873 Mechthild

873 Mechthild (prov. designation: A917 KJ or 1917 CA) is a dark background asteroid from the central regions of the asteroid belt. It was discovered by German astronomer Max Wolf at the Heidelberg Observatory on 21 May 1917.[1] The primitive P-type asteroid has a rotation period of 11.0 hours and measures approximately 34 kilometers (21 miles) in diameter. The origin of the asteroid's name remains unknown.[2]

873 Mechthild
Modelled shape of Mechthild from its lightcurve
Discovery [1]
Discovered byM. F. Wolf
Discovery siteHeidelberg Obs.
Discovery date21 May 1917
Designations
(873) Mechthild
Named after
unknown [2]
A917 KJ · 1917 CA
Orbital characteristics [3]
Epoch 31 May 2020 (JD 2459000.5)
Uncertainty parameter 0
Observation arc102.24 yr (37,343 d)
Aphelion3.0199 AU
Perihelion2.2346 AU
2.6273 AU
Eccentricity0.1495
4.26 yr (1,555 d)
48.264°
0° 13m 53.04s / day
Inclination5.2763°
150.00°
109.99°
Physical characteristics
Mean diameter
  • 29.04±1.9 km[6]
  • 33.56±0.59 km[7]
  • 34.471±0.103 km[8]
11.006±0.001 h[9]
  • (249.0°, −52.0°) (λ1/β1)[5]
  • (51.0°, −61.0°) (λ2/β2)[5]
  • 0.040±0.004[8]
  • 0.041±0.002[7]
  • 0.0531±0.008[6]
11.4[1][3]

    Orbit and classification

    Mechthild is a non-family asteroid of the main belt's background population when applying the hierarchical clustering method to its proper orbital elements.[4][5] It orbits the Sun in the central asteroid belt at a distance of 2.2–3.0 AU once every 4 years and 3 months (1,555 days; semi-major axis of 2.63 AU). Its orbit has an eccentricity of 0.15 and an inclination of 5° with respect to the ecliptic.[3] The body's observation arc begins with its first and official discovery observation at Heidelberg Observatory on 21 May 1917.[1]

    Naming

    This minor planet is named "Mechthild", a German feminine given name. Any reference of this name to a specific person or occurrence is unknown.[2]

    Unknown meaning

    Among the many thousands of named minor planets, Mechthild is one of 120 asteroids, for which no official naming citation has been published. All of these low-numbered asteroids have numbers between 164 Eva and 1514 Ricouxa and were discovered between 1876 and the 1930s, predominantly by astronomers Auguste Charlois, Johann Palisa, Max Wolf and Karl Reinmuth.[10]

    Physical characteristics

    In the Tholen classification, Mechthild is closest to a very dark, primitive P-type, and somewhat similar to a common C-type asteroid. In the taxonomy by Barucci, it is a C0-type.[3][5] P-type asteroids are more common in the outer asteroid belt and among the Jupiter trojan population.

    Rotation period

    In May 2015, a rotational lightcurve of Mechthild was obtained from photometric observations by Brian Warner at his Palmer Divide Observatory (716) in Colorado. Lightcurve analysis gave a rotation period of 11.006±0.001 hours with a brightness amplitude of 0.27±0.02 magnitude (U=3).[9]

    Alternative period determinations were made by Claes-Ingvar Lagerkvist (10.6 h) in March 1976, by astronomers at the Palomar Transient Factory (11.007±0.0069 h) in January 2014, and by the Spanish group of asteroid observers, OBAS (10.99±0.01 h) in May 2015 (U=2/2/3).[11][12][13] In 2016, a modeled lightcurve gave a concurring sidereal period of 11.00639±0.00005 hours using data from a large collaboration of individual observers (such as above). The study also determined two spin axes of (249.0°, −52.0°) and (51.0°, −61.0°) in ecliptic coordinates (λ, β).[14]

    Diameter and albedo

    According to the surveys carried out by the Infrared Astronomical Satellite IRAS, and the Japanese Akari satellite, and the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer (WISE), Mechthild measures (29.04±1.9), (33.56±0.59) and (34.471±0.103) kilometers in diameter and its surface has an albedo of (0.0531±0.008), (0.041±0.002) and (0.040±0.004), respectively.[6][7][8] The Collaborative Asteroid Lightcurve Link adopts the results from IRAS, that is, an albedo of 0.0531 and a diameter of 29.04 kilometers based on an absolute magnitude of 11.49.[15] Alternative mean-diameter measurements published by the WISE team include (29.124±10.26 km) and (36.327±0.290 km) with corresponding albedos of (0.0785±0.0687) and (0.0339±0.0063).[15]

    References
    1. "873 Mechthild (A917 KJ)". Minor Planet Center. Retrieved 1 March 2020.
    2. Schmadel, Lutz D. (2007). "(873) Mechthild". Dictionary of Minor Planet Names. Springer Berlin Heidelberg. p. 79. doi:10.1007/978-3-540-29925-7_874. ISBN 978-3-540-00238-3.
    3. "JPL Small-Body Database Browser: 873 Mechthild (A917 KJ)" (2019-08-17 last obs.). Jet Propulsion Laboratory. Retrieved 1 March 2020.
    4. "Asteroid 873 Mechthild – Proper Elements". AstDyS-2, Asteroids – Dynamic Site. Retrieved 1 March 2020.
    5. "Asteroid 873 Mechthild". Small Bodies Data Ferret. Retrieved 1 March 2020.
    6. Tedesco, E. F.; Noah, P. V.; Noah, M.; Price, S. D. (October 2004). "IRAS Minor Planet Survey V6.0". NASA Planetary Data System. 12: IRAS-A-FPA-3-RDR-IMPS-V6.0. Bibcode:2004PDSS...12.....T. Retrieved 1 March 2020.
    7. 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. (online, AcuA catalog p. 153)
    8. Masiero, 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.
    9. Warner, Brian D. (October 2009). "Asteroid Lightcurve Analysis at the Palmer Divide Observatory: 2009 March-June" (PDF). Minor Planet Bulletin. 36 (4): 172–176. Bibcode:2009MPBu...36..172W. ISSN 1052-8091.
    10. 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. ISBN 978-3-540-00238-3.
    11. Lagerkvist, C. -I. (March 1978). "Photographic photometry of 110 main-belt asteroids". Astronomy and Astrophysics Supplement Series. 31: 361–381. Bibcode:1978A&AS...31..361L. ISSN 0365-0138.
    12. Waszczak, Adam; Chang, Chan-Kao; Ofek, Eran O.; Laher, Russ; Masci, Frank; Levitan, David; et al. (September 2015). "Asteroid Light Curves from the Palomar Transient Factory Survey: Rotation Periods and Phase Functions from Sparse Photometry". The Astronomical Journal. 150 (3): 75. arXiv:1504.04041. Bibcode:2015AJ....150...75W. doi:10.1088/0004-6256/150/3/75. ISSN 0004-6256.
    13. Garceran, Alfonso Carreno; Aznar, Amadeo; Mansego, Enrique Arce; Rodriguez, Pedro Brines; de Haro, Juan Lozano; Silva, Alvaro Fornas; et al. (January 2016). "Nineteen Asteroids Lightcurves at Asteroids Observers (OBAS) - MPPD: 2015 April - September" (PDF). Minor Planet Bulletin. 43 (1): 92–97. Bibcode:2016MPBu...43...92G. ISSN 1052-8091. Archived from the original (PDF) on 3 October 2020. Retrieved 1 March 2020.
    14. Hanuš, J.; Ďurech, 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: A108. arXiv:1510.07422. Bibcode:2016A&A...586A.108H. doi:10.1051/0004-6361/201527441. ISSN 0004-6361.
    15. "LCDB Data for (873) Mechthild". Asteroid Lightcurve Database (LCDB). Retrieved 1 March 2020.
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