Astronomical Objects and Phenomena  

Boson Stars > s.a. black-hole mimickers; dark-matter types.
* Idea: Localized configurations (e.g., of a Klein-Gordon scalar field or a field with an added λφ4 term in the potential) kept together by their self-gravity, and supported by the uncertainty principle.
* History: Descendents of Wheeler's non-topological geons, developed in Ruffini's PhD dissertation; 2009, Phenomenologically they are now almost ruled out, but not dead, as alternatives to black holes.
@ References: & Ruffini & Bonazzola; Mielke & Schunck gq/98-MG8; Schunck & Mielke CQG(03) [rev]; Brihaye et al PLB(05) [SU(2) Yang-Mills scalar field theory]; Guzmán PRD(06)gq/05; Guzmán JPCS(11)-a1109 [restrictions as black-hole mimickers]; Liebling & Palenzuela LRR(12)-a1202; Bin-Nun a1301 [Sgr A* as a boson star, and gravitational lensing]; Pugliese et al PRD(13)-a1305 [charged]; Macedo et al PRD(13)-a1307 [astrophysical signatures].

Magnetars > s.a. gamma-ray astronomy [GRBs].
* Idea: Neutron stars with ultra-strong magnetic fields, of the order of 1015 G; 2015, About two dozen magnetars, plus several candidates, are currently known in our Galaxy and in the Magellanic Clouds. They appear as highly variable X-ray sources and in some cases as radio and/or optical pulsars.
@ References: in Schutz 03; Kouveliotou et al SA(03)feb; Cea ap/05 [as chromomagnetic condensate of u, d, and e]; Freytsis & Gralla JCAP(16)-a1503 [and QED plasma]; Mereghetti et al SSR(15)-a1503 [rev]; Kaspi & Beloborodov ARAA-a1703.

Quark Stars > s.a. phase transitions; QCD phenomenology [quark matter].
* Idea: Stars of intermediate density between neutron stars and objects that collapse to form black holes; Predictions of their existence depend on assumptions about the equation of state of quark matter, obtained by extrapolating lattice QCD results.
@ Reviews: Jaikumar et al IJMPA(04)ap-proc [vs neutron stars]; Weber PPNP(05)ap/04; Jaikumar et al MPLA(06)ap; Jaikumar EPJC(07)ap-proc; Ghosh a0808-conf.
@ Theory: Glendenning et al PRL(97)ap; Banerjee et al JPG(00)ap [Chandrasekhar limit]; Fraga et al PRD(01) [perturbative QCD]; Ivanov et al PRC(05)ap [and QCD equation of state]; Drago et al ApJ(07)ap/05 [formation]; Jaikumar et al PRL(06) + pn(06)jan [surface and luminosity]; Schaffner-Bielich ap/06-proc; Kovacs et al MNRAS(09)-a0908 [vs black holes, phenomenology]; news pw(10)jan; Drago & Lavagno a1004 [masses and sizes]; Pagliara et al PRD(13)-a1304 [conversion from a neutron star].
@ Possible evidence: Drake et al ApJ(02)ap, Prasanna & Ray ap/02 [RXJ1856]; Thoma et al JPG(04)ap/03-proc [Chandra & XMM]; Dunning-Davies ap/04 [near galactic center]; Leahy & Ouyed MNRAS(08)-a0708, Ouyed et al MNRAS(12)-a1010 [SN2006gy as a quark nova]; news sr(08)jun; > s.a. gamma-ray bursts.

Stars > s.a. neutron stars and pulsars; star clusters; star types [including novae]; supernovae.

Strangelets > s.a. QCD phenomenology.
* Idea: Lumps of strange quark matter; They have been invoked as a possible explanation for the exotic nuclear fragments, with highly unusual charge to mass ratio, reportedly seen in some cosmic ray experiments.
@ General references: Abers et al PRD(09)-a0712; Pérez-García et al PRL(10) [from neutron stars, and WIMP annihilation].
@ In cosmic rays: Banerjee et al PRL(00)hp, ASS(00)ap; Madsen ap/06-MGXI.

Other Objects > s.a. cosmic rays; galaxies; Intergalactic Matter; interstellar matter [and nebulae]; magnetic fields; quasars.
* Planck stars: The explosive decay of old primordial black holes via quantum tunnelling.
@ References: Andreon et al ap/98-wd [identification by neural networks]; Jaikumar & Ouyed ApJ(06)ap/05 [skyrmion stars]; Hayasaki & Okazaki ApJL(08)-a0809 [circumbinary disks]; Dai et al JCAP(10)-a0912, pw(09)dec [electroweak stars]; Strigari et al MNRAS(12)-a1201 [nomads in the Galaxy]; Rovelli nAst-a1708 [Planck stars].
> Substellar objects: see Brown Dwarves; solar planets; solar system.

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