809 Lundia is a small,

binary Binary may refer to: Science and technology Mathematics * Binary number, a representation of numbers using only two digits (0 and 1) * Binary function, a function that takes two arguments * Binary operation, a mathematical operation that ta ...

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 ...

orbiting within the

Flora family The Flora family (''adj. Florian''; ; also known as ''Ariadne family'') is a prominent family of stony asteroids located in the inner region of the asteroid belt. It is one of the largest families with more than 13,000 known members, or approxi ...

in the

main 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 ...

. It is named after Lund Observatory, Sweden.

Characteristics

Lundia orbits within the

. However, its V-type spectrum indicates that it is not genetically related to the Flora family, but rather is probably a fragment (two fragments, if its moon is included) ejected from the surface 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, t ...

by a large impact in the past. Its orbit lies too far from Vesta for it to actually be a member of the

Vesta family The Vesta family (adj. ''Vestian''; ) is a family of asteroids. The cratering family is located in the inner asteroid belt in the vicinity of its namesake and principal body, 4 Vesta. It is one of the largest asteroid families with more than ...

. It is not clear how it arrived at an orbit so far from Vesta, but other examples of V-type asteroids orbiting fairly far from their parent body are known. A mechanism of interplay between 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 ...

and nonlinear

secular resonance A secular resonance is a type of orbital resonance between two bodies with synchronized precessional frequencies. In celestial mechanics, secular refers to the long-term motion of a system, and resonance is periods or frequencies being a simple n ...

s (primarily involving Jupiter and Saturn) has been proposed.

Binary system

Lightcurve In astronomy, a light curve is a graph of light intensity of a celestial object or region as a function of time, typically with the magnitude of light received on the y axis and with time on the x axis. The light is usually in a particular freq ...

observations in 2005 revealed that Lundia is a binary system of two similarly sized objects orbiting their common

centre of gravity In physics, the center of mass of a distribution of mass in space (sometimes referred to as the balance point) is the unique point where the weighted relative position of the distributed mass sums to zero. This is the point to which a force ma ...

. "Lundia" now refers to one of the objects, the other being provisionally designated S/2005 (809) 1. The similarity of size between the two components is suspected because during mutual

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 ...

s the brightness drops by a similar amount independently of which component is hidden.

Poznań Poznań () is a city on the River Warta in west-central Poland, within the Greater Poland region. The city is an important cultural and business centre, and one of Poland's most populous regions with many regional customs such as Saint Joh ...

observatory (Lightcurve showing signature of the binary) Due to the similar size of the primary and secondary the Minor Planet Center lists this as a binary companion. Assuming an albedo similar to

(around 0.4) suggests that the components are about 7 km across. They orbit each other in a period of 15.4 hours, which roughly indicates that the separation between them is very close: to the order of 10–20 km if typical asteroid albedo and density values are assumed.

References

External links

Electronic Telegram No. 239
announcing the binary system (2005 October 1)

– Minor Planet Center

datasheet, johnstonsarchive.net

Robert Johnston, johnstonsarchive.net
Lightcurve showing signature of the binary
* * {{DEFAULTSORT:Lundia 000809 Discoveries by Max Wolf Named minor planets 000809 000809 19150811