NASA’s X-ray Observatory Chandra and its NuSTAR (Nuclear Spectroscopic Telescopic Array) have indirectly discovered what it considers to be the remnant of the 1987A supernova’s stellar core, the first naked eye to be discovered in more than 400 years. Located in the nearby Large Magellanic Cloud, a dwarf galaxy about 170,000 light-years away, Supernova 1987A (or SN 1987A) was first observed from the lonely top of the Chilean Mountain Observatory on February 23, 1987.
In a paper published in Astrophysical Journal, an international team of astronomers notes that after three decades of searching, they used X-ray emission to discover the nucleus of a neutron star supernova. The team also used data from the terrestrial Atacama Large Millimeter Array (ALMA) in Chile to support their claims.
“For 34 years, astronomers have been searching through the stellar remnants of the 1987A SN to find a neutron star that we expect to be there,” said Emanuele Greco of the University of Palermo in Italy, the study’s leader said in a statement. “There have been a lot of hints that have turned out to be dead ends, but we think our latest results could be different.”
These objects are called neutron stars because they are made almost exclusively of densely charged neutrons, NASA says. Fast-rotating and highly magnetized neutron stars, called pulsars, produce a beacon-like ray that astronomers detect as a pulse when its rotation crosses a beam in the sky, the space agency notes. However, there is a subset of pulsars, says NASA. which create winds from their surfaces – sometimes almost at the speed of light – which create intricate structures of charged particles and magnetic fields known as “pulsar wind nebulae”.
NASA says the most likely explanation for this energetic X-ray emission is that it produces just such a wind nebula pulsar.
As for the type of supernova explosion that created such a neutron star?
The most likely scenario involves supernova nuclei collapsing. Pedigrees of the supernova of the collapse nucleus are massive stars that go through the collapse of the nuclei of their iron nuclei. That is, when a star’s nuclear material simply can no longer bear the weight of the star’s gravity.
In fact, SN 1987A offered astronomers the first direct confirmation that heavy elements are produced in supernovae.
SN 1987A is known to be a supernova collapse type II nucleus that left behind a compact residue, either a neutron star or a black hole, as I noted here in a previous post. But in the case of SN 1987A, there is still debate as to whether the explosion could have been caused by the merging of the two stars.
Astronomers have long known that the 1987A light curve behaved strangely from the start. For one reason, it has never become as bright as a typical supernova in a collapsing nucleus, which is why it is officially classified as a “special” type II supernova. This means that it simply does not fit into any of the known subcategories of the Type II supernova nucleus.
As for the progenitor of the supernova?
It is known that at least one of its ancestors was Sanduleak -69 202, a blue supergiant star of about 20 solar masses. It remains open to debate whether the explosion in the heart of the supernova was caused by the collapse of one massive blue star or the merging of two stars.
But NASA thinks it would be the youngest ever found if there was a pulsar at the center of this 34-year-old remnant of a supernova. As a result, it will therefore be ideal for monitoring its development.
He hopes the stellar debris surrounding the alleged pulsar will spread over the next few years. If so, NASA says that in about a decade, pulsar emissions will occur unhindered, revealing the existence of this recently formed, rotating neutron star.