Beta Pictoris b (abbreviated as β Pic b) is an

exoplanet An exoplanet or extrasolar planet is a planet outside the Solar System. The first possible evidence of an exoplanet was noted in 1917 but was not recognized as such. The first confirmation of detection occurred in 1992. A different planet, init ...

orbiting the young

debris disk A debris disk (American English), or debris disc (Commonwealth English), is a circumstellar disk of dust and debris in orbit around a star. Sometimes these disks contain prominent rings, as seen in the image of Fomalhaut on the right. Debris di ...

A-type main sequence star

Beta Pictoris Beta Pictoris (abbreviated β Pictoris or β Pic) is the second brightest star in the constellation Pictor. It is located from the Solar System, and is 1.75 times as massive and 8.7 times as luminous as the Sun. The Beta Pictoris s ...

located approximately 63

light-year A light-year, alternatively spelled light year, is a large unit of length used to express astronomical distance, astronomical distances and is equivalent to about 9.46 Orders of magnitude (numbers)#1012, trillion kilometers (), or 5.88 ...

s (19.4

parsec The parsec (symbol: pc) is a unit of length used to measure the large distances to astronomical objects outside the Solar System, approximately equal to or (au), i.e. . The parsec unit is obtained by the use of parallax and trigonometry, an ...

s, or km) away from

Earth Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's sur ...

in the

constellation A constellation is an area on the celestial sphere in which a group of visible stars forms a perceived pattern or outline, typically representing an animal, mythological subject, or inanimate object. The origins of the earliest constellation ...

Pictor Pictor is a constellation in the Southern Celestial Hemisphere, located between the star Canopus and the Large Magellanic Cloud. Its name is Latin for painter, and is an abbreviation of the older name Equuleus Pictoris (the "painter's easel" ...

. It has a mass around 13 Jupiter masses and a radius around 46% larger than

Jupiter Jupiter is the fifth planet from the Sun and the largest in the Solar System. It is a gas giant with a mass more than two and a half times that of all the other planets in the Solar System combined, but slightly less than one-thousand ...

's. It orbits at 9 AU from Beta Pictoris, which is about 3.5 times farther than the orbit of Beta Pictoris c. It orbits close to the plane of the debris disk orbiting the star, with a low eccentricity and a period of 20–21 years.

Physical characteristics

Mass, radius and temperature

Beta Pictoris b is a super-Jupiter, an exoplanet that has a radius and mass greater than that of the planet

. It has a temperature of , most likely due to its dusty atmosphere and mass (normally it would be much colder). It has a mass of between 9 and 13 Jupiter masses (), and a radius of 1.46 . In 2018, a study directly measured the astrometric perturbation of Beta Pictoris by Beta Pictoris b, one of the first examples of an exoplanet being measured directly by its astrometric perturbation. Its mass was directly measured as .

Host star

The planet orbits an ( A-type)

star A star is an astronomical object comprising a luminous spheroid of plasma (physics), plasma held together by its gravity. The List of nearest stars and brown dwarfs, nearest star to Earth is the Sun. Many other stars are visible to the naked ...

named

. The star has a mass of 1.75

solar mass The solar mass () is a standard unit of mass in astronomy, equal to approximately . It is often used to indicate the masses of other stars, as well as stellar clusters, nebulae, galaxies and black holes. It is approximately equal to the mass ...

es () and a radius of 1.8 solar radii (). It has a surface temperature of 8056 K and is 12 million years old. In comparison, the Sun is about 4.6 billion years old and has a surface temperature of 5778 K. It is slightly metal-rich, with a

metallicity In astronomy, metallicity is the abundance of elements present in an object that are heavier than hydrogen and helium. Most of the normal physical matter in the Universe is either hydrogen or helium, and astronomers use the word ''"metals"'' as ...

( e/H of 0.06, or 112% of that found in the Sun. Its luminosity () is 8.7 times that of the Sun. The star's

apparent magnitude Apparent magnitude () is a measure of the brightness of a star or other astronomical object observed from Earth. An object's apparent magnitude depends on its intrinsic luminosity, its distance from Earth, and any extinction of the object's ...

, or how bright it appears from Earth's perspective, is 3. Therefore, it can be seen with the naked eye.

Orbit

Beta Pictoris b orbits its host star every 21 years at a distance of 9.2 AU (about the same as

Saturn Saturn is the sixth planet from the Sun and the second-largest in the Solar System, after Jupiter. It is a gas giant with an average radius of about nine and a half times that of Earth. It has only one-eighth the average density of Earth; h ...

's distance, which is about 9.55 AU). It receives 11% of the amount of

sunlight Sunlight is a portion of the electromagnetic radiation given off by the Sun, in particular infrared, visible, and ultraviolet light. On Earth, sunlight is scattered and filtered through Earth's atmosphere, and is obvious as daylight when ...

that Earth does from the Sun.http://www.hpcf.upr.edu/~abel/phl/hec_plots/hec_orbit/hec_orbit_beta_Pic_b.png

Planetary rotation

In 2014, the rotation period of Beta Pictoris b was calculated from the broadening of its carbon monoxide infrared absorption line. This makes it, , the first extrasolar planet to have its rotation rate measured. With a rotation period of 8.1 hours, it is the fastest-spinning planet known. Its rotation period is faster than that of

, which has a rotation period of around 10 hours. The rotation axis of the planet is well aligned to the axis of the parent star and debris disk, with misalignment measured to be 3 degrees in 2020.

Discovery

The planet was discovered on November 18, 2008 by

Anne-Marie Lagrange Anne-Marie Lagrange, born in the Rhône-Alpes region of France, is a French astrophysicist. Lagrange's work focuses on the research and study of extrasolar planetary systems. Lagrange is the holder of numerous scientific awards and honorary d ...

''et al.'', using the NACO instrument on the

Very Large Telescope The Very Large Telescope (VLT) is a telescope facility operated by the European Southern Observatory on Cerro Paranal in the Atacama Desert of northern Chile. It consists of four individual telescopes, each with a primary mirror 8.2 m acro ...

at Cerro Paranal in northern

Chile Chile, officially the Republic of Chile, is a country in the western part of South America. It is the southernmost country in the world, and the closest to Antarctica, occupying a long and narrow strip of land between the Andes to the eas ...

. This planet was discovered using the direct imaging technique, using reference star differential imaging. The discovery image was taken in 2003, but the planet was not detected when the data were first reduced. A re-reduction of the data in 2008 using modern image processing tools revealed the faint point source now known to be a planet.

Further studies

Follow-up observations performed in late 2009 and early 2010 using the same instrument recovered and confirmed the planet, but on the opposite side of the star. These findings were published in the journal ''

Science Science is a systematic endeavor that builds and organizes knowledge in the form of testable explanations and predictions about the universe. Science may be as old as the human species, and some of the earliest archeological evidence ...

'' and represented the closest orbiting planet to its star ever imaged. Observations performed in late 2010 and early 2011 allowed scientists to establish an

inclination Orbital inclination measures the tilt of an object's orbit around a celestial body. It is expressed as the angle between a reference plane and the orbital plane or axis of direction of the orbiting object. For a satellite orbiting the Ea ...

angle of the planet's orbit of 88.5 degrees, nearly edge-on. The location of the planet was found to be approximately 3.5 to 4 degrees tilted from the main disk in this system, indicating that the planet is aligned with the warped inner disk in the Beta Pictoris system. The first study of the spectral energy distribution of the planet was published in July 2013. This study shows detections at 1.265, 1.66, 2.18, 3.80, 4.05 and 4.78

µm The micrometre ( international spelling as used by the International Bureau of Weights and Measures; SI symbol: μm) or micrometer ( American spelling), also commonly known as a micron, is a unit of length in the International System of Uni ...

demonstrating that the planet has a very dusty and/or cloudy atmosphere. The SED is consistent with that of an early

L dwarf Brown dwarfs (also called failed stars) are substellar objects that are not massive enough to sustain nuclear fusion of ordinary hydrogen ( 1H) into helium in their cores, unlike a main-sequence star. Instead, they have a mass between the most ma ...

, but with a lower surface gravity. The effective temperature is constrained to and the surface gravity to log g = . A second study, published in September 2013, provided a new detection at 3.1 µm obtained at the

Gemini Observatory The Gemini Observatory is an astronomical observatory consisting of two 8.1-metre (26.6 ft) telescopes, Gemini North and Gemini South, which are located at two separate sites in Hawaii and Chile, respectively. The twin Gemini telescopes prov ...

along with a reanalysis of previous data. They found the planet to be overluminous in the

mid-infrared Infrared (IR), sometimes called infrared light, is electromagnetic radiation (EMR) with wavelengths longer than those of visible light. It is therefore invisible to the human eye. IR is generally understood to encompass wavelengths from around ...

3.1 µm band compared to models of early L dwarfs. Models incorporating small dust particles and thick clouds provided the best fit to the SED. The effective temperature is constrained to and the surface gravity to log g = . This fit corresponds to a planet radius of 1.65 times that of Jupiter, arguing that Beta Pictoris b may be younger than its host star (finished forming at 5 Ma). In 2015, a short video was made from direct images of Beta Pictoris b taken by the Gemini Planet Imager over the course of about two years showing a time-lapse of the planet orbiting around its parent star. It may have been responsible for a

transit Transit may refer to: Arts and entertainment Film * ''Transit'' (1979 film), a 1979 Israeli film * ''Transit'' (2005 film), a film produced by MTV and Staying-Alive about four people in countries in the world * ''Transit'' (2006 film), a 2006 ...

-like event observed in 1981. In 2018, the PicSat cubesat was launched in a mission to image the planet Beta Pictoris b transiting its host star Beta Pictoris. As of 2022, the orbital parameters and mass of Beta Pictoris b have been measured using a combination of data from

radial velocity The radial velocity or line-of-sight velocity, also known as radial speed or range rate, of a target with respect to an observer is the rate of change of the distance or range between the two points. It is equivalent to the vector projection ...

astrometry 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. Hist ...

, and imaging, showing that it is about 11.7 times the mass of Jupiter with a

semi-major axis In geometry, the major axis of an ellipse is its longest diameter: a line segment that runs through the center and both foci, with ends at the two most widely separated points of the perimeter. The semi-major axis (major semiaxis) is the lon ...

of about 10 AU and an orbital period of about 23.6 years.

Gallery

Stunning Exoplanet Time-lapse Beta Pictoris b.tif, Beta Pictoris b time-lapse. Beta_Pictoris_system_annotated.jpg, An annotated view of the Beta Pictoris system. Beta Pictoris b - The universal relation between mass and rotation speed of planets.jpg, Equatorial spin velocity vs mass for planets comparing Beta Pictoris b to the

Solar System The Solar System Capitalization 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 "Solar ...

planets. Beta Pictoris b orbit animated (2013-2018).webm, The motion of Beta Pictoris b. The orbital plane is viewed side-on; the planet is not moving towards the star. Beta Pictoris star system.jpg, Artistic rendering of the Beta Pictoris system, showing the

accretion disk An accretion disk is a structure (often a circumstellar disk) formed by diffuse material in orbital motion around a massive central body. The central body is typically a star. Friction, uneven irradiance, magnetohydrodynamic effects, and other ...

, and the two planets.

Notes

References

{{Sky, 5, 47, 17.1, -, 51, 03, 59 Exoplanets detected by direct imaging Exoplanets detected by astrometry Exoplanets detected by radial velocity Exoplanets discovered in 2008 Giant planets Pictor (constellation)