7803 Adachi

7803 Adachi, provisional designation 1997 EW2, is a stony Agnia asteroid from the middle region of the asteroid belt, approximately 6.4 kilometers (4 miles) in diameter. The asteroid was discovered on 4 March 1997, by Japanese amateur astronomer Takao Kobayashi at the Ōizumi Observatory in central Japan. It was named for Japanese amateur astronomer Makoto Adachi.[1] The S-type asteroid has a rotation period of 5.2 hours.[6]

7803 Adachi
Discovery [1]
Discovered byT. Kobayashi
Discovery siteŌizumi Obs.
Discovery date4 March 1997
Designations
(7803) Adachi
Named after
Makoto Adachi [1]
(amateur astronomer)
1997 EW2 · 1973 AA3
1976 UY17 · 1978 EM1
1992 CF2
main-belt [1][2] · (middle)
Agnia [3]
Orbital characteristics [2]
Epoch 23 March 2018 (JD 2458200.5)
Uncertainty parameter 0
Observation arc63.96 yr (23,363 d)
Aphelion2.9253 AU
Perihelion2.6459 AU
2.7856 AU
Eccentricity0.0502
4.65 yr (1,698 d)
239.11°
0° 12m 43.2s / day
Inclination4.9969°
110.63°
8.8759°
Physical characteristics
Dimensions6.359±0.129 km[4][5]
10.31 km (calculated)[6]
5.1966±0.0082 h[7]
0.057 (assumed)[6]
0.251±0.055[4][5]
S [8] · C (generic)[6]
13.1[4] · 13.212±0.005 (R)[7] · 13.3[2] · 13.65±0.27[8] · 13.66[6]

    Orbit and classification

    Adachi is a member of the Agnia family (514),[3][9] a very large family of stony asteroids with more than 2000 known members.[10] They most likely formed from the breakup of a basalt object, which in turn was spawned from a larger parent body that underwent igneous differentiation.[9] The family's parent body and namesake is the asteroid 847 Agnia.[10]

    It orbits the Sun in the central asteroid belt at a distance of 2.6–2.9 AU once every 4 years and 8 months (1,698 days; semi-major axis of 2.79 AU). Its orbit has an eccentricity of 0.05 and an inclination of 5° with respect to the ecliptic.[2] The first precovery was taken at the U.S. Palomar Observatory in 1953, extending the asteroid's observation arc by 44 years prior to it discovery.[1]

    Physical characteristics

    Adachi has been characterized as a stony S-type asteroid by Pan-STARRS photometric survey,[8] which agrees with the Agnia family's overall spectral type.[10] :23

    Diameter and albedo

    According to the survey carried out by the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, Adachi measures 6.359 kilometers in diameter and its surface has an albedo between 0.251 and 0.2513.[4][5] The Collaborative Asteroid Lightcurve Link assumes a generic, carbonaceous albedo of 0.057 for all minor planets with a semi-major axis of more than 2.7 AU, and consequently calculates a larger diameter of 10.31 kilometers using an absolute magnitude of 13.66.[6]

    Rotation period

    In August 2013, a rotational lightcurve of Adachi was obtained through photometric observations at the Palomar Transient Factory in California. It showed a period of 5.1966 hours with a brightness variation of 0.31 magnitude (U=2).[7]

    Naming

    This minor planet was named after Makoto Adachi (born 1953), Japanese amateur astronomer and elementary school teacher from Kyoto. He is the director of the Oriental Astronomical Association and a long-time direct observer of the Solar System's planets, especially Jupiter.[1] The approved naming citation was published by the Minor Planet Center on 6 August 2003 (M.P.C. 49279).[11]

    References
    1. "7803 Adachi (1997 EW2)". Minor Planet Center. Retrieved 28 April 2016.
    2. "JPL Small-Body Database Browser: 7803 Adachi (1997 EW2)" (2017-09-27 last obs.). Jet Propulsion Laboratory. Retrieved 8 March 2018.
    3. "Asteroid 7803 Adachi – Nesvorny HCM Asteroid Families V3.0". Small Bodies Data Ferret. Retrieved 27 October 2019.
    4. Mainzer, A.; Grav, T.; Masiero, J.; Hand, E.; Bauer, J.; Tholen, D.; et al. (November 2011). "NEOWISE Studies of Spectrophotometrically Classified Asteroids: Preliminary Results". The Astrophysical Journal. 741 (2): 25. arXiv:1109.6407. Bibcode:2011ApJ...741...90M. doi:10.1088/0004-637X/741/2/90.
    5. Masiero, Joseph R.; Mainzer, A. K.; Grav, T.; Bauer, J. M.; Cutri, R. M.; Dailey, J.; et al. (November 2011). "Main Belt Asteroids with WISE/NEOWISE. I. Preliminary Albedos and Diameters". The Astrophysical Journal. 741 (2): 20. arXiv:1109.4096. Bibcode:2011ApJ...741...68M. doi:10.1088/0004-637X/741/2/68.
    6. "LCDB Data for (7803) Adachi". Asteroid Lightcurve Database (LCDB). Retrieved 28 April 2016.
    7. 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): 35. arXiv:1504.04041. Bibcode:2015AJ....150...75W. doi:10.1088/0004-6256/150/3/75.
    8. Veres, Peter; Jedicke, Robert; Fitzsimmons, Alan; Denneau, Larry; Granvik, Mikael; Bolin, Bryce; et al. (November 2015). "Absolute magnitudes and slope parameters for 250,000 asteroids observed by Pan-STARRS PS1 - Preliminary results". Icarus. 261: 34–47. arXiv:1506.00762. Bibcode:2015Icar..261...34V. doi:10.1016/j.icarus.2015.08.007.
    9. Sunshine, Jessica M.; Bus, Schelte J.; McCoy, Timothy J.; Burbine, Thomas H.; Corrigan, Catherine M.; Binzel, Richard P. (August 2004). "High-calcium pyroxene as an indicator of igneous differentiation in asteroids and meteorites". Meteoritics and Planetary Science. 39 (8): 1343–1357. Bibcode:2004M&PS...39.1343S. doi:10.1111/j.1945-5100.2004.tb00950.x. Retrieved 8 March 2018.
    10. Nesvorný, D.; Broz, M.; Carruba, V. (December 2014). Identification and Dynamical Properties of Asteroid Families. Asteroids IV. pp. 297–321. arXiv:1502.01628. Bibcode:2015aste.book..297N. doi:10.2458/azu_uapress_9780816532131-ch016. ISBN 9780816532131.
    11. "MPC/MPO/MPS Archive". Minor Planet Center. Retrieved 28 April 2016.

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