Neutron stars are the densest celestial bodies in the entire universe except black holes, and the lower limit of mass is 1.1 times that of the sun. But recently, astronomers discovered that a neutron star named HESS J1731-347 has a smaller mass than the sun. It is likely not a neutron star at all, but a more special and never-before-seen “strange star” composed of quark particles and unknown exotic matter.
Neutron stars are compact remnants of stars with a mass about 8 to 30 times the sun’s mass that have undergone a supernova explosion. Most neutron stars are about 1.4 times the mass of the sun, and theoretically can be between 1.1 and 2.3 solar masses (the heavier will become a black hole, the lighter become white dwarfs, the difference between white dwarfs and neutron stars can be judged by different X-radiation), these substances are all packed in a sphere with a diameter of only 20 kilometers, so the nucleus is squeezed by extremely high pressure, and the electrons are forced to come into close contact with protons, so that they transform into neutron.
Previously, scientists measured the lightest neutron star to be 1.17 times the mass of the sun, but the latest research analyzed a neutron star named HESS J1731-347, but found that its distance from the earth was modified from more than 10,000 light-years to 8,150 light-years, with a radius of 10.4 Kilometers, the mass is only 77% of the sun, it is the lowest known mass among similar objects, and even lower than the theoretical prediction.
This may indicate that the theory needs to be revised, or that HESS J1731-347 is a super-special neutron star, or that HESS J1731-347 is not a neutron star at all, but a new and unknown strange star: it looks a lot like a neutron star in nature, but contains more Elementary particles, often called quarks, are made up of exotic fluids containing up quarks, down quarks, and strange quarks.
The new paper was published in the journal Nature Astronomy.
(The first picture is a schematic diagram, source: pixabay)
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