3430 Bradfield

3430 Bradfield (prov. designation: 1980 TF4) is a stony Agnia asteroid from the central regions of the asteroid belt, approximately 8 kilometers (5 miles) in diameter. It was discovered on 9 October 1980, by American astronomer Carolyn Shoemaker at the Palomar Observatory in California. The Sq-type asteroid was named after comet hunter William A. Bradfield.[1]

3430 Bradfield
Shape model of Bradfield from its lightcurve
Discovery [1]
Discovered byC. Shoemaker
Discovery sitePalomar Obs.
Discovery date9 October 1980
Designations
(3430) Bradfield
Named after
William A. Bradfield
(discoverer of comets)
1980 TF4 · 1974 HY1
1976 YS7
main-belt [1][2] · (middle)
Agnia [3]
Orbital characteristics [2]
Epoch 23 March 2018 (JD 2458200.5)
Uncertainty parameter 0
Observation arc43.93 yr (16,044 d)
Aphelion3.0293 AU
Perihelion2.4890 AU
2.7592 AU
Eccentricity0.0979
4.58 yr (1,674 d)
102.11°
0° 12m 54s / day
Inclination4.4281°
43.225°
278.60°
Physical characteristics
Mean diameter
8.492±0.263 km[4]
0.269±0.035[4]
SMASS = Sq [2]
12.5[1][2]

    Orbit and classification

    When applying the hierarchical clustering method to its proper orbital elements according to Nesvorný, Bradfield is a member of the Agnia family (514),[3] a very large family of stony asteroids with more than 2000 known members.[5] 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.[6] The family's parent body and namesake is the asteroid 847 Agnia.[5] In the 1995-HCM analysis by Zappalà, however, it is a member of the Liberatrix family (also described as Nemesis family by Nesvorný).[3][7]

    It orbits the Sun in the central main-belt at a distance of 2.5–3.0 AU once every 4 years and 7 months (1,674 days; semi-major axis of 2.76 AU). Its orbit has an eccentricity of 0.10 and an inclination of 4° with respect to the ecliptic.[2] The body's observation arc begins with its observations as 1974 HY1 at Cerro El Roble Observatory in April 1974, more than 6 years prior to its official discovery observation at Palomar.[1]

    Naming

    This minor planet was named after New Zealand-born Australian amateur astronomer and rocket engineer William A. Bradfield (1927–2014). A discoverer of several comets himself, he significantly increased the rate of discovery of bright comets from the southern hemisphere during the 1970s and 1980s.[1] The official naming citation was published by the Minor Planet Center on 14 April 1987 (M.P.C. 11750).[8]

    Physical characteristics

    In the SMASS classification, Bradfield is an Sq-subtype, that transitions between the common, stony S-type and Q-type asteroids.[2]

    Diameter and albedo

    According to the survey carried out by the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, Bradfield measures 8.492 kilometers in diameter and its surface has an albedo of 0.269.[4]

    Rotation period

    As of 2018, no rotational lightcurve of Bradfield has been obtained from photometric observations. The body's rotation period, pole and shape remain unknown.[2]

    gollark: Oh, we don't have a column for gibson!
    gollark: Just in general.
    gollark: I should put lyric down as 0 for insults.
    gollark: I don't know, andrew.
    gollark: Computing power?

    References
    1. "3430 Bradfield (1980 TF4)". Minor Planet Center. Retrieved 12 April 2018.
    2. "JPL Small-Body Database Browser: 3430 Bradfield (1980 TF4)" (2018-03-28 last obs.). Jet Propulsion Laboratory. Retrieved 12 April 2018.
    3. "Asteroid 3430 Bradfield – Nesvorny HCM Asteroid Families V3.0". Small Bodies Data Ferret. Retrieved 26 October 2019.
    4. 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.
    5. 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.
    6. 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 12 April 2018.
    7. Zappalà, V.; Bendjoya, Ph.; Cellino, A.; Farinella, P.; Froeschle, C. (1997). "Asteroid Dynamical Families". NASA Planetary Data System: EAR-A-5-DDR-FAMILY-V4.1. Retrieved 19 March 2020.} (PDS main page)
    8. "MPC/MPO/MPS Archive". Minor Planet Center. Retrieved 12 April 2018.
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