New Measurement of Lead Nucleus Suggests Neutron Stars are Larger than Previously Predicted
takyon writes:
Neutron stars may be bigger than expected, measurement of lead nucleus suggests
Say what you want about lead, it's got a surprisingly thick skin-of neutrons, that is. In fact, the layer of neutrons on the outside of a lead nucleus is twice as thick as physicists thought, according to a new study. The seemingly abstruse result could have out-of-this-world implications: Neutron stars, the ultradense spheres left behind when stars explode in supernova explosions, could be stiffer and bigger than theory generally predicts.
"It's a fantastic experimental achievement," says Anna Watts, an astrophysicist at the University of Amsterdam who studies neutron stars. "It's been talked about for years and years and years, and it's so cool to finally see it done."
[...] Even though an atomic nucleus is several times less dense than a neutron star, the former can be used to make inferences about the later, explains Jorge Piekarewicz, a nuclear theorist at Florida State University. In particular, a thicker neutron skin implies that neutron stars are less compressible than many theories predict, he says, which would make them bigger. In fact, in another paper published today in Physical Review Letters, Piekarewicz and colleagues calculate that the PREX result implies a radius between 13.25 and 14.25 kilometers for a run-of-the-mill neutron star 1.4 times as massive as the Sun. Most theories yield estimates closer to 10 kilometers.
Also at Physics and Science News.
Journal References:
1.) D. Adhikari et al. (PREX Collaboration). Accurate Determination of the Neutron Skin Thickness of 208Pb through Parity-Violation in Electron Scattering, Physical Review Letters (DOI: 10.1103/PhysRevLett.126.172502)
2.) Brendan T. Reed, F.J. Fattoyev, C.J. Horowitz, et al. Implications of PREX-2 on the Equation of State of Neutron-Rich Matter, Physical Review Letters (DOI: 10.1103/PhysRevLett.126.172503)
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