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]
  • Tholen = PC [3]
  • C0 (Barucci)
  • B–V = 0.684±0.022[3]
  • U–B = 0.319±0.037[3]
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 (also see category).[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]

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    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. Retrieved 1 March 2020. (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.
    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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