923 Herluga

923 Herluga (prov. designation: A919 SK or 1919 GB) is a three-body resonant background asteroid, approximately 34 kilometers (21 miles) in diameter, located in the central region of the asteroid belt. It was discovered on 30 September 1919, by astronomer Karl Reinmuth at the Heidelberg Observatory in southwest Germany.[1] The carbonaceous C-type asteroid has a rotation period of 19.7 hours. It was named "Herluga", a common German female name unrelated to the discoverer's contemporaries, that was taken from the almanac Lahrer Hinkender Bote.[2][3]

923 Herluga
Discovery [1]
Discovered byK. Reinmuth
Discovery siteHeidelberg Obs.
Discovery date30 September 1919
Designations
(923) Herluga
Named after
Name picked from the almanac
Lahrer Hinkender Bote [2][3]
A919 SK · A915 VD
1919 GB · 1915 VD
main-belt [1][4] · (middle)
background [5][6]
Orbital characteristics [4]
Epoch 31 May 2020 (JD 2459000.5)
Uncertainty parameter 0
Observation arc99.61 yr (36,382 d)
Aphelion3.1271 AU
Perihelion2.1071 AU
2.6171 AU
Eccentricity0.1949
4.23 yr (1,546 d)
268.52°
0° 13m 58.08s / day
Inclination14.458°
197.52°
201.11°
Physical characteristics
Mean diameter
  • 32.47±0.8 km[7]
  • 34.553±0.269 km[8]
  • 34.78±0.63 km[9]
19.746±0.002 h[10]
  • 0.037±0.002[9]
  • 0.037±0.006[8]
  • 0.0421±0.002[7]
C (S3OS2)[11]
11.50[1][4]

    Orbit and classification

    Herluga is a non-family asteroid of the main belt's background population when applying the hierarchical clustering method to its proper orbital elements.[5][6] Located in the orbital region of the Eunomia family,[12] Herluga orbits the Sun in the central asteroid belt at a distance of 2.1–3.1 AU once every 4 years and 3 months (1,546 days; semi-major axis of 2.62 AU). Its orbit has an eccentricity of 0.19 and an inclination of 14° with respect to the ecliptic.[4] This brings the object into a pure three-body resonance (2/2/-1) with Jupiter and Saturn (ares 2.615 AU).[5][13]:6 Other asteroids in this resonant group of 34 known objects include 70 Panopaea, 194 Prokne, 258 Tyche, 839 Valborg and 995 Sternberga.[13]:24 Herluga was first observed as A915 VD (1915 VD) at Simeiz Observatory on the Crimean peninsula on 9 November 1915. The body's observation arc begins at Heidelberg Observatory on 10 December 1919, more than two months after its official discovery observation.[1]

    Naming

    This minor planet was named "Herluga", after a female name picked from the Lahrer Hinkender Bote, published in Lahr, southern Germany.[2] A Hinkender Bote (lit. "limping messenger") was a very popular almanac,[3] especially in the alemannic-speaking region from the late 17th throughout the early 20th century. The calendar section contains feast days, the dates of important fairs and astronomical ephemerides. For 2 March, the calendar gives "Herluga" as the German name day analogue next to Simplizius and Luise, the protestant and catholic entries in the calendar of saints.[14]

    Reinmuth's calendar names

    As with 22 other asteroids – starting with 913 Otila, and ending with 1144 Oda – Reinmuth selected names from this calendar due to his many asteroid discoveries that he had trouble thinking of proper names. These names are not related to the discoverer's contemporaries. Lutz Schmadel, the author of the Dictionary of Minor Planet Names learned about Reinmuth's source of inspiration from private communications with Dutch astronomer Ingrid van Houten-Groeneveld, who worked as a young astronomer at Heidelberg.[2]

    Physical characteristics

    In both the Tholen- and SMASS-like taxonomy of the Small Solar System Objects Spectroscopic Survey (S3OS2), Herluga is a common, carbonaceous C-type asteroid.[6][11]

    Rotation period

    In November 2008, a rotational lightcurve of Herluga was obtained from photometric observations by James W. Brinsfield at the Via Capote Observatory (G69) in California. Lightcurve analysis gave a rotation period of 19.746±0.002 hours with a brightness variation of 0.16±0.02 magnitude (U=2).[10] In August 2016, an alternative period determination of 29.71±0.04 hours with an amplitude of 0.28±0.02 mag was published (U=2).[15]

    Diameter and albedo

    According to the survey carried out by the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer (WISE), the Japanese Akari satellite, and the Infrared Astronomical Satellite IRAS, Herluga measures (32.47±0.8), (34.553±0.269) and (34.78±0.63) kilometers in diameter and its surface has a low albedo of (0.0421±0.002), (0.037±0.006) and (0.037±0.002), respectively.[7][8][9] The Collaborative Asteroid Lightcurve Link adopts the results obtained by IRAS, that is, an albedo of 0.0421 and a diameter of 32.47 km based on an absolute magnitude of 11.5.[12] Further published mean-diameters by the WISE team in ascending order include (30.558±10.39 km), (31.89±10.59 km), (33.794±7.947 km), (34.142±10.733 km) and (37.638±0.190 km) with albedos between 0.03 and 0.06.[6][12]

    References
    1. "923 Herluga (A919 SK)". Minor Planet Center. Retrieved 21 February 2020.
    2. Schmadel, Lutz D. (2007). "(923) Herluga". Dictionary of Minor Planet Names. Springer Berlin Heidelberg. p. 82. doi:10.1007/978-3-540-29925-7_924. ISBN 978-3-540-00238-3.
    3. "Lahrer hinkender Bote – Kalender 1925". Badischen Landesbibliothek. 1925. p. 1. Retrieved 21 February 2020. Lahrer Bote archive
    4. "JPL Small-Body Database Browser: 923 Herluga (A919 SK)" (2019-05-10 last obs.). Jet Propulsion Laboratory. Retrieved 21 February 2020.
    5. "Asteroid 923 Herluga – Proper Elements". AstDyS-2, Asteroids – Dynamic Site. Retrieved 21 February 2020.
    6. "Asteroid 923 Herluga". Small Bodies Data Ferret. Retrieved 21 February 2020.
    7. 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 21 February 2020.
    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. 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 21 February 2020. (online, AcuA catalog p. 153)
    10. Brinsfield, James W. (April 2009). "Asteroid Lightcurve Analysis at the Via Capote Observatory: 2008 4th Quarter" (PDF). Minor Planet Bulletin. 36 (2): 64–66. Bibcode:2009MPBu...36...64B. ISSN 1052-8091.
    11. 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 21 February 2020.
    12. "LCDB Data for (923) Herluga". Asteroid Lightcurve Database (LCDB). Retrieved 21 February 2020.
    13. Smirnov, E. A.; Shevchenko, I. I. (May 2012). "Massive Identification of Asteroids in Three-Body Resonances". Asteroids, Comets, Meteors 2012. 1667: 6012. arXiv:1206.1451. Bibcode:2012LPICo1667.6012S. ISSN 0161-5297.
    14. "Lahrer hinkender Bote – Kalender 1925". Badischen Landesbibliothek. 1925. p. 6. Retrieved 21 February 2020.
    15. Marciniak, A.; Bartczak, P.; Müller, T.; Sanabria, J. J.; Alí-Lagoa, V.; Antonini, P.; et al. (February 2018). "Photometric survey, modelling, and scaling of long-period and low-amplitude asteroids". Astronomy and Astrophysics. 610: A7. arXiv:1711.01893. Bibcode:2018A&A...610A...7M. ISSN 0004-6361.
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