64 Angelina
Encyclopedia
64 Angelina is a medium-sized main belt E-type asteroid
discovered in 1861. It is an unusually bright form of E-type asteroid
.
discoverer, E. W. Tempel, observing from Marseilles, France. It was the first of his five asteroid discoveries.
Angelina's name caused some controversy. It was chosen by Benjamin Valz
, director of the Marseilles Observatory, in honour of the astronomical station of that name operated by Baron Franz Xaver von Zach on the mountains above the city. At the time, asteroids were supposed to receive names from classical mythology, and several astronomers protested the choice. Tempel noted that if the second 'n' were removed, the complaints would be satisfied (referring to Angelia
, a minor Greek deity). However, Valz's choice stayed.
; it is the third largest E-type after 44 Nysa
and 55 Pandora
, and has an exceptionally high albedo
. As of 1991, it is thought to have an average radius of about 30 kilometres (18.6 mi). Back when asteroids were generally assumed to have low albedos, Angelina was thought to be the largest of this class, but modern research has shown that its diameter is only a quarter of what was previously assumed, an error caused by its exceptional brightness. Traditional calculations had suggested that since Angelina has an absolute magnitude of 7.7 and an albedo
of 0.15, its diameter would have been around 100 km. However, a 2004 occultation showed a cross-sectional profile of only 48x53 km. However, since an occultation only produces a 2D cross-sectional profile of the shape of an asteroid, it is possible that the primary axis of the asteroid was hidden from view during the occultation.
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...
discovered in 1861. It is an unusually bright form of E-type asteroid
E-type asteroid
E-type asteroids are asteroids thought to have enstatite achondrite surfaces. They form a large proportion of asteroids inward of the main belt known as Hungaria asteroids, but rapidly become very rare as the main belt proper is entered. There are, however, some that are quite far from the inner...
.
Discovery and naming
Angelina was discovered on March 4, 1861, by a prolific cometComet
A comet is an icy small Solar System body that, when close enough to the Sun, displays a visible coma and sometimes also a tail. These phenomena are both due to the effects of solar radiation and the solar wind upon the nucleus of the comet...
discoverer, E. W. Tempel, observing from Marseilles, France. It was the first of his five asteroid discoveries.
Angelina's name caused some controversy. It was chosen by Benjamin Valz
Benjamin Valz
Jean Elias Benjamin Valz was a French astronomer.He was born in Nîmes and trained as an engineer. He became interested in astronomy and comets in particular, observing the return of what would later be named Comet Encke...
, director of the Marseilles Observatory, in honour of the astronomical station of that name operated by Baron Franz Xaver von Zach on the mountains above the city. At the time, asteroids were supposed to receive names from classical mythology, and several astronomers protested the choice. Tempel noted that if the second 'n' were removed, the complaints would be satisfied (referring to Angelia
Angelia
In Greek mythology, Angelia was a daughter of Hermes, the messenger of the gods. She personified messages, tidings and proclamations.-External links:*...
, a minor Greek deity). However, Valz's choice stayed.
Physical characteristics
Angelina is an uncommon form of E-type asteroidE-type asteroid
E-type asteroids are asteroids thought to have enstatite achondrite surfaces. They form a large proportion of asteroids inward of the main belt known as Hungaria asteroids, but rapidly become very rare as the main belt proper is entered. There are, however, some that are quite far from the inner...
; it is the third largest E-type after 44 Nysa
44 Nysa
44 Nysa is a large and very bright main-belt asteroid, and the brightest member of the Nysian asteroid family. It is classified as a rare class E asteroid and is probably the largest of this type .-Discovery:...
and 55 Pandora
55 Pandora
55 Pandora is a fairly large and very bright main belt asteroid. Pandora was discovered by George Mary Searle on September 10, 1858 from the Dudley Observatory near Albany, NY. It was his first and only asteroid discovery....
, and has an exceptionally high albedo
Albedo
Albedo , or reflection coefficient, is the diffuse reflectivity or reflecting power of a surface. It is defined as the ratio of reflected radiation from the surface to incident radiation upon it...
. As of 1991, it is thought to have an average radius of about 30 kilometres (18.6 mi). Back when asteroids were generally assumed to have low albedos, Angelina was thought to be the largest of this class, but modern research has shown that its diameter is only a quarter of what was previously assumed, an error caused by its exceptional brightness. Traditional calculations had suggested that since Angelina has an absolute magnitude of 7.7 and an albedo
Albedo
Albedo , or reflection coefficient, is the diffuse reflectivity or reflecting power of a surface. It is defined as the ratio of reflected radiation from the surface to incident radiation upon it...
of 0.15, its diameter would have been around 100 km. However, a 2004 occultation showed a cross-sectional profile of only 48x53 km. However, since an occultation only produces a 2D cross-sectional profile of the shape of an asteroid, it is possible that the primary axis of the asteroid was hidden from view during the occultation.
External links
- Orbital simulation from JPL (Java) / Ephemeris
- 2004 Angelina occultation (cross-sectional profile of 48x53 km)
