Spin vectors in the Koronis family: III. (832) Karin

Abstract

Studies of asteroid families constrain models of asteroid collisions and evolution processes, and the Karin cluster within the Koronis family is among the youngest families known (Nesvorný, D., Bottke, Jr., W.F., Dones, L., Levison, H.F. [2002]. Nature 417, 720–722). (832) Karin itself is by far the largest member of the Karin cluster, thus knowledge of Karin’s spin vector is important to constrain family formation and evolution models that include spin, and to test whether its spin properties are consistent with the Karin cluster being a very young family. We observed rotation lightcurves of Karin during its four consecutive apparitions in 2006–2009, and combined the new observations with previously published lightcurves to determine its spin vector orientation and preliminary model shape. Karin is a prograde rotator with a period of (18.352±0.003) h, spin obliquity near (42±5)°, and pole ecliptic longitude near either (52±5)° or (230±5)°. The spin vector and shape results for Karin will constrain models of family formation that include spin properties; in the meantime we briefly discuss Karin’s own spin in the context of those of other members of the Karin cluster and the parent body’s siblings in the Koronis family.