# Strange star

A strange star is a quark star made of strange quark matter. They form a subgroup under the quark star category.[1][2][3]

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.[4] Such strange stars will naturally have a crust layer of neutron star material. 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.[5] Stars partially made up of quark matter (including strange quark matter) are also referred to as hybrid stars.[6][7][8][9]

This theoretical strange star crust is proposed to be a possible reason behind fast radio bursts (FRBs). This is still theoretical, but there is good evidence[6][7][8][9] that the collapse of these strange star crusts may be a FRB point of origin.

For said crust to collapse from a strange star, it must accrete matter from its environment in some form. This release of even small amounts of its matter cause a cascading effect on the stars crust. This is thought to result in a massive release of magnetic energy as well as electron and 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 FRBs.

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.[10] If these primordial quark stars transform into strange quark matter before the external temperature and pressure conditions of the early universe makes them unstable, they might turn out stable, if the Bodmer–Witten assumption holds true. Such primordial strange stars could survive to this day.[10]

## Characteristics

Recent theoretical research has found the mechanisms by which the quark stars with "strange quark nuggets" may decrease the objects' electric fields and the densities from previous theoretical expectations, causing such stars to appear very much like — and nearly indistinguishable from — ordinary neutron stars. This suggests that many, or even all, known neutron stars might be the strange stars. However, the investigating team of Prashanth Jaikumar, Sanjay Reddy, and Andrew W. Steiner made some fundamental assumptions that led to uncertainties in their results significant enough that the question is not settled. More research, both observational and theoretical, remains to be done on strange stars in the future.[11]

Other theoretical work contends that: "A sharp interface between quark matter and the vacuum would have very different properties from the surface of a neutron star"; and, 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.[12]

## References

1. ^ Alcock, Charles; Farhi, Edward; Olinto, Angela (1986). "Strange stars". Astrophys. J. 310: 261–272. Bibcode:1986ApJ...310..261A. doi:10.1086/164679.
2. ^ P., Haensel; R., Schaeffer; J.L., Zdunik (1986). "Strange quark stars". Astron. Astrophys. 160.
3. ^ Fridolin Weber; et al. (1994). Strange-matter Stars. Proceedings: Strangeness and Quark Matter. World Scientific. Bibcode:1994sqm..symp....1W.
4. ^ Stuart L. Shapiro; Saul A. Teukolsky (20 November 2008). Black Holes, White Dwarfs, and Neutron Stars: The Physics of Compact Objects. John Wiley & Sons. pp. 2–. ISBN 978-3-527-61767-8.
5. ^ Kodama Takeshi; Chung Kai Cheong; Duarte Sergio Jose Barbosa (1 March 1990). Relativistic Aspects Of Nuclear Physics - Rio De Janeiro International Workshop. #N/A. pp. 241–. ISBN 978-981-4611-69-5.
6. ^ a b Alford, Mark G; Han, Sophia; Prakash, Madappa (2013). "Generic conditions for stable hybrid stars". Physical Review D. 88 (8): 083013. arXiv:1302.4732. Bibcode:2013PhRvD..88h3013A. doi:10.1103/PhysRevD.88.083013.
7. ^ a b Goyal, Ashok (2004). "Hybrid stars". Pramana. 62 (3): 753–756. arXiv:hep-ph/0303180. Bibcode:2004Prama..62..753G. doi:10.1007/BF02705363.
8. ^ a b Benić, Sanjin; Blaschke, David; Alvarez-Castillo, David E; Fischer, Tobias; Typel, Stefan (2015). "A new quark-hadron hybrid equation of state for astrophysics". Astronomy & Astrophysics. 577: A40. arXiv:1411.2856. Bibcode:2015A&A...577A..40B. doi:10.1051/0004-6361/201425318.
9. ^ a b Alvarez-Castillo, D; Benic, S; Blaschke, D; Han, Sophia; Typel, S (2016). "Neutron star mass limit at 2M⊙ supports the existence of a CEP". The European Physical Journal A. 52 (8): 232. arXiv:1608.02425. Bibcode:2016EPJA...52..232A. doi:10.1140/epja/i2016-16232-9.
10. ^ a b Witten, Edward (1984). "Cosmic separation of phases". Physical Review D. 30 (2): 272–285. Bibcode:1984PhRvD..30..272W. doi:10.1103/PhysRevD.30.272.
11. ^ Jaikumar, P; Reddy, S; Steiner, A. W (2006). "Strange star surface: A crust with nuggets". Physical Review Letters. 96 (4): 041101. arXiv:nucl-th/0507055. Bibcode:2006PhRvL..96d1101J. doi:10.1103/PhysRevLett.96.041101. PMID 16486800.
12. ^ Alford, Mark G; Rajagopal, Krishna; Reddy, Sanjay; Steiner, Andrew W (2006). "Stability of strange star crusts and strangelets". Physical Review D. 73 (11): 114016. arXiv:hep-ph/0604134. Bibcode:2006PhRvD..73k4016A. doi:10.1103/PhysRevD.73.114016.

## Further reading

Beyond the Horizon Line

Beyond the Horizon Line is the debut solo album of Lycia front man Mike VanPortfleet, released on September 14, 2004 by Silber Records.

Carrie Fisher

Carrie Frances Fisher (October 21, 1956 – December 27, 2016) was an American actress, writer and comedian. Fisher is best known for playing Princess Leia in the Star Wars films, a role for which she was nominated for four Saturn Awards. Her other film credits include Shampoo (1975), The Blues Brothers (1980), Hannah and Her Sisters (1986), The 'Burbs (1989), When Harry Met Sally... (1989), Soapdish (1991), and The Women (2008). She was nominated twice for the Primetime Emmy Award for Outstanding Guest Actress in a Comedy Series for her performances on the television series 30 Rock and Catastrophe. She was posthumously made a Disney Legend in 2017, and in 2018 she was awarded a posthumous Grammy Award for Best Spoken Word Album.

Fisher wrote several semi-autobiographical novels, including Postcards from the Edge and an autobiographical one-woman play, and its non-fiction book, Wishful Drinking, based on the play. She wrote the screenplay for the film version of Postcards From The Edge which garnered her a BAFTA Award for Best Adapted Screenplay nomination, and her one-woman stage show of Wishful Drinking was filmed for television and received a nomination for the Primetime Emmy Award for Outstanding Variety Special. She worked on other writers' screenplays as a script doctor, including tightening the scripts for Hook (1991), Sister Act (1992), The Wedding Singer (1998), and many of the films from the Star Wars franchise, among others. In later years, she earned praise for speaking publicly about her experiences with bipolar disorder and drug addiction.

Fisher was the daughter of singer Eddie Fisher and actress Debbie Reynolds. She and her mother appear in Bright Lights: Starring Carrie Fisher and Debbie Reynolds, a documentary about their relationship. It premiered at the 2016 Cannes Film Festival. Fisher died of a sudden cardiac arrest on December 27, 2016, at age 60, four days after experiencing a medical emergency during a transatlantic flight from London to Los Angeles. One of her final films, Star Wars: The Last Jedi, was released on December 15, 2017, and is dedicated to her. Fisher will appear in Star Wars: The Rise of Skywalker through the use of unreleased footage from The Force Awakens and The Last Jedi.

Common envelope

In astronomy, a common envelope (CE) is gas that contains a binary star system. The gas does not rotate at the same rate as the embedded binary system. A system with such a configuration is said to be in a common envelope phase or undergoing common envelope evolution.

During a common envelope phase the embedded binary system is subject to drag forces from the envelope which cause the separation of the two stars to decrease. The phase ends either when the envelope is ejected to leave the binary system with much smaller orbital separation, or when the two stars become sufficiently close to merge and form a single star. A common envelope phase is short-lived relative to the lifetime of the stars involved.

Evolution through a common envelope phase with ejection of the envelope can lead to the formation of a binary system composed of a compact object with a close companion. Cataclysmic variables, X-ray binaries and systems of close double white dwarfs or neutron stars are examples of systems of this type which can be explained as having undergone common envelope evolution. In all these examples there is a compact remnant (a white dwarf, neutron star or black hole) which must have been the core of a star which was much larger than the current orbital separation. If these systems have undergone common envelope evolution then their present close separation is explained. Short-period systems containing compact objects are sources of gravitational waves and Type Ia supernovae.

Predictions of the outcome of common envelope evolution are uncertain.A common envelope is sometimes confused with a contact binary. In a common envelope binary system the envelope does not generally rotate at the same rate as the embedded binary system; thus it is not constrained by the equipotential surface passing through the L2 Lagrangian point. In a contact binary system the shared envelope rotates with the binary system and fills an equipotential surface.

Compact star

In astronomy, the term compact star (or compact object) refers collectively to white dwarfs, neutron stars, and black holes. It would grow to include exotic stars if such hypothetical, dense bodies are confirmed to exist. All compact objects have a high mass relative to their radius, giving them a very high density, compared to ordinary atomic matter.

Compact stars are often the endpoints of stellar evolution, and are in this respect also called stellar remnants. The state and type of a stellar remnant depends primarily on the mass of the star that it formed from. The ambiguous term compact star is often used when the exact nature of the star is not known, but evidence suggests that it has a very small radius compared to ordinary stars. A compact star that is not a black hole may be called a degenerate star.

Corey Burton

Corey Gregg Weinberg (born August 3, 1955), known professionally as Corey Burton, is an American voice actor, known as the current voice of Ludwig Von Drake, Captain Hook and others for The Walt Disney Company, Brainiac in the DC animated universe, Count Dooku and Cad Bane in multiple Star Wars projects, Shockwave in The Transformers, Hugo Strange in Batman: Arkham City and Zeus in the God of War series.

Hypothetical star

A hypothetical star is a star, or type of star, that is speculated to exist but has yet to be definitively observed. Hypothetical types of stars have been conjectured to exist, have existed or will exist in the future universe.

Jiro Kuwata

Jiro Kuwata (桑田 二郎, Kuwata Jirō, alternatively 桑田 次郎, born April 17, 1935 in Suita, Osaka) is a Japanese manga artist.

KIC 8462852

KIC 8462852 (also Tabby's Star or Boyajian's Star) is an F-type main-sequence star located in the constellation Cygnus approximately 1,470 light-years (450 pc) from Earth. Unusual light fluctuations of the star, including up to a 22% dimming in brightness, were discovered by citizen scientists as part of the Planet Hunters project. In September 2015, astronomers and citizen scientists associated with the project posted a preprint of an article describing the data and possible interpretations. The discovery was made from data collected by the Kepler space telescope, which observed changes in the brightness of distant stars to detect exoplanets.Several hypotheses have been proposed to explain the star's large irregular changes in brightness as measured by its light curve, but none to date fully explain all aspects of the curve. One explanation is that an "uneven ring of dust" orbits KIC 8462852. In another explanation, the star's luminosity is modulated by changes in the efficiency of heat transport to its photosphere, so no external obscuration is required. A third hypothesis, based on a lack of observed infrared light, posits a swarm of cold, dusty comet fragments in a highly eccentric orbit, however, the notion that disturbed comets from such a cloud could exist in high enough numbers to obscure 22% of the star's observed luminosity has been doubted. Another hypothesis is that a large number of small masses in "tight formation" are orbiting the star. Furthermore, spectroscopic study of the system has found no evidence for coalescing material or hot close-in dust or circumstellar matter from an evaporating or exploding planet within a few astronomical units of the mature central star. It has also been hypothesized that the changes in brightness could be signs of activity associated with intelligent extraterrestrial life constructing a Dyson swarm; however, further analysis based on data until the end of 2017 showed wavelength-dependent dimming consistent with dust but not an opaque object such as an alien megastructure which would block all wavelengths of light equally.KIC 8462852 is not the only star that has large irregular dimmings, but all other such stars are young stellar objects called YSO dippers, which have different dimming patterns. An example of such an object is EPIC 204278916.New light fluctuation events of KIC 8462852 began in the middle of May 2017. Except for a period between late-December 2017 and mid-February 2018 when the star was obscured by the Sun, the fluctuations have been observed to have continued as of July 2018.

Kardashev scale

The Kardashev scale is a method of measuring a civilization's level of technological advancement based on the amount of energy a civilization is able to use. It was proposed by Soviet astronomer Nikolai Kardashev in 1964. The scale has three designated categories:

A Type I civilization—also called a planetary civilization—can use and store all of the energy available on its planet.

A Type II civilization—also called a stellar civilization—can harness the total energy of its planet's parent star (the most popular hypothetical concept being the Dyson sphere—a device which would encompass the entire star and transfer its energy to the planet(s)).

A Type III civilization—also called a galactic civilization—can control energy at the scale of its entire host galaxy.The scale is hypothetical, and regards energy consumption on a cosmic scale. Various extensions of the scale have since been proposed, including a wider range of power levels (types 0, IV and V) and the use of metrics other than pure power.

Kekuʻiapoiwa II

Kekuʻiapoiwa II was a Hawaiian chiefess and the mother of the king Kamehameha I.

PSR J1719−1438

PSR J1719-1438 is a millisecond pulsar with a spin period of 5.8 ms located about 4,000 ly from Earth in the direction of Serpens Cauda, one minute from the border with Ophiuchus. Millisecond pulsars are generally thought to begin as normal pulsars and then spin up by accreting matter from a binary companion.

Princess Leia

Princess Leia Organa of Alderaan (also Senator Leia Organa or General Leia Organa) is a fictional character in the Star Wars franchise, portrayed in films by Carrie Fisher. Introduced in the original Star Wars film in 1977, Leia is princess of the planet Alderaan, a member of the Imperial Senate and an agent of the Rebel Alliance. She thwarts the sinister Sith Lord Darth Vader and helps bring about the destruction of the Empire's cataclysmic superweapon, the Death Star. In The Empire Strikes Back (1980), Leia commands a Rebel base and evades Vader as she falls in love with the smuggler, Han Solo. In Return of the Jedi (1983), Leia leads the operation to rescue Han from the crime lord Jabba the Hutt, and is revealed to be Vader's daughter and the twin sister of Luke Skywalker. The prequel film Revenge of the Sith (2005) establishes that the twins' mother is Senator (and former queen) Padmé Amidala of Naboo, who dies after childbirth. Leia is adopted by Senator Bail and Queen Breha Organa of Alderaan. In The Force Awakens (2015) and The Last Jedi (2017), Leia is the founder and General of the Resistance against the First Order. She and Han have a son named Ben, who adopted the name Kylo Ren after turning to the dark side of the Force.

In the Star Wars Legends series of novels, comics and video games (1977–2014), which are set in an alternate continuity, Leia continues her adventures with Han and Luke after Return of the Jedi, fighting Imperial resurgences and new threats to the galaxy. She becomes the Chief of State of the New Republic and a Jedi Master, and is the mother to three children by Han: Jaina, Jacen and Anakin Solo.

One of the more popular Star Wars characters, Leia has been called a 1980s icon, a feminist hero and model for other adventure heroines. She has appeared in many derivative works and merchandising, and has been referenced or parodied in several TV shows and films. Her "cinnamon buns" hairstyle from Star Wars (1977) and metal bikini from Return of the Jedi have become cultural icons.

Principal Galaxies Catalogue

The Catalogue of Principal Galaxies (PGC) is an astronomical catalog published in 1989 that lists B1950 and J2000 equatorial coordinates and cross-identifications for 73,197 galaxies. It is based on the Lyon-Meudon Extragalactic Database (LEDA), which was originally started in 1983. 40,932 coordinates (56%) have standard deviations smaller than 10″. A total of 131,601 names from the 38 most common sources are listed. Available mean data for each object are given:

49,102 morphological descriptions,

52,954 apparent major and minor axis,

67,116 apparent magnitudes,

20,046 radial velocities and

24,361 position angles.The Lyon-Meudon Extragalactic Database was eventually expanded into HyperLEDA, a database of a few million galaxies. Galaxies in the original PGC catalogue are numbered with their original PGC number in HyperLEDA. Numbers have also been assigned for the other galaxies, although for those galaxies not in the original PGC catalogue, it is not recommended to use that number as a name.

SN 185

SN 185 was a transient astronomical event observed in AD 185, likely a supernova. The transient occurred in the direction of Alpha Centauri, between the constellations Circinus and Centaurus, centered at RA 14h 43m Dec −62° 30′, in Circinus. This "guest star" was observed by Chinese astronomers in the Book of Later Han (后汉书), and might have been recorded in Roman literature. It remained visible in the night sky for eight months. This is believed to be the first supernova for which records exist.

The Book of Later Han gives the following description:

In the 2nd year of the epoch Zhongping [中平], the 10th month, on the day Kwei Hae [December 7], a strange star appeared in the middle of Nan Mun [asterism containing Alpha Centauri], It was like a large bamboo mat. It displayed various colors, both pleasing and otherwise. It gradually lessened. In the 6th month of the succeeding year it disappeared.

The gaseous shell RCW 86 is probably the supernova remnant of this event and has a relatively large angular size of roughly 45 arc minutes (larger than the apparent size of the full moon, which varies from 29 to 34 arc minutes). The distance to RCW 86 is estimated to be 2,800 parsecs (9,100 light-years). Recent X-ray studies show a good match for the expected age.Infrared observations from NASA's Spitzer Space Telescope and Wide-field Infrared Survey Explorer (WISE) reveal how the supernova occurred and how its shattered remains ultimately spread out to great distances. The findings show that the stellar explosion took place in a hollowed-out cavity, allowing material expelled by the star to travel much faster and farther than it would have otherwise.Differing modern interpretations of the Chinese records of the guest star have led to quite different suggestions for the astronomical mechanism behind the event, from a core-collapse supernova to a distant, slow-moving comet – with correspondingly wide-ranging estimates of its apparent visual magnitude (−8 to +4). The recent Chandra results suggest that it was most likely a Type Ia supernova (a type with consistent absolute magnitude), and therefore similar to Tycho's Supernova (SN 1572), which had apparent magnitude −4 at a similar distance.

Strange quark

The strange quark or s quark (from its symbol, s) is the third lightest of all quarks, a type of elementary particle. Strange quarks are found in subatomic particles called hadrons. Example of hadrons containing strange quarks include kaons (K), strange D mesons (Ds), Sigma baryons (Σ), and other strange particles.

According to the IUPAP the symbol s is the official name, while strange is to be considered only as a mnemonic. The name sideways has also been used because the s quark has a I3 value of 0 while the u (“up”) and d (“down”) quarks have values of +1/2 and −1/2 respectively.Along with the charm quark, it is part of the second generation of matter, and has an electric charge of −1/3 e and a bare mass of 95+9−3 MeV/c2. Like all quarks, the strange quark is an elementary fermion with spin 1/2, and experiences all four fundamental interactions: gravitation, electromagnetism, weak interactions, and strong interactions. The antiparticle of the strange quark is the strange antiquark (sometimes called antistrange quark or simply antistrange), which differs from it only in that some of its properties have equal magnitude but opposite sign.

The first strange particle (a particle containing a strange quark) was discovered in 1947 (kaons), but the existence of the strange quark itself (and that of the up and down quarks) was only postulated in 1964 by Murray Gell-Mann and George Zweig to explain the Eightfold Way classification scheme of hadrons. The first evidence for the existence of quarks came in 1968, in deep inelastic scattering experiments at the Stanford Linear Accelerator Center. These experiments confirmed the existence of up and down quarks, and by extension, strange quarks, as they were required to explain the Eightfold Way.

Strangelet

A strangelet is a hypothetical particle consisting of a bound state of roughly equal numbers of up, down, and strange quarks. An equivalent description is that a strangelet is a small fragment of strange matter, small enough to be considered a particle. The size of an object composed of strange matter could, theoretically, range from a few femtometers across (with the mass of a light nucleus) to arbitrarily large. Once the size becomes macroscopic (on the order of metres across), such an object is usually called a strange star. The term "strangelet" originates with Edward Farhi and Robert Jaffe. Strangelets have been suggested as a dark matter candidate.

The Lost Empire (1984 film)

The Lost Empire is a 1984 fantasy adventure film directed by Jim Wynorski. It was the first feature Wynorski directed.

It stars Melanie Vincz, Raven De La Croix, Angela Aames and Angus Scrimm. Its general release was in February 1985 after a limited release on June 22, 1984 in Wilmington, North Carolina.

Ultra-high-energy cosmic ray

In astroparticle physics, an ultra-high-energy cosmic ray (UHECR) is a cosmic ray with an energy greater than 1 EeV (1018 electronvolts, approximately 0.16 joules), far beyond both the rest mass and energies typical of other cosmic ray particles.

An extreme-energy cosmic ray (EECR) is an UHECR with energy exceeding 5×1019 eV (about 8 joule), the so-called Greisen–Zatsepin–Kuzmin limit (GZK limit). This limit should be the maximum energy of cosmic ray protons that have traveled long distances (about 160 million light years), since higher-energy protons would have lost energy over that distance due to scattering from photons in the cosmic microwave background (CMB). It follows that EECR could not be survivors from the early universe, but are cosmologically "young", emitted somewhere in the Local Supercluster by some unknown physical process. If an EECR is not a proton, but a nucleus with ${\displaystyle A}$ nucleons, then the GZK limit applies to its nucleons, which carry only a fraction ${\displaystyle 1/A}$ of the total energy of the nucleus. For an iron nucleus, the corresponding limit would be 2.8×1021 eV. However, nuclear physics processes lead to limits for iron nuclei similar to that of protons. Other abundant nuclei have even much lower limits.

These particles are extremely rare; between 2004 and 2007, the initial runs of the Pierre Auger Observatory (PAO) detected 27 events with estimated arrival energies above 5.7×1019 eV, i.e., about one such event every four weeks in the 3000 km2 area surveyed by the observatory.

There is evidence that these highest-energy cosmic rays might be iron nuclei, rather than the protons that make up most cosmic rays.

The postulated (hypothetical) sources of EECR are known as Zevatrons, named in analogy to Lawrence Berkeley National Laboratory's Bevatron and Fermilab's Tevatron, and therefore capable of accelerating particles to 1 ZeV (1021 eV, zetta-electronvolt). In 2004 there was a consideration of the possibility of galactic jets acting as Zevatrons, due to diffusive acceleration of particles caused by shock waves inside the jets. In particular, models suggested that shock waves from the nearby M87 galactic jet could accelerate an iron nucleus to ZeV ranges. In 2007, the Pierre Auge Observatory oberved a correlation of EECR with extragalactic supermassive black holes at the center of nearby galaxies called active galactic nuclei (AGN). However, the strength of the correlation became weaker while continuing observations. Extremely high energies might be explained also by the Centrifugal mechanism of acceleration in the magnetospheres of AGN. Although newer results indicate that fewer than 40% of these cosmic rays seemed to be coming from the AGN, a much weaker correlation than previously reported. A more speculative suggestion by Grib and Pavlov (2007, 2008) envisages the decay of superheavy dark matter by means of the Penrose process.

Yoshio Sawai

Yoshio Sawai (澤井啓夫, Sawai Yoshio, born March 14, 1977 in Toyohashi, Aichi Prefecture) is a Japanese gag manga creator best known for his series Bobobo-bo Bo-bobo and sequel Shinsetsu Bobobo-bo Bo-bobo, both serialized on Weekly Shōnen Jump. Bobobo-bo Bo-bobo was adapted into a 76 episodes anime series by the Toei Animation studio between 2003 and 2005.

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