B-type asteroids are a relatively uncommon type of carbonaceous asteroid, falling into the wider C-group; the 'B' indicates these objects are spectrally blue. [1] In the asteroid population, B-class objects can be found in the outer asteroid belt, and also dominate the high-inclination Pallas family which includes the third-largest asteroid 2 Pallas. They are thought to be primitive, volatile-rich remnants from the early Solar System. There are 65 known B-type asteroids in the SMASS classification, [2] and 9 in the Tholen classification as of March 2015.
Generally similar to the C-type objects, but differing in that the ultraviolet absorption below 0.5 μm is small or absent, and the spectrum is rather slightly bluish than reddish. The albedo also tends to be greater than in the generally very dark C type. Spectroscopy of B-class objects suggests major surface constituents of anhydrous silicates, hydrated clay minerals, organic polymers, magnetite, and sulfides. The closest matches to B-class asteroids have been obtained on carbonaceous chondrite meteorites that have been gently heated in the laboratory.
The majority of asteroids that have been observed to display cometary-like activity are B-types. [3] [4] Some of these objects display indications of aqueous alteration in the past, and they may have incorporated significant amounts of water ice. [1]
Asteroid 101955 Bennu is a B-type asteroid which is the target of the OSIRIS-REx mission. The mission seeks to characterize the asteroid by mapping the surface, studying the Yarkovsky effect, 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:
The Themis family is a family of carbonaceous asteroids located in the outer portion of the asteroid belt, at a mean distance of 3.13 AU from the Sun. It is one of the largest families with over 4700 known members, and consists of a well-defined core of larger bodies surrounded by a region of smaller ones. The collisional Themis family is named after its parent body, the asteroid 24 Themis, discovered on 5 April 1853 by Italian astronomer Annibale de Gasparis.
222 Lucia is a large Themistian asteroid. It was discovered by Johann Palisa on 9 February 1882 in Vienna and named after Lucia, daughter of Austro-Hungarian explorer Graf Wilczek.
468 Lina, provisional designation 1901 FZ, is a dark Themistian asteroid from the outer region of the asteroid belt, approximately 60 kilometers in diameter. It was discovered on 18 January 1901, by German astronomer Max Wolf at the Heidelberg Observatory in southwest Germany. The carbonaceous asteroid was named for the housemaid of the discoverer's family.
555 Norma, provisional designation 1905 PT, 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 Wolf at Heidelberg Observatory in southwest Germany. The asteroid was named after the title character of Bellini's opera Norma.
1615 Bardwell, provisional designation 1950 BW, is a rare-type Themistian asteroid from the outer region of the asteroid belt, approximately 27 kilometers in diameter. It was discovered on 28 January 1950, by IU's Indiana Asteroid Program at Goethe Link Observatory near Brooklyn, Indiana, United States. It is named for American astronomer Conrad Bardwell.
Lilofee, provisional designation 1923 OK, is a carbonaceous Themistian asteroid from the outer regions of the asteroid belt, approximately 33 kilometers in diameter. It was discovered on 13 September 1923, by astronomer Karl Reinmuth at the Heidelberg-Königstuhl State Observatory in southwest Germany. The asteroid was named after the Black Forest mermaid "Lilofee" from German folklore.
3204 Lindgren, provisional designation 1978 RH, is a carbonaceous background asteroid from the outer regions of the asteroid belt, approximately 20 kilometers in diameter. It was discovered on 1 September 1978, by Soviet astronomer Nikolai Chernykh at the Crimean Astrophysical Observatory in Nauchnij, on the Crimean peninsula. The B-type asteroid has a rotation period of 5.6 hours. It was named after Swedish writer Astrid Lindgren.
1154 Astronomia, provisional designation 1927 CB, is a carbonaceous background asteroid from the outer regions of the asteroid belt, approximately 60 kilometers in diameter. It was discovered by German astronomer Karl Reinmuth at the Heidelberg-Königstuhl State Observatory on 8 February 1927. The asteroid was named for the natural science of astronomy.
3581 Alvarez, provisional designation 1985 HC, is a carbonaceous asteroid and a very large Mars-crosser on an eccentric orbit from the asteroid belt, approximately 13.7 kilometers in diameter. It was discovered on 23 April 1985, by American astronomer couple Carolyn and Eugene Shoemaker at the Palomar Observatory in California. The likely spherical B-type asteroid has a rotation period of 33.4 hours. It was named for scientists Luis Alvarez and his son Walter Alvarez.
1474 Beira, provisional designation 1935 QY, 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 Cyril Jackson at the Union Observatory in Johannesburg. The asteroid was named after the port city of Beira in Mozambique.
2708 Burns is a carbonaceous Themistian asteroid from the outer regions of the asteroid belt, approximately 19 kilometers in diameter. It was discovered on 24 November 1981, by American astronomer Edward Bowell at the Anderson Mesa Station near Flagstaff, Arizona, in the United States. It was named after American planetary scientist Joseph A. Burns. The likely elongated B-type asteroid has a rotation period of 5.3 hours.
1576 Fabiola, provisional designation 1948 SA, is a Themistian asteroid from the outer regions of the asteroid belt, approximately 27 kilometers in diameter. It was discovered on 30 September 1948, by Belgian astronomer Sylvain Arend at the Royal Observatory of Belgium in Uccle. The asteroid was named after Queen Fabiola of Belgium.
20898 Fountainhills (provisional designation 2000 WE147) is a dark asteroid in a cometary orbit (ACO) from the outermost regions of the asteroid belt, approximately 37 kilometers (23 miles) in diameter. It was discovered on 30 November 2000, by American amateur astronomer Charles W. Juels at the Fountain Hills Observatory in Arizona, United States. The D-type asteroid has a rotation period of 12.84 hours. It was named for the city of Fountain Hills, Arizona, in the United States.
1362 Griqua, provisional designation 1935 QG1 is a dark, Jupiter-resonant background asteroid on an eccentric, cometary-like orbit and the namesake of the Griqua group, located in the Hecuba gap in the outermost region of the asteroid belt. The carbonaceous asteroid measures approximately 28 kilometers (17 miles) in diameter and has a rotation period of 6.9 hours. It was discovered on 31 July 1935, by South-African astronomer Cyril Jackson at Union Observatory in Johannesburg. The asteroid was named after the Griqua people in South Africa and Namibia.
1508 Kemi, provisional designation 1938 UP, is an eccentric, carbonaceous asteroid and one of the largest Mars-crossers, approximately 17 kilometers in diameter. Discovered by Heikki Alikoski at Turku Observatory in 1938, the asteroid was later named after the Finnish town of Kemi and the Kemi River.
7604 Kridsadaporn, provisional designation 1995 QY2, is an unusual, carbonaceous asteroid and Mars-crosser on a highly eccentric orbit from the outer regions of the asteroid belt, approximately 12 kilometers (7.5 miles) in diameter. It was discovered on 31 August 1995, by Australian astronomer Robert McNaught at Siding Spring Observatory near Coonabarabran, Australia. Due to its particular orbit, the C-type asteroid belongs to MPC's list of "other" unusual objects, and has been classified as an "asteroid in cometary orbit", or ACO. The asteroid was named in memory of Thai astronomer Kridsadaporn Ritsmitchai.
1484 Postrema, provisional designation 1938 HC, is a carbonaceous Postremian asteroid and namesake of the Postrema family from the central regions of the asteroid belt, approximately 41 kilometers in diameter. It was discovered on 29 April 1938, by Soviet astronomer Grigory Neujmin at the Simeiz Observatory on the Crimean peninsula. The name "Postrema" celebrates the astronomer's last minor planet discovery.
2629 Rudra, provisional designation 1980 RB1, is a sizable Mars-crossing asteroid and slow rotator inside the asteroid belt, approximately 5.3 kilometers (3.3 miles) in diameter. It was discovered on 13 September 1980, by American astronomer Charles Kowal at the Palomar Observatory in California. The dark B-type asteroid has a long rotation period 123 hours and likely an elongated shape. It was named after Rudra from Hindu mythology.
1493 Sigrid, provisional designation 1938 QB, is a dark Nysian asteroid from the inner regions of the asteroid belt, approximately 24 kilometers in diameter. It was discovered on 26 August 1938, by Belgian astronomer Eugène Delporte at the Royal Observatory of Belgium in Uccle. It was named after Sigrid Strömgren, wife of astronomer Bengt Strömgren.
1340 Yvette, provisional designation 1934 YA, is a carbonaceous Themistian asteroid from the outer regions of the asteroid belt, approximately 29 kilometers in diameter. It was discovered on 27 December 1934, by astronomer Louis Boyer at the Algiers Observatory, who named it after his niece, Yvette.