A strange star, also called a strange quark star,<ref name=PageReddy2006>Template:Cite journal</ref>Template:Rp is a hypothetical compact astronomical object, a quark star made of strange quark matter.<ref>Template:Cite journal</ref><ref>Template:Cite journal</ref><ref name=Weber/>
Strange stars might exist without regard to the Bodmer–Witten assumption of stability at near-zero temperatures and pressures, as strange quark matter might form and remain stable at the core of neutron stars, in the same way as ordinary quark matter could.<ref name=Shapiro/> Such strange stars will naturally have a crust layer of neutron matter. The depth of the crust layer will depend on the physical conditions and circumstances of the entire star and on the properties of strange quark matter in general.<ref name=glendenning/> Stars partially made up of quark matter (including strange quark matter) are also referred to as hybrid stars.<ref name=alford/><ref name=goyal/><ref name=benic/><ref name=a-c/>
The collapse of the crust layer of strange stars is one of the proposed causes of fast radio bursts.<ref name=alford/><ref name=goyal/><ref name=benic/><ref name=a-c/>
Theoretical descriptionEdit
Neutron stars are formed when the collapse of a star occurs with such intense force that gravity forces subatomic particles such as protons and electrons to merge into neutrally charged neutron particles, releasing a shower of neutrinos. If the resultant neutral core is able to maintain form and not collapse into a black hole, the result is an incredibly dense celestial body composed almost entirely of uncharged particles.
Protons and neutrons are composed of three quarks: a proton by two up quarks and one down quark, a neutron by two down quarks and one up quark. It is hypothesized that within neutron stars, the conditions are so extreme that a process known as deconfinement occurs: where subatomic particles dissolve and leave their constituent quarks behind as free particles. The temperature and pressure would then force these quarks to be squeezed together to such an extent that they would form a hypothetical phase of matter known as quark matter. If this occurs, the neutron star becomes a "quark star". If the pressure is great enough, the quarks could be affected even further and transform into strange quarks, which would then interact with the other "non-strange" quarks to form strange matter. If this occurs, the quark star would then become a strange star.
CharacteristicsEdit
Early work on strange quark matter suggested that it would be a homogeneous liquid, but other models propose<ref name=prashanth/> a heterogeneous alternative with positively charged "strange quark nuggets" embedded in a negatively charged electron gas.<ref name=PageReddy2006/> This structure decreases the stars' external electric field and density variation from previous theoretical expectations, with the result that such stars appear nearly indistinguishable from ordinary neutron stars.
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Addressing key parameters like surface tension and electrical forces that were neglected in the original study, the results show that as long as the surface tension is below a low critical value, the large strangelets are indeed unstable to fragmentation and strange stars naturally come with complex strangelet crusts, analogous to those of neutron stars.<ref name=rajagopal/>
Crust collapseEdit
For a strange star's crust to collapse, it must accrete matter from its environment in some form.
The release of even small amounts of its matter causes a cascading effect on the star's crust.<ref>Template:Cite journal</ref> This is thought to result in a massive release of magnetic energy as well as electron-positron pairs in the initial phases of the collapsing stage. This release of high-energy particles and magnetic energy in such a short period of time causes the newly released electron-positron pairs to be directed towards the poles of the strange star due to the increased magnetic energy created by the initial secretion of the strange star's matter. Once these electron-positron pairs are directed to the star's poles, they are then ejected at relativistic velocities, which is proposed to be one of the causes of fast radio bursts.
Primordial strange starsEdit
Theoretical investigations have revealed that quark stars might not only be produced from neutron stars and powerful supernovae, they could also be created in the early cosmic phase separations following the Big Bang.<ref name=Witten/>
If these primordial quark stars can transform into strange quark matter before the external temperature and pressure conditions of the early universe renders them unstable, they might become stable, if the Bodmer–Witten assumption holds true. Such primordial strange stars could survive to this day.<ref name=Witten/>
Strange dwarf starsEdit
Hypothetical strange-quark dwarfs would be white dwarf stars with strange-quark cores. Some studies predict these objects would be stable, while others predict instability.<ref>Template:Cite book</ref> A survey examined the mass–radius relation for 40,000 white dwarfs and found eight exceptions were much smaller in size and matched predictions for a strange dwarf.<ref>Template:Cite journal</ref>
See alsoEdit
ReferencesEdit
Further readingEdit
- Template:Cite journal – Original scientific paper source
- {{#invoke:citation/CS1|citation
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