4949 Akasofu

4949 Akasofu, provisional designation 1988 WE, is a stony Flora asteroid from the inner regions of the asteroid belt, approximately 5 kilometers in diameter. It was discovered by Japanese amateur astronomer Takuo Kojima at the YGCO Chiyoda Station in Japan on 29 November 1988.[8] The asteroid was named for Japanese geophysicist Syun-Ichi Akasofu

4949 Akasofu
Discovery [1]
Discovered byT. Kojima
Discovery siteYGCO Chiyoda Stn.
Discovery date29 November 1988
Designations
(4949) Akasofu
Named after
Syun-Ichi Akasofu
(geophysicist)[2]
1988 WE · 1978 YE
1981 RL5 · 1981 SV6
main-belt · Flora [3]
Orbital characteristics [1]
Epoch 4 September 2017 (JD 2458000.5)
Uncertainty parameter 0
Observation arc38.45 yr (14,044 days)
Aphelion2.6555 AU
Perihelion1.8904 AU
2.2729 AU
Eccentricity0.1683
3.43 yr (1,252 days)
163.34°
0° 17m 15.36s / day
Inclination4.8106°
108.70°
275.40°
Physical characteristics
Dimensions4.460±0.181 km[4][5]
5.67 km (calculated)[3]
2.6798±0.0002 h[6]
2.6800±0.0003 h[lower-alpha 1]
0.24 (assumed)[3]
0.322±0.055[4][5]
S [3]
13.4[1][3] · 13.6[4] · 13.49±0.14[7]

    Orbit and classification

    Akasofu is a member of the Flora family, one of the largest groups of stony asteroids in the main-belt. It orbits the Sun in the inner main-belt at a distance of 1.9–2.7 AU once every 3 years and 5 months (1,252 days). Its orbit has an eccentricity of 0.17 and an inclination of 5° with respect to the ecliptic.[1] In 1978, it was first identified as 1978 YE at the Purple Mountain Observatory, extending the body's observation arc by 10 years prior to its official discovery observation at Chiyoda Station.[8]

    Physical characteristics

    Rotation period

    According to the survey carried out by the NEOWISE mission of NASA's space-based Wide-field Infrared Survey Explorer, Akasofu measures 4.5 kilometers in diameter and its surface has an albedo of 0.32,[4][5] while the Collaborative Asteroid Lightcurve Link assumes an intermediate albedo of 0.24 – which derives from 8 Flora, the largest member and namesake of this orbital family – and calculates a diameter of 5.7 kilometers with an absolute magnitude of 13.4.[3]

    Diameter and albedo

    In October 2005, a rotational lightcurve of Akasofu was obtained from photometric observations made by David Higgins at Hunters Hill Observatory, Australia. It showed a rotation period of 2.6798 hours with a brightness variation of 0.10 in magnitude (U=3).[6]

    Observations by Czech astronomer Petr Pravec in March 2007, gave another well-defined and concurring lightcurve with a period of 2.6800 hours and an amplitude of 0.15 in magnitude (U=3).[lower-alpha 1]

    Naming

    This minor planet was named in honor of Japanese-born geophysicist Syun-Ichi Akasofu (born 1930), professor at University of Alaska Fairbanks. He was the director of the International Arctic Research Center from 1998 to 2007, and is known for studies of the aurora borealis.[2] The official naming citation was published by the Minor Planet Center on 30 March 2010 (M.P.C. 69491).[9]

    Notes
    1. Pravec (2007): lightcuve plot for (4949) Akasofu, with a rotation period 2.6800±0.0003 hours with a brightness amplitude of 0.15 magnitude. Summary figures at Collaborative Asteroid Lightcurve Link (CALL)

    References
    1. "JPL Small-Body Database Browser: 4949 Akasofu (1988 WE)" (2017-06-05 last obs.). Jet Propulsion Laboratory. Retrieved 20 June 2017.
    2. Schmadel, Lutz D. (2003). Dictionary of Minor Planet Names – (4949) Akasofu. Springer Berlin Heidelberg. p. 402. ISBN 978-3-540-29925-7. Retrieved 30 December 2015.
    3. "LCDB Data for (4949) Akasofu". Asteroid Lightcurve Database (LCDB). Retrieved 3 May 2016.
    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. Retrieved 3 May 2016.
    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. Retrieved 5 December 2016.
    6. Higgins, David; Pravec, Petr; Kusnirak, Peter; Masi, Gianluca; Galad, Adrian; Gajdos, Stefan; et al. (March 2006). "Asteriod [sic] lightcurve analysis at Hunters Hill Observatory and collaborating stations - autumn/winter 2005". The Minor Planet Bulletin. 33 (1): 8–10. Bibcode:2006MPBu...33....8H. ISSN 1052-8091. Retrieved 3 May 2016.
    7. 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. Retrieved 3 May 2016.
    8. "4949 Akasofu (1988 WE)". Minor Planet Center. Retrieved 3 May 2016.
    9. "MPC/MPO/MPS Archive". Minor Planet Center. Retrieved 3 May 2016.

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