The Koronis or Koronian family (), also known as the Lacrimosa family, is a very large asteroid family of stony asteroids, located in the outer region of the asteroid belt. They are thought to have been formed at least two billion years ago in a catastrophic collision between two larger bodies. The family is named after its lowest-numbered member 158 Koronis, and the largest known member (208 Lacrimosa) is about in diameter. Koronis family members travel in independent heliocentric orbits which share similar semimajor axes, eccentricities, and inclinations, but the asteroids themselves are not physically clustered in space. The spin poles of several of the large members do appear to be aligned in space. The family has at least 5949 members.
This family has two subfamilies. The Karin family () was formed remarkably recently in a catastrophic collision (destroying the parent body), with an estimated age of 5.72 million years. The Koronis(2) family () with 246 members is the other. It formed 15 million years ago by a non-catastrophic collision with 158 Koronis.
On August 28, 1993, the Galileo spacecraft visited a member of this family, 243 Ida. A photo of Ida (and its tiny moon Dactyl) is part of the composite image at right (numbered 243).
Large members
Asteroid Mediandiameter Semi-major axis Orbitalinclination Orbitaleccentricity Discovered Refs 158 Koronis 35.4 km 2.867 AU 1.00° 0.057 1876 167 Urda 39.9 km 2.855 AU 2.21° 0.035 1876 208 Lacrimosa 41.0 km 2.895 AU 1.751° 0.015 1879 243 Ida 31.3 km 2.861 AU 1.138° 0.046 1884 263 Dresda 23.0 km 2.886 AU 1.314° 0.079 1886 277 Elvira 27.0 km 2.887 AU 1.156° 0.089 1888 311 Claudia 24.0 km 2.897 AU 3.225° 0.008 1891 321 Florentina 27.0 km 2.886 AU 2.594° 0.043 1891 534 Nassovia 32.3 km 2.884 AU 3.277° 0.057 1904 720 Bohlinia 33.7 km 2.888 AU 2.359° 0.014 1911 1223 Neckar 22.8 km 2.869 AU 2.55052º 0.061 1931
References
External links Astronomical studies of the Koronis Family Spins on Koronis family