Editing Compact object (section)

==Exotic stars==
{{Main|Exotic star}}
An ''[[exotic star]]'' is a hypothetical compact star composed of something other than [[electron]]s, [[proton]]s, and [[neutron]]s balanced against [[gravitational collapse]] by [[degeneracy pressure]] or other quantum properties. These include [[strange star]]s (composed of [[strange matter]]) and the more speculative [[preon star]]s (composed of [[preon]]s).

Exotic stars are hypothetical, but observations released by the [[Chandra X-Ray Observatory]] on April 10, 2002, detected two candidate strange stars, designated [[RX J1856.5-3754]] and [[3C58]], which had previously been thought to be neutron stars. Based on the known laws of physics, the former appeared much smaller and the latter much colder than they should, suggesting that they are composed of material denser than [[neutronium]]. However, these observations are met with skepticism by researchers who say the results were not conclusive.{{citation needed|date=March 2014}}

===Quark stars and strange stars===
{{Main|Quark star}}
If neutrons are squeezed enough at a high temperature, they will decompose into their component [[quark]]s, forming what is known as a [[quark matter]]. In this case, the star will shrink further and become denser, but instead of a total collapse into a black hole, it is possible that the star may stabilize itself and survive in this state indefinitely, so long as no more mass is added. It has, to an extent, become a very large [[nucleon]]. A star in this hypothetical state is called a "[[quark star]]" or more specifically a "strange star". The pulsar [[3C58]] has been suggested as a possible quark star. Most neutron stars are thought to hold a core of quark matter but this has proven difficult to determine observationally.{{citation needed|date=January 2019}}

===Preon stars===
A ''preon star'' is a [[List of hypothetical astronomical objects|proposed]] type of compact star made of [[preon]]s, a group of [[:Category:Hypothetical elementary particles|hypothetical]] [[subatomic particle]]s. Preon stars would be expected to have huge [[density|densities]], exceeding 10<sup>23</sup> kilogram per cubic meter – intermediate between quark stars and black holes.
Preon stars could originate from supernova explosions or the [[Big Bang]]; however, current observations from particle accelerators speak against the existence of preons.{{citation needed|date=March 2014}}

===Q stars===
{{Main|Q star}}
''Q stars'' are hypothetical compact, heavier neutron stars with an exotic state of matter where particle numbers are preserved with radii less than 1.5 times the corresponding [[Schwarzschild radius]]. Q stars are also called "gray holes".

===Electroweak stars===
{{Main|Electroweak star}}
An ''electroweak star'' is a theoretical type of exotic star, whereby the gravitational collapse of the star is prevented by [[radiation pressure]] resulting from [[electroweak burning]], that is, the energy released by conversion of [[quark]]s to [[lepton]]s through the [[electroweak force]]. This process occurs in a volume at the star's core approximately the size of an [[apple]], containing about two Earth masses.<ref name="newscientist">
{{cite web
|last1=Shiga |first1=D.
|date=4 January 2010
|title=Exotic stars may mimic big bang
|url=https://www.newscientist.com/article/dn18334-exotic-stars-may-mimic-big-bang.html
|work=[[New Scientist]]
|access-date=2010-02-18
}}</ref>

===Boson star===
A [[boson star]] is a hypothetical [[astronomical object]] that is formed out of particles called [[boson]]s (conventional [[star]]s are formed out of [[fermion]]s). For this type of star to exist, there must be a stable type of boson with repulsive self-interaction. As of 2016 there is no significant evidence that such a star exists. However, it may become possible to detect them by the gravitational radiation emitted by a pair of co-orbiting boson stars.<ref>{{cite book
 | first=Bernard F. | last=Schutz
 | title=Gravity from the ground up | url=https://archive.org/details/gravityfromgroun00schu_469 | url-access=limited | edition=3rd
 | publisher=[[Cambridge University Press]] | date=2003
 | isbn=0-521-45506-5 | page=[https://archive.org/details/gravityfromgroun00schu_469/page/n170 143]
}}</ref><ref>{{cite journal
 | author=Palenzuela, C.
 | author2=Lehner, L.
 | author3=Liebling, S. L.
 | title=Orbital dynamics of binary boson star systems
 | journal=Physical Review D | volume=77 | issue=4
 | doi=10.1103/PhysRevD.77.044036
 | date=2008
 | page=044036 |bibcode = 2008PhRvD..77d4036P |arxiv = 0706.2435 | s2cid=115159490
 }}</ref>