32 Pomona ( ;) is a stony main-belt

asteroid An asteroid is a minor planet—an object larger than a meteoroid that is neither a planet nor an identified comet—that orbits within the Solar System#Inner Solar System, inner Solar System or is co-orbital with Jupiter (Trojan asteroids). As ...

that is in diameter. It was discovered by German-French astronomer

Hermann Mayer Salomon Goldschmidt Hermann Mayer Salomon Goldschmidt (June 17, 1802 – August 30 or September 10 1866) was a German-French astronomer and painter who spent much of his life in France. He started out as a painter, but after attending a lecture by the famous Fren ...

on October 26, 1854, and is named after Pōmōna, the

Roman Roman or Romans most often refers to: *Rome, the capital city of Italy *Ancient Rome, Roman civilization from 8th century BC to 5th century AD *Roman people, the people of Roman civilization *Epistle to the Romans, shortened to Romans, a letter w ...

goddess of

fruit tree A fruit tree is a tree which bears fruit that is consumed or used by animals and humans. All trees that are flowering plants produce fruit, which are the ripened ovaries of flowers containing one or more seeds. In horticultural usage, the te ...

s. Photometric observations of this asteroid gave a

light curve In astronomy, a light curve is a graph (discrete mathematics), graph of the Radiance, light intensity of a celestial object or region as a function of time, typically with the magnitude (astronomy), magnitude of light received on the ''y''-axis ...

with a synodic

rotation period In astronomy, the rotation period or spin period of a celestial object (e.g., star, planet, moon, asteroid) has two definitions. The first one corresponds to the '' sidereal rotation period'' (or ''sidereal day''), i.e., the time that the objec ...

of 9.448 hours. The data was used to construct a model for the asteroid, revealing it to be an angular object that is spinning about a pole with

ecliptic coordinates In astronomy, the ecliptic coordinate system is a celestial coordinate system commonly used for representing the apparent positions, orbits, and pole orientations of Solar System objects. Because most planets (except Mercury) and many small So ...

(β, λ) = (+58°, 267°). The ratio of the major to minor axes' lengths is roughly equal to 1.3. The spectrum of 32 Pomona matches an S-type in the Tholen classification system, and is similar to primitive

achondrite An achondrite is a stony meteorite that does not contain chondrules. It consists of material similar to terrestrial basalts or plutonic rocks and has been differentiated and reprocessed to a lesser or greater degree due to melting and recrystalli ...

meteorites. Measurements of the

thermal inertia Thermal inertia is a term commonly used to describe the observed delays in a body's temperature response during heat transfers. The phenomenon exists because of a body's ability to both store and transport heat relative to its environment. Sinc ...

of 32 Pomona give a value of around 20–120 m⁻² K⁻¹ s^−1/2, compared to 50 for

lunar regolith Lunar regolith is the unconsolidated material found on the surface of the Moon The Moon is Earth's only natural satellite. It Orbit of the Moon, orbits around Earth at Lunar distance, an average distance of (; about 30 times Earth d ...

and 400 for coarse sand in an atmosphere.

Observations

Australian amateur astronomer Jonathan Bradshaw recorded an unusual

asteroid 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 f ...

by 32 Pomona on 16 August 2008. The expected maximum duration of the occultation was 7.1 secs; however, the video recording shows two separate occultations of equal depth each lasting 1.2 seconds, separated by 0.8 secs. Those durations convert to chord lengths at the asteroid of 15 km, 10 km, and 15 km – for a total length of 40 km. The

IRAS The Infrared Astronomical Satellite (Dutch language, Dutch: ''Infrarood Astronomische Satelliet'') (IRAS) was the first space telescope to perform a astronomical survey, survey of the entire night sky at infrared wavelengths. Launched on 25 Janu ...

diameter for Pomona is 80.76 ± 1.6 km. The most likely explanation for this observation is that the asteroid is either

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

(including a contact binary), or is a unitary asteroid with a significant concave region on its surface. The video of this occultation can be viewed o
YouTube.

Notes

References

External links

* * {{DEFAULTSORT:000032 Background asteroids Pomona Pomona S-type asteroids (Tholen) S-type asteroids (SMASS) 18541026