Another article I’ve written for BINTEL –
23rd Feb 2023: What we see in the night sky seem timeless and eternal – things change on the timescale of millions or billions or years. Even the rare, fleeting or transient events like supernova will often take hundreds of years for the remnants to be seen.
But…..
Back in 1987, when BINTEL had only been in business for only a few years, a star in the LMC (Large Magellanic Cloud) exploded as a type II supernova. SN 1987A was the first supernova that was visible to your eyes alone since 1604, which occurred before the development of the telescope*. The LMC is a satellite galaxy of our Milky Way galaxy and can easily seen with just your eyes in the far southern skies.
A supernova is the dramatic end stage of a large star. It happens in a few hours and then slowly fades in the following weeks and months. We find remnants of supernovae scattered throughout the Milky Way. For example, the Crab Nebula corresponds to observations of Chinese astronomers in 1054 of a “guest star”. We also know that many of these supernova remnants have neutron stars at their core. A neutron star made up of a super dense form of matter where every proton and electron been crushed together to form just neutrons. They’re the most extreme objects in the Universe apart from whatever is inside a black hole. Just how dense is a neutron star? According to NASA, a single sugar cube chunk of a neutron star would weigh about 1 trillion kilograms.
It’s thought there could be a billion neutron stars in our Milky Way.
Even though SN 1987A was some 160,000 light years away, it was near enough to be studied in more detail than any previous supernova. One observation of SN 1987A was a strong blast of neutrinos that preceded its optical discovery by a few hours. The confirmation of these types of observations helped confirm theories about the core collapse of the star involved in SN 1987A. There was a strong chance that the host star which exploded could form a neutron star or even a black hole. Despite multiple searches, no evidence for a central star in the remains of SN 1987A have been found.
Today, results published in Science indicate early signs of the newly born, neutron star at the centre of SN 1987A.
Argon emission in SN1987A indicating a central neutron star has been formed
These are from observations taken by the JWST (James Webb Space Telescope) on 16th July 2023, shortly after it began full time science operations.
“From theoretical models of SN 1987A, the 10-second burst of neutrinos observed just before the supernova implied that a neutron star or black hole was formed in the explosion. But we have not observed any compelling signature of such a newborn object from any supernova explosion. With JWST, we have now found direct evidence for emission triggered by the newborn compact object, most likely a neutron star.” – commented Claes Fransson of Stockholm University, and the lead author on study.
There’s follow up observations planned this year with the JWST as well as ground based telescopes. The aim is to not just study SN 1987A, but also also help our understanding of the various types of supernovae.
Amazing to think that we’ve seen the catastrophic destruction of a star and the discovery the “new” star that’s been born from the massive event – all within a few decades!
Cheers,
Earl White
BINTEL
*Yes – we are possibly “overdue” for a major supernova event in the Milky Way itself.
Article originally appeared here
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