335 Roberta

335 Roberta

Discovery
Discovered by	Anton Staus
Discovery date	September 1, 1892
Designations
Named after	Karl Robert Osten-Sacken
Alternative names	1892 C
Minor planet category	Main belt
Orbital characteristics
Epoch 30 January 2005 (JD 2453400.5)
Aphelion	434.501 Gm (2.904 AU)
Perihelion	305.856 Gm (2.045 AU)
Semi-major axis	370.178 Gm (2.474 AU)
Eccentricity	0.174
Orbital period
Average orbital speed	18.93 km/s
Mean anomaly	12.696°
Inclination	5.093°
Longitude of ascending node	148.541°
Argument of perihelion	139.567°
Physical characteristics
Dimensions	89.1 km
Rotation period	12.054 h
Albedo	0.058
Spectral type	FP/B
Absolute magnitude (H)	8.96

335 Roberta is a large main belt asteroid. It was discovered by German astronomer Anton Staus on September 1, 1892 in Heidelberg. This was his only asteroid discovery.

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.

Under the SMASS classification taxonomy, Polana is listed as a B-type asteroid; 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.

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. All three asteroids were known to have low-albedo (not reflect as much light) and be close to "meteorite producing resonances". Chrondrites are the most common type of meteor found on Earth, accounting for over 80% of all meteors. They are named for the tiny spherical silicate particles that are found inside them (those particles are called chondrules).