335 Roberta

Roberta (minor planet designation: 335 Roberta) is a large main belt asteroid. It was discovered on 1 September 1892, by German astronomer Anton Staus at Heidelberg Observatory.[3] Roberta was the 12th asteroid that was discovered using photography, and the only asteroid discovery made by Staus.[4]

Photometric observations of this asteroid from multiple sites during 2007 gave a light curve with a period of 12.054 ± 0.003 hours and a brightness variation of 0.13 ± 0.02 in magnitude. This agrees with a result reported in 1992, but differs from period estimates of 8.03 hours and 4.349 reported in 1987 and 2001, respectively.[5]

Under the SMASS classification taxonomy, this asteroid is listed as a B-type; a group that combines both the Tholen B and F types. The spectrum of this object suggests the presence of magnetite (Fe₃O₄), which gives it the spectrally-blue coloration that is a characteristic of this SMASS class. The spectrum of this asteroid also displays a band feature near 2.9 μm that indicate the presence of a hydrated mineral. This suggests that the asteroid has undergone significant water-based alteration.[2]

335 Roberta was identified as one of three asteroids that were likely to be a parent body for chondrites along with 449 Hamburga and 304 Olga.[6] All three asteroids were known to have low-albedo (not reflect as much light) and be close to "meteorite producing resonances".[6] Chrondrites are the most common type of meteor found on Earth, accounting for over 80% of all meteors.[7] They are named for the tiny spherical silicate particles that are found inside them (those particles are called chondrules).[7]