B-type asteroids are a relatively uncommon type of

carbon Carbon () is a chemical element with the symbol C and atomic number 6. It is nonmetallic and tetravalent—its atom making four electrons available to form covalent chemical bonds. It belongs to group 14 of the periodic table. Carbon makes ...

aceous

asteroid An asteroid is a minor planet of the Solar System#Inner solar system, inner Solar System. Sizes and shapes of asteroids vary significantly, ranging from 1-meter rocks to a dwarf planet almost 1000 km in diameter; they are rocky, metallic o ...

, falling into the wider C-group; the 'B' indicates these objects are spectrally blue. In the asteroid population, B-class objects can be found in the outer

asteroid belt The asteroid belt is a torus-shaped region in the Solar System, located roughly between the orbits of the planets Jupiter and Mars. It contains a great many solid, irregularly shaped bodies, of many sizes, but much smaller than planets, called ...

, and also dominate the high-

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

Pallas family The Pallas family (''adj. Palladian''; ) is a small asteroid family of B-type asteroids at very high inclinations in the intermediate asteroid belt. The namesake of the family is 2 Pallas, an extremely large asteroid with a mean diameter of about 5 ...

which includes the third-largest asteroid

2 Pallas Pallas ( minor-planet designation: 2 Pallas) is the second asteroid to have been discovered, after Ceres. It is believed to have a mineral composition similar to carbonaceous chondrite meteorites, like Ceres, though significantly less hy ...

. They are thought to be

primitive Primitive may refer to: Mathematics * Primitive element (field theory) * Primitive element (finite field) * Primitive cell (crystallography) * Primitive notion, axiomatic systems * Primitive polynomial (disambiguation), one of two concepts * Pr ...

, volatile-rich remnants from the early

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 ...

. There are 65 known B-type asteroids in the SMASS classification, and 9 in the Tholen classification as of March 2015.

Characteristics

Generally similar to the C-type objects, but differing in that the

ultraviolet Ultraviolet (UV) is a form of electromagnetic radiation with wavelength from 10 nm (with a corresponding frequency around 30 PHz) to 400 nm (750 THz), shorter than that of visible light, but longer than X-rays. UV radiati ...

absorption below 0.5 μm is small or absent, and the

spectrum A spectrum (plural ''spectra'' or ''spectrums'') is a condition that is not limited to a specific set of values but can vary, without gaps, across a continuum. The word was first used scientifically in optics to describe the rainbow of color ...

is rather slightly bluish than reddish. The

albedo Albedo (; ) is the measure of the diffuse reflection of solar radiation out of the total solar radiation and measured on a scale from 0, corresponding to a black body that absorbs all incident radiation, to 1, corresponding to a body that refl ...

also tends to be greater than in the generally very dark C type.

Spectroscopy Spectroscopy is the field of study that measures and interprets the electromagnetic spectra that result from the interaction between electromagnetic radiation and matter as a function of the wavelength or frequency of the radiation. Matter ...

of B-class objects suggests major surface constituents of

anhydrous A substance is anhydrous if it contains no water. Many processes in chemistry can be impeded by the presence of water; therefore, it is important that water-free reagents and techniques are used. In practice, however, it is very difficult to achi ...

silicates In chemistry, a silicate is any member of a family of polyatomic anions consisting of silicon and oxygen, usually with the general formula , where . The family includes orthosilicate (), metasilicate (), and pyrosilicate (, ). The name i ...

, hydrated

clay Clay is a type of fine-grained natural soil material containing clay minerals (hydrous aluminium phyllosilicates, e.g. kaolin, Al2 Si2 O5( OH)4). Clays develop plasticity when wet, due to a molecular film of water surrounding the clay part ...

mineral In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid chemical compound with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form.John P. Rafferty, ed. ...

organic polymer A polymer (; Greek ''poly-'', "many" + ''-mer'', "part") is a substance or material consisting of very large molecules called macromolecules, composed of many repeating subunits. Due to their broad spectrum of properties, both synthetic and ...

magnetite Magnetite is a mineral and one of the main iron ores, with the chemical formula Fe2+Fe3+2O4. It is one of the oxides of iron, and is ferrimagnetic; it is attracted to a magnet and can be magnetized to become a permanent magnet itself. With ...

, and

sulfide Sulfide (British English also sulphide) is an inorganic anion of sulfur with the chemical formula S2− or a compound containing one or more S2− ions. Solutions of sulfide salts are corrosive. ''Sulfide'' also refers to chemical compounds l ...

s. The closest matches to B-class asteroids have been obtained on carbonaceous

chondrite A chondrite is a stony (non- metallic) meteorite that has not been modified, by either melting or differentiation of the parent body. They are formed when various types of dust and small grains in the early Solar System accreted to form pri ...

meteorite A meteorite is a solid piece of debris from an object, such as a comet, asteroid, or meteoroid, that originates in outer space and survives its passage through the atmosphere to reach the surface of a planet or moon. When the original object en ...

s that have been gently heated in the

laboratory A laboratory (; ; colloquially lab) is a facility that provides controlled conditions in which scientific or technological research, experiments, and measurement may be performed. Laboratory services are provided in a variety of settings: physici ...

. The majority of asteroids that have been observed to display cometary-like activity are B-types. 1. Introduction: "the majority of asteroids that have been observed to display cometary-like activity are B-types" Some of these objects display indications of aqueous alteration in the past, and they may have incorporated significant amounts of water ice.

Well studied B-type asteroids

Asteroid

101955 Bennu 101955 Bennu (provisional designation ) is a carbonaceous asteroid in the Apollo group discovered by the LINEAR Project on 11 September 1999. It is a potentially hazardous object that is listed on the Sentry Risk Table and has the highest cumu ...

is a B-type asteroid which is the target of the

OSIRIS-REx OSIRIS-REx (Origins, Spectral Interpretation, Resource Identification, Security, Regolith Explorer) is a NASA asteroid-study and sample-return mission. The mission's primary goal is to obtain a sample of at least from 101955 Bennu, a carbo ...

mission. The mission seeks to characterize the asteroid by mapping the surface, studying the

Yarkovsky effect The Yarkovsky effect is a force acting on a rotating body in space caused by the anisotropic emission of thermal photons, which carry momentum. It is usually considered in relation to meteoroids or small asteroids (about 10 cm to 10 km ...

, and retrieving a sample of the asteroid to return in 2023. The spacecraft was launched in 2016 and has been at Bennu since December 2018. Other B-type asteroids include: *

24 Themis Themis (minor planet designation: 24 Themis) is one of the largest asteroids in the asteroid belt. It is also the largest member of the Themistian family. It was discovered by Annibale de Gasparis on 5 April 1853. It is named after Themis, t ...

47 Aglaja 47 Aglaja is a large, dark main belt asteroid. It was discovered by Robert Luther on 15 September 1857 from Düsseldorf. The name was chosen by the Philosophical Faculty of the University of Bonn and refers to Aglaea, one of the Charites in Gr ...

59 Elpis Elpis, minor planet designation: 59 Elpis, is a large main belt asteroid that orbits the Sun with a period of 4.47 years. It is a C-type asteroid, meaning that it is very dark and carbonaceous in composition. In the Tholen scheme it has a ...

85 Io Io (minor planet designation: 85 Io is carbonaceous asteroid from the central region of the asteroid belt, approximately 170 kilometers in diameter. It is an identified Eunomian interloper. Discovery and naming It was discovered by C. H. F. ...

* 88 Thisbe *

142 Polana Polana (minor planet designation: 142 Polana) is a very dark asteroid from the asteroid belt. It was discovered by Johann Palisa on January 28, 1875, and named after the city of Pola (now Pula, Croatia), home of the Austrian Naval Observatory wh ...

* 213 Lilaea * 241 Germania * 282 Clorinde *

335 Roberta Roberta (minor planet designation: 335 Roberta) is a large main belt asteroid. It was discovered on 1 September 1892, by German astronomer Anton Staus at Heidelberg Observatory. ''Roberta'' was the 12th asteroid that was discovered using photogra ...

* 372 Palma *

383 Janina Janina (minor planet designation: 383 Janina) is a Themistian asteroid, approximately in diameter. It is spectral B-type and is probably composed of primitive carbonaceous chondritic material. It was discovered by Auguste Charlois on 29 Janua ...

* 431 Nephele *

531 Zerlina 531 Zerlina, provisional designation 1904 NW, carbonaceous Palladian asteroid from the central region of the asteroid belt, approximately 18 kilometers in diameter. It was discovered by German astronomer Max Wolf at the Heidelberg-Königstuhl St ...

* 541 Deborah *

555 Norma Norma (minor planet designation: 555 Norma), provisional designation , is a background asteroid from the outer regions of the asteroid belt, approximately 33 kilometers in diameter. It was discovered on 14 January 1905, by German astronomer Max Wo ...

560 Delila Delila (minor planet designation A formal minor-planet designation is, in its final form, a number–name combination given to a minor planet (asteroid, centaur, trans-Neptunian object and dwarf planet but not comet). Such designation always f ...

702 Alauda 702 Alauda , provisional designation , is a carbonaceous asteroid and binary system from the outer asteroid belt, approximately 190 kilometers in diameter. It is the parent body of the Alauda family. Discovered in 1910 by German astronomer Josep ...

704 Interamnia 704 Interamnia is a large F-type asteroid. With a mean diameter of around 330 kilometres, it is the fifth-largest asteroid, after Ceres, Vesta, Pallas and Hygiea. Its mean distance from the Sun is 3.067 ( AU). It was discovered on 2 October ...

767 Bondia 767 Bondia ('' prov. designation:'' ''or'' ) is a Themis asteroid from the outer regions of the asteroid belt, approximately in diameter. It was discovered on 23 September 1913, by American astronomer Joel Hastings Metcalf at his observatory ...

* 895 Helio * 1021 Flammario * 1331 Solvejg *

1474 Beira 1474 Beira, provisional designation , is a bright carbonaceous asteroid and large Mars-crosser on an eccentric orbit from the asteroid belt, approximately 15 kilometers in diameter. It was discovered on 20 August 1935, by South African astronomer ...

* 1484 Postrema *

1539 Borrelly __NOTOC__ Year 1539 ( MDXXXIX) was a common year starting on Wednesday (link will display the full calendar) of the Julian calendar. Events January–June * January – Toungoo–Hanthawaddy War – Battle of Naungyo, Burma ...

1655 Comas Sola Events January–March * January 5 – Emperor Go-Sai ascends to the throne of Japan. * January 7 – Pope Innocent X, leader of the Roman Catholic Church and the Papal States, dies after more than 10 years of rule. * Februa ...

* 1705 Tapio * 1724 Vladimir * 2382 Nonie *

2446 Lunacharsky __NOTOC__ Year 446 ( CDXLVI) was a common year starting on Tuesday (link will display the full calendar) of the Julian calendar. At the time, it was known as the Year of the Consulship of Aetius and Symmachus (or, less frequently, year 1199 '' ...

* 2527 Gregory *

2629 Rudra 2629 Rudra, provisional designation ', is a sizable Mars-crossing asteroid and slow rotator inside the asteroid belt, approximately in diameter. It was discovered on 13 September 1980, by American astronomer Charles Kowal at the Palomar Observ ...

* 2659 Millis *

2708 Burns 2708 Burns ( ''prov. designation'': ) is a carbonaceous Themistian asteroid from the outer regions of the asteroid belt, approximately in diameter. It was discovered on 24 November 1981, by American astronomer Edward Bowell at the Anderson Me ...

* 2772 Dugan *

2809 Vernadskij 8 (eight) is the natural number following 7 and preceding 9. In mathematics 8 is: * a composite number, its proper divisors being , , and . It is twice 4 or four times 2. * a power of two, being 2 (two cubed), and is the first number ...

* 2816 Pien *

2973 Paola Year 973 ( CMLXXIII) was a common year starting on Wednesday (link will display the full calendar) of the Julian calendar. Events By place Byzantine Empire * Spring – The Byzantine army, led by General Melias ( Domestic of th ...

* 3000 Leonardo *

3074 Popov 3074 Popov, provisional designation , is a carbonaceous Nysian asteroid from the inner regions of the asteroid belt, approximately in diameter. It was discovered on 24 December 1979, by Soviet–Russian astronomer Lyudmila Zhuravleva at the Cri ...

3200 Phaethon 3200 Phaethon (previously sometimes spelled Phaeton), provisional designation , is an active Apollo asteroid with an orbit that brings it closer to the Sun than any other named asteroid (though there are numerous unnamed asteroids with small ...

* 3566 Levitan * 3579 Rockholt * 3581 Alvarez * 3627 Sayers * 3647 Dermott * 4124 Herriot * 4396 Gressmann * 4686 Maisica * 4997 Ksana * 5079 Brubeck *

5102 Benfranklin 51 may refer to: * 51 (number) * The year ** 51 BC ** AD 51 ** 1951 ** 2051 In contemporary history, the third millennium of the anno Domini or Common Era in the Gregorian calendar is the current millennium spanning the years 2001 to 3000 ( 2 ...

* 5133 Phillipadams *

5222 Ioffe 5222 Ioffe, provisional designation , is a rare-type carbonaceous Palladian asteroid from the central region of the asteroid belt, approximately 18 kilometers in diameter. It was discovered on 11 October 1980, by Soviet astronomer Nikolai Chernyk ...

* 5234 Sechenov * 5330 Senrikyu * 5344 Ryabov * (5690) 1992 EU * 6500 Kodaira * (7753) 1988 XB * * (65679) 1989 UQ *

References

{{Small Solar System bodies Asteroid spectral classes

Characteristics

Well studied B-type asteroids

See also

References