PSR J1719−1438 b is an

extrasolar planet An exoplanet or extrasolar planet is a planet outside the Solar System. The first confirmed detection of an exoplanet was in 1992 around a pulsar, and the first detection around a main-sequence star was in 1995. A different planet, first detect ...

that was discovered on August 25, 2011, in orbit around PSR J1719−1438, a

millisecond pulsar A millisecond pulsar (MSP) is a pulsar with a rotational period less than about 10 milliseconds. Millisecond pulsars have been detected in radio pulsar, radio, X-ray pulsar, X-ray, and gamma ray portions of the electromagnetic spectrum. The leadi ...

. The

pulsar planet Pulsar planets are planets that are orbiting pulsars. The first such planets to be discovered were around a millisecond pulsar in 1992 and were the first extrasolar planets to be confirmed as discovered. Pulsars are extremely precise clocks and ...

is most likely composed largely of crystalline carbon but with a

density Density (volumetric mass density or specific mass) is the ratio of a substance's mass to its volume. The symbol most often used for density is ''ρ'' (the lower case Greek letter rho), although the Latin letter ''D'' (or ''d'') can also be u ...

far greater than

diamond Diamond is a Allotropes of carbon, solid form of the element carbon with its atoms arranged in a crystal structure called diamond cubic. Diamond is tasteless, odourless, strong, brittle solid, colourless in pure form, a poor conductor of e ...

. PSR J1719-1438 b orbits so closely to its host star that its orbit would fit inside the

Sun The Sun is the star at the centre of the Solar System. It is a massive, nearly perfect sphere of hot plasma, heated to incandescence by nuclear fusion reactions in its core, radiating the energy from its surface mainly as visible light a ...

. The existence of such

carbon planet A carbon planet is a hypothetical type of planet that contains more carbon than oxygen. Carbon is the fourth most abundant element in the universe by mass after hydrogen, helium, and oxygen. Marc Kuchner and Sara Seager coined the term "carb ...

s had been theoretically postulated.

Observational history

PSR J1719−1438 was first observed in 2009 by a team headed by Matthew Bailes of

Swinburne University of Technology The Swinburne University of Technology (or simply Swinburne) is a public university, public research university in Melbourne, Australia. It is the modern descendant of the Eastern Suburbs Technical College established in 1908, renamed Swinburne ...

in Melbourne, Australia. The orbiting planet was published in the journal ''

Science Science is a systematic discipline that builds and organises knowledge in the form of testable hypotheses and predictions about the universe. Modern science is typically divided into twoor threemajor branches: the natural sciences, which stu ...

'' on August 25, 2011. The planet was confirmed through

pulsar timing Methods of detecting exoplanets usually rely on indirect strategies – that is, they do not directly Astrophotography, image the planet but deduce its existence from another signal. Any planet is an extremely faint light source compared to its ...

, in which small modulations detected in the highly regular pulsar signature are measured and extrapolated. Observatories in

Britain Britain most often refers to: * Great Britain, a large island comprising the countries of England, Scotland and Wales * The United Kingdom of Great Britain and Northern Ireland, a sovereign state in Europe comprising Great Britain and the north-eas ...

Hawaii Hawaii ( ; ) is an island U.S. state, state of the United States, in the Pacific Ocean about southwest of the U.S. mainland. One of the two Non-contiguous United States, non-contiguous U.S. states (along with Alaska), it is the only sta ...

, and

Australia Australia, officially the Commonwealth of Australia, is a country comprising mainland Australia, the mainland of the Australia (continent), Australian continent, the island of Tasmania and list of islands of Australia, numerous smaller isl ...

were used to confirm these observations.

Host star

PSR J1719−1438 is a pulsar some away from Earth in the

Serpens Cauda Serpens () is a constellation in the northern celestial hemisphere. One of the 48 constellations listed by the 2nd-century astronomer Ptolemy, it remains one of the 88 modern constellations designated by the International Astronomical Union. It ...

constellation, approximately one minute from the border with

Ophiuchus Ophiuchus () is a large constellation straddling the celestial equator. Its name comes from the Ancient Greek (), meaning "serpent-bearer", and it is commonly represented as a man grasping a snake. The serpent is represented by the constellati ...

. The pulsar completes more than 10,000 rotations a minute. It is approximately across but with 1.4

solar mass The solar mass () is a frequently used unit of mass in astronomy, equal to approximately . It is approximately equal to the mass of the Sun. It is often used to indicate the masses of other stars, as well as stellar clusters, nebulae, galaxie ...

es.

Characteristics

PSR J1719−1438 b was, at the time of its August 25, 2011, discovery, the densest planet ever discovered, at nearly 20 times the density of Jupiter (about 23 times the density of water). It is slightly more massive than Jupiter. It is thought to be composed of oxygen and carbon (as opposed to hydrogen and helium, the main components of

gas giant A gas giant is a giant planet composed mainly of hydrogen and helium. Jupiter and Saturn are the gas giants of the Solar System. The term "gas giant" was originally synonymous with "giant planet". However, in the 1990s, it became known that Uranu ...

s like Jupiter and Saturn). The oxygen is most likely on the surface of the planet, with increasingly higher quantities of carbon deeper inside the planet. The intense pressure acting upon the planet suggests that the carbon is crystallized, much like

is. PSR J1719−1438 b orbits its host star with a period of 2.17 hours and at a distance of 0.89 solar radii ().

Formation

It is highly unlikely that this planet would have formed before its parent pulsar, as the resulting supernova would destroy any nearby planets. It has been proposed that PSR J1719−1438 b is not a planet but a star. Specifically, PSR J1719−1438 b was a

yellow dwarf star A G-type main-sequence star (spectral type: G-V), also often, and imprecisely, called a yellow dwarf, or G star, is a main-sequence star (luminosity class V) of spectral type G. Such a star has about 0.9 to 1.1 solar masses and an effective tempe ...

similar to the Sun in a binary with PSR J1719−1438, a higher-mass star. PSR J1719−1438 swelled up to become a

red supergiant Red supergiants (RSGs) are stars with a supergiant luminosity class ( Yerkes class I) and a stellar classification K or M. They are the largest stars in the universe in terms of volume, although they are not the most massive or luminous. Betelg ...

, but the yellow dwarf star survived the supernova. Billions of years later, PSR J1719−1438 b became a red giant and then a

white dwarf A white dwarf is a Compact star, stellar core remnant composed mostly of electron-degenerate matter. A white dwarf is very density, dense: in an Earth sized volume, it packs a mass that is comparable to the Sun. No nuclear fusion takes place i ...

. The gravity from the pulsar stole hydrogen and helium, and the remaining carbon crystallized, forming the diamond planet.

Observational history

Host star

Characteristics

Formation

See also

References

Further reading