986 Amelia

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.[lower-alpha 1] It was named after the discoverer's wife, Amelia Solà.[2]

986 Amelia
Modelled shape of Amelia from its lightcurve
Discovery [1]
Discovered byJ. Comas Solà
Discovery siteFabra Obs.
Discovery date19 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 arc93.64 yr (34,203 d)
Aphelion3.7674 AU
Perihelion2.4961 AU
3.1317 AU
Eccentricity0.2030
5.54 yr (2,024 d)
210.80°
0° 10m 40.08s / day
Inclination14.815°
92.601°
265.52°
Physical characteristics
Mean diameter
  • 48.677±0.159 km[6]
  • 50.94±1.2 km[7]
  • 52.30±0.78 km[8]
9.52±0.01 h[9][lower-alpha 1]
  • 0.113±0.004[8]
  • 0.1183±0.006[7]
  • 0.218±0.024[6]
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][lower-alpha 1]

    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
    1. Lightcurve plot of (986) Amelia by Robert A. Koff (Oct 2000). Rotation period 9.52 hours with a brightness amplitude of 0.43 mag. LCDB quality code of 3. Summary figures and more information at Bob Koff's website and at the LCDB.

    References
    1. "986 Amelia (A922 UA)". Minor Planet Center. Retrieved 5 February 2020.
    2. Schmadel, Lutz D. (2007). "(986) Amelia". Dictionary of Minor Planet Names. Springer Berlin Heidelberg. p. 86. doi:10.1007/978-3-540-29925-7_987. ISBN 978-3-540-00238-3.
    3. "JPL Small-Body Database Browser: 986 Amelia (A922 UA)" (2020-01-06 last obs.). Jet Propulsion Laboratory. Retrieved 5 February 2020.
    4. "Asteroid 986 Amelia – Proper Elements". AstDyS-2, Asteroids – Dynamic Site. Retrieved 5 February 2020.
    5. "Asteroid 986 Amelia". Small Bodies Data Ferret. Retrieved 5 February 2020.
    6. Masiero, Joseph R.; Grav, T.; Mainzer, A. K.; Nugent, C. R.; Bauer, J. M.; Stevenson, R.; et al. (August 2014). "Main-belt Asteroids with WISE/NEOWISE: Near-infrared Albedos". The Astrophysical Journal. 791 (2): 11. arXiv:1406.6645. Bibcode:2014ApJ...791..121M. doi:10.1088/0004-637X/791/2/121.
    7. Tedesco, E. F.; Noah, P. V.; Noah, M.; Price, S. D. (October 2004). "IRAS Minor Planet Survey V6.0". NASA Planetary Data System. 12: IRAS-A-FPA-3-RDR-IMPS-V6.0. Bibcode:2004PDSS...12.....T. Retrieved 5 February 2020.
    8. Usui, Fumihiko; Kuroda, Daisuke; Müller, Thomas G.; Hasegawa, Sunao; Ishiguro, Masateru; Ootsubo, Takafumi; et al. (October 2011). "Asteroid Catalog Using Akari: AKARI/IRC Mid-Infrared Asteroid Survey". Publications of the Astronomical Society of Japan. 63 (5): 1117–1138. Bibcode:2011PASJ...63.1117U. doi:10.1093/pasj/63.5.1117. Retrieved 5 February 2020. (online, AcuA catalog p. 153)
    9. Koff, R. A. (December 2001). "Lightcurve Photometry of 611 Valeria and 986 Amelia" (PDF). Minor Planet Bulletin. 28 (1): 77–78. Bibcode:2001MPBu...28...77K.
    10. Hanuš, J.; Ďurech, J.; Oszkiewicz, D. A.; Behrend, R.; Carry, B.; Delbo, M.; et al. (February 2016). "New and updated convex shape models of asteroids based on optical data from a large collaboration network". Astronomy and Astrophysics. 586: 24. arXiv:1510.07422. Bibcode:2016A&A...586A.108H. doi:10.1051/0004-6361/201527441. ISSN 0004-6361.
    11. Lazzaro, D.; Angeli, C. A.; Carvano, J. M.; Mothé-Diniz, T.; Duffard, R.; Florczak, M. (November 2004). "S3OS2: the visible spectroscopic survey of 820 asteroids" (PDF). Icarus. 172 (1): 179–220. Bibcode:2004Icar..172..179L. doi:10.1016/j.icarus.2004.06.006. Retrieved 5 February 2020.
    12. Carvano, J. M.; Hasselmann, P. H.; Lazzaro, D.; Mothé-Diniz, T. (February 2010). "SDSS-based taxonomic classification and orbital distribution of main belt asteroids". Astronomy and Astrophysics. 510: 12. Bibcode:2010A&A...510A..43C. doi:10.1051/0004-6361/200913322. Retrieved 5 February 2020. (PDS data set)
    13. Behrend, Raoul. "Asteroids and comets rotation curves – (986) Amelia". Geneva Observatory. Retrieved 5 February 2020.
    14. "LCDB Data for (986) Amelia". Asteroid Lightcurve Database (LCDB). Retrieved 5 February 2020.

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