List of extrasolar planet extremes - AbsoluteAstronomy.com

The following are lists of extremes among the known extrasolar 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...

s. The properties listed here are those for which values are known reliably.

Extremes

Title	Planet	Star	Data	Notes
Most distant				An analysis of the lightcurve of the microlensing event PA-99-N2 suggests the presence of a planet orbiting a star in the Andromeda Galaxy Andromeda Galaxy The Andromeda Galaxy is a spiral galaxy approximately 2.5 million light-years from Earth in the constellation Andromeda. It is also known as Messier 31, M31, or NGC 224, and is often referred to as the Great Andromeda Nebula in older texts. Andromeda is the nearest spiral galaxy to the... . A controversial microlensing event of lobe A of the double gravitationally lensed Q0957+561 Twin Quasar The Twin Quasar , also known as SBS 0957+561, or TXS 0957+561 , was the first identified gravitationally lensed object.-Quasar:... suggests that there is a planet in the lensing galaxy lying at redshift 0.355 (3.7 Gly).
Least distant			10.4 light years	Claims have been made by Gatewood George David Gatewood George David Gatewood also known as George G. Gatewood, is an American astronomer and presently is professor emeritus at the University of Pittsburgh and at the Allegheny Observatory... that Lalande 21185 Lalande 21185 Lalande 21185 is a red dwarf star in the constellation of Ursa Major. Although relatively close by, it is only magnitude 7 in visible light and thus is too dim to see with the unaided eye... (the fourth nearest star system to our Sun at 8.3 light-years distance) may have an exoplanet or two. These claims have not been confirmed.

Planetary characteristics

Title	Data	Notes
Least massive	0.02 M_Earth Earth mass Earth mass is the unit of mass equal to that of the Earth. 1 M⊕ = 5.9722 × 1024 kg. Earth mass is often used to describe masses of rocky terrestrial planets....	The mass of PSR B1257+12 A is based on an assumption of coplanarity Coplanarity In geometry, a set of points in space is coplanar if all the points lie in the same geometric plane. For example, three distinct points are always coplanar; but a fourth point or more added in space can exist in another plane, incoplanarly.... with the outer two planets. It may be an asteroid Asteroid Asteroids are a class of small Solar System bodies in orbit around the Sun. They have also been called planetoids, especially the larger ones... al object, i.e. possibly not massive enough to qualify as a planet. (However, no low mass cut-off for an exoplanet is currently defined.)
Biggest radius		WASP-17b WASP-17b WASP-17b is an exoplanet in the constellation Scorpius that is orbiting the star WASP-17. Its discovery was announced on 11 August 2009. It is the first planet discovered to have a retrograde orbit, meaning it orbits in a direction counter to the rotation of its host star. This discovery changed... may be larger.
Smallest radius		PSR B1257+12 A is likely to be smaller.
Most dense	~ 23 g/cm³ (~ 23,000 kg/m³)	This "planet" is thought to be the remnant inner core of a degraded star. It is 4x denser than the Earth, the densest known planet previously.
Least dense	80–185 kg/m³
Lowest albedo	Geometric albedo Geometric albedo The geometric albedo of an astronomical body is the ratio of its actual brightness at zero phase angle to that of an idealized flat, fully reflecting, diffusively scattering disk with the same cross-section.... < 1%	Best-fit model for albedo gives even 0.04%

Orbit characteristics

Title	Data	Notes
Longest orbit Orbit In physics, an orbit is the gravitationally curved path of an object around a point in space, for example the orbit of a planet around the center of a star system, such as the Solar System... al period (Longest year)
Shortest orbital period (Shortest year)		SWEEPS-10 SWEEPS-10 \|- style="vertical-align: top;"SWEEPS-10 is, as of June 2007, the planet candidate with the shortest orbital period yet found. The planet orbits the star SWEEPS J175902.00−291323.7 located in the Galactic bulge at a distance of approximately 22000 light years from Earth... (awaiting confirmation) has an orbital period of 0.424 days (10.2 hours).
Most eccentric orbit Orbital eccentricity The orbital eccentricity of an astronomical body is the amount by which its orbit deviates from a perfect circle, where 0 is perfectly circular, and 1.0 is a parabola, and no longer a closed orbit...	eccentricity of 0.9349
Least eccentric orbit	eccentricity of 0.001
Most inclined orbit (relative to sky plane)	inclination 90°
Largest orbit	~330 AU	Proper motion Proper motion The proper motion of a star is its angular change in position over time as seen from the center of mass of the solar system. It is measured in seconds of arc per year, arcsec/yr, where 3600 arcseconds equal one degree. This contrasts with radial velocity, which is the time rate of change in... confirmed Nov 9, 2010
Smallest orbit	0.014 AU	SWEEPS-10 SWEEPS-10 \|- style="vertical-align: top;"SWEEPS-10 is, as of June 2007, the planet candidate with the shortest orbital period yet found. The planet orbits the star SWEEPS J175902.00−291323.7 located in the Galactic bulge at a distance of approximately 22000 light years from Earth... (awaiting confirmation) has an orbital distance of 0.008 AU (1.2 million km).
Smallest orbit around binary star	3.14 ± 0.01	Ratio of planet orbit to binary star orbit (by semi-major axis Semi-major axis The major axis of an ellipse is its longest diameter, a line that runs through the centre and both foci, its ends being at the widest points of the shape... )

Stellar characteristics

Title	Planet	Star	Data	Notes
Highest metallicity Metallicity In astronomy and physical cosmology, the metallicity of an object is the proportion of its matter made up of chemical elements other than hydrogen and helium...			+0.56 dex Logarithm The logarithm of a number is the exponent by which another fixed value, the base, has to be raised to produce that number. For example, the logarithm of 1000 to base 10 is 3, because 1000 is 10 to the power 3: More generally, if x = by, then y is the logarithm of x to base b, and is written...
Lowest metallicity	HIP 13044 b HIP 13044 b HIP 13044 b is a Jupiter-like extrasolar planet orbiting the old and metal-poor red giant star HIP 13044, which is situated approximately 2,000 light years away from the Earth in the constellation Fornax. Its discovery was announced on November 18, 2010 after observations using the FEROS...	HIP 13044 HIP 13044 HIP 13044 is a red horizontal branch star about 2,300 light years away from the Earth in the constellation Fornax. The star is part of the Helmi stream, a former dwarf galaxy that merged with the Milky Way between six and nine billion years ago. As a result, HIP 13044 circles the galactic center...	−2.09±0.26 dex	This star came from another galaxy Galaxy A galaxy is a massive, gravitationally bound system that consists of stars and stellar remnants, an interstellar medium of gas and dust, and an important but poorly understood component tentatively dubbed dark matter. The word galaxy is derived from the Greek galaxias , literally "milky", a... that merged into the Milky Way Milky Way The Milky Way is the galaxy that contains the Solar System. This name derives from its appearance as a dim un-resolved "milky" glowing band arching across the night sky... 6–9 billion years ago.
Highest stellar mass			4.5±2.5 M_☉ Solar mass The solar mass , , is a standard unit of mass in astronomy, used to indicate the masses of other stars and galaxies...	Margin of error means it is possible this it not the most massive known planet-harboring star. NGC 4349-127 NGC 4349-127 NGC 4349-127 is a probable red giant star approximately 7,097 light-years away in the constellation of Crux. As a member of the open cluster NGC 4349 , it is located about 2000 parsecs from the Sun. Its mass is estimated at 3.9 times Solar, and its age is about 200 million years... has a stellar mass of 3.9±0.3 M_☉
Lowest stellar mass			0.02 M_☉

System characteristics

Title	System	Planet(s)	Star(s)	Notes
System with most (confirmed) planets	Kepler-11 Kepler-11 Kepler-11 is a sun-like star slightly larger than the Sun in the constellation Cygnus, located some 2,000 light years from Earth. It is located within the field of vision of the Kepler spacecraft, the satellite that NASA's Kepler Mission uses to detect planets that may be transiting their stars...	6	1	the planets are Kepler-11b, c, ..., g
System with most stars	91 Aquarii	91 Aquarii Ab	3 (possibly 5)	Two of the 5 stars are probably not part of the system

External links

WiredScience, Top 5 Most Extreme Exoplanets, Clara Moskowitz, 21 January 2009