1508 Kemi

1508 Kemi, provisional designation 1938 UP, is an eccentric, carbonaceous asteroid and one of the largest Mars-crossers, approximately 17 kilometers in diameter. Discovered by Heikki Alikoski at Turku Observatory in 1938,[3] the asteroid was later named after the Finnish town of Kemi and the Kemi River.[2]

1508 Kemi
Shape model of Kemi from its lightcurve
Discovery [1]
Discovered byH. Alikoski
Discovery siteTurku Obs.
Discovery date21 October 1938
Designations
(1508) Kemi
Named after
Kemi and Kemi River [2]  
(Finnish town and river)
1938 UP · 1935 FA
1938 UO
Mars-crosser [1][3][4]
Orbital characteristics [1]
Epoch 4 September 2017 (JD 2458000.5)
Uncertainty parameter 0
Observation arc81.79 yr (29,873 days)
Aphelion3.9264 AU
Perihelion1.6167 AU
2.7716 AU
Eccentricity0.4167
4.61 yr (1,685 days)
354.04°
0° 12m 48.96s / day
Inclination28.723°
14.298°
92.892°
Mars MOID0.3966 AU
Physical characteristics
Dimensions15.78±1.58 km[5]
15.9±1.6 km[6]
16±2 km[7]
17.98±1.34 km[8]
21.86 km (calculated)[4]
9.15 h[9]
9.19±0.05 h[10]
9.19182±0.00005 h[11]
9.196±0.001 h[12][lower-alpha 1]
11.36 h[13]
0.057 (assumed)[4]
0.084±0.013[8]
0.109±0.022[5]
0.11±0.02[6][7]
Tholen = BCF [1]
SMASS = C [1][4]
B–V = 0.645 [1]
U–B = 0.249 [1]
12.03[1][4][5][6][7][8]

    Discovery

    Kemi was discovered on 21 October 1938, by Finnish astronomer Heikki Alikoski at the Iso-Heikkilä Observatory in Turku, Finland.[3] It was independently discovered by Hungarian astronomer György Kulin at Konkoly Observatory near Budapest on 30 October 1938.[2] The Minor Planet Center, however, only acknowledges the first discoverer.[3] The asteroid was first identified as 1935 FA at Uccle Observatory in March 1935.[3]

    Orbit and classification

    Kemi is a Mars-crossing asteroid as it crosses the orbit of Mars at 1.666 AU. Because of its high inclination, it has been grouped with the Pallas family (801), an asteroid family of bright carbonaceous asteroids, as well as with the "Phaethon group", despite its untypical spectrum.[14][15]

    It orbits the Sun at a distance of 1.6–3.9 AU once every 4 years and 7 months (1,685 days). Its orbit has an eccentricity of 0.42 and an inclination of 29° with respect to the ecliptic.[1] The body's observation arc begins at Uccle in May 1935, more than 3 years prior to its official discovery observation at Turku.[3]

    Physical characteristics

    In the SMASS classification, Kemi is a common carbonaceous C-type asteroid.[1] In the Tholen classification, the body's spectral type is ambiguous (BCF), closest to that of a bright carbonaceous B-type and somewhat similar to a C- and F-type asteroid.[1]

    Rotation period

    Several rotational lightcurves of Kemi have been obtained from photometric observations since the 1990s. Analysis of the lightcurves gave a consolidated rotation period of 9.196 hours with a brightness variation between of 0.25 and 0.55 magnitude (U=2/3/3/2).[9][10][12][13][lower-alpha 1]

    Poles

    In 2016, an international study modeled a lightcurve with a concurring period of 9.19182 hours. It also determined two spin axis at (352.0°, 72.0°) and (166.0°, 73.0°) in ecliptic coordinates (λ, β).[11]

    Diameter and albedo

    According to the surveys carried out by the Japanese Akari satellite and the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, Kemi measures between 15.78 and 17.98 kilometers in diameter and its surface has an albedo between 0.084 and 0.11.[5][6][7][8] The Collaborative Asteroid Lightcurve Link assumes a standard albedo for carbonaceous asteroids of 0.057 and calculates a diameter of 21.86 kilometers based on an absolute magnitude of 12.03.[4]

    Naming

    This minor planet was named after the Finnish town of Kemi and the Kemi River (Kemijoki), the largest river in Finland, on which the town lies. The naming agrees with the established pattern of giving high-inclination asteroids four-letter names.[2] The official naming citation was published by the Minor Planet Center on 20 February 1976 (M.P.C. 3928).[16]

    Notes
    1. Lightcurve plot of (1508) Kemi, Robert Koff, Antelope Hills Observatory (H09). Summary figures at LCDB

    References
    1. "JPL Small-Body Database Browser: 1508 Kemi (1938 UP)" (2017-01-09 last obs.). Jet Propulsion Laboratory. Retrieved 18 October 2017.
    2. Schmadel, Lutz D. (2007). "(1508) Kemi". Dictionary of Minor Planet Names – (1508) Kemi. Springer Berlin Heidelberg. p. 120. doi:10.1007/978-3-540-29925-7_1509. ISBN 978-3-540-00238-3.
    3. "1508 Kemi (1938 UP)". Minor Planet Center. Retrieved 18 October 2017.
    4. "LCDB Data for (1508) Kemi". Asteroid Lightcurve Database (LCDB). Retrieved 18 October 2017.
    5. Alí-Lagoa, V.; Delbo', M. (July 2017). "Sizes and albedos of Mars-crossing asteroids from WISE/NEOWISE data". Astronomy and Astrophysics. 603: 8. arXiv:1705.10263. Bibcode:2017A&A...603A..55A. doi:10.1051/0004-6361/201629917.
    6. Alí-Lagoa, V.; Licandro, J.; Gil-Hutton, R.; Cañ; ada-Assandri, M.; Delbo', M.; et al. (June 2016). "Differences between the Pallas collisional family and similarly sized B-type asteroids". Astronomy and Astrophysics. 591: 11. Bibcode:2016A&A...591A..14A. doi:10.1051/0004-6361/201527660. Retrieved 18 October 2017.
    7. Alí-Lagoa, V.; de León, J.; Licandro, J.; Delbó, M.; Campins, H.; Pinilla-Alonso, N.; et al. (June 2013). "Physical properties of B-type asteroids from WISE data". Astronomy and Astrophysics. 554: 16. arXiv:1303.5487. Bibcode:2013A&A...554A..71A. doi:10.1051/0004-6361/201220680. Retrieved 18 October 2017.
    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 17 October 2019. (online, AcuA catalog p. 153)
    9. Sárneczky, K.; Szabó, Gy.; Kiss, L. L. (June 1999). "CCD observations of 11 faint asteroids". Astronomy and Astrophysics Supplement. 137 (2): 363–368. Bibcode:1999A&AS..137..363S. doi:10.1051/aas:1999251. Retrieved 18 October 2017.
    10. Jamieson, Quentin; Klinglesmith, Daniel A., III (December 2004). "Period determination of asteroids 1508 Kemi and 5036 Tuttle". The Minor Planet Bulletin. 31 (4): 88–89. Bibcode:2004MPBu...31...88J. ISSN 1052-8091. Retrieved 18 October 2017.
    11. Hanus, J.; Durech, 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.
    12. Koff, Robert A. (September 2004). "Lightcurve photometry of asteroids 306, 1508, 3223, 3270 and 3712". The Minor Planet Bulletin. 31 (3): 58–60. Bibcode:2004MPBu...31...58K. ISSN 1052-8091. Retrieved 18 October 2017.
    13. Holliday, B. (December 1995). "Lightcurve Observations of Minor Planets 1508 Kemi and 2014 Vasilevskis". The Minor Planet Bulletin. 22.: 43. Bibcode:1995MPBu...22...43H. Retrieved 18 October 2017.
    14. Novaković, Bojan; Cellino, Alberto; Knežević, Zoran (November 2011). "Families among high-inclination asteroids". Icarus. 216 (1): 69–81. arXiv:1108.3740. Bibcode:2011Icar..216...69N. doi:10.1016/j.icarus.2011.08.016.
    15. Jenniskens, Peter; Vaubaillon, Jérémie; Binzel, Richard P.; DeMeo, Francesca E.; Nesvorný, David; Bottke, William F.; et al. (October 2010). "Almahata Sitta (=asteroid 2008 TC3) and the search for the ureilite parent body" (PDF). Meteoritics and Planetary Science. 45 (1590): 1590–1617. Bibcode:2010M&PS...45.1590J. doi:10.1111/j.1945-5100.2010.01153.x. Retrieved 19 October 2017.
    16. Schmadel, Lutz D. "Appendix – Publication Dates of the MPCs". Dictionary of Minor Planet Names – Addendum to Fifth Edition (2006–2008). Springer Berlin Heidelberg. p. 221. doi:10.1007/978-3-642-01965-4. ISBN 978-3-642-01964-7.

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