The Ennomos family (009[1]) is a small collisional asteroid family of at least 28 known asteroids,[2] named for its largest member, the 81km (50miles)-across asteroid 4709 Ennomos. It lies within the larger dynamical group of Jupiter trojans, a group of asteroids in an orbital resonance with Jupiter such that they stay about 60 degrees ahead of/behind the planet in its orbit at all times in the Lagrange points L4 and L5, with the Ennomos family being part of the trailing cloud around L5, also known as the Trojan camp. All members of the family are dark (assumed to be C-type asteroids) with albedos of around 0.09.
An asteroid family is a group of physically related asteroids usually created by a collision with an original larger asteroid, with the fragments continuing on similar orbits to the original. This is distinct from a dynamical group in that the members of a dynamical group only share similar orbits because of gravitational interactions with planets, which concentrate asteroids in a particular orbital range. Members of the Ennomos family are both part of the wider Trojan dynamical group, and fragments of 4709 Ennomos. The family is considered a non-catastrophic asteroid family because 4709 Ennomos, its largest member, makes up a majority of the family's total mass, rather than simply being the largest of a number of fragments each making up a small fraction of the original destroyed asteroid.[3]
The trojan 1867 Deiphobus is a large interloper in the family's orbital region. A 2024 study found Deiphobus to have its own overlapping family to the Ennomos family, albeit with a slightly higher inclination.[4] As a result, some of the members included as part of the Ennomos family may actually belong to the Deiphobus family and vice versa.
| Name | Size (km) | proper a (AU) | proper i | |||
|---|---|---|---|---|---|---|
| 8.66 | 81 | 5.2965 | 0.032 | 26.825 | ||
| 10.08 | 54 | 5.3316 | 0.028 | 27.611 | ||
| 10.49 | 43 | 5.2616 | 0.027 | 28.136 | ||
| 11.25 | 31 | 5.3069 | 0.038 | 27.498 | ||
| 11.67 | 32 | 5.2851 | 0.027 | 27.377 | ||
| 12.17 | 20 | 5.3347 | 0.038 | 27.786 | ||
| 12.51 | 14 | 5.3308 | 0.034 | 27.114 | ||
| 12.60 | 21 | 5.3210 | 0.041 | 27.276 | ||
| 12.63 | 20 | 5.2996 | 0.034 | 27.868 | ||
| 12.63 | 21 | 5.2841 | 0.029 | 28.044 |