234 Barbara

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. It is possibly named for Saint Barbara, patron saint of mathematicians.^[3][4]

234 Barbara

Discovery
Discovered by	C. H. F. Peters
Discovery date	12 August 1883
Designations
MPC designation	(234) Barbara
Named after	Saint Barbara?
Alternative designations	A883 PA, 1942 RL1 1953 RE,1975 XP
Minor planet category	Main belt
Orbital characteristics[1]
Epoch 31 July 2016 (JD 2457600.5)
Uncertainty parameter 0
Observation arc	131.26 yr (47944 d)
Aphelion	2.97153 AU (444.535 Gm)
Perihelion	1.79939 AU (269.185 Gm)
Semi-major axis	2.38546 AU (356.860 Gm)
Eccentricity	0.24569
Orbital period (sidereal)	3.68 yr (1345.7 d)
Average orbital speed	19.28 km/s
Mean anomaly	16.9454°
Mean motion	0° 16m 3.05s / day
Inclination	15.3746°
Longitude of ascending node	144.553°
Argument of perihelion	192.344°
Physical characteristics
Dimensions	43.75±1.0 km[1] 45.62 ± 1.93 km[2]
Mass	(0.44 ± 1.45) × 1018 kg[2]
Synodic rotation period	26.4744 h (1.10310 d)
Geometric albedo	0.2276±0.011
Spectral type	S
Absolute magnitude (H)	9.02

Observations of light curves and stellar occultations suggest the surface exhibits large concave areas.^[5] 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.^[6] 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.^[7]

Observations made in 2009 with ESO's Very Large Telescope Interferometer (VLTI) suggested that 234 Barbara may be a binary asteroid,^[8] although a paper published in 2015 states that "the VLTI observations can be explained without the presence of a large satellite".^[5]