748 Simeïsa

748 Simeïsa (prov. designation: A913 EL or 1913 RD) is a very large Hilda asteroid from the outermost regions of the asteroid belt, approximately 104 kilometers (65 miles) in diameter. It was discovered on 14 March 1913, by Russian astronomer Grigory Neujmin at the Simeiz Observatory on the Crimean peninsula.[1] The dark P-type asteroid has a rotation period of 11.9 hours and a shape that is reminiscent of a tetrahedron. It was the first asteroid discovery made in Russia and named after the discovering observatory and its nearby Crimean town, Simeiz.[2]

748 Simeïsa
Modelled shape of Simeïsa from its lightcurve
Discovery [1]
Discovered byG. Neujmin
Discovery siteSimeiz Obs.
Discovery date14 March 1913
Designations
(748) Simeïsa
Named after
Simeiz/Simeiz Obs. [2]
(Town and Observatory)
A913 EL · 1925 QG
1936 BG · 1941 SU
1942 XU · 1944 DC
1951 CX · 1957 UL1
1963 MC · 1913 RD
Orbital characteristics [3]
Epoch 31 May 2020 (JD 2459000.5)
Uncertainty parameter 0
Observation arc99.96 yr (36,509 d)
Aphelion4.6898 AU
Perihelion3.2045 AU
3.9472 AU
Eccentricity0.1881
7.84 yr (2,864 d)
324.14°
0° 7m 32.52s / day
Inclination2.2587°
265.46°
177.73°
Jupiter MOID0.5637 AU
TJupiter3.0280
Physical characteristics
Dimensions(109.7 km × 93.2 km)
Mean diameter
  • 102.97±2.2 km[5]
  • 103.725±1.034 km[6][7]
  • 111.75±2.31 km[8]
11.919±0.002 h[9]

    Orbit and classification

    Simeïsa is a member of the distant orbital Hilda group of asteroids, which stay in a 3:2 orbital resonance with the gas giant Jupiter.[1][11][12] It is however not a member of the collisional Hilda family (001) but a non-family asteroid of the background population when applying the hierarchical clustering method to its proper orbital elements.[11] It orbits the Sun in the outermost asteroid belt at a distance of 3.2–4.7 AU once every 7 years and 10 months (2,864 days; semi-major axis of 3.95 AU). Its orbit has an eccentricity of 0.19 and an inclination of 2° with respect to the ecliptic.[3] The body's observation arc begins at the Heidelberg Observatory on 19 February 1920, almost 7 years after its official discovery observation by Grigory Neujmin at Simeiz.[1]

    Naming

    This minor planet was named after the discovering Simeiz Observatory and its nearby Crimean town, Simeiz. Simeïsa was the first minor planet discovered in Russia. The naming citation was mentioned in The Names of the Minor Planets by Paul Herget in 1955 (H 75).[2]

    Physical characteristics

    In the Tholen classification, Simeïsa is a dark and primitive P-type asteroid,[3] which are common in the outer regions of asteroid belt and among the Jupiter trojan population. In the SDSS-based taxonomy, it is an X-type asteroid.[10][12]

    Rotation period

    In October 2011, a rotational lightcurve of Simeïsa was obtained from photometric observations by French amateur astronomer René Roy. Lightcurve analysis gave a rotation period of (11.919±0.002) hours with a brightness variation of (0.36±0.03) magnitude (U=2).[9] In the 1990s, Mats Dahlgren already determined a period of 11.88 hours with an amplitude of 0.22 magnitude (U=2).[13]

    Diameter and albedo

    According to the surveys carried out by the Infrared Astronomical Satellite IRAS, the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer (WISE), and the Japanese Akari satellite, Simeïsa measures (102.97±2.2), (103.725±1.034) and (111.75±2.31) kilometers in diameter and its surface has a low albedo of (0.0415±0.002), (0.041±0.007) and (0.035±0.002), respectively.[5][6][7][8]

    The Collaborative Asteroid Lightcurve Link assumes an albedo of 0.0376 and derives a diameter of 102.79 kilometers based on an absolute magnitude of 9.12.[4] Alternative mean-diameter measurements published by the WISE team include (103.714±1.128 km) and (109.069±38.907 km) with corresponding albedos of (0.041±0.007) and (0.045±0.027).[4][12]

    Two asteroid occultations on 4 March 1999 and 7 January 2006, gave a best-fit ellipse dimension of (106.0 km × 106.0 km) and (109.7 km × 93.2 km), respectively, each with a quality rating of 2.[12] These timed observations are taken when the asteroid passes in front of a distant star.[12]

    References
    1. "748 Simeisa (A913 EL)". Minor Planet Center. Retrieved 5 June 2020.
    2. Schmadel, Lutz D. (2007). "(748) Simeïsa". Dictionary of Minor Planet Names. Springer Berlin Heidelberg. p. 71. doi:10.1007/978-3-540-29925-7_749. ISBN 978-3-540-00238-3.
    3. "JPL Small-Body Database Browser: 748 Simeisa (A913 EL)" (2020-02-03 last obs.). Jet Propulsion Laboratory. Retrieved 5 June 2020.
    4. "LCDB Data for (748) Simeïsa". Asteroid Lightcurve Database (LCDB). Retrieved 5 June 2020.
    5. 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 5 June 2020.
    6. Grav, T.; Mainzer, A. K.; Bauer, J.; Masiero, J.; Spahr, T.; McMillan, R. S.; et al. (January 2012). "WISE/NEOWISE Observations of the Hilda Population: Preliminary Results". The Astrophysical Journal. 744 (2): 15. arXiv:1110.0283. Bibcode:2012ApJ...744..197G. doi:10.1088/0004-637X/744/2/197.
    7. Mainzer, A. K.; Bauer, J. M.; Cutri, R. M.; Grav, T.; Kramer, E. A.; Masiero, J. R.; et al. (June 2016). "NEOWISE Diameters and Albedos V1.0". NASA Planetary Data System. Bibcode:2016PDSS..247.....M. Retrieved 5 June 2020.
    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 5 June 2020. (online, AcuA catalog p. 153)
    9. Behrend, Raoul. "Asteroids and comets rotation curves – (748) Simeïsa". Geneva Observatory. Retrieved 5 June 2020.
    10. 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 5 June 2020. (PDS data set)
    11. "Asteroid 748 Simeisa – Proper Elements". AstDyS-2, Asteroids – Dynamic Site. Retrieved 5 June 2020.
    12. "Asteroid 748 Simeisa". Small Bodies Data Ferret. Retrieved 5 June 2020.
    13. Dahlgren, M.; Lahulla, J. F.; Lagerkvist, C. -I.; Lagerros, J.; Mottola, S.; Erikson, A.; et al. (June 1998). "A Study of Hilda Asteroids. V. Lightcurves of 47 Hilda Asteroids". Icarus. 133 (2): 247–285. Bibcode:1998Icar..133..247D. doi:10.1006/icar.1998.5919. ISSN 0019-1035.
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