The Padua family (FIN:

507 __NOTOC__ Year 507 ( DVII) was a common year starting on Monday (link will display the full calendar) of the Julian calendar. At the time, it was known as the Year of the Consulship of Anastasius and Venantius (or, less frequently, year 1260 ...

), also known as the Lydia family, is a mid-sized family of asteroids of more than a thousand members. The family is at least 25 million years old. Its members were previously associated to

110 Lydia Lydia (minor planet designation: 110 Lydia) is a large belt asteroid with an M-type spectrum, and thus may be metallic in composition, consisting primarily of nickel-iron. It was discovered by French astronomer Alphonse Borrelly on 19 April 18 ...

, and are predominantly X-type asteroids with an

albedo Albedo (; ) is the measure of the diffuse reflection of sunlight, solar radiation out of the total solar radiation and measured on a scale from 0, corresponding to a black body that absorbs all incident radiation, to 1, corresponding to a body ...

of approximately 0.1. Together with the Agnia family, the Padua family is the only other family to have most of its members in a nonlinear secular resonance configuration with more than 75% of its members in a z1 librating state. The Paduan (Lydian) asteroids are located in the outer part of the central asteroid belt having a

semi-major axis In geometry, the major axis of an ellipse is its longest diameter: a line segment that runs through the center and both foci, with ends at the two most widely separated points of the perimeter. The semi-major axis (major semiaxis) is the long ...

of approximately 2.75. The family's namesake is the asteroid 363 Padua, while 110 Lydia is now a suspected

interloper Interloper, Interlopers or The Interlopers may refer to: Entertainment * '' The Interloper: Lee Harvey Oswald Inside the Soviet Union'', a 2013 book by Peter Savodnik * Interloper (comics), a fictional character in the Marvel Comics universe * I ...

, despite having the same spectral type.

Members

Some prominent members with known spectral type. A list of all Paduan aststeroids is given at the "Small Bodies Data Ferret".

Lydia former namesake and potential interloper

In previous works (Zappala et al. 1995), this family was named Lydia after

, which is an

X-type asteroid The X-group of asteroids collects together several types with similar spectra, but probably quite different compositions. Tholen classification In the Tholen classification the X-group consists of the following types: * E-type – with high al ...

in the

SMASS classification An asteroid spectral type is assigned to asteroids based on their emission spectrum, color, and sometimes albedo. These types are thought to correspond to an asteroid's surface composition. For small bodies that are not internally differentiat ...

(Tholen: M-type). While Lydia is still a member of the now-called Padua family (Nesvorny 2005, AstDyS), it has been suspected that it might be an

in its "own" family despite its matching spectral type (Carruba 2009; Mothe-Diniz et al. 2005). Also, the asteroid

308 Polyxo Polyxo ( minor planet designation: 308 Polyxo) is a main-belt asteroid that was discovered by A. Borrelly on March 31, 1891, in Marseilles. It is orbiting the Sun at a distance of with a low orbital eccentricity (ovalness) of 0.04 and a perio ...

was formerly considered the family's largest member. This

T-type asteroid T-type asteroids are rare inner-belt asteroids of unknown composition with dark, featureless and moderately red spectra, and a moderate absorption feature shortwards of 0.85 μm. No direct meteorite analog has been found to date. Thought to b ...

is no-longer considered a family member and is categorized as a background asteroid on AstDyS.

References

{{DEFAULTSORT:Lydia Family Asteroid groups and families *