789 Lena

789 Lena
Discovery [1]
Discovered by G. Neujmin
Discovery site Simeiz Obs.
Discovery date 24 June 1914
Designations
MPC designation 789 Lena
Named after
 Elena Neujmina
(discoverer's family)[2]
1914 UU · 1970 CE
main-belt · (middle) [3]
Orbital characteristics [1]
Epoch 31 July 2016 (JD 2457600.5)
Uncertainty parameter 0
Observation arc 81.29 yr (29,692 days)   
Aphelion 3.0815 AU
Perihelion 2.2910 AU
2.6862 AU
Eccentricity 0.1471
4.40 yr (1,608 days)
65.250°
0° 13m 26.04s / day
Inclination 10.780°
232.63°
44.013°
Physical characteristics
Dimensions 20.56±0.34 km[4]
23.871±0.162 km[5]
24.18 km (calculated)[3]
5.84239±0.00001 h[6]
5.848±0.001 h[7]
5.85±0.05 h[8]
22 h[9]
0.10 (assumed)[3]
0.1373±0.0147[5]
0.186±0.007[4]
SMASS = X [1]
M [5] · X [3]
10.47±0.60[10]
10.9[4][5]
11.2[1][3]

    789 Lena, provisional designation 1914 UU, is an asteroid from the middle region of the asteroid belt, approximately 24 kilometers in diameter. It was discovered on 24 June 1914, by Soviet–Russian astronomer Grigory Neujmin at Simeiz Observatory on the Crimean peninsula.[11]

    The X-type asteroid is also classified as a M-type by NASA's Wide-field Infrared Survey Explorer (WISE).[5] It orbits the Sun at a distance of 2.3–3.1 AU once every 4 years and 5 months (1,608 days). Its orbit has an eccentricity of 0.15 and an inclination of 11° with respect to the plane of the ecliptic.[1] Although its orbital elements resemble those of the asteroids in the Eunomia family, true members of this family have a S-type composition, so it is almost certainly an unrelated interloper. The first used observation was made much later at the U.S Yerkes Observatory in 1935, reducing the asteroid's observation arc by 21 years with respect to its discovery date.[11]

    In 1993, a rotational light-curve which was later proven incorrect, was obtained from photometric observations at the Félix Aguilar Observatory, Argentina. It gave an unusual light-curve, indicating a very irregular shape and/or a relatively long rotation period of 22 hours with an exceptionally high amplitude of 1.5 in magnitude (U=0).[9] In August and September 2007, two new light-curves were obtained by Italian astronomer Silvano Casulli and by members at the U.S.Oakley Observatory, and gave a period of 5.848±0.001 and 5.85±0.05 hours, with a brightness variation of 0.50 and of 0.40 in magnitude, respectively (U=3/2+).[lower-alpha 1][7][8]

    According to the space-based surveys carried out by the Japanese Akari satellite and the NEOWISE mission of the WISE telescope, the asteroid has an albedo of 0.19 and 0.14, with a diameter of 20.6 and 23.9 kilometers, respectively.[4][5] The Collaborative Asteroid Lightcurve Link assumes a much lower albedo of 0.10 and calculates a diameter of 24.2 kilometer, as the lower the albedo (reflectivety), the larger a body's diameter, at a constant absolute magnitude (brightness).[3]

    The minor planet was named in honor of Elena ("Lena") Petrovna Neujmina (1860–1942), mother of the discovering astronomer.[2]

    References

    1. ↑ The Collaborative Asteroid Lightcurve Link (CALL) assigns a quality code to light-curve observations, ranging from 0 ("result later proven incorrect") to 3 ("secure result within the precision given and no ambiguity"). The 1993-lightcurve obtained at the Félix Aguilar Observatory was rated "0", while CALL tags the more recent 2007-observations with a quality code of "2+" and "3", respectively. Summary figures at Collaborative Asteroid Lightcurve Link (CALL) for (789) Lena
    1. 1 2 3 4 5 "JPL Small-Body Database Browser: 789 Lena (1914 UU)" (2016-06-16 last obs.). Jet Propulsion Laboratory. Retrieved 4 July 2016.
    2. 1 2 Schmadel, Lutz D. (2007). Dictionary of Minor Planet Names – (789) Lena. Springer Berlin Heidelberg. p. 74. ISBN 978-3-540-00238-3. Retrieved 4 July 2016.
    3. 1 2 3 4 5 6 "LCDB Data for (789) Lena". Asteroid Lightcurve Database (LCDB). Retrieved 4 July 2016.
    4. 1 2 3 4 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 4 July 2016.
    5. 1 2 3 4 5 6 Mainzer, A.; Grav, T.; Masiero, J.; Hand, E.; Bauer, J.; Tholen, D.; et al. (November 2011). "NEOWISE Studies of Spectrophotometrically Classified Asteroids: Preliminary Results" (PDF). The Astrophysical Journal. 741 (2): 25. arXiv:1109.6407Freely accessible. Bibcode:2011ApJ...741...90M. doi:10.1088/0004-637X/741/2/90. Retrieved 4 July 2016.
    6. ↑ Durech, J.; Hanus, J.; Oszkiewicz, D.; Vanco, R. (March 2016). "Asteroid models from the Lowell photometric database". Astronomy and Astrophysics. 587: 6. arXiv:1601.02909Freely accessible. Bibcode:2016A&A...587A..48D. doi:10.1051/0004-6361/201527573. Retrieved 4 July 2016.
    7. 1 2 Behrend, Raoul. "Asteroids and comets rotation curves – (789) Lena". Geneva Observatory. Retrieved 4 July 2016.
    8. 1 2 Shipley, Heath; Dillard, Alex; Kendall, Jordan; Reichert, Matthew; Sauppe, Jason; Shaffer, Nelson; et al. (September 2008). "Asteroid Lightcurve Analysis at the Oakley Observatory - September 2007". The Minor Planet Bulletin. 35 (3): 99–102. Bibcode:2008MPBu...35...99S. ISSN 1052-8091. Retrieved 4 July 2016.
    9. 1 2 Gil-Hutton, R. (October 1995). "Research Note: Photometry of Asteroids 359 Georgia and 789 Lena". Revista Mexicana de Astronomia y Astrofisica. Bibcode:1995RMxAA..31..143G. Retrieved 4 July 2016.
    10. ↑ Veres, Peter; Jedicke, Robert; Fitzsimmons, Alan; Denneau, Larry; Granvik, Mikael; Bolin, Bryce; et al. (November 2015). "Absolute magnitudes and slope parameters for 250,000 asteroids observed by Pan-STARRS PS1 - Preliminary results". Icarus. 261: 34–47. arXiv:1506.00762Freely accessible. Bibcode:2015Icar..261...34V. doi:10.1016/j.icarus.2015.08.007. Retrieved 4 July 2016.
    11. 1 2 "789 Lena (1914 UU)". Minor Planet Center. Retrieved 4 July 2016.

    External links

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