(term for theoretical stars not made of atoms/ions)
The term exotic star is a catch-all for very unusual
theoretical types of stars. Some examples:
- quark star - containing quark matter, matter broken down into quarks.
- strange star - a quark star including strange quark matter, a type of quark matter including strange quarks.
- preon star - preons are theoretical particles that would be the building-blocks of quarks.
- boson star - composed of some sort of bosons (the primary constituent of most stars, 1H, is not a boson) such as axion.
- dark star aka dark matter star - early-universe-giant star incorporating enough dark matter in the form of neutralinos that halts its collapse, preventing its surface temperature from rising; possibly the progenitors of supermassive black holes.
- quasi-star aka black hole star - early-universe very large/massive star (1000 solar masses) powered through a core consisting of a black hole; also possible progenitors of SMBHs.
- iron star - star in far future composed entirely of iron.
Note that the term dark star was also a very early term
for black holes.