The Nysa or Nysian asteroids (also known as the Hertha family or the Polana family) are a group of asteroids in the asteroid belt orbiting the Sun between 2.41 and 2.5 AU. Asteroids in this family have eccentricities between 0.12 and 0.21 and inclinations of 1.4 to 4.3. The family derives its name from its most massive member, 44 Nysa. It has also been known as the Hertha (Herthian) family.
Asteroids in the Nysa family are typically divided into two, mineralogically different subgroups: Nysa and Polana. Aside from 44 Nysa and 135 Hertha, asteroids in the Nysian subgroup are S-type asteroids. Asteroids in the Polanian subgroup, like 142 Polana, are F-type asteroids.
- EasySky - Screenshots
- [5.05] The puzzling case of the Nysa-Polana family finally solved ?
- A. Cellino; V. Zappala; A. Doressoundiram; M. Di Martino; et al. (August 2001). "The Puzzling Case of the Nysa-Polana Family". Icarus (Icarus) 152 (2): 225–237. Bibcode:2001Icar..152..225C. doi:10.1006/icar.2001.6634.
- Zappalà, Vincenzo; Bendjoya, Philippe; Cellino, Alberto; Farinella, Paolo; Froeschlé, Claude (1997). "Asteroid Dynamical Families". EAR-A-5-DDR-FAMILY-V4.1. NASA Planetary Data System.
- JPL Small-Body Database Browser
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