55 Cancri d (abbreviated 55 Cnc d), formally named Lipperhey , 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 ...

in a long-period

orbit In celestial mechanics, an orbit (also known as orbital revolution) is the curved trajectory of an object such as the trajectory of a planet around a star, or of a natural satellite around a planet, or of an artificial satellite around an ...

around 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 ...

-like star 55 Cancri A. Located at a similar distance from its star as

Jupiter Jupiter is the fifth planet from the Sun and the List of Solar System objects by size, largest in the Solar System. It is a gas giant with a Jupiter mass, mass more than 2.5 times that of all the other planets in the Solar System combined a ...

is from the Sun, it is the fifth and outermost known planet in its

planetary system A planetary system is a set of gravity, gravitationally bound non-stellar Astronomical object, bodies in or out of orbit around a star or star system. Generally speaking, systems with one or more planets constitute a planetary system, although ...

. 55 Cancri d was discovered on June 13, 2002.

Name

In July 2014 the

International Astronomical Union The International Astronomical Union (IAU; , UAI) is an international non-governmental organization (INGO) with the objective of advancing astronomy in all aspects, including promoting astronomical research, outreach, education, and developmen ...

launched

NameExoWorlds NameExoWorlds (also known as IAU NameExoWorlds) were various projects managed by the International Astronomical Union (I.A.U.) to encourage names to be submitted for astronomical objects, notably exoplanets. The accepted names would later be cons ...

, a process for giving proper names to certain exoplanets and their host stars. The process involved public nomination and voting for the new names. In December 2015, the IAU announced the winning name was Lippershey for this planet.Final Results of NameExoWorlds Public Vote Released
International Astronomical Union, 15 December 2015. The winning name was submitted by the Royal Netherlands Association for Meteorology and Astronomy of the

Netherlands , Terminology of the Low Countries, informally Holland, is a country in Northwestern Europe, with Caribbean Netherlands, overseas territories in the Caribbean. It is the largest of the four constituent countries of the Kingdom of the Nether ...

. It honors the spectacle maker and telescope pioneer

Hans Lippershey Hans Lipperhey ( – buried 29 September 1619), also known as Johann Lippershey or simply Lippershey, was a Germany, German-Netherlands, Dutch Glasses, spectacle-maker. He is commonly associated with the invention of the telescope, because he was ...

. In January 2016, in recognition that his actual name was Lipperhey (with Lippershey an error introduced in the 19th century), the exoplanet name was corrected to Lipperhey by the IAU and that name was submitted to the official sites that keep track of astronomical information.

Discovery

Like the majority of known extrasolar planets found at the time, 55 Cancri d was detected by observing changes in its star's

radial velocity The radial velocity or line-of-sight velocity of a target with respect to an observer is the rate of change of the vector displacement between the two points. It is formulated as the vector projection of the target-observer relative velocity ...

. This was achieved by making sensitive measurements of the

Doppler shift The Doppler effect (also Doppler shift) is the change in the frequency of a wave in relation to an observer who is moving relative to the source of the wave. The ''Doppler effect'' is named after the physicist Christian Doppler, who described t ...

of the star's

spectrum A spectrum (: spectra or spectrums) is a set of related ideas, objects, or properties whose features overlap such that they blend to form a continuum. The word ''spectrum'' was first used scientifically in optics to describe the rainbow of co ...

. At the time of discovery, 55 Cancri A was already known to possess one planet (

55 Cancri b 55 Cancri b (abbreviated 55 Cnc b), occasionally designated 55 Cancri Ab (to distinguish it from the star 55 Cancri B), formally named Galileo, is an exoplanet orbiting the Sun-like star 55 Cancri A every 14.65 days. It is the second planet in ...

), however there was still a drift in the radial velocity measurements which was unaccounted-for. In 2002, further measurements revealed the presence of a long-period planet in an orbit at around 5 AU from the star. The same measurements also indicated the presence of another inner planet, designated

55 Cancri c 55 Cancri c (abbreviated 55 Cnc c), formally named Brahe (pronounced or ), is an extrasolar planet in an eccentricity (orbit), eccentric orbit around the Sun-like star 55 Cancri, 55 Cancri A, making one orbital revolution, revolution every 44. ...

Orbit and mass

When 55 Cancri d was discovered, it was thought to be on a fairly low

eccentricity Eccentricity or eccentric may refer to: * Eccentricity (behavior), odd behavior on the part of a person, as opposed to being "normal" Mathematics, science and technology Mathematics * Off-Centre (geometry), center, in geometry * Eccentricity (g ...

orbit similar to Jupiter in the

Solar System The Solar SystemCapitalization of the name varies. The International Astronomical Union, the authoritative body regarding astronomical nomenclature, specifies capitalizing the names of all individual astronomical objects but uses mixed "Sola ...

, though the

orbital elements Orbital elements are the parameters required to uniquely identify a specific orbit. In celestial mechanics these elements are considered in two-body systems using a Kepler orbit. There are many different ways to mathematically describe the same o ...

were not well determined. As more data were collected, the best-fit solution for this planet turned out to be highly eccentric, more so than any of the planets in the Solar System. In 2008, after a complete orbit of this planet had been observed, the true orbit was revealed, indicating that as had been originally suspected, the planet's 14 year orbit was in fact near-circular, located about 5.77 AU from the star. A limitation of the radial velocity method used to discover 55 Cancri d is that only a lower limit on the planet's

mass Mass is an Intrinsic and extrinsic properties, intrinsic property of a physical body, body. It was traditionally believed to be related to the physical quantity, quantity of matter in a body, until the discovery of the atom and particle physi ...

can be obtained. In the case of 55 Cancri d, this lower limit was around 3.835 times the mass of

. In 2004,

astrometric Astrometry is a branch of astronomy that involves precise measurements of the positions and movements of stars and other celestial bodies. It provides the kinematics and physical origin of the Solar System and this galaxy, the Milky Way. History ...

measurements with the Fine Guidance Sensors on the

Hubble Space Telescope The Hubble Space Telescope (HST or Hubble) is a space telescope that was launched into low Earth orbit in 1990 and remains in operation. It was not the Orbiting Solar Observatory, first space telescope, but it is one of the largest and most ...

suggest that the planet's orbit is inclined by around 53° with respect to the plane of the sky. If this measurement is confirmed, it implies that the planet's

true mass In astronomy, minimum mass is the lower-bound calculated mass of observed objects such as planets, stars, binary systems, nebulae, and black holes. Minimum mass is a widely cited statistic for extrasolar planets detected by the radial velocit ...

is 25% greater than the lower limit, at around 4.8 Jupiter masses; and that 55 Cancri d is not coplanar with the innermost planets e and b (both at about 85°). This measurement is dependent on the planet's accurate orbital period, estimates for which have changed since 2004.

Characteristics

Given the planet's high mass, the planet is a

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 ...

with no

solid Solid is a state of matter where molecules are closely packed and can not slide past each other. Solids resist compression, expansion, or external forces that would alter its shape, with the degree to which they are resisted dependent upon the ...

surface. Since the planet has only been detected indirectly, parameters such as its

radius In classical geometry, a radius (: radii or radiuses) of a circle or sphere is any of the line segments from its Centre (geometry), center to its perimeter, and in more modern usage, it is also their length. The radius of a regular polygon is th ...

, composition, and

temperature Temperature is a physical quantity that quantitatively expresses the attribute of hotness or coldness. Temperature is measurement, measured with a thermometer. It reflects the average kinetic energy of the vibrating and colliding atoms making ...

are unknown. Assuming a composition similar to that of Jupiter and that the planet's

atmosphere An atmosphere () is a layer of gases that envelop an astronomical object, held in place by the gravity of the object. A planet retains an atmosphere when the gravity is great and the temperature of the atmosphere is low. A stellar atmosph ...

is close to

chemical equilibrium In a chemical reaction, chemical equilibrium is the state in which both the Reagent, reactants and Product (chemistry), products are present in concentrations which have no further tendency to change with time, so that there is no observable chan ...

, it is predicted that 55 Cancri d is covered in a layer of

water Water is an inorganic compound with the chemical formula . It is a transparent, tasteless, odorless, and Color of water, nearly colorless chemical substance. It is the main constituent of Earth's hydrosphere and the fluids of all known liv ...

cloud In meteorology, a cloud is an aerosol consisting of a visible mass of miniature liquid droplets, frozen crystals, or other particles, suspended in the atmosphere of a planetary body or similar space. Water or various other chemicals may ...

s: the planet's internal

heat In thermodynamics, heat is energy in transfer between a thermodynamic system and its surroundings by such mechanisms as thermal conduction, electromagnetic radiation, and friction, which are microscopic in nature, involving sub-atomic, ato ...

probably keeps it too warm to form the

ammonia Ammonia is an inorganic chemical compound of nitrogen and hydrogen with the chemical formula, formula . A Binary compounds of hydrogen, stable binary hydride and the simplest pnictogen hydride, ammonia is a colourless gas with a distinctive pu ...

-based clouds that are typical of Jupiter. Its surface gravity is likely to be about 4 to 5 times stronger than Jupiter, or about 10 to 15 times that of Earth which is because the radius of the planet is unlikely to be much more than Jupiter's and is probably slightly smaller than Jupiter due to the high metal content in the parent star.

References

External links