4391 Balodis

4391 Balodis, provisional designation 1977 QW2, is a dark and rare Erigone asteroid from the inner regions of the asteroid belt, approximately 8 kilometers in diameter. It was discovered by Soviet–Russian astronomer Nikolai Chernykh at the Crimean Astrophysical Observatory in Nauchnyj, on the Crimean peninsula, on 21 August 1977.[7] The asteroid was named for Latvian geodesist Jānis Balodis.[2]

4391 Balodis
Discovery [1]
Discovered byN. Chernykh
Discovery siteCrimean Astrophysical Obs.
Discovery date21 August 1977
Designations
(4391) Balodis
Named after
Jānis Balodis
(Latvian cosmic geodesist)[2]
1977 QW2 · 1977 RR2
1980 GZ
main-belt · Erigone [3]
Orbital characteristics [1]
Epoch 4 September 2017 (JD 2458000.5)
Uncertainty parameter 0
Observation arc39.70 yr (14,499 days)
Aphelion2.8989 AU
Perihelion1.8794 AU
2.3892 AU
Eccentricity0.2134
3.69 yr (1,349 days)
330.57°
0° 16m 0.84s / day
Inclination5.3519°
190.30°
108.27°
Physical characteristics
Dimensions3.36±0.17 km[4]
8.05 km (calculated)[3]
3.448±0.001 h[5]
0.057 (assumed)[3]
0.393±0.072[4]
C [3]
14.2[1][3] · 14.00[4] · 14.37±0.36[6]

    Orbit and classification

    Balodis orbits the Sun in the inner main-belt at a distance of 1.9–2.9 AU once every 3 years and 8 months (1,349 days). Its orbit has an eccentricity of 0.21 and an inclination of 5° with respect to the ecliptic.[1] Based on its orbital elements, the Collaborative Asteroid Lightcurve Link (CALL) classifies the asteroid as a member of the Erigone family, which is named after its largest member and namesake, 163 Erigone, also a dark body of carbonaceous composition.[3]

    Physical characteristics

    Diameter and albedo

    According to observations by NASA's space-based Wide-field Infrared Survey Explorer with its subsequent NEOWISE mission, Balodis measures 3.4 kilometers in diameter, and its surface has an exceptionally high albedo of 0.40.[4] However, the CALL assumes a standard albedo for a C-type asteroid of 0.057 and calculates a diameter of 8.4 kilometers with an absolute magnitude of 14.2, as the lower the albedo (reflectivity) the larger the body's diameter.[3]

    Rotation period

    In July 2010, a rotational lightcurve of Balodis was obtained by Italian astronomer Albino Carbognani from photometric observations taken at the Astronomical Observatory of the Autonomous Region of the Aosta Valley (OAVdA) in Italy. It showed rotation period of 3.448±0.001 hours with a brightness amplitude of 0.29 in magnitude (U=2).[5]

    Naming

    This minor planet was named after Latvian cosmic geodesist Jānis Balodis, head of the Astronomical Observatory at University of Latvia.[2]

    Balodis' research includes astrometry, observations of artificial satellites using laser, as well as computational methods for astrometric interpretations of photographic plates. The Crimean minor planet service has used his algorithms for a long time.[2] (The honored astronomer should not to be confused with Soviet army General Jānis Balodis.) The official naming citation was published by the Minor Planet Center on 12 September 1992 (M.P.C. 20837).[8]

    References
    1. "JPL Small-Body Database Browser: 4391 Balodis (1977 QW2)" (2017-05-02 last obs.). Jet Propulsion Laboratory. Retrieved 20 June 2017.
    2. Schmadel, Lutz D. (2007). "(4391) Balodis". Dictionary of Minor Planet Names – (4391) Balodis. Springer Berlin Heidelberg. p. 377. doi:10.1007/978-3-540-29925-7_4341. ISBN 978-3-540-00238-3.
    3. "LCDB Data for (4391) Balodis". Asteroid Lightcurve Database (LCDB). Retrieved 2 May 2016.
    4. Masiero, Joseph R.; Mainzer, A. K.; Grav, T.; Bauer, J. M.; Cutri, R. M.; Nugent, C.; et al. (November 2012). "Preliminary Analysis of WISE/NEOWISE 3-Band Cryogenic and Post-cryogenic Observations of Main Belt Asteroids". The Astrophysical Journal Letters. 759 (1): 5. arXiv:1209.5794. Bibcode:2012ApJ...759L...8M. doi:10.1088/2041-8205/759/1/L8. Retrieved 2 May 2016.
    5. Carbognani, Albino (January 2011). "Lightcurves and Periods of Eighteen NEAs and MBAs". The Minor Planet Bulletin. 38 (1): 57–63. Bibcode:2011MPBu...38...57C. ISSN 1052-8091. Retrieved 2 May 2016.
    6. 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:1506.00762. Bibcode:2015Icar..261...34V. doi:10.1016/j.icarus.2015.08.007. Retrieved 2 May 2016.
    7. "4391 Balodis (1977 QW2)". Minor Planet Center. Retrieved 2 May 2016.
    8. "MPC/MPO/MPS Archive". Minor Planet Center. Retrieved 2 May 2016.

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