| Discovery[1] | |
|---|---|
| Discovered by | K. Reinmuth |
| Discovery site | Heidelberg Obs. |
| Discovery date | 18 March 1922 |
| Designations | |
| (973) Aralia | |
| Pronunciation | /əˈreɪliə/[2] |
Named after | Aralia[3] (genus of plants) |
| A922 FB · 1954 SE 1922 LR | |
| main-belt[1] · (outer)[4] Ursula[5][6] | |
| Orbital characteristics[4] | |
| Epoch 31 May 2020 (JD 2459000.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 97.80yr (35,720 d) |
| Aphelion | 3.5717AU |
| Perihelion | 2.8522 AU |
| 3.2119 AU | |
| Eccentricity | 0.1120 |
| 5.76 yr (2,103 d) | |
| 63.633° | |
| 0° 10m 16.32s / day | |
| Inclination | 15.828° |
| 348.44° | |
| 87.856° | |
| Physical characteristics | |
| 7.3662±0.0003 h | |
| 10.1[1][4] | |
973 Aralia (prov. designation:A922 FBor1922 LR) is anasteroid of theUrsula family located in the outer regions of theasteroid belt, approximately 52 kilometers (32 miles) in diameter. It was discovered on 18 March 1922, by German astronomerKarl Reinmuth at theHeidelberg Observatory in southern Germany.[1] TheXk-type asteroid has arotation period of 7.3 hours. It was named after the genus of ivy-like plantAralia, also known as "spikenard".[3]
Aralia is a core member of theUrsula family (631), a largefamily ofC- andX-type asteroids, named after375 Ursula.[6][5][11]: 23 It orbits the Sun in theouter main-belt at a distance of 2.9–3.6 AU once every 5 years and 9 months (2,103 days;semi-major axis of 3.21 AU). Its orbit has aneccentricity of 0.11 and aninclination of 16° with respect to theecliptic.[4] The body'sobservation arc begins atVienna Observatory on 28 March 1922, or 10 days after its official discovery observation at Heidelberg.[1]
Thisminor planet was named after the genus of the Eurasian ivy-like plantAralia, also known as "spikenard". A member of theGinseng family, it has evergreen leaves, small yellowish flowers, and black berries. Thenaming was mentioned inThe Names of the Minor Planets byPaul Herget in 1955 (H 93).[3]
In theSMASS classification,Aralia is a Xk-type, a transitional subtype of theX-type to the less commonK-type asteroids.[4] In both the Tholen- and SMASS-like taxonomy of theSmall Solar System Objects Spectroscopic Survey (S3OS2), it is anX-type asteroid.[5][10] The overall spectral type of the Ursula family is that of aC and X-type.[11]: 23
In May 2015, a rotationallightcurve ofAralia was obtained fromphotometric observations byJulian Oey, Hasen Williams and Roger Groom at the Blue Mountains Observatory (Q68) and Darling Range Observatory (DRO). Lightcurve analysis gave arotation period of7.3662±0.0003 hours with a brightness variation of0.23±0.02magnitude (U=3).[12] Alternative observations byRobert Stephens at the Santana Observatory (646) in 2001 and Michael S. Alkema at the Elephant Head Observatory (G35) in 2012, gave a similar period determination of7.29±0.01 and7.291±0.003 hours, with an amplitude of0.25±0.03 and0.20±0.02, respectively (U=2/2+).[13]
According to the surveys carried out by the Infrared Astronomical SatelliteIRAS, theNEOWISE mission of NASA'sWide-field Infrared Survey Explorer (WISE), and the JapaneseAkari satellite,Aralia measures between 51.6 and 55.5 kilometers in diameter and its surface analbedo between 0.08 and 0.10.[7][8][9] Additional publications by WISE in 2012 and 2015, gave amean diameter56.403±5.687 and46.724±16.447, with an albedo of0.069±0.402 and0.073±0.041, respectively.[5][13] TheCollaborative Asteroid Lightcurve Link derives an albedo of 0.0614 and a diameter of 51.24 kilometers based on anabsolute magnitude of 10.1.[13]
