Neutron stars are covered with only a small “mountain” 1 millimeter high, which means that these uplifts are hundreds of times smaller than previous estimates suggested, according to new research.
Neutron star Is a compact stellar object that resembles a large city about 6.2 miles (10 km) in diameter and weighs at least 1.4 solar mass (1.4 times the weight of the sun). They arise from the explosive death of stars weighing 10 to 25 solar masses. As a result, they are some of the densest objects in the universe, with an incredibly strong gravitational field, about two billion times stronger. Earthof.This extreme gravity Crush the neutron star into a nearly perfect sphere surrounded by a smooth, hard crust. However, crustal deformation creates mountains on the surface of these stars, previous studies have discovered.
New discoveries, now presented at the National Astronomy Conference 2021 in the United Kingdom on July 19, suggest that these mountains are likely to be hundreds of times smaller than scientists had previously thought. I will.
“They should probably be called” ridges “or” hills “rather than” mountains, “” Fabian Gittins, a senior researcher at the University of Southampton in the United Kingdom, told Live Science.
The crust of a neutron star, like the Earth’s crust, is a solid layer outside the star, made up of decomposed heavy elemental nuclei containing an ultra-dense soup of neutrons within the star. Space.com.. It is about 0.6 miles (1 km) thick and is the region of the least dense stars, Gittins said.
Mountains form when the crust begins to crack under very large strains. “There are many ways [for] “All that is required for these mountains to form is for the stars to change shape,” Gittins said.
Possible explanations for mountain formation include increased tension from its strength electromagnetic The fact that the fields or they rotate more slowly over time. But it may also be caused by a phenomenon known as glitch, where stars suddenly start spinning fast, Gittins said.
However, regardless of the cause of the formation of the mountain, the size of the mountain is limited by the amount of strain that can be received before the crust breaks. “The stronger the crust, the larger the mountains it can support,” Gittins said.
Smaller than expected
Gittins and his team predicted the size of a neutron star mountain by creating it. computer A model that accurately simulates the crust of a neutron star.
“We have exposed these models to the various mathematical forces that create the mountains,” says Gittins. “I increased the amount of force until the crust broke.”
This allowed the team to predict the maximum mountain size that a neutron star could sustain without breaking. Their new predictions suggest that previous estimates of fixing these mountains to a height of up to 1 centimeter may have been seriously flawed.
“When we investigated this issue, previous studies found that there was a technical problem with the approach,” said Gittins.
One of the main problems was that previous predictions assumed that the neutron star’s crust had the most distorted shape at all points, but it turned out to be physically impossible. is. “Our approach did not put the greatest strain on the crust at every point, but at a single point,” he added.
Ripples of space-time
Neutron stars are known to rotate rapidly due to the angular momentum held by the exploding parent star, Gitins said.
“When an asymmetrically deformed neutron star is rotating, ripples occur in its structure. Space-time “These ripples are known as gravitational waves,” Gittins said.
researcher First detected gravitational wave, Emitted from two rotating black holes, Laser Interferometer Gravitational Wave Observatory (LIGO) In 2015, Live Science previously reported. Since then, LIGO has detected two separate gravitational wave events resulting from neutron star collisions. Live science previously reportedHowever, isolated neutron stars remain elusive.
“Currently, it cannot be detected. Gravitational waves From a rotating neutron star. ” But these non-detections also tell scientists a lot about neutron stars, he added.
The smaller the neutron star peaks, the smaller the gravitational waves they generate. Therefore, their lack of detection may support Gittins’ predictions.
“If we know the sensitivity of the detector, we can put an upper limit on the size of the neutron star peak,” says Gittins. “The general trend is that the upper limit is getting smaller and smaller.”
Therefore, it may take some time before scientists can build a detector large enough to detect the space-time ripples emitted by these rapidly rotating microscopic ridges. ..
This study was first published online in the journal on November 21, 2020. Monthly Notification of the Royal Astronomical Society..
Originally published in Live Science.
A “mountain” of a neutron star is actually a microscopic ridge less than a millimeter in height.
Source link A “mountain” of a neutron star is actually a microscopic ridge less than a millimeter in height.