_Mechthild.png) Modelled shape ofMechthild from itslightcurve | |
| Discovery[1] | |
|---|---|
| Discovered by | M. F. Wolf |
| Discovery site | Heidelberg Obs. |
| Discovery date | 21 May 1917 |
| Designations | |
| (873) Mechthild | |
Named after | unknown[2] |
| A917 KJ · 1917 CA | |
| Orbital characteristics[3] | |
| Epoch 31 May 2020 (JD 2459000.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 102.24yr (37,343 d) |
| Aphelion | 3.0199AU |
| Perihelion | 2.2346 AU |
| 2.6273 AU | |
| Eccentricity | 0.1495 |
| 4.26 yr (1,555 d) | |
| 48.264° | |
| 0° 13m 53.04s / day | |
| Inclination | 5.2763° |
| 150.00° | |
| 109.99° | |
| Physical characteristics | |
| 11.006±0.001 h[9] | |
| 11.4[1][3] | |
873 Mechthild (prov. designation:A917 KJor1917 CA) is a darkbackground asteroid from the central regions of theasteroid belt. It was discovered by German astronomerMax Wolf at theHeidelberg Observatory on 21 May 1917.[1] The primitiveP-type asteroid has arotation period of 11.0 hours and measures approximately 34 kilometers (21 miles) in diameter. The origin of the asteroid's name remains unknown.[2]
Mechthild 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 thecentral asteroid belt at a distance of 2.2–3.0 AU once every 4 years and 3 months (1,555 days;semi-major axis of 2.63 AU). Its orbit has aneccentricity of 0.15 and aninclination of 5° with respect to theecliptic.[3] The body'sobservation arc begins with its first and official discovery observation atHeidelberg Observatory on 21 May 1917.[1]
Thisminor planet is named "Mechthild", a German feminine given name. Any reference of this name to a specific person or occurrence is unknown.[2]
Among the many thousands ofnamed minor planets,Mechthild 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.[10]
In theTholen classification,Mechthild is closest to a very dark, primitiveP-type, and somewhat similar to a commonC-type asteroid. In the taxonomy by Barucci, it is a C0-type.[3][5] P-type asteroids are more common in the outer asteroid belt and among theJupiter trojan population.
In May 2015, a rotationallightcurve ofMechthild was obtained fromphotometric observations byBrian Warner at hisPalmer Divide Observatory (716) in Colorado. Lightcurve analysis gave arotation period of11.006±0.001 hours with a brightness amplitude of0.27±0.02magnitude (U=3).[9]
Alternative period determinations were made byClaes-Ingvar Lagerkvist (10.6 h) in March 1976, by astronomers at thePalomar Transient Factory (11.007±0.0069 h) in January 2014, and by the Spanish group of asteroid observers, OBAS (10.99±0.01 h) in May 2015 (U=2/2/3).[11][12][13] In 2016, a modeled lightcurve gave a concurring sidereal period of11.00639±0.00005 hours using data from a large collaboration of individual observers (such as above). The study also determined twospin axes of (249.0°, −52.0°) and (51.0°, −61.0°) inecliptic coordinates (λ, β).[14]
According to the surveys carried out by the Infrared Astronomical SatelliteIRAS, and the JapaneseAkari satellite, and theNEOWISE mission of NASA'sWide-field Infrared Survey Explorer (WISE),Mechthild measures (29.04±1.9), (33.56±0.59) and (34.471±0.103) kilometers in diameter and its surface has analbedo of (0.0531±0.008), (0.041±0.002) and (0.040±0.004), respectively.[6][7][8] TheCollaborative Asteroid Lightcurve Link adopts the results from IRAS, that is, an albedo of 0.0531 and a diameter of 29.04 kilometers based on anabsolute magnitude of 11.49.[15] Alternative mean-diameter measurements published by the WISE team include (29.124±10.26 km) and (36.327±0.290 km) with corresponding albedos of (0.0785±0.0687) and (0.0339±0.0063).[15]
