917 Lyka

Lyka is a non-family asteroid of the main belt's background population when applying the hierarchical clustering method to its proper orbital elements. It orbits the Sun in the inner main-belt at a distance of 1.9–2.9 AU once every 3 years and 8 months (1,342 days; semi-major axis of 2.38 AU). Its orbit has an eccentricity of 0.20 and an inclination of 5° with respect to the ecliptic. The body's observation arc begins at Simeiz on 1 September 1926, eleven years after to its official discovery observation.

This minor planet was named after Lyka, a friend of the sister of discoverer Grigory Neujmin. Lutz Schmadel, the author of the Dictionary of Minor Planet Names learned about the meaning of the asteroid's name from private communications with long-time Simeiz astronomer Nikolai Chernykh.

In both the Tholen- and SMASS-like taxonomy of the Small Solar System Objects Spectroscopic Survey (S3OS2), Lyka is an X-type asteroid.

In January 2005, a rotational lightcurve of Lyka was obtained from photometric observations by Matthieu Conjat. Lightcurve analysis gave a well-defined rotation period of {{val|7.867|0.006}} hours with a low brightness variation of {{val|0.17|0.02}} magnitude, indicative of a rather spherical shape ({{small|U=3}}). In October 2018, the period was confirmed by Laurent Bernasconi ({{val|7.8838|0.0003|ul=h}}) and by Alfonso Carreño of OBAS ({{val|7.889|0.007|u=h}}) with amplitudes of {{val|0.12|0.01}} and {{val|0.26|0.03}}, respectively ({{small|U=3/3}}).

According to the survey carried out by the Infrared Astronomical Satellite IRAS, the Japanese Akari satellite, and the NEOWISE mission of NASA's WISE telescope (WISE), Lyka measures ({{val|28.10|3.9}}), ({{val|31.29|0.49}}) and ({{val|34.878|0.184}}) kilometers in diameter and its surface has an albedo of ({{val|0.0891|0.031}}), ({{val|0.072|0.003}}) and ({{val|0.056|0.008}}), respectively. The Collaborative Asteroid Lightcurve Link derives an albedo of 0.0520 and a diameter of 27.89 km based on an absolute magnitude of 11.6. Further published mean-diameters by the WISE team include ({{val|21.60|4.99|u=km}}), ({{val|26.65|9.28|u=km}}), ({{val|34.789|2.565|u=km}}) and ({{val|37.843|0.227|u=km}}) with albedos between ({{val|0.026|0.009}}) and ({{val|0.05|0.02}}). An asteroid occultation, observed on 4 March 2005, gave a best-fit ellipse dimension of 28.0×28.0 kilometers. These timed observations are taken when the asteroid passes in front of a distant star. However the quality of the measurement is rated poorly.

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• [http://www.minorplanet.info/PHP/OneAsteroidInfo.php Lightcurve Database Query] (LCDB), at www.minorplanet.info
• [https://books.google.com/books?id=aeAg1X7afOoC&pg Dictionary of Minor Planet Names], Google books
• [http://obswww.unige.ch/~behrend/page_cou.html Asteroids and comets rotation curves, CdR] – Geneva Observatory, Raoul Behrend
• [http://www.minorplanetcenter.net/iau/lists/NumberedMPs000001.html Discovery Circumstances: Numbered Minor Planets (1)-(5000)] – Minor Planet Center
• {{AstDys|917}}
• {{JPL small body}}

{{Minor planets navigator |916 America |number=917 |918 Itha}}

{{Small Solar System bodies}}

{{Authority control}}

{{DEFAULTSORT:Lyka}}

000917

Category:Discoveries by Grigory Neujmin

Category:Named minor planets

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