_Gunhild.png) Modelled shape ofGunhild from itslightcurve | |
| Discovery[1] | |
|---|---|
| Discovered by | M. F. Wolf |
| Discovery site | Heidelberg Obs. |
| Discovery date | 17 May 1918 |
| Designations | |
| (891) Gunhild | |
Named after | unknown[2] |
| A918 KB · 1977 FH 1999 CF154 · A915 VE 1918 DQ · 1915 VE | |
| main-belt[1][3] · (outer) background[4][5] | |
| Orbital characteristics[3] | |
| Epoch 31 May 2020 (JD 2459000.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 101.70yr (37,145 d) |
| Aphelion | 2.9444AU |
| Perihelion | 2.7799 AU |
| 2.8622 AU | |
| Eccentricity | 0.0287 |
| 4.84 yr (1,769 d) | |
| 232.57° | |
| 0° 12m 12.6s / day | |
| Inclination | 13.559° |
| 105.85° | |
| 292.38° | |
| Physical characteristics | |
| 11.892±0.001 h[9] | |
| 10.0[1][3] | |
891 Gunhild (prov. designation:A918 KBor1918 DQ) is a largebackground asteroid from the outer regions of theasteroid belt, that measures approximately 58 kilometers (36 miles) in diameter. It was discovered on 17 May 1918, by astronomerMax Wolf at theHeidelberg-Königstuhl State Observatory in southwest Germany.[1] The darkD-type asteroid has arotation period of 11.9 hours. Any reference of the asteroid's name to a person is unknown.[2]
Gunhild is a non-family asteroid of the main belt'sbackground population when applying thehierarchical clustering method to itsproper orbital elements.[4][5] It orbits the Sun in theouter asteroid belt at a distance of 2.8–2.9 AU once every 4 years and 10 months (1,769 days;semi-major axis of 2.86 AU). Its orbit has aneccentricity of 0.03 and aninclination of 14° with respect to theecliptic.[3] The asteroid was first observed asA915 VE (1915 VE) atSimeiz Observatory in November 1915. The body'sobservation arc begins atHeidelberg Observatory on 18 May 1918, the night after its official discovery observation.[1]
Thisminor planet is named after a Feminine German first name. Any reference of this name to a person or occurrence is unknown.[2]
Among the many thousands ofnamed minor planets,Gunhild is one of 120 asteroids, for which no official naming citation has been published. All of these low-numbered asteroids have numbers between164 Eva and1514 Ricouxa and were discovered between 1876 and the 1930s, predominantly by astronomersAuguste Charlois,Johann Palisa,Max Wolf andKarl Reinmuth.[12]
In both the Tholen- and SMASS-like taxonomy of theSmall Solar System Objects Spectroscopic Survey (S3OS2), as well as in theSDSS-based taxonomy,Gunhild is a darkD-type asteroid.[5][10][11] Thisasteroid spectral type is common among outer belt asteroids and very common among theJupiter trojan population.
In July 2015, a rotationallightcurve ofGunhild was obtained fromphotometric observations by the Spanish group of asteroid observers, OBAS. Lightcurve analysis gave arotation period of11.892±0.001 hours with a brightness amplitude of0.36±0.02magnitude (U=3−).[9] The result supersedes period determinations of (7.93±0.01 h) byRobert Stephens in 2000,[13] (11.853±0.006 h) byLaurent Bernasconi in 2005,[14] and (10.556±0.003 h) by Janus Kozdon in 2015 (U=2/2/2+).[15]
According to the survey carried out by the Infrared Astronomical SatelliteIRAS, the JapaneseAkari satellite, and theNEOWISE mission of NASA'sWide-field Infrared Survey Explorer (WISE),Gunhild measures (51.95±5.6), (55.747±0.321) and (63.80±0.67) kilometers in diameter and its surface has analbedo of (0.0718±0.018), (0.057±0.019) and (0.049±0.001), respectively.[6][7][8] TheCollaborative Asteroid Lightcurve Link derives an albedo of 0.0656 and a diameter of 51.89 kilometers based on anabsolute magnitude of 10.0.[16] Alternative mean-diameter measurements published by the WISE team include (51.05±8.60 km), (58.064±1.384 km) and (65.12±15.84 km) with corresponding albedos of (0.07±0.04), (0.0574±0.0017) and (0.05±0.02).[5][16][17] Severalasteroid occultation observed between 2010 and 2014 gave a best-fit ellipse dimension of 52.0 × 52.0 kilometers (one observation) and 63.0 × 63.0 kilometers (three observations). These timed observations are taken when the asteroid passes in front of a distant star.[5]
