Do you remember anything about February 24, 1987? I don’t. Maybe if I had been south of the equator…
On that day in the Large Magellanic Cloud a star burst forth so bright it could be seen with the naked eye. I read about it in astronomy focused magazines and let it go. Not in my hemisphere. Boy, my reaction would have been different if I lived in Australia!
SN1987A was the first supernova observed in 1987, hence the moniker. Astronomers tend to be an organized lot and try to apply the KISS (Keep It Simple, Stupid) principle. But this wasn’t just any supernova. It was the closest supernova to Earth observed since the time of Galileo. The Large Magellanic Cloud (LMC), a satellite galaxy of our Milky Way, is just 170000 light years away. It’s like going from New Braunfels to Gruene in cosmic scale. SN1987A was a windfall for astronomers, astrophysicists, and cosmologists. They jumped on it.
We must keep in mind the cosmic scale. The LMC is 170000 light years from us so the supernova had occurred 170000 years before it was first observed here on Earth. When it was exploding, humans were, well, still working on the top of the food chain thing. The first photons to reach eyes, imaging film, yes film, and sensors had made a 170000-year journey. How many miles? That’s 186000 (speed of light in miles per second) x 60 seconds per minute x 60 minutes per hour x 24 hours per day x 365 days per year x 170000 years (approximately).
So, the last time a supernova this close occurred astronomers had rudimentary telescopes. In 1987 astronomers had more tools with which to observe and measure this “great new star”. In the 33+ years since SN1987A appeared astronomers have been observing and measuring its aftermath. Using infrared, ultraviolet, visible and x-ray imaging, astronomers have followed the shell of gas and dust expanding outward.
Supernovae are the result of a star having too much mass for its own good. Its fusion process goes through hydrogen, helium, oxygen, carbon, silicon etc., so fast that when it hits the iron wall it still has a lot of mass. Too much mass to just form a white dwarf, like the Sun will do in about 5-6 billion years. It has so much mass the nuclear forces in its core cannot resist gravity and ka-boom! There is a huge shock wave. The remaining object is either a neutron star or black hole, depending on its mass.
Astronomers think SN1987A produced a neutron star. High resolution infrared imaging from the ALMA radio telescope shows a bright, hot “blob” right where a neutron star would be expected. Time and continued observation will tell.
What’s in the Sky?
Last call for Jupiter. It is near the southwestern horizon with Mercury just after sunset.
January 19-21; 1 hour after sunset; south: A waxing Moon joins Mars high in the sky