789 Lena

789 Lena
Discovery [1]
Discovered by G. Neujmin
Discovery site Simeiz Observatory
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 81.14 yr (29635 d)
Aphelion 3.0815 AU (460.99 Gm)
Perihelion 2.2910 AU (342.73 Gm)
2.6862 AU (401.85 Gm)
Eccentricity 0.14715
4.40 yr (1608.1 d)
65.250°
0° 13m 25.932s / day
Inclination 10.780°
232.63°
44.013°
Earth MOID 1.28833 AU (192.731 Gm)
Jupiter MOID 2.03418 AU (304.309 Gm)
Jupiter Tisserand parameter 3.333
Physical characteristics
Dimensions 20.56±0.34 km[4]
23.871±0.162 km[5]
24.18 km (calculated)[3]
5.848±0.001 h[6]
22 h[7]
5.85±0.05 h[8]
5.848 h (0.2437 d)[1]
0.186±0.007[4]
0.1373±0.0147[5]
0.10 (assumed)[3]

SMASS = X[1]

X [3]
11.2[1][3]
10.90[4]
10.9[5]

    789 Lena, provisional designation 1914 UU, is an asteroid from the middle region of the asteroid belt, about 24 kilometers in diameter. It was discovered by Soviet–Russian astronomer Grigory Neujmin at the Simeiz Observatory on the Crimean peninsula, on 24 June 1914.[9]

    The X-type asteroid orbits the Sun at a distance of 2.3–3.1 AU once every 4 years and 5 months (1,608 days). Its orbit shows an eccentricity of 0.15 and an inclination of 11 degrees from 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.

    Observations made in 1993 at the Félix Aguilar Observatory in Argentina showed that the asteroid had 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.[7] In 2007, however, two Photometric light-curve analysis rendered a well-defined period of 5.85 hours, superseding the incorrect measurement from th 1990s.[lower-alpha 1] The first and best rated measurement was made by Italian astronomer Silvano Casulli and gave a period of 5.848±0.001 hours and a brightness variation of 0.50 in magnitude,[6] while the second, concurring analysis was performed at the U.S. Oakley Observatory, Indiana, which rendered a period of 5.85±0.05 hours with a magnitude of 0.40.[8]

    According to the space-based surveys carried out by the Japanese Akari satellite and the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, the asteroid has an albedo of 0.19 and 0.14, with a diameter of 20.6 and 23.9 kilometers, respectively.[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, for a given 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 6 "JPL Small-Body Database Browser: 789 Lena (1914 UU)" (2015-09-26 last obs.). Jet Propulsion Laboratory. Retrieved 4 May 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 January 2016.
    3. 1 2 3 4 5 6 "LCDB Data for (789) Lena". Asteroid Lightcurve Database (LCDB). Retrieved January 2016.
    4. 1 2 3 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 January 2016.
    5. 1 2 3 4 Mainzer, A.; Grav, T.; Masiero, J.; Hand, E.; Bauer, J.; Tholen, D.; et al. (November 2011). "NEOWISE Studies of Spectrophotometrically Classified Asteroids: Preliminary Results". The Astrophysical Journal 741 (2): 25. arXiv:1109.6407. Bibcode:2011ApJ...741...90M. doi:10.1088/0004-637X/741/2/90. Retrieved January 2016.
    6. 1 2 Behrend, Raoul. "Asteroids and comets rotation curves – (789) Lena". Geneva Observatory. Retrieved January 2016.
    7. 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 January 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 January 2016.
    9. ↑ "789 Lena (1914 UU)". Minor Planet Center. Retrieved January 2016.

    External links


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