234 Barbara

Barbara (minor planet designation: 234 Barbara) is a main belt asteroid that was discovered by German-American astronomer Christian Heinrich Friedrich Peters on August 12, 1883, in Clinton, New York. The object is orbiting the Sun with a semimajor axis of 2.385 AU, a period of 3.68 years, and an eccentricity of 0.25. The orbital plane is inclined by 15.37° to the plane of the ecliptic. It is classified as a stony S-type asteroid based upon its spectrum. The mean diameter of this object is estimated as 45.6 km.[2] It has a rotation rate of 26.5 hours, or a little over a day.

234 Barbara
Discovery
Discovered byC. H. F. Peters
Discovery date12 August 1883
Designations
(234) Barbara
1942 RL1, 1953 RE,
1975 XP
Main belt
Orbital characteristics[1]
Epoch 31 July 2016 (JD 2457600.5)
Uncertainty parameter 0
Observation arc131.26 yr (47944 d)
Aphelion2.97153 AU (444.535 Gm)
Perihelion1.79939 AU (269.185 Gm)
2.38546 AU (356.860 Gm)
Eccentricity0.24569
3.68 yr (1345.7 d)
19.28 km/s
16.9454°
0° 16m 3.05s / day
Inclination15.3746°
144.553°
192.344°
Physical characteristics
Dimensions43.75±1.0 km[1]
45.62 ± 1.93 km[2]
Mass(0.44 ± 1.45) × 1018 kg[2]
26.4744 h (1.10310 d)
0.2276±0.011
S
9.02

    Observations of light curves and stellar occultations suggest the surface exhibits large concave areas.[3] Polarimetric study of this asteroid reveals anomalous properties that suggests the regolith consists of a mixture of low and high albedo material. This may have been caused by fragmentation of an asteroid substrate with the spectral properties of CO3/CV3 carbonaceous chondrites.[4] It is the prototype for a class of asteroids called "Barbarians" that display a strong infrared absorption band at 2μm, which is a characteristic of an FeO–enriched spinel mineral. Multiple other examples of this class have since been discovered.[5]

    Observations made in 2009 with ESO's Very Large Telescope Interferometer (VLTI) suggested that 234 Barbara may be a binary asteroid,[6] although a paper published in 2015 states that "the VLTI observations can be explained without the presence of a large satellite".[3]

    References
    1. Yeomans, Donald K., "234 Barbara", JPL Small-Body Database Browser, NASA Jet Propulsion Laboratory, retrieved 12 May 2016.
    2. Carry, B. (December 2012), "Density of asteroids", Planetary and Space Science, 73, pp. 98–118, arXiv:1203.4336, Bibcode:2012P&SS...73...98C, doi:10.1016/j.pss.2012.03.009. See Table 1.
    3. Tanga, P.; et al. (April 2015), "The non-convex shape of (234) Barbara, the first Barbarian*", Monthly Notices of the Royal Astronomical Society, 448 (4): 3382–3390, arXiv:1502.00460, Bibcode:2015MNRAS.448.3382T, doi:10.1093/mnras/stv229.
    4. Gil-Hutton, R.; et al. (April 2008), "New cases of unusual polarimetric behavior in asteroids", Astronomy and Astrophysics, 482 (1), pp. 309–314, Bibcode:2008A&A...482..309G, doi:10.1051/0004-6361:20078965.
    5. Devogèle, M.; et al. (April 2018), "New polarimetric and spectroscopic evidence of anomalous enrichment in spinel-bearing calcium-aluminium-rich inclusions among L-type asteroids", Icarus, 304: 31–57, arXiv:1802.06975, Bibcode:2018Icar..304...31D, doi:10.1016/j.icarus.2017.12.026
    6. "Powerful New Technique to Measure Asteroids' Sizes and Shapes". European Southern Observatory. Archived from the original on 22 December 2015. Retrieved 19 December 2015.

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