986 Amelia (prov. designation: A922 UA or 1922 MQ) is a large background asteroid from the outer regions of the asteroid belt, approximately 50 kilometers (31 miles) in diameter. It was discovered on 19 October 1922, by Spanish astronomer Josep Comas i Solà at the Fabra Observatory in Barcelona.[1] The L/D-type asteroid has a rotation period of 9.5 hours.[a] It was named after the discoverer's wife, Amelia Solà.[2]
_Amelia.png) Modelled shape of Amelia from its lightcurve | |
| Discovery [1] | |
|---|---|
| Discovered by | J. Comas Solà |
| Discovery site | Fabra Obs. |
| Discovery date | 19 October 1922 |
| Designations | |
| (986) Amelia | |
Named after | Amelia Solà (discoverer's wife)[2] |
| A922 UA · 1922 MQ 1935 BK · 1966 VA A915 JC | |
| main-belt [1][3] · (outer) background [4][5] | |
| Orbital characteristics [3] | |
| Epoch 31 May 2020 (JD 2459000.5) | |
| Uncertainty parameter 0 | |
| Observation arc | 93.64 yr (34,203 d) |
| Aphelion | 3.7674 AU |
| Perihelion | 2.4961 AU |
| 3.1317 AU | |
| Eccentricity | 0.2030 |
| 5.54 yr (2,024 d) | |
| 210.80° | |
| 0° 10m 40.08s / day | |
| Inclination | 14.815° |
| 92.601° | |
| 265.52° | |
| Physical characteristics | |
| 9.52±0.01 h[9][a] | |
Pole ecliptic latitude | |
| 9.4[1][3] | |
Orbit and classification
Amelia is a non-family asteroid of the main belt's background population when applying the hierarchical clustering method to its proper orbital elements.[4][5] It orbits the Sun in the outer asteroid belt at a distance of 2.5–3.8 AU once every 5 years and 6 months (2,024 days; semi-major axis of 3.13 AU). Its orbit has an eccentricity of 0.20 and an inclination of 15° with respect to the ecliptic.[3]
On 12 May 2015, Amelia was first observed as A915 JC (1915 JC) at the Simeiz Observatory on the Crimean peninsula. The body's observation arc begins at the Algiers Observatory in May 1926, more than 3 years after to its official discovery observation at the Fabra Observatory.[1]
Naming
This minor planet was named after Amelia Solà, wife of the discoverer Josep Comas i Solà (1868–1937). The official naming citation was mentioned in The Names of the Minor Planets by Paul Herget in 1955 (H 94).[2]
Physical characteristics
In both the Tholen- and SMASS-like taxonomy of the Small Solar System Objects Spectroscopic Survey (S3OS2), Amelia is a T-type asteroid,[11] while in the SDSS-based taxonomy, the asteroid has been classified as an L-type.[5][12]
Rotation period and poles
In October 2000, a rotational lightcurve of Amelia was obtained from photometric observations by American amateur astronomer Robert A. Koff at the Thornton Observatory (713) in Colorado. Lightcurve analysis gave a well-defined rotation period of 9.52±0.01 hours with a brightness amplitude of 0.43±0.03 magnitude (U=3).[5][9][a]
In December 2006, a concurring period determination of 9.517 hours (0.396533 days) was made by astronomers Raymond Poncy, Enric Forné, Hiromi Hamanowa, Hiroko Hamanowa and Hilari Pallarés (U=3).[13] In 2016, a modeled lightcurves using photometric data from various sources, rendered a concurring sidereal period of 9.51856±0.00005 h and two spin axes of (80.0°, 30.0°) and (282.0°, 30.0°) in ecliptic coordinates.[10]
Diameter and albedo
According to the survey carried out by the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, the Infrared Astronomical Satellite IRAS, and the Japanese Akari satellite, Amelia measures 48.677±0.159, 50.94±1.2 and 52.30±0.78 kilometers in diameter and its surface has an albedo of 0.218±0.024, 0.1183±0.006 and 0.113±0.004, respectively.[6][7][8] The Collaborative Asteroid Lightcurve Link derives an albedo of 0.1183 and a diameter of 50.94 kilometers based on an absolute magnitude of 9.4.[14] An asteroid occultation, observed on 2 November 2006, gave a best-fit ellipse dimension of 51.0 × 51.0 kilometers.[5] These timed observations are taken when the asteroid passes in front of a distant star. However the quality of the measurement is rated poorly.[5]
Notes
References
External links
- Lightcurve Database Query (LCDB), at www.minorplanet.info
- Dictionary of Minor Planet Names, Google books
- Asteroids and comets rotation curves, CdR – Geneva Observatory, Raoul Behrend
- Discovery Circumstances: Numbered Minor Planets (1)-(5000) – Minor Planet Center
- 986 Amelia at AstDyS-2, Asteroids—Dynamic Site
- 986 Amelia at the JPL Small-Body Database
