type of binary system," said Binder. The discovery was published in the journal Monthly Notices of the Royal Astronomical Society on Feb. 11.
Photo : Hubble ESA | Flickr
