_Hagar.png) Modelled shape ofHagar from itslightcurve | |
| Discovery[1] | |
|---|---|
| Discovered by | A. Kopff |
| Discovery site | Heidelberg Obs. |
| Discovery date | 17 June 1909 |
| Designations | |
| (682) Hagar | |
| Pronunciation | /ˈheɪɡɑːr/[2] |
Named after | Hagar(Biblical woman)[3] |
| A909 MA · 1943 GK 1953 VU3 · 1975 VO5 1909 HA | |
| main-belt[1][4] · (middle) Eunomia[5][6][7] | |
| Orbital characteristics[4] | |
| Epoch 31 May 2020 (JD 2459000.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 110.96yr (40,529 d) |
| Aphelion | 3.1105AU |
| Perihelion | 2.1966 AU |
| 2.6536 AU | |
| Eccentricity | 0.1722 |
| 4.32 yr (1,579 d) | |
| 225.55° | |
| 0° 13m 40.8s / day | |
| Inclination | 11.507° |
| 190.78° | |
| 105.08° | |
| Physical characteristics | |
| 19±4 km[8] | |
| 4.8503±0.0001 h[8][a] | |
| 0.057(assumed)[8] | |
682 Hagar (prov. designation:A909 MAor1909 HA) is anEunomia asteroid from the central regions of theasteroid belt. It was discovered on 17 June 1909, by German astronomerAugust Kopff at theHeidelberg-Königstuhl State Observatory.[1] The presumedS-type asteroid has a shortrotation period of 4.9 hours and measures approximately 19 kilometers (12 miles) in diameter. Possibly inspired by the asteroid's provisional designation "1909 HA", it was named for the biblical womanHagar.[3]
When applying thehierarchical clustering method to itsproper orbital elements,Hagar is a core member of theEunomia family (502),[5][6][7] a prominentfamily of stonyS-type asteroids and the largest one in the intermediate main belt with more than 5,000 known members.[11]: 23 It orbits the Sun in thecentral main-belt at a distance of 2.2–3.1 AU once every 4 years and 4 months (1,579 days;semi-major axis of 2.65 AU). Its orbit has aneccentricity of 0.17 and aninclination of 12° with respect to theecliptic.[4] The body'sobservation arc begins atVienna Observatory on 28 June 1909, just eleven nights after prior to its official discovery observation byAugust Kopff atHeidelberg.[1]
Thisminor planet was named after the biblical womanHagar from theBook of Genesis. She was an Ancient Egyptian servant ofSarah and the mother ofAbraham's firstborn,Ishmael. The asteroid's name may have been inspired by the two letters of its provisional designation, "1909 HA".[3] It is also speculated that the name comes from a list created in 1913 by theAstronomisches Rechen-Institut (ARI) containing suggestions of female names from history and mythology for the naming of minor planets (AN 196, 137). At the time, the naming process was not well developed and the ARI feared inconsistencies and potential confusion. The list was sent to several German astronomers, including Kopff, with the invitation to name all of their made discoveries up to number 700.[12]
Based on the overallspectral type of the Eunomia family,[11]: 23 Hagar is possibly a common, stonyS-type asteroid.[10] However, observations by Pilcher(see below) found aV–R color index of0.400±0.040, which rather suggest a low albedo of a carbonaceousC-type asteroid.[8]
In August 2013, a rotationallightcurve ofHagar was obtained from nine nights ofphotometric observations byFrederick Pilcher at the Organ Mesa Observatory (G50) in Arizona. Analysis gave a well-defined, classically shaped bimodal lightcurve with arotation period of (4.8503±0.0001) hours and a high brightness variation of0.52±0.03magnitude (U=3).[8][a] At the same time, Alexander Kurtenkov at Sofia University, and a team of Bulgarian students obtained a concurring period of4.854±0.011 hours with an amplitude of0.49±0.03 magnitude (U=3).[13] In July 2017, French and Swiss astronomersRené Roy andRaoul Behrend confirmed the period measuring a nearly identical rotation of (4.8516±0.0003) hours and an amplitude of0.51±0.02 magnitude (U=3).[14]
Two lightcurves, published in 2016, using modeled photometric data from the Lowell Photometric Database (LPD) and other sources, gave a concurring sidereal period of (4.850417±0.000001) and (4.85042±0.00005) hours, respectively. Each modeled lightcurve also determined twospin axes of (93.0°, −71.0°) and (277.0°, −35.0°), as well as (56.0°, −78.0°) and (255.0°, −57.0°) inecliptic coordinates (λ, β), respectively.[15][16]
American photometrist Frederick Pilcher also determined a diameter of19±4 kilometers based on a visualabsolute magnitude of12.27±0.07, and analbedo of 0.057 derived from its measured V–R color index(see above).[8] TheCollaborative Asteroid Lightcurve Link adopts Pilcher's albedo of 0.057 and derives a diameter of 19.57 kilometers.[10]
