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ALMA finds possible signs of a neutron star in the 1987A supernova



ALMA finds possible signs of a neutron star in the 1<div class="e3lan e3lan-in-post1"></div>987A supernova

The artist’s illustration Supernova 1987A shows the dusty interior of the remains of an exploded star (red), in which a neutron star can hide. This inner region contrasts with the outer shell (blue), where the energy from the supernova collides (green) with the shell of the gas ejected by the star to its powerful detonation. Credit: NRAO / AUI / NSF, B. Saxton

Two teams of astronomers made a compelling case in a 33-year mystery surrounding the 1987A Supernova. Based on observations of the large millimeter / submillimeter Atacama Massif (ALMA) and theoretical follow-up research, scientists provide a new understanding of the argument that a neutron star is hidden deep inside the remnants of an exploding star. It would be the youngest neutron star known to date.

Ever since astronomers witnessed one of the brightest explosions of a star in the night sky, creating Supernova 1987A (SN 1987A), they have been looking for a compact object that was to form in the remnants of the explosion.

Because particles known as neutrinos were discovered on Earth on the day of the explosion (February 23, 1987), astronomers expected a neutron star to form in the destroyed center of the star. But when scientists could not find any evidence for this star, they began to wonder if it later fell into a black hole. For decades, the scientific community has been looking forward to the signal from this object, which was hidden behind a very thick cloud of dust.

‘Drops’

Recently, observations from the ALMA radio telescope gave the first indication of a missing neutron star after the explosion. Extremely high resolution images revealed a hot spot in the dusty SN 1987A nucleus, which is brighter than its surroundings and corresponds to the suspected location of the neutron star.

ALMA finds possible signs of a neutron star in the 1987A supernova

The extremely high resolution of the ALMA images revealed a hot spot in the dusty Supernova 1987A nucleus (insert) that could have been the site of a missing neutron star. The red color shows dust and cold gas in the center of the supernova remnant, recorded on radio waves from ALMA. Shades of green and blue reveal where an expanding shock wave from an exploding star collides with a ring of material around a supernova. Green is a radiance of visible light captured by NASA’s Hubble Space Telescope. The blue color reveals the hottest gas and is based on data from NASA’s Chandra X-ray Observatory. The ring was originally made to glow with a flash of light from the initial explosion. In the following years, the ring material turned noticeably blue when the shock wave of the explosion hit it. Credit: ALMA (ESO / NAOJ / NRAO), P. Gypsy and R. Indebetouw; NRAO / AUI / NSF, B. Saxton; NASA / ESA

“We were very surprised to see this warm spot made by a thick cloud of dust in the remnants of a supernova,” said Mikako Matsuura of Cardiff University and a member of the team that found the spot from ALMA. “There must be something in the cloud that heated the dust, and that makes it shine. That’s why we assumed that a neutron star was hiding inside the dust cloud.”

Although Matsuura and her team were excited about the result, they reflected on the brightness of the drop. “We thought a neutron star might be too bright to exist, but then Danny Page and his team published a study that showed that a neutron star could really be so bright because it’s so young,” Matsuura said.

Dani Paige is an astrophysicist at the National Autonomous University of Mexico who has been studying SN 1987A since the beginning. “I was halfway through my PhD when the supernova happened,” he said. “It was one of the biggest events in my life that made me change the course of my career to try to solve this mystery. It was like the modern holy grail. ».

A theoretical study of Paige and his team, published today in Astrophysical Journal, strongly supports the ALMA team’s proposal that the neutron star feeds dust. “Despite the highest complexity of the supernova explosion and the extreme conditions prevailing in the interior of the neutron star, the detection of a warm dust spot is a confirmation of several predictions,” Paige explained.

These predictions were the location and temperature of the neutron star. According to supernova computer models, the explosion “expelled” the neutron star from its birthplace at a speed of hundreds of kilometers per second (tens of times faster than the fastest rocket). The drop is exactly where astronomers think there would be a neutron star today. And the temperature of the neutron star, which is projected to be about 5 million degrees Celsius, provides enough energy to explain the brightness of the drop.

ALMA finds possible signs of a neutron star in the 1987A supernova

This colorful, multi-wave image of the complex remnants of Supernova 1987A was created using data from three different observatories. The red color shows dust and cold gas in the center of the supernova remnant, recorded on radio waves from ALMA. Shades of green and blue reveal where an expanding shock wave from an exploding star collides with a ring of material around a supernova. Green is a radiance of visible light captured by NASA’s Hubble Space Telescope. The blue color reveals the hottest gas and is based on data from NASA’s Chandra X-ray Observatory. The ring was originally made to glow with a flash of light from the initial explosion. In the following years, the ring material turned noticeably blue when the shock wave of the explosion hit it. Credit: ALMA (ESO / NAOJ / NRAO), P. Gypsy and R. Indebetouw; NRAO / AUI / NSF, B. Saxton; NASA / ESA

Not a pulsar or a black hole

Contrary to popular belief, the neutron star is not likely to be a pulsar. “The power of a pulsar depends on how fast it rotates and the strength of its magnetic field. And both need to have very precise values ​​to match the observations,” Paige said, “while the thermal energy emitted by the hot surface of young neutrons. the star naturally corresponds to the data “.

“The neutron star is behaving as we expected,” added James Lettimer of Stony Brook University in New York and a member of Paige’s research team. Lettimer also closely followed SN 1987A, publishing before SN 1987A a prediction of a neutral supernova signal, which subsequently corresponded to observations. “These neutrinos assumed that a black hole never formed. Moreover, a black hole seems difficult to explain the observed brightness of a droplet. We compared all possibilities and concluded that a hot neutron star is the most plausible explanation.”

This neutron star is an extremely hot ball of ultradense matter 25 km wide. A teaspoon of his material would weigh more than all the buildings in New York combined. Since he may be only 33 years old, this 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 picture of a neutron star would provide some evidence of its existence, but astronomers may have to wait several more decades for dust and gas in the supernova remnant to become more transparent.






Credit: National Observatory of Radio Astronomy

Detailed images of ALMA

Although many telescopes have imaged SN 1987A, none of them has been able to observe its core with such high accuracy as ALMA. Earlier (3-D) observations with ALMA have already shown the types of molecules found in the supernatant residue, and confirmed that they form a huge amount of dust.

“This discovery is based on many years of ALMA observations, showing the supernova core in more detail thanks to continuous improvements in telescope and data processing,” said Remy Idebetov of the National Radio Astronomy Observatory and the University of Virginia, part of the ALMA imaging group.


Scientists are finding evidence of the absence of a neutron star


More information:
Data Paige et al., NS 1987A in SN 1987A, Astrophysical Journal (2020). DOI: 10.3847 / 1538-4357 / ab93c2

Provided by the National Observatory of Radio Astronomy



Citation: ALMA finds possible signs of a neutron star in the 1987A supernova (2020, July 30), received on July 30, 2020 from https://phys.org/news/2020-07-alma-neutron-star-supernova-1987a.html

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