| Discovery [1] | |
|---|---|
| Discovered by | S. Ueda H. Kaneda |
| Discovery site | Kushiro Obs. |
| Discovery date | 4 January 1989 |
| Designations | |
| (4000) Hipparchus | |
| Pronunciation | /hɪˈpɑːrkəs/[2] |
Named after | Hipparchus [3] (ancient Greek astronomer) |
| 1989 AV · 1963 XA 1975 TW4 · 1977 FZ2 1978 NG8 · 1979 WU4 1984 YX5 · 1987 SD18 | |
| main-belt [1][4] · (middle) background [5] · Astraea [6] | |
| Orbital characteristics [4] | |
| Epoch 27 April 2019 (JD 2458600.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 63.50yr (23,192 d) |
| Aphelion | 2.8835AU |
| Perihelion | 2.2968 AU |
| 2.5901 AU | |
| Eccentricity | 0.1133 |
| 4.17 yr (1,523 d) | |
| 78.842° | |
| 0° 14m 11.04s / day | |
| Inclination | 2.7163° |
| 318.53° | |
| 173.15° | |
| Physical characteristics | |
| 15.13±4.81 km[7] 17.485±0.032 km[8][9] 18.217±0.094 km[10] 18.87±0.59 km[11] | |
| 3.418±0.001 h[12] | |
| 0.0388[10] 0.046[11] 0.05[7] 0.052[8][9] | |
| 12.60[8][10][11] 12.8[1][4][13] 13.01[7] | |
4000 Hipparchus/hɪˈpɑːrkəs/ is a dark backgroundasteroid from the central regions of theasteroid belt, approximately 17 kilometers (11 miles) in diameter. It was discovered on 4 January 1989, by Japanese astronomersSeiji Ueda andHiroshi Kaneda at theKushiro Observatory on Hokkaido, Japan.[1] The likelycarbonaceous asteroid has a shortrotation period of 3.4 hours.[13] It was named for the ancient Greek astronomerHipparchus.[3]
Hipparchus is a non-family asteroid from the main belt'sbackground population (according to Nesvorný).[5] Conversely, an alternative application of thehierarchical clustering method found it to be a core member of theAstraea family (according to Milani and Knežević).[6] It orbits the Sun in thecentral asteroid belt at a distance of 2.3–2.9 AU once every 4 years and 2 months (1,523 days;semi-major axis of 2.59 AU). Its orbit has aneccentricity of 0.11 and aninclination of 3° with respect to theecliptic.[4] The body'sobservation arc begins with aprecovery taken at thePalomar Observatory in November 1954, or more than 34 years prior to its official discovery observation at Kushiro (399).[1]
Thisminor planet was named by IAU'sWorking Group for Planetary System Nomenclature after the Greek astronomerHipparchus (c. 190 – c. 120 BC), considered to be the greatest astronomer of ancient times. Hipparchus introduced a systematic and critical approach to both theoretical and observational astronomy. He is also honored by a lunar and a Martian crater (Hipparchus andHipparchus, respectively).[3] The official naming citation was published by theMinor Planet Center on 21 November 1991 (M.P.C. 19335).[14] The asteroid is one of several early "kilo-numbered" minor planets that were dedicated to renowned scientists or institutions including:[15]
4000 Hipparchus is follow by the asteroids5000 IAU (for theInternational Astronomical Union),6000 United Nations (for theUnited Nations),7000 Curie (for the pioneers on radioactivity,Marie andPierre Curie), and8000 Isaac Newton (forIsaac Newton),[15] while9000 Hal (afterHAL 9000 from the movie2001: A Space Odyssey) and10000 Myriostos (after the Greek word for ten-thousandth, and to honor all astronomers) were named based on their direct numeric accordance.
Based on its low albedo of around 0.04–0.05(see below),Hipparchus is likely of a carbonaceous rather than siliceous composition, among which theC-type asteroid are the most common ones in the asteroid belt.
In February 2014, a rotationallightcurve ofHipparchus was obtained fromphotometric observations by astronomers at the Phillips Academy (I12) and HUT (H16) observatories. Lightcurve analysis gave arotation period of3.418±0.001 hours with a brightness amplitude of 0.11magnitude (U=2).[12] A previous observation at thePalomar Transient Factory from August 2012, only gave a fragmentary lightcurve with a longer period of 7.935 hours (U=1).[16]
According to the surveys carried out by the JapaneseAkari satellite and theNEOWISE mission of NASA'sWide-field Infrared Survey Explorer,Hipparchus measures between 15.13 and 18.87 kilometers in diameter and its surface has a lowalbedo between 0.039 and 0.052.[7][8][9][10][11] TheCollaborative Asteroid Lightcurve Link assumes a standard albedo for a stony asteroid (rather than for a carbonaceous one) and consequently and calculates a smaller diameter of 8.18 kilometers based on anabsolute magnitude of 12.8.[13]
