845 Naëma (prov. designation:A916 WMor1916 AS) is a large asteroid and the parent body of the Naëma family located in the outer regions of the asteroid belt. It was discovered on 16 November 1916, by astronomer Max Wolf at the Heidelberg-Königstuhl State Observatory in southwest Germany.[1] The carbonaceous C-type asteroid has a rotation period of 20.9 hours and measures approximately 54 kilometers (34 miles) in diameter on average, as it is likely elongated in shape. Any reference of the asteroid's name to a person is unknown.[2]
Among the many thousands of named minor planets, Naëma is one of 120 asteroids for which no official naming citation has been published. All of these asteroids have low numbers, the first being 164 Eva. The last asteroid with a name of unknown meaning is 1514 Ricouxa. They were discovered between 1876 and the 1930s, predominantly by astronomers Auguste Charlois, Johann Palisa, Max Wolf and Karl Reinmuth.[15]
In September 2006, a rotational lightcurveofNaëma was obtained from photometric observations by Collin Bembrick at the Mount Tarana Observatory (431), Australia, in collaboration with Bill Allen and Greg Bolt. Lightcurve analysis gave a relatively long rotation periodof20.892±0.019 hours with a brightness variation of 0.16±0.02magnitude (U=2).[10] In December 2017, French amateur astronomer René Roy determined a lower-rated, tentative period of 12.1±0.3 hours with an amplitude of 0.05±0.01 magnitude (U=1).[17]
According to the surveys carried out by the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer (WISE), the Infrared Astronomical Satellite IRAS, and the Japanese Akari satellite, Naëma measures (52.677±0.291), (54.36±2.8) and (60.52±1.06) kilometers in diameter and its surface has an albedo of (0.080±0.019), (0.0788±0.009) and (0.065±0.003), respectively.[6][7][8][9] The Collaborative Asteroid Lightcurve Link derives an albedo of 0.0503 and a diameter of 54.05 kilometers based on an absolute magnitude of 10.2.[18] Alternative mean diameter measurements published by the WISE team include (47.19±13.93 km), (52.419±20.30 km), (52.91±11.64 km), (56.933±0.338 km) and (60.12±2.45 km) with corresponding albedos of (0.06±0.05), (0.0417±0.0296), (0.04±0.02), (0.0718±0.0189) and (0.041±0.006).[16][18]
Several asteroid occultationsofNaëma have been observed between 2002 and 2010. The best-rated one from 10 April 2010, gave a best-fit ellipse dimension of (63.1 km × 42.5 km).[16] These timed observations are taken when the asteroid passes in front of a distant star.
^ abcMainzer, A. K.; Bauer, J. M.; Cutri, R. M.; Grav, T.; Kramer, E. A.; Masiero, J. R.; et al. (June 2016). "NEOWISE Diameters and Albedos V1.0". NASA Planetary Data System: EAR-A-COMPIL-5-NEOWISEDIAM-V1.0. Bibcode:2016PDSS..247.....M. Retrieved 7 March 2020.
^ abcMasiero, 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.
^Zappalà, V.; Bendjoya, Ph.; Cellino, A.; Farinella, P.; Froeschle, C. (1997). "Asteroid Dynamical Families". NASA Planetary Data System: EAR-A-5-DDR-FAMILY-V4.1. Retrieved 4 March 2020.} (PDS main page)
^Zappalà, V.; Bendjoya, Ph.; Cellino, A.; Farinella, P.; Froeschlé, C. (August 1995). "Asteroid families: Search of a 12,487-asteroid sample using two different clustering techniques". Icarus. 116 (2): 291–314. Bibcode:1995Icar..116..291Z. doi:10.1006/icar.1995.1127. ISSN0019-1035.
^Nicodemus Frischlin (1606) Methodus declamandi posthuma, in laudatione, thesi de laudibus mulierum demonstrata, p. 165-166
^Schmadel, Lutz D. (2007). "Appendix 11 – Minor Planet Names with Unknown Meaning". Dictionary of Minor Planet Names – Fifth Revised and Enlarged revision. Springer Berlin Heidelberg. pp. 927–929. ISBN978-3-540-00238-3.
