As of: February 23, 2024, 6:37 p.m
By: Julian Mayr
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No supernova has been better studied than SN 1987A.
Nevertheless, the remains of the stellar explosion hid a secret for decades - until now.
Munich – The James Webb Space Telescope (JWST) has been in operation for just two years.
Its images are already turning space research on its head.
The successor to the Hubble Telescope provides more detailed insights into the vastness of the universe than ever before.
With the help of the space telescope, researchers have now been able to uncover the secret of a supernova, which has been investigated for decades.
Black hole or neutron star?
Decades-long mystery surrounding the remains of legendary supernovas
In February 1987, a supernova appeared in the southern hemisphere, the likes of which humanity had not seen in more than 300 years.
The star Sanduleak -69 202 in a satellite galaxy of our Milky Way had reached the end of its life as a so-called blue supergiant.
On February 24th, the light of the massive supernova SN 1987A, which dates back around 160,000 years, reached our planet.
The red supergiant Betelgeuse could also be in front of a supernova.
Researchers have long suspected a neutron star in the center of the remnants of supernova 1987A.
© spacephotos/Imago
The remains of this stellar explosion have been studied better than any previously discovered.
But for a long time, astronomers were puzzled as to what remained in the place where such a massive star with around 15 to 20 solar masses once stood.
Could a black hole have formed at the center of SN 1987A?
Or did a compact neutron star form from the remnants of the supernova?
Now this question has been answered thanks to the technology of the James Webb Space Telescope.
New study provides evidence of the existence of a neutron star at the center of a supernova
For three decades, astronomers have been concerned with the question of what happened to the enormous amount of matter and energy released by the stellar explosion.
The detection of neutrinos (extremely light elementary particles) as a product of the supernova already suggested that a neutron star could have formed in the center of SN 1987A.
Numerous studies have provided further evidence that this assumption is most likely.
Star explosion “SN 1987A”
Supernova SN 1987A occurred at a distance of 160,000 light-years from Earth in the Large Magellanic Cloud, a satellite galaxy of the Milky Way.
Its first observation from Earth took place in February 1987, and it reached its maximum brightness in May of that year.
It was the first time a supernova could be seen with the naked eye since the sighting of Kepler's supernova in 1604.
In recent years there has been increasing evidence of the existence of a neutron star at the center of the supernova remnants.
However, no direct evidence of a neutron star has been provided so far.
Source: NASA
On February 22, just two days before the anniversary of the supernova, a research paper was published in the journal
Science
that appears to provide evidence for the existence of such a neutron star.
Using the James Webb Telescope, the researchers observed spectral lines that were generated either by the hot neutron star itself or by a so-called pulsar wind nebula around the neutron star.
James Webb Telescope Allows Science to Peek into Hidden Center of SN 1987A
The researchers were able to take a look into the otherwise hidden center of the supernova remnant.
“We now know that there is a compact source of ionizing radiation there, which is probably a neutron star.
This was predicted by the explosion models, and we ran simulations in 1992 that showed how this might be observed.
However, it was only with JWST that it really became possible,” explains Claes Fransson, professor at the Institute of Astronomy at Stockholm University and lead author of the study.
According to Fransson, the emission of neutrinos shortly before the supernova also suggested that either a neutron star was born or a black hole was formed.
However, due to the large amounts of dust created by the death of the star, this has not yet been measurable.
Observations from the JWST have now provided direct evidence for the existence of a neutron star, although it is still not directly observable.
Using the James Webb Space Telescope, researchers were able to collect evidence of the existence of a neutron star at the center of SN 1987A using infrared measurements of ionized argon.
© NASA, ESA, CSA, STScI, Claes Fransson (Stockholm University), Mikako Matsuura (Cardiff University), M. Barlow (UCL), Patrick Kavanagh (Maynooth University), Josefin Larsson (KTH)
Two possible explanations for spectral lines, one conclusion: object in the center is a neutron star
The James Webb Telescope is able to detect light in the infrared range, which, unlike visible light, can also penetrate dust.
Using the space telescope, the researchers were able to use the spectral lines of argon and sulfur ions to identify a point-like energy source in the center of the supernova remnants, as reported in a release on
EurekAlert!
explain.
The international research team cannot see the neutron star, but can infer its existence by observing how the star's radiation affects its surroundings.
Therefore, the measured spectral lines can be traced back directly to the neutron star, which is around a million degrees hot, or to energetic particles that were created in the magnetic field of the rotating neutron star (pulsar vortex).
Further investigations must show what exactly is responsible for the spectrum.
In any case, there is probably unmistakable evidence for the existence of a compact object.
The neutron star at the center of SN 1987A probably has a radius of only about 10 kilometers.
Its density is probably comparable to that of an atomic nucleus.
As the scientists explain, the mass of one square millimeter of this stellar matter would be equivalent to the weight of a large oil tanker.
Other cosmological phenomena that can also arise in the course of a supernova reach significantly larger weight classes.
An extremely massive black hole was recently discovered, weighing around 30 billion solar masses.
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