PSR J1719-1438 b
Encyclopedia
PSR J1719-1438 b is an extrasolar planet
that was discovered on August 25, 2011 in orbit around PSR J1719-1438, a millisecond pulsar
. The pulsar planet
is most likely composed largely of crystalline carbon, or diamond
. PSR J1719 -1438 b and PSR J1719 -1438 were formerly two stars in a binary star
system, but after PSR J1719 -1438 went supernova
and became a pulsar
, PSR J1719 -1438 b expanded into its red giant
phase and diminished into a white dwarf
. The intense conditions of the system converted the white dwarf into a planet
composed largely of heavy elements like carbon and oxygen. PSR J1719 -1438 b orbits so closely to its host star, the planet's orbit would fit inside the Sun
. The existence of such diamond planets
had been theoretically postulated.
in Melbourne, Australia. The orbiting planet was published in the journal Science
on August 25, 2011. The planet was confirmed through pulsar timing, in which small modulations detected in the highly regular pulsar signature are measured and extrapolated. Observatories in Britain, Hawaii, and Australia were used to confirm these observations.
system experienced a supernova
, leaving behind its rapidly spinning core, which became the pulsar itself. The secondary, less prominent companion was a main sequence star that became a red giant
before shrinking into a white dwarf
. During its life, the pulsar siphoned gases from the secondary star, speeding up as more matter was added to it.
The white dwarf, however, did not enter an unstable orbit and merge with the pulsar, which happens to a significant minority of star-pulsar binary systems. Instead, the white dwarf stabilized at an orbit approximately one solar radius away from the pulsar. The proximity caused the white dwarf to lose the majority of its remaining matter, leaving behind a bare core. The intense gravitational pressure caused by the proximity crystallized the carbon-composed planet (now that all fusion reactions have stopped, it was reclassified), forming a substance similar to that of diamond
.
es. The pulsar was originally part of a binary star system, with the other star being PSR J1719 -1438 b (when it still completed fusion reactions).
. It is slightly more massive than Jupiter. Because it is hypothesized to be the remnant of a white dwarf, it is believed to be composed of oxygen and carbon (as opposed to hydrogen and helium, which composes gas giant
s like Jupiter and Saturn). However, all known white dwarfs have densities that are on the order of millions of times the density of water and are composed of electron-degenerate matter, which makes this object extremely non-dense for a white dwarf. Also, white dwarfs emit light due to their temperature based on trapped heat from gravitational collapse. It is unknown why this hypothesized white dwarf remnant does not retain enough temperature to emit light.
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 diamond
is and according to Bailes "If you could grab big chunks and bring it home you could turn it into a pretty useful diamond.".
PSR J1719 -1438 b orbits its host star with a period of 2.177 hours and at a distance of a little bit less than one (0.89) solar radius , and would thus fit inside the Sun if compared to the Solar System
.
PSR J1719 -1438 b was formerly a star that was a red giant for a period in its lifetime. During this period, gas from PSR J1719 -1438 b was pulled onto PSR J1719 -1438 after it had become a pulsar, speeding up its rotation significantly. When PSR J1719 -1438 b became a white dwarf, over 99.9% of its constituents were blown away because of its proximity to the pulsar, leaving behind a core that could no longer perform fusion reactions. The core was then reclassified as a planet.
Extrasolar planet
An extrasolar planet, or exoplanet, is a planet outside the Solar System. A total of such planets have been identified as of . It is now known that a substantial fraction of stars have planets, including perhaps half of all Sun-like stars...
that was discovered on August 25, 2011 in orbit around PSR J1719-1438, a millisecond pulsar
Millisecond pulsar
A millisecond pulsar is a pulsar with a rotational period in the range of about 1-10 milliseconds. Millisecond pulsars have been detected in the radio, X-ray, and gamma ray portions of the electromagnetic spectrum. The origin of millisecond pulsars is still unknown...
. The pulsar planet
Pulsar planet
Pulsar planets are planets that are found orbiting pulsars, or rapidly rotating neutron stars. The first such planet to be discovered was around a millisecond pulsar and was the first extrasolar planet to be confirmed as discovered.-Pulsar planets:...
is most likely composed largely of crystalline carbon, or diamond
Diamond
In mineralogy, diamond is an allotrope of carbon, where the carbon atoms are arranged in a variation of the face-centered cubic crystal structure called a diamond lattice. Diamond is less stable than graphite, but the conversion rate from diamond to graphite is negligible at ambient conditions...
. PSR J1719 -1438 b and PSR J1719 -1438 were formerly two stars in a binary star
Binary star
A binary star is a star system consisting of two stars orbiting around their common center of mass. The brighter star is called the primary and the other is its companion star, comes, or secondary...
system, but after PSR J1719 -1438 went supernova
Supernova
A supernova is a stellar explosion that is more energetic than a nova. It is pronounced with the plural supernovae or supernovas. Supernovae are extremely luminous and cause a burst of radiation that often briefly outshines an entire galaxy, before fading from view over several weeks or months...
and became a pulsar
Pulsar
A pulsar is a highly magnetized, rotating neutron star that emits a beam of electromagnetic radiation. The radiation can only be observed when the beam of emission is pointing towards the Earth. This is called the lighthouse effect and gives rise to the pulsed nature that gives pulsars their name...
, PSR J1719 -1438 b expanded into its red giant
Red giant
A red giant is a luminous giant star of low or intermediate mass in a late phase of stellar evolution. The outer atmosphere is inflated and tenuous, making the radius immense and the surface temperature low, somewhere from 5,000 K and lower...
phase and diminished into a white dwarf
White dwarf
A white dwarf, also called a degenerate dwarf, is a small star composed mostly of electron-degenerate matter. They are very dense; a white dwarf's mass is comparable to that of the Sun and its volume is comparable to that of the Earth. Its faint luminosity comes from the emission of stored...
. The intense conditions of the system converted the white dwarf into a planet
Planet
A planet is a celestial body orbiting a star or stellar remnant that is massive enough to be rounded by its own gravity, is not massive enough to cause thermonuclear fusion, and has cleared its neighbouring region of planetesimals.The term planet is ancient, with ties to history, science,...
composed largely of heavy elements like carbon and oxygen. PSR J1719 -1438 b orbits so closely to its host star, the planet's orbit would fit inside the Sun
Sun
The Sun is the star at the center of the Solar System. It is almost perfectly spherical and consists of hot plasma interwoven with magnetic fields...
. The existence of such diamond planets
Carbon planet
A carbon planet, also referred to as a diamond planet or carbide planet, is a theoretical type of planet proposed by Marc Kuchner that could form if protoplanetary discs are carbon-rich and oxygen-poor. According to planetary science, it would develop differently from Earth, Mars and Venus, planets...
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 TechnologySwinburne University of Technology
Swinburne University of Technology is an Australian public dual sector university based in Melbourne, Victoria. The institution was founded by the Honourable George Swinburne in 1908 and achieved university status in June 1992...
in Melbourne, Australia. The orbiting planet was published in the journal Science
Science (journal)
Science is the academic journal of the American Association for the Advancement of Science and is one of the world's top scientific journals....
on August 25, 2011. The planet was confirmed through pulsar timing, in which small modulations detected in the highly regular pulsar signature are measured and extrapolated. Observatories in Britain, Hawaii, and Australia were used to confirm these observations.
Formation
The pulsar was formed when the primary member of a binary starBinary star
A binary star is a star system consisting of two stars orbiting around their common center of mass. The brighter star is called the primary and the other is its companion star, comes, or secondary...
system experienced a supernova
Supernova
A supernova is a stellar explosion that is more energetic than a nova. It is pronounced with the plural supernovae or supernovas. Supernovae are extremely luminous and cause a burst of radiation that often briefly outshines an entire galaxy, before fading from view over several weeks or months...
, leaving behind its rapidly spinning core, which became the pulsar itself. The secondary, less prominent companion was a main sequence star that became a red giant
Red giant
A red giant is a luminous giant star of low or intermediate mass in a late phase of stellar evolution. The outer atmosphere is inflated and tenuous, making the radius immense and the surface temperature low, somewhere from 5,000 K and lower...
before shrinking into a white dwarf
White dwarf
A white dwarf, also called a degenerate dwarf, is a small star composed mostly of electron-degenerate matter. They are very dense; a white dwarf's mass is comparable to that of the Sun and its volume is comparable to that of the Earth. Its faint luminosity comes from the emission of stored...
. During its life, the pulsar siphoned gases from the secondary star, speeding up as more matter was added to it.
The white dwarf, however, did not enter an unstable orbit and merge with the pulsar, which happens to a significant minority of star-pulsar binary systems. Instead, the white dwarf stabilized at an orbit approximately one solar radius away from the pulsar. The proximity caused the white dwarf to lose the majority of its remaining matter, leaving behind a bare core. The intense gravitational pressure caused by the proximity crystallized the carbon-composed planet (now that all fusion reactions have stopped, it was reclassified), forming a substance similar to that of diamond
Diamond
In mineralogy, diamond is an allotrope of carbon, where the carbon atoms are arranged in a variation of the face-centered cubic crystal structure called a diamond lattice. Diamond is less stable than graphite, but the conversion rate from diamond to graphite is negligible at ambient conditions...
.
Host star
PSR J1719 -1438 is a pulsar some 4,000 light years away from earth in the Serpens Cauda constellation, approximately one minute from the border with Ophiuchus. The pulsar completes more than 10,000 rotations a minute. It is approximately 12 miles across, but has a mass that is 1.4 solar massSolar mass
The solar mass , , is a standard unit of mass in astronomy, used to indicate the masses of other stars and galaxies...
es. The pulsar was originally part of a binary star system, with the other star being PSR J1719 -1438 b (when it still completed fusion reactions).
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). Thus, it must be partially composed of degenerate matterDegenerate matter
Degenerate matter is matter that has such extraordinarily high density that the dominant contribution to its pressure is attributable to the Pauli exclusion principle. The pressure maintained by a body of degenerate matter is called the degeneracy pressure, and arises because the Pauli principle...
. It is slightly more massive than Jupiter. Because it is hypothesized to be the remnant of a white dwarf, it is believed to be composed of oxygen and carbon (as opposed to hydrogen and helium, which composes gas giant
Gas giant
A gas giant is a large planet that is not primarily composed of rock or other solid matter. There are four gas giants in the Solar System: Jupiter, Saturn, Uranus, and Neptune...
s like Jupiter and Saturn). However, all known white dwarfs have densities that are on the order of millions of times the density of water and are composed of electron-degenerate matter, which makes this object extremely non-dense for a white dwarf. Also, white dwarfs emit light due to their temperature based on trapped heat from gravitational collapse. It is unknown why this hypothesized white dwarf remnant does not retain enough temperature to emit light.
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 diamond
Diamond
In mineralogy, diamond is an allotrope of carbon, where the carbon atoms are arranged in a variation of the face-centered cubic crystal structure called a diamond lattice. Diamond is less stable than graphite, but the conversion rate from diamond to graphite is negligible at ambient conditions...
is and according to Bailes "If you could grab big chunks and bring it home you could turn it into a pretty useful diamond.".
PSR J1719 -1438 b orbits its host star with a period of 2.177 hours and at a distance of a little bit less than one (0.89) solar radius , and would thus fit inside the Sun if compared to the Solar System
Solar System
The Solar System consists of the Sun and the astronomical objects gravitationally bound in orbit around it, all of which formed from the collapse of a giant molecular cloud approximately 4.6 billion years ago. The vast majority of the system's mass is in the Sun...
.
PSR J1719 -1438 b was formerly a star that was a red giant for a period in its lifetime. During this period, gas from PSR J1719 -1438 b was pulled onto PSR J1719 -1438 after it had become a pulsar, speeding up its rotation significantly. When PSR J1719 -1438 b became a white dwarf, over 99.9% of its constituents were blown away because of its proximity to the pulsar, leaving behind a core that could no longer perform fusion reactions. The core was then reclassified as a planet.
See also
- WASP-12bWASP-12bWASP-12b is an extrasolar planet orbiting the star WASP-12, discovered by the SuperWASP planetary transit survey. Its discovery was announced on April 1, 2008. Due to its extremely close orbit to its star, it has one of the lowest densities for exoplanets...
, a "diamond planet" - BPM 37093BPM 37093BPM 37093 is a variable white dwarf star of the DAV, or ZZ Ceti, type, with a hydrogen atmosphere and an unusually high mass of approximately 1.1 times the Sun's. It is about 50 light-years from Earth, in the constellation Centaurus, and vibrates; these pulsations cause its luminosity to vary...
, a "diamond star" - EF EridaniEF EridaniEF Eridani is a variable star of the type known as polars, AM Herculis stars, or magnetic cataclysmic variable stars. Historically it has varied between apparent magnitudes 14.5 and 17.3, although since 1995 it has generally remained at the lower limit...
, a star system with a compact star and a degraded planetary-mass former star