1693 Hertzsprung ( ''prov. designation'': ) is a dark and elongated background asteroid from the middle region of the asteroid belt, approximately 39 kilometers in diameter. It was discovered on 5 May 1935, by Dutch astronomer

Hendrik van Gent Hendrik van Gent (14 September 1899, Pernis – March 29, 1947, Amsterdam)''Album studiosorum Academiæ lugduno-batavæ MDCCCLXXV-MCMXXV'', A. W. Sijthoff, 1925, p. 376 was a Dutch astronomer. He moved to South Africa in 1928 in order to o ...

at the Leiden Southern Station, annex to the Johannesburg Observatory in South Africa.

Classification and orbit

''Hertzsprung'' orbits the Sun in the

central Central is an adjective usually referring to being in the center of some place or (mathematical) object. Central may also refer to: Directions and generalised locations * Central Africa, a region in the centre of Africa continent, also known as ...

main-belt at a distance of 2.0–3.6 AU once every 4 years and 8 months (1,707 days). Its orbit has an eccentricity of 0.27 and an inclination of 12 ° with respect to the ecliptic. The asteroid was already observed as at

Crimea-Simeis Simeiz Observatory (also spelled Simeis or Simeïs) was an astronomy research observatory until the mid-1950s. It is located on Mount Koshka, Crimea, , by the town of Simeiz. Part of the Crimean Astrophysical Observatory, it is currently used fo ...

in 1930. This observation, however, remained unused and the body's observation arc begins with its official discovery observation at Johannesburg in 1935.

Naming

This minor planet was named in memory of Danish chemist and astronomer Ejnar Hertzsprung (1873–1967), best known for the famous

Hertzsprung–Russell diagram The Hertzsprung–Russell diagram, abbreviated as H–R diagram, HR diagram or HRD, is a scatter plot of stars showing the relationship between the stars' absolute magnitudes or luminosity, luminosities versus their stellar classifications or eff ...

, a spectral classification system for stars he developed jointly with Russel, after whom the asteroid was named. From 1934 to 1945, Hertzsprung was the head of the Leiden Observatory in the Netherlands. As a prominent expert in

photometry Photometry can refer to: * Photometry (optics), the science of measurement of visible light in terms of its perceived brightness to human vision * Photometry (astronomy), the measurement of the flux or intensity of an astronomical object's electrom ...

, he initiated a survey of variable stars in the Southern Milky Way at the Leiden Southern Station. A number of asteroids and comets were also discovered during the course of this survey. The asteroid's name was suggested by the staff at Leiden Observatory. The official was published by the

Minor Planet Center The Minor Planet Center (MPC) is the official body for observing and reporting on minor planets under the auspices of the International Astronomical Union (IAU). Founded in 1947, it operates at the Smithsonian Astrophysical Observatory. Function ...

on 15 December 1967 ().

Physical characteristics

Diameter and albedo

According to the space-based surveys carried out by the Infrared Astronomical Satellite IRAS, the Japanese Akari satellite, and NASA's Wide-field Infrared Survey Explorer with its subsequent NEOWISE mission, ''Hertzsprung'' measures between 30.95 and 41.97 kilometers in diameter and its surface has an albedo between 0.03 and 0.059. The ''Collaborative Asteroid Lightcurve Link'' agrees with the results obtained by IRAS, that is an albedo of 0.048 and a diameter of 38.7 kilometers with an absolute magnitude of 10.97. While the dark C-type asteroid is classified as a rare CBU-subtype on the

Tholen Tholen () is a 25,000 people municipality in the southwest of the Netherlands. The municipality of Tholen takes its name from the town of Tholen, which is the largest population center in the municipality. The municipality consists of two peninsu ...

taxonomic scheme, the NEOWISE mission groups the body to the rare and reddish

P-type asteroid P-type asteroids are asteroids that have low albedo and a featureless reddish spectrum. It has been suggested that they have a composition of organic rich silicates, carbon and anhydrous silicates, possibly with water ice in their interior. P-type ...

Rotation and shape

In August 1987, a rotational lightcurve of ''Hertzsprung'' was obtained from photometric observations made with the

ESO 1-metre telescope La Silla Observatory is an astronomical observatory in Chile with three telescopes built and operated by the European Southern Observatory (ESO). Several other telescopes are located at the site and are partly maintained by ESO. The observatory is ...

at La Silla Observatory in Chile. The lightcurve gave it a well-defined

rotation period The rotation period of a celestial object (e.g., star, gas giant, planet, moon, asteroid) may refer to its sidereal rotation period, i.e. the time that the object takes to complete a single revolution around its axis of rotation relative to the ...

of hours with a brightness amplitude of 0.45 magnitude (). Observations by the NEOWISE mission found higher amplitudes of 0.70 and 1.05, which indicates that the body has a non-spheroidal or elongated shape.

References

External links

Asteroid Lightcurve Database (LCDB)
query form

)
Dictionary of Minor Planet Names
Google books

– Observatoire de Genève, Raoul Behrend

– Minor Planet Center * * {{DEFAULTSORT:Hertzsprung 001693 Discoveries by Hendrik van Gent Named minor planets 001693 19350505