2016/06/12 by M. E. Caplan, C. J. Horowitz · 1 voice · 107 citations
Physics and Astronomy · #Astronomy #Astrophysics #Dense matter #Gamma-ray bursts and supernovae #Neutron star #Nuclear astrophysics #Nuclear matter #Nuclear physics #Nuclear physics research studies #Nucleon #Physics #Pulsars and Gravitational Waves Research #Stars #Theoretical physics #White dwarf #astro-ph.HE #cond-mat.mtrl-sci #cond-mat.soft #nucl-th
paper · pdf · doi:10.1103/revmodphys.89.041002
published in Reviews of Modern Physics 89(4) (American Physical Society) · 16 pages, 7 figures, added references and revised for clarity, Reviews of Modern Physics in press
openalex created_date 2016/06/24 · arxiv created 2017/06/26 · openalex publication_date 2017/10/23 · arxiv updated 2017/10/25 · openalex updated_date 2026/08/05
We define `astromaterial science' as the study of materials in astronomical objects that are qualitatively denser than materials on earth. Astromaterials can have unique properties related to their large density, though they may be organized in ways similar to more conventional materials. By analogy to terrestrial materials, we divide our study of astromaterials into hard and soft and discuss one example of each. The hard astromaterial discussed here is a crystalline lattice, such as the Coulomb crystals in the interior of cold white dwarfs and in the crust of neutron stars, while the soft astromaterial is nuclear pasta found in the inner crusts of neutron stars. In particular, we discuss how molecular dynamics simulations have been used to calculate the properties of astromaterials to interpret observations of white dwarfs and neutron stars. Coulomb crystals are studied to understand how compact stars freeze. Their incredible strength may make crust "mountains" on rotating neutron stars a source for gravitational waves that the Laser Interferometer Gravitational-Wave Observatory (LIGO) may detect. Nuclear pasta is expected near the base of the neutron star crust at densities of 1014 g/cm3. Competition between nuclear attraction and Coulomb repulsion rearranges neutrons and protons into complex non-spherical shapes such as sheets (lasagna) or tubes (spaghetti). Semi-classical molecular dynamics simulations of nuclear pasta have been used to study these phases and calculate their transport properties such as neutrino opacity, thermal conductivity, and electrical conductivity. Observations of neutron stars may be sensitive to these properties, and can be be used to interpret observations of supernova neutrinos, magnetic field decay, and crust cooling of accreting neutron stars. We end by comparing nuclear pasta shapes with some similar shapes seen in biological systems.