The Vesta family (adj. ''Vestian''; ) is a

family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...

asteroid An asteroid is a minor planet of the 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 or icy bodies with no atmosphere. ...

s. The cratering family is located in the inner

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 ...

in the vicinity of its namesake and principal body, 4 Vesta. It is one of the largest asteroid families with more than 15,000 known members and consists of mostly bright

V-type asteroid A V-type asteroid or Vestoid is an asteroid whose spectral type is that of 4 Vesta. Approximately 6% of main-belt asteroids are vestoids, with Vesta being by far the largest of them. They are relatively bright, and rather similar to the more common ...

s, so-called "vestoids".

Characteristics

The Vestian asteroids consist of

4 Vesta Vesta (minor-planet designation: 4 Vesta) is one of the largest objects in the asteroid belt, with a mean diameter of . It was discovered by the German astronomer Heinrich Wilhelm Matthias Olbers on 29 March 1807 and is named after Vesta, the ...

, the second-most-massive of all asteroids (mean diameter of 530 km), and many small asteroids below 10 km diameter. The brightest of these,

1929 Kollaa 1929 Kollaa, provisional designation , is a stony Vestian asteroid from the inner regions of the asteroid belt, approximately 7 kilometers in diameter. It was discovered by Finnish astronomer Yrjö Väisälä at Turku Observatory in Southwest Fin ...

and

2045 Peking 45 may refer to: * 45 (number) * one of the years 45 BC, AD 45, 1945, 2045 Film * ''45'' (film), directed by Peter Coster (2009) * ''.45'' (film), directed by Gary Lennon (2006) Music * ''45'' (Jaguares album), 2008 * ''45'' (Kino album), 1982 * ...

, have an

absolute magnitude Absolute magnitude () is a measure of the luminosity of a celestial object on an inverse Logarithmic scale, logarithmic Magnitude (astronomy), astronomical magnitude scale. An object's absolute magnitude is defined to be equal to the apparent mag ...

of 12.2, which would give them a radius of about 7.5 km assuming the same high albedo as

. The

originated from an impact on asteroid

, with the giant south-polar crater the likely impact site. The family are thought to be the source of the

HED meteorite HED meteorites are a clan (subgroup) of achondrite meteorites. HED stands for "howardite– eucrite–diogenite". These achondrites came from a differentiated parent body and experienced extensive igneous processing not much different from the mag ...

s. The Vesta family also includes a few J-type asteroids (related to the V-type), which are thought to have come from the deeper layers of Vesta's crust, and are similar to the

diogenite Diogenites are a group of the HED meteorite clan, a type of achondritic stony meteorites. Origin and composition Diogenites are currently believed to originate from deep within the crust of the asteroid 4 Vesta, and as such are part of the HED m ...

meteorites. A HCM numerical analysis (by Zappala 1995) determined a large group of 'core' family members, whose

proper orbital elements __NOTOC__ The proper orbital elements or proper elements of an orbit are constants of motion of an object in space that remain practically unchanged over an astronomically long timescale. The term is usually used to describe the three quantitie ...

lie in the approximate ranges: This gives the approximate boundaries of the family. At the present

epoch In chronology and periodization, an epoch or reference epoch is an instant in time chosen as the origin of a particular calendar era. The "epoch" serves as a reference point from which time is measured. The moment of epoch is usually decided by ...

, the range of osculating

orbital elements Orbital elements are the parameters required to uniquely identify a specific orbit. In celestial mechanics these elements are considered in two-body systems using a Kepler orbit. There are many different ways to mathematically describe the same ...

of these core members is: The Zappala 1995 analysis found 235 core members. A search of a recent proper-element database
AstDys
for 96,944

minor planet According to the International Astronomical Union (IAU), a minor planet is an astronomical object in direct orbit around the Sun that is exclusively classified as neither a planet nor a comet. Before 2006, the IAU officially used the term ''minor ...

s in 2005 yielded 6,051 objects (about 6% of the total) lying within the Vesta-family region as per the first table above.

Interlopers

Spectroscopic analyses have shown that some of the largest Vestians are in fact interlopers. They are not of the V or J spectral class, but have similar orbital elements by coincidence. These include 306 Unitas, 442 Eichsfeldia, 1697 Koskenniemi, 1781 Van Biesbroeck, 2024 McLaughlin, 2029 Binomi, 2086 Newell, 2346 Lilio, and others. (Identified by inspection of th
PDS asteroid taxonomy data set
.

References

* Zappalà, Vincenzo; Bendjoya, Philippe; Cellino, Alberto; Farinella, Paolo; and Froeschlé, Claude;
Asteroid Families: Search of a 12,487-Asteroid Sample Using Two Different Clustering Techniques
', Icarus, Volume 116, Issue 2 (August 1995), pages 291–314 * Bus, Schelte J.; and Binzel, Richard P.; ''Phase II of the Small Main-Belt Asteroid Spectroscopic Survey'', Icarus Vo.. 158, p. 106 (2002)
Data set online here

AstDys site
Proper elements for 96944 numbered minor planets. {{DEFAULTSORT:Vesta Family * Asteroid groups and families