Astronomers are stuck observing the appearance of neutron stars from a distance to try to understand them. Physical and mathematical models help, but luckily, sometimes neutron stars endure "bugs," and these bugs are an opportunity to learn something about these ultra-dense bodies.
The neutron stars rotate. They can also emit electromagnetic radiation from their poles, and when this radiation is periodically directed to Earth during the star's rotation, we can see the rays. These neutron stars are called pulsars.
For the most part, rotation is very regular and very fast. But sometimes they spin faster, and this happens when parts of the star's interior move toward the exterior. For a brief astronomical moment, this problem may allow astronomers to gain some insight into these disturbing objects.
In 2016, astronomers using Mt. A nice telescope watched Vela Pulsar shine. Vela Pulsar is about 1000 light-years away, in the constellation Vela. It is the lightest pulsar in the sky in radio frequencies and is also the most famous of all shiny pulsars. Only about 5% of pulsars shine, and Vela fails every three years.
<img src = "https://www.universetoday.com/wp-content/uploads/2011/11/Vela_Pulsar_jet.jpg" alt = "This image of Chandra shows Vela Pulsar as a bright white spot in the middle of the photo surrounded by hot gas, shown in yellow and orange.With hot gas in the upper right, a stream of material is rocking Credit: NASA / CXC / PSU / G.Pavlov et al. – http: //heasarc.gsfc .nasa.gov / docs / objects / heapow / archive / compact_objects / vela_pulsar_jet.html, Public Domain, https://commons.wikimedia.org/w/index.php?curid=135898  This image of Chandra shows Vela Pulsar as a bright white spot in the middle of the photo, surrounded by hot gas, shown in yellow and orange. A stream of material is shaking from the hot gas on the upper right Credit: NASA / CXC / PSU / G. Pavlov et al – http://heasarc.gsfc.nasa.gov/docs/objects/heapow/archive/compact_objects /vela_pulsar_jet.html, Public Domain, https://commons.wikimedia.org/w/index.php?curid=135898  This neutron star, which, like all neutron stars, is only a few kilometers in diameter, usually rotates with about 11 times per second. But during the 2016 bug, the star's rotation accelerated. It was the first time she had been seen shining live.
In a document published in the journal Nature Astronomy, a team of scientists re-analyzes the bug data in 2016. The document is called "The Rotational Evolution of the Vela Pulsar During the Buddha in 2016." The first author is Dr. Greg Ashton from the school of physics and astronomy in Monash.
The main finding of their re-analysis is that the problem is more than just simply increasing the speed of rotation. The star quickly rotated before releasing to an error rate. According to the authors, Vela's behavior during the interruption gave them a glimpse into the composition of the neutron star's interior.
They say that neutron stars have three different layers. In a press release, co-author Paul Lasky, also of the Monash School of Physics and Astronomy, said: "One of these components, a superfluid neutron soup in the inner layer of the crust, first moves outward and hits the star's outer outer crust, which hits it. makes it spin. But then, the second superfluid soup, which moves in the core, is leveled to the first, causing the star to rotate back.
They call this phenomenon a hug. According to the authors, other scientists have predicted this in studies, but this has not been observed.
"This skip has been predicted several times in the literature, but it is the first real point identified in the observations," said Laski.
Study co-author Dr. Vanessa Graber of McGill University was one of the scientists who predicted this leap, and she spoke about it in her 2018 article, "Fast-binding the crust and problems with supernatant neutron star spills. "
But during Vela's observation in 2016, the rotating neutron star displayed some other strange behavior: before it actually slowed down. This is something that has never been observed before.
"Just before the interruption, we noticed that the star seemed to slow down the rotation speed before turning back," said Dr. Ashton. "We really have no idea why this is, and this is the first time it's ever been seen."
The artist's illustration of a rotating neutron star, the remnants of a super new explosion. Credit: NASA, Caltech-JPL
"This may be related to the cause of the problems, but we're honestly not sure," Ashton said.
This study is a new piece of the puzzle when it comes to neutron stars. They call the delay that precedes the spin an "anti-bug". The anti-bug is followed by a "rewind" that was predicted by co-author Graber and others. Then there is the relaxation to the real speed of the bug. This three-step sequence has not been observed so far. The authors believe that this three-step bug model is an important discovery.
In the conclusion of their report, they say: "During the 2016 Vela pulsar, it first rotated. A few seconds later, she quickly rotated before finally turning down with exponential relaxation time? 60 s. This model is largely preferred by one step break or one with only one turn. "
It is the observation of the key that is the key. If astronomers are able to observe other pulsars behaving in this way, then they can test forecasts against them.
An illustration of the artist of a neutron star, a tiny remnant that remains after the eruption of his previous star. Here, a 12-mile (20-kilometer) sphere compares to the size of Hanover, Germany. Credit: NASA's Goddard Space Flight Center
But so far, there is only one observed copy of the issue. Without more evidence of observation, scientists are limited to models. As the authors conclude in their paper, "Analyzes such as those presented here evaluate only the relative evidence of models." Also, "Even the most appropriate models tested here do not explain all the characteristics in the data."
The authors suspect that their analysis will regain more observation and study of neutron stars and their bugs and will inspire some new theories.