Davida (

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 features a leading number (catalog or ...

: 511 Davida) is a large C-type

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. ...

. It is the one of the

largest asteroids The following is a collection of lists of asteroids of the Solar System that are exceptional in some way, such as their size or orbit. For the purposes of this article, "asteroid" refers to minor planets out to the orbit of Neptune, and includ ...

; approximately tied for 7th place, to within measurement uncertainties, and the 5th or 6th most massive. It was discovered by R. S. Dugan in 1903. Davida is named after

David Peck Todd David Peck Todd (March 19, 1855 — June 1, 1939) was an American astronomer. He produced a complete set of photographs of the 1882 transit of Venus. Biography Todd was born in Lake Ridge, New York, the son of Sereno Edwards Todd and Rhoda (Pe ...

, an astronomy professor at

Amherst College Amherst College ( ) is a private liberal arts college in Amherst, Massachusetts. Founded in 1821 as an attempt to relocate Williams College by its then-president Zephaniah Swift Moore, Amherst is the third oldest institution of higher educatio ...

Physical characteristics

Davida is approximately 270–310 km in

diameter In geometry, a diameter of a circle is any straight line segment that passes through the center of the circle and whose endpoints lie on the circle. It can also be defined as the longest chord of the circle. Both definitions are also valid for ...

and comprises an estimated 1.5% of the total mass of the asteroid belt. It is a

C-type asteroid C-type (carbonaceous) asteroids are the most common variety, forming around 75% of known asteroids. They are volatile-rich and distinguished by a very low albedo because their composition includes a large amount of carbon, in addition to rocks ...

, which means that it is dark in colouring with a

carbonaceous chondrite Carbonaceous chondrites or C chondrites are a class of chondritic meteorites comprising at least 8 known groups and many ungrouped meteorites. They include some of the most primitive known meteorites. The C chondrites represent only a small prop ...

composition. From 2002 to 2007, astronomers at the

Keck Observatory The W. M. Keck Observatory is an astronomical observatory with two telescopes at an elevation of 4,145 meters (13,600 ft) near the summit of Mauna Kea in the U.S. state of Hawaii. Both telescopes have aperture primary mirrors, and when comp ...

used the Keck II telescope, which is fitted with

adaptive optics Adaptive optics (AO) is a technology used to improve the performance of optical systems by reducing the effect of incoming wavefront distortions by deforming a mirror in order to compensate for the distortion. It is used in astronomical tele ...

, to photograph Davida. The asteroid is not a

dwarf planet A dwarf planet is a small planetary-mass object that is in direct orbit of the Sun, smaller than any of the eight classical planets but still a world in its own right. The prototypical dwarf planet is Pluto. The interest of dwarf planets to p ...

: there are at least two

promontories A promontory is a raised mass of land that projects into a lowland or a body of water (in which case it is a peninsula). Most promontories either are formed from a hard ridge of rock that has resisted the erosive forces that have removed the sof ...

and at least one flat facet with 15-km deviations from a best-fit

ellipsoid An ellipsoid is a surface that may be obtained from a sphere by deforming it by means of directional scalings, or more generally, of an affine transformation. An ellipsoid is a quadric surface; that is, a surface that may be defined as the ...

. The facet is presumably a 150-km global-scale crater like the ones seen on

253 Mathilde Mathilde (minor planet designation: 253 Mathilde) is an asteroid in the intermediate asteroid belt, approximately 50 kilometers in diameter, that was discovered by Austrian astronomer Johann Palisa at Vienna Observatory on 12 November 1885. It h ...

. Conrad et al. (2007) show that craters of this size "can be expected from the impactor size distribution, without likelihood of catastrophic disruption of Davida."

Mass

In 2001, Michalak estimated Davida to have a mass of () kg. In 2007, Baer and Chesley estimated Davida to have a mass of () kg. , Baer suggests Davida has a mass of () kg. This most recent estimate by Baer indicates that Davida is approximately tied with

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 1 ...

as the fifth-most-massive asteroid, though the

error bar Error bars are graphical representations of the variability of data and used on graphs to indicate the error or uncertainty in a reported measurement. They give a general idea of how precise a measurement is, or conversely, how far from the repor ...

s of Interamnia are large.

Occultations

There have been 9

occultation An occultation is an event that occurs when one object is hidden from the observer by another object that passes between them. The term is often used in astronomy, but can also refer to any situation in which an object in the foreground blocks ...

events observed since 1987, many of which produced two or three

chords Chord may refer to: * Chord (music), an aggregate of musical pitches sounded simultaneously ** Guitar chord a chord played on a guitar, which has a particular tuning * Chord (geometry), a line segment joining two points on a curve * Chord (as ...

. Two examples shown here. 511Davida 20160805 (SteppedOccultationLightCurve)

Notes

References

External links

Asteroid occultations
IOTA – International Occultation Timing Association (2011)

Al Conrad's research page at Keck
* * {{DEFAULTSORT:000511 Meliboea asteroids Davida Davida C-type asteroids (Tholen) C-type asteroids (SMASS) 1903 in science 19030530