Fortuna is 225 km in diameter and has one of the darkest known geometric albedos for an asteroid over 150 km in diameter. Its albedo has been measured at 0.028 and 0.037.[8] The spectra of the asteroid displays evidence of aqueous alteration.[9]
The Hubble Space Telescope observed Fortuna in 1993. It was resolved with an apparent diameter of 0.20 arcseconds (4.5 pixels in the Planetary Camera) and its shape was found to be nearly spherical. Satellites were searched for but none were detected.
It was discovered by J. R. Hind on 22 August 1852, and named after Fortuna, the Roman goddess of luck. Its historical symbol was a star over Fortune's wheel; it is in the pipeline for Unicode 17.0 as U+1CECC ().[11][12]
Fortuna has been perturbed by the 80 km 135 Hertha and was initially estimated by Baer to have a mass of 1.08×1019 kg.[6] A more recent estimate by Baer suggests it has a mass of 1.27×1019 kg.[3]
On 21 December 2012, Fortuna (~200 km) harmlessly passed within 6.5 Gm of asteroid 687 Tinette.[13]
Notes
^Flattening derived from the maximum aspect ratio (c/a): , where (c/a) = 0.79±0.05.[4]
References
^Noah Webster (1884) A Practical Dictionary of the English Language
^ abcdefghijkP. Vernazza et al. (2021) VLT/SPHERE imaging survey of the largest main-belt asteroids: Final results and synthesis. Astronomy & Astrophysics 54, A56