891 Gunhild

891 Gunhild (prov. designation: A918 KB or 1918 DQ) is a large background asteroid from the outer regions of the asteroid belt, that measures approximately 58 kilometers (36 miles) in diameter. It was discovered on 17 May 1918, by astronomer Max Wolf at the Heidelberg-Königstuhl State Observatory in southwest Germany.[1] The dark D-type asteroid has a rotation period of 11.9 hours. Any reference of the asteroid's name to a person is unknown.[2]

891 Gunhild
Modelled shape of Gunhild from its lightcurve
Discovery [1]
Discovered byM. F. Wolf
Discovery siteHeidelberg Obs.
Discovery date17 May 1918
Designations
(891) Gunhild
Named after
unknown [2]
A918 KB · 1977 FH
1999 CF154 · A915 VE
1918 DQ · 1915 VE
main-belt [1][3] · (outer)
background [4][5]
Orbital characteristics [3]
Epoch 31 May 2020 (JD 2459000.5)
Uncertainty parameter 0
Observation arc101.70 yr (37,145 d)
Aphelion2.9444 AU
Perihelion2.7799 AU
2.8622 AU
Eccentricity0.0287
4.84 yr (1,769 d)
232.57°
0° 12m 12.6s / day
Inclination13.559°
105.85°
292.38°
Physical characteristics
Mean diameter
  • 51.95±5.6 km[6]
  • 55.747±0.321 km[7]
  • 63.80±0.67 km[8]
11.892±0.001 h[9]
  • 0.049±0.001[8]
  • 0.057±0.019[7]
  • 0.0718±0.018[6]
10.0[1][3]

    Orbit and classification

    Gunhild 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 outer asteroid belt at a distance of 2.8–2.9 AU once every 4 years and 10 months (1,769 days; semi-major axis of 2.86 AU). Its orbit has an eccentricity of 0.03 and an inclination of 14° with respect to the ecliptic.[3] The asteroid was first observed as A915 VE (1915 VE) at Simeiz Observatory in November 1915. The body's observation arc begins at Heidelberg Observatory on 18 May 1918, the night after its official discovery observation.[1]

    Naming

    This minor planet is named after a Feminine German first name. Any reference of this name to a person or occurrence is unknown.[2]

    Unknown meaning

    Among the many thousands of named minor planets, Gunhild 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).[12]

    Physical characteristics

    In both the Tholen- and SMASS-like taxonomy of the Small Solar System Objects Spectroscopic Survey (S3OS2), as well as in the SDSS-based taxonomy, Gunhild is a dark D-type asteroid.[5][10][11] This asteroid spectral type is common among outer belt asteroids and very common among the Jupiter trojan population.

    Rotation period

    In July 2015, a rotational lightcurve of Gunhild was obtained from photometric observations by the Spanish group of asteroid observers, OBAS. Lightcurve analysis gave a rotation period of 11.892±0.001 hours with a brightness amplitude of 0.36±0.02 magnitude (U=3−).[9] The result supersedes period determinations of (7.93±0.01 h) by Robert Stephens in 2000,[13] (11.853±0.006 h) by Laurent Bernasconi in 2005,[14] and (10.556±0.003 h) by Janus Kozdon in 2015 (U=2/2/2+).[15]

    Diameter and albedo

    According to the survey carried out by the Infrared Astronomical Satellite IRAS, the Japanese Akari satellite, and the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer (WISE), Gunhild measures (51.95±5.6), (55.747±0.321) and (63.80±0.67) kilometers in diameter and its surface has an albedo of (0.0718±0.018), (0.057±0.019) and (0.049±0.001), respectively.[6][7][8] The Collaborative Asteroid Lightcurve Link derives an albedo of 0.0656 and a diameter of 51.89 kilometers based on an absolute magnitude of 10.0.[16] Alternative mean-diameter measurements published by the WISE team include (51.05±8.60 km), (58.064±1.384 km) and (65.12±15.84 km) with corresponding albedos of (0.07±0.04), (0.0574±0.0017) and (0.05±0.02).[5][16][17] Several asteroid occultation observed between 2010 and 2014 gave a best-fit ellipse dimension of 52.0 × 52.0 kilometers (one observation) and 63.0 × 63.0 kilometers (three observations). These timed observations are taken when the asteroid passes in front of a distant star.[5]

    References
    1. "891 Gunhild (A918 KB)". Minor Planet Center. Retrieved 25 February 2020.
    2. Schmadel, Lutz D. (2007). "(891) Gunhild". Dictionary of Minor Planet Names. Springer Berlin Heidelberg. p. 80. doi:10.1007/978-3-540-29925-7_892. ISBN 978-3-540-00238-3.
    3. "JPL Small-Body Database Browser: 891 Gunhild (A918 KB)" (2020-01-28 last obs.). Jet Propulsion Laboratory. Retrieved 25 February 2020.
    4. "Asteroid 891 Gunhild – Proper Elements". AstDyS-2, Asteroids – Dynamic Site. Retrieved 25 February 2020.
    5. "Asteroid 891 Gunhild". Small Bodies Data Ferret. Retrieved 25 February 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 25 February 2020.
    7. 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.
    8. 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 25 February 2020. (online, AcuA catalog p. 153)
    9. 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.
    10. Lazzaro, D.; Angeli, C. A.; Carvano, J. M.; Mothé-Diniz, T.; Duffard, R.; Florczak, M. (November 2004). "S3OS2: the visible spectroscopic survey of 820 asteroids" (PDF). Icarus. 172 (1): 179–220. Bibcode:2004Icar..172..179L. doi:10.1016/j.icarus.2004.06.006. Retrieved 25 February 2020.
    11. Carvano, J. M.; Hasselmann, P. H.; Lazzaro, D.; Mothé-Diniz, T. (February 2010). "SDSS-based taxonomic classification and orbital distribution of main belt asteroids". Astronomy and Astrophysics. 510: 12. Bibcode:2010A&A...510A..43C. doi:10.1051/0004-6361/200913322. Retrieved 25 February 2020. (PDS data set)
    12. 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.
    13. Stephens, R. D. (December 2000). "Rotational Periods and Lightcurves of 891 Gunhild and 1017 Jacqueline" (PDF). Minor Planet Bulletin. 27 (1): 54–55. Bibcode:2000MPBu...27...54S.
    14. Behrend, Raoul. "Asteroids and comets rotation curves – (891) Gunhild". Geneva Observatory. Retrieved 25 February 2020.
    15. Kozdon, Janus; Cantue, Sarah; Montgomery, Kent (April 2016). "Lightcurves of Asteroids 891 Gunhild and 1614 Goldschmidt" (PDF). Minor Planet Bulletin. 43 (2): 171–172. Bibcode:2016MPBu...43..171K. ISSN 1052-8091.
    16. "LCDB Data for (891) Gunhild". Asteroid Lightcurve Database (LCDB). Retrieved 25 February 2020.
    17. Nugent, C. R.; Mainzer, A.; Bauer, J.; Cutri, R. M.; Kramer, E. A.; Grav, T.; et al. (September 2016). "NEOWISE Reactivation Mission Year Two: Asteroid Diameters and Albedos". The Astronomical Journal. 152 (3): 63. arXiv:1606.08923. Bibcode:2016AJ....152...63N. doi:10.3847/0004-6256/152/3/63. ISSN 0004-6256.
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