_Hertzsprung.png) Shape model ofHertzsprung from itslightcurve | |
| Discovery[1] | |
|---|---|
| Discovered by | H. van Gent |
| Discovery site | Johannesburg Obs. (Leiden Southern Station) |
| Discovery date | 5 May 1935 |
| Designations | |
| (1693) Hertzsprung | |
Named after | Ejnar Hertzsprung (chemist, astronomer)[2] |
| 1935 LA · 1930 HG 1944 HA · 1950 VM | |
| main-belt · (central) | |
| Orbital characteristics[3] | |
| Epoch 4 September 2017 (JD 2458000.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 81.90 yr (29,914 days) |
| Aphelion | 3.5603AU |
| Perihelion | 2.0306 AU |
| 2.7955 AU | |
| Eccentricity | 0.2736 |
| 4.67yr (1,707 days) | |
| 164.16° | |
| 0° 12m 39.24s / day | |
| Inclination | 11.942° |
| 69.989° | |
| 234.93° | |
| Physical characteristics | |
| Dimensions | 30.95±8.64[4] 35.27±0.47 km[5] 37.772±0.320[6] 38.67±1.5 km(IRAS:5)[7] 39±4 km[8] 40.396±0.972 km[9] 41.97±3.65[10] |
| 8.825h[11] | |
| 0.03±0.01[10] 0.0330±0.0034[9] 0.0484±0.004(IRAS:5)[7] 0.05±0.01[8] 0.05±0.05[4] 0.051±0.011[6] 0.059±0.002[5] | |
| Tholen = CBU[3] P[9] · C[12] B–V = 0.762[3] U–B = 0.358[3] | |
| 10.97[3][5][7][8][9][12] · 11.39±0.82[13] | |
1693 Hertzsprung (prov. designation:1935 LA) is a dark and elongatedbackground asteroid from the middle region of theasteroid belt, approximately 39 kilometers in diameter. It was discovered on 5 May 1935, by Dutch astronomerHendrik van Gent at the Leiden Southern Station, annex to theJohannesburg Observatory in South Africa.[1]
Hertzsprung orbits the Sun in thecentral main-belt at a distance of 2.0–3.6 AU once every 4 years and 8 months (1,707 days). Its orbit has aneccentricity of 0.27 and aninclination of 12° with respect to theecliptic.[3] The asteroid was already observed as1930 HG atCrimea-Simeis in 1930. This observation, however, remained unused and the body'sobservation arc begins with its official discovery observation at Johannesburg in 1935.[1]
Thisminor planet was named in memory of Danish chemist and astronomerEjnar Hertzsprung (1873–1967), best known for the famousHertzsprung–Russell diagram, a spectral classification system for stars he developed jointly with Russel, after whom the asteroid1762 Russell was named. From 1934 to 1945, Hertzsprung was the head of theLeiden Observatory in the Netherlands.[2]
As a prominent expert inphotometry, 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.[2] The officialnaming citation was published by theMinor Planet Center on 15 December 1967 (M.P.C. 2822).[14]
According to the space-based surveys carried out by the Infrared Astronomical SatelliteIRAS, the JapaneseAkari satellite, and NASA'sWide-field Infrared Survey Explorer with its subsequentNEOWISE mission,Hertzsprung measures between 30.95 and 41.97 kilometers in diameter and its surface has analbedo between 0.03 and 0.059.[4][5][6][7][8][9][10]
TheCollaborative 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 anabsolute magnitude of 10.97.[12] While the darkC-type asteroid is classified as a rare CBU-subtype on theTholen taxonomic scheme, the NEOWISE mission groups the body to the rare and reddishP-type asteroids.[9]
In August 1987, a rotationallightcurve ofHertzsprung was obtained from photometric observations made with theESO 1-metre telescope atLa Silla Observatory in Chile. The lightcurve gave it a well-definedrotation period of8.825 hours with a brightness amplitude of 0.45magnitude (U=3).[11] 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.[4][10]
