SN1987A, Past and Present | In the Dark


There’s a new paper in Science featuring observations using the MIRI and NIRSpec instruments on JWST of Supernova SN1987A in the Large Magellanic Cloud. I couldn’t resist doing a short post about this result, partly because the paper features Maynooth colleague Paddy Kavanagh, and partly because I’m old enough to remember when this supernova was detected, in 1987. In fact I was doing my PhD at the time. When I started lecturing a few years later I used to use it as an example of a Type II (core-collapse) supernova. At first I would say “you will remember SN1987A” then, as the years passed, I realized that students would have been quite young in 1987 so I changed this to “some of you will remember SN1987A”. Still later, I realized that none of my students had even been born in 1987 so I forgot about the remembering bit and just talked about SN1987A. As of 2024, nobody under the age of 37 was born in 1987. Tempus has a distinct tendency to Fugit.

In 1987 I was in Sussex and I remember Roger Tayler getting very excited about the detection of anti-neutrinos from SN1987A at the Kamioka Observatory in Japan. There weren’t many – 12 altogether – but he wanted to do a statistical analysis of the arrival times to see if there was any evidence that might indicate the neutrinos had mass. Being rather “old-school”, he did a Monte Carlo experiment involving drawing numbers written on bits of paper out of a cardboard box. After a brief chat I suggested I could do a much better job using a random-number generator on a computer so I wrote a bit of code and did the computation. The results showed no evidence for neutrino mass.

Anyway, this type of supernova should produce a neutron star or black hole sitting inside a ring-shaped remnant. The ring has been well studied, but in 37 years of observation the central object has not been detected. The results in the latest paper (by Fransson et al.) involve a spectroscopic study of the emission lines of ionized argon from the SN1987a remnant at sufficiently high spectral resolution to map the velocity structure. The results suggest that ionizing radiation from a neutron star is illuminating gas from the inner parts of the remnant.

For more details, see the paper.

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