Two teams of astronomers have presented a compelling case of a 33-year secret about the 1987A Supernova. Based on observations of the Atacama Large Millimeter / submillimeter Array (ALMA) and a theoretical follow-up study, scientists provide a new perspective on the argument that a neutron star is hidden deep in the remnants of an exploded star. That would be the youngest neutron star yet.
Ever since astronomers witnessed one of the star’s brightest explosions in the night sky and created the Supernova 1987A (SN 1987A), they have been looking for a compact object to form the remnants of an explosion.
Because particles known as neutrinos were found on Earth on the day of the explosion (February 23, 1987), astronomers expected a neutron star to form in the collapsed center of the star. But when scientists could find no evidence for the star, they began to wonder if it had subsequently collapsed into a black hole. For decades, the scientific community has been impatiently waiting for a signal from this object, which is hidden behind a very dense cloud of dust.
Observations from the ALMA radio telescope recently provided the first indication of a missing neutron star after the explosion. The high-resolution images revealed hot “drops” in the dusty core of SN 1987A, which is brighter than its surroundings and coincides with the suspicion of the location of a neutron star.
“We were very surprised to see this warm drop created by a dense cloud of dust in the rest of the supernova,” said Mikako Matsuura of Cardiff University and a member of the team who found the drop with ALMA. “There must be something in the cloud that heats the dust and makes it radiant. That’s why we suggested that a neutron star be hidden in a cloud of dust. “
Although Matsuura and her team were excited about this result, they thought about the brightness of the block. “We thought a neutron star might be too bright, but then Dany Page and his team published a study that suggested that a neutron star might be so bright because it’s so young,” Matsuura said.
Dany Page is an astrophysicist at the National Autonomous University of Mexico, who has been studying SN 1987A since the beginning. “I was halfway through my doctorate when it became a supernova,” he said, “it was one of the biggest events of my life that forced me to change the course of my career to try to solve this mystery. It was like a modern holy grail. ‘ “
A theoretical study of Page and its team, published today in The Astrophysical Journal, strongly supports the ALMA team ‘s proposal that a neutral star propel a dustball. “Despite the supreme complexity of the supernova explosion and the extreme conditions inside the neutron star, the detection of a warm layer of dust is a confirmation of several predictions,” Page explained.
These predictions were the location and temperature of the neutron star. According to computer models, the supernova explosion “launched” a neutron star from its birthplace at hundreds of kilometers per second (tens of times faster than the fastest rocket). The block is exactly where astronomers think the neutron star will be today. And the temperature of the neutron star, which was supposed to be around 5 million degrees Celsius, provides enough energy to explain the brightness of the drop.
No pulsar or black hole
Contrary to common expectations, a neutron star is probably not a pulsar. “The strength of the pulsar depends on the speed of rotation and the strength of the magnetic field, which should have very fine-tuned values to match the observations,” Page said, “while the thermal energy emitted by the hot surface of young people is naturally matched by the neutron star. ‘ “
“The neutron star is behaving exactly as we expected,” added James Lattimer of Stony Brook University in New York and a member of Page’s research team. The lattimer also closely monitored SN 1987A and published predictions of the supernova neutrino signal before SN 1987A, which subsequently matched the observations. “These neutrinos suggest that the black hole never formed, and in addition, it seems difficult for the black hole to explain the observed brightness of the block. We compared all the possibilities and came to the conclusion that the most likely explanation is a hot neutron star. “
This neutron star is a 25 km wide, extremely hot sphere of ultra-dense substances. A teaspoon of his material would weigh more than all the buildings in New York combined. Because it can only be 33 years old, it would be the youngest neutron star ever found. The second youngest neutron star we know of is in the remnant of the supernova Cassiopeia A and is 330 years old.
Only a direct image of a neutron star would provide definitive proof that it exists, but astronomers may have to wait decades before the dust and gas in the rest of the supernova become transparent.
Detailed pictures ALMA
Although many telescopes have taken SN 1987A images, none of them have been able to observe their core with the same accuracy as ALMA. Previous (3-D) observations with ALMA have already shown the types of molecules found in the rest of the supernova and confirmed that they produced huge amounts of dust.
“This discovery is based on years of ALMA observations that show increasingly detailed the core of the supernova through continuous improvements in telescope and data processing,” said Remy Indebetouw of the National Radio Observatory and the University of Virginia, who was part of the ALMA imaging team.
Scientists have found evidence of a missing neutron star
Dany Page et al., NS 1987A in SN 1987A, The Astrophysical Journal (2020). DOI: 10.3847 / 1538-4357 / ab93c2
Provided by the National Radiocommunication Observatory
Citations: ALMA finds possible sign of neutron star in supernova 1987A (2020, July 30) obtained on July 30, 2020 from https://phys.org/news/2020-07-alma-neutron-star-supernova-1987a.html
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