Astronomers believe they have found the remains of neutron stars left by Supernova 1987A

It was the brightest supernova for nearly 400 years when it lit the southern hemisphere sky in February 1987. Supernova 1987A – the explosion of a blue supergiant star in the nearby mini-galaxy known as the name of Large Magellanic Cloud – amazed the astronomical community. This gave them an unprecedented opportunity to observe an exploding star in real time with modern instruments and telescopes. But something was missing. After the supernova disappeared, astronomers expected to find a neutron star (a hyper-dense, collapsed stellar core, made up largely of neutrons) at the heart of the explosion. They didn’t see anything.

Over the next 34 years, astronomers searched, unsuccessfully, for the missing neutron star. Various theories have arisen. Maybe he hadn’t had time to train yet. Or maybe the mass of the blue supergiant was larger than expected, and the supernova created a black hole instead of a neutron star. Perhaps the neutron star was hidden, obscured by dust from the explosion. If the missing star was there at all, it was really hard to see.

But perseverance pays off. Astronomers may have finally found it.

The first clue came from the Atacama Large Millimeter / submillimeter Array (ALMA) in Chile last summer. The radio telescope observed a hot “spot” in the core of the supernova. The “blob” itself is not a neutron star, but rather a heated mass of dust and gas that can hide the neutron star behind it: after all, something is providing the heat. But to confirm the presence of a neutron star would require further observations.

With the promising results of the ALMA radio signal in hand, a team of researchers followed up by observing the supernova in x-ray wavelengths, using data from two different NASA spacecraft: the Chandra X- Ray Observatory and the Nuclear Spectroscopic Telescope Array (NuSTAR). Their results are published in the Astrophysical Journal this month. What they found was an X-ray emission near the core of the supernova explosion, with two possible explanations.

First, the emission could be the result of particles accelerated by the shock wave of the explosion. This shock wave theory cannot be fully ruled out, but the evidence seems to point to a second more likely explanation – a pulsar wind nebula.

Pulsars are a type of energetic neutron star that spin rapidly, projecting radiation outward like a beacon as they spin. Pulsars can sometimes create high speed winds that blow outward and create nebulae, shaped by charged particles and magnetic fields. This is what the researchers think they are seeing.

Chandra and NuSTAR data supports last year’s ALMA detection. Somewhere in the center of Supernova 1987A is a young pulsar. It may be a decade or more before the supernova’s core emerges enough to observe the pulsar directly, but for the first time in 30 years, astronomers can be fairly convinced it’s there.

The discovery is fascinating. “Being able to watch a pulsar essentially from birth would be unprecedented,” said Salvatore Orlando, one of the researchers involved in the detection. “This could be a unique opportunity to study the development of a baby pulsar.”

So, with a 30-year mystery solved and plenty of new science to do in the years and decades to come, Supernova 1987A promises to keep our attention. After all, it’s the closest, brightest supernova we’ll ever see.

Unless Betelgeuse explodes …

(Betelgeuse is not likely to explode anytime soon)

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