Two teams of astronomers made a compelling case in the 33-year-old mystery about 1987A Supernova. Based on observations of the Atacama Large Millimeter / Submillimeter Array (ALMA) and a theoretical follow-up study, scientists provide a new look at the argument that a neutron star is hidden deep inside the remnants of the star that exploded. It will be the smallest neutron star known to date.
Ever since astronomers saw one of the most beautiful explosions of stars in the night sky, which created Supernova 1987A (SN 1987A), they have been looking for a compact object that should have formed a remnant from the foundry.
Because particles known as neutrons were discovered on Earth on the day of the explosion (February 23, 1987), astronomers expected a neutron star to form at the crashed center of the star. But when scientists could find no evidence for that star, they began to wonder if it had fallen into a black hole instead. For decades the scientific community has been eagerly awaiting a sign from this object that has been hiding behind a very thick cloud of dust.
Recently, observations from the ALMA radio telescope provided the first indication of the missing neutron star after the explosion. Extremely high-resolution images revealed a hot “blob” at the core in the dust of SN 1987A, which is brighter than its surroundings and matches the suspected location of the neutron star.
“We were very surprised to see this hot blob made of a thick cloud of dust in the remnant of the supernova,” said Mikako Matsuura from Cardiff University and a member of the team that found the blob with ALMA. “There must be something in the clouds that heats the dust and makes it glow. That’s why we suggested having a neutron star hidden inside the dust cloud.”
Even though Matsuura and her team were excited by this result, they wondered about the light of the blob’s brightness. “We thought the neutron star might be too bright to exist, but then Dany Page and his team published a study that indicated that the neutron star could indeed be so beautiful because it’s very small,” he said. Matsuura.
Dany Page is an astrophysicist at the National Autonomous University of Mexico, who has been studying SN 1987A since the beginning. “I was in the middle of my Ph.D. when the supernova happened,” he said, “it was one of the biggest events in my life that forced me to change the course of my career to try to solve this mystery. like a modern holy grail. “
The theoretical study by Page and his team, published today in The Astrophysical Journal, strongly supports the suggestion made by the ALMA team that a neutron star is beating the dust blob. “Despite the supreme complexity of a supernova explosion and the extreme conditions that reign in the interior of a neutron star, the discovery of a hot blob of dust is a confirmation of many predictions,” Page explained.
These predictions were the location and temperature of the neutron star. According to supernova computer models, the explosion “started” the neutron star from its birthplace at a speed of hundreds of kilometers per second (tens of times faster than the rocket’s fastest). ). The blob is exactly where astronomers think the neutron star would be today. And the temperature of the neutron star, which was predicted to be around 5 million degrees Celsius, provides enough energy to explain the brightness of the blob.
Not a pulsar or a black hole
Contrary to common expectations, the neutron star is unlikely to be a pulsar. “The power of a pulsar depends on how fast it rotates and on the strength of its magnetic field, both of which need to have highly refined values to match the observations,” Page said, “while the thermal energy emitted by the hot surface of the young neutron star matches the data naturally. “
“The neutron star behaves exactly as expected,” added James Lattimer of Stony Brook University in New York, and a member of Page’s research team. Lattimer also closely followed SN 1987A, having previously published a SN 1987A prediction of the supernova neutrino signal which subsequently compared the observations. “Those neutrons suggested that a black hole was never formed, and moreover it seems difficult for a black hole to explain the observed brightness of the blob. We compared all the possibilities and concluded that a hot neutron star is the more likely explanation. “
This neutron star is 25 km wide, an extremely hot ball of ultra-dense material. A teaspoon of its material weighs more than the entire building in New York City combined. Because it can only be 33 years old, it will be the smallest neutron star ever found. The second smallest neutron star we know of is in the remnant of the Cassiopeia A supernova and is 330 years old.
A direct picture of the neutron star gives definite proof that it exists, but for this astronomers may need to wait a few decades for the dust and gas in the supernova remnant to become more transparent.
Detailed images of ALMA
Although many telescopes made images of SN 1987A, none of them were able to observe its core with such high precision as ALMA. Previous observations (3-D) with ALMA have already shown the types of molecules found in the supernova remnant and confirmed that they produced massive amounts of dust.
“This discovery builds on years of ALMA observations, showing the core of the supernova in more and more detail thanks to continuous telescope improvements and data processing,” said Remy Indebetouw from -National Observatory of Radio Astronomy and the University of Virginia, which was part of the ALMA imaging team.
Scientists find evidence of a missing neutron star
Dany Page et al, NS 1987A to SN 1987A, The Astrophysical Journal (2020). DOI: 10.3847 / 1538-4357 / ab93c2
Provided by the National Radio-Astronomy Observatory
Citation: ALMA finds possible neutron star signal in 1987A (2020, 30 July) supernova obtained on 30 July 2020 from https://phys.org/news/2020-07-alma-neutron- star-supernova-1987a.html
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