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How neon can make a star destroy itself



The heart of the Cancer Nebula, which may have ended through the processes described in the following story.

The heart of the Cancer Nebula, which may have ended through the processes described in the following story.
image:: NASA and ESA; Recognition: J. Hester (ASU) and M. Weisskopf (NASA / MSFC

Some stars have the element Neon to thank for their final, explosive death, according to astrophysical research.

Astronomers love to learn the life cycles of stars, including Which stars die in which way? Less massive stars, like our Sun, expand and lose their layers if they pass into white dwarfs for a lot greater Stars explode in violent supernovae, and Their nuclei turn into black holes or neutron stars. But there are questions the end of medium size Stars that have between seven and 11 times the mass of the sun. Do they spill their layers? or explode? And if they become supernova, what is the end product? Partial understanding of these stars depends on understanding the behavior of the element Neon.

When they die, medium-sized stars burn through their hydrogen and the resulting helium. Simulations have shown that they can form nuclei of the elements oxygen, neon and magnesium. These stars could either lose part of their outer hydrogen shell and become dark white dwarf stars, or if the The nucleus grows large enough to collapse into a neutron star.

But these cores are strange objects, in which the pressure due to the squeezing gravity is balanced by the applicable quantum mechanical rules Electrons. Two electrons cannot have exactly the same quantum properties, which limits the proximity between them and exerting “degenerative pressure” on the core. Crucial for the development of this process is the speed with which neon atoms capture electrons in the nucleus. This process releases energy that can be released the oxygen in the starand create an explosion. But when the energy release and subsequent An explosion can change the fate of the star.

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A new paper, led by Oliver Kirsebom von Dalhousie University in Canada examined the reversal of neon electronAcquisition process, in which a fluorine atom spits out an electron and becomes Neon. You did that by slamming a carbon film with a fluorine beam from the JYFL Accelerator Laboratory in Finland. By determining the likelihood that fluorine will decay to neon, you can calculate the opposite: How often would neon capture an electron in the oxygen-neon-magnesium core? The rate they calculated was much higher than in previous measurements, which released the oxygen while the core was at a lower density, resulting in a thermonuclear explosion and a white dwarf instead of one Neutron star.

“It is noteworthy that this is a unique nuclear transition and a very rare transition that you normally neglect,” said Kirsebom told Gizmodo. “Under the specific conditions in these stars, this could have a profound impact on evolution.”

The The team’s measurements were “a milestone in precision nuclear disaster physics,” said Carla Fröhlich of the Faculty of Physics North Carolina State University (who was not involved in research) wrote in a physics position. You wrote that tit results Complete a decade-long search to measure this “forbidden transition,” a type of atomic process that is rare on Earth, but may be more common in the extreme star nuclei.

In another study, published in the Astrophysical Journal and directed by Shuai Zha, postdoctoral fellow at Stockholm University, scientists built a computer model of the death of a star that is 8.4 times the mass of the sun. The energy released when capturing electrons causes ignition of oxygen, which burns the other metals and sets of the nucleus from an explosive wave. The paper found that fate depended on the number of electrons and the value of a critical density above which the nucleus collapses into a neutron star and below which it tears apart in a thermonuclear explosion.

The researchers estimate the density of the core higher than the critical density, and therefore they believe that neon will cause the nuclei to collapse into neutron stars. Your work however before Kirsebomsand they’re planning comparisons in an upcoming article.

Kirsebom told Gizmodo that there are still open questions about these stars. The theoretical understanding of convection by scientists in particular is characterized by great uncertainty in stellar Cores or how moving matter transports them Heat around. There are other difficult onesto-examine nuclear processes that are likely to play a role.

“It is fair to say that there are conflicting opinions about the ultimate fate of these stars and a better understanding of especially convection … is necessary to make progress, ”he said to Gizmodo. He hopes that better accelerator laboratories will help scientists to study increasingly unstable exotic particles and isotopes. In addition, astronomical studies could reveal the presence of white dwarfs with heavier elements than expected. This could be a physical remnant of an exploding oxygen-neon-magnesium core.


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