This is a list ofslow rotators—minor planets that have anexceptionally longrotation period. This period, typically given in hours, and sometimes called rotation rate or spin rate, is a fundamental standardphysical property for minor planets. In recent years, the periods of many thousands of bodies have been obtained fromphotometric and, to a lesser extent,radiometric observations.

The periods given in this list are sourced from theLight Curve Data Base (LCDB),^[2] which containslightcurve data for more than 15,000 bodies. Most minor planets have rotation periods between 2 and 20 hours.^[1][3] As of 2019^[update], a group of approximately 650 bodies, typically measuring 1–20kilometers indiameter, have periods of more than 100 hours or 41⁄6 days. Among theslowest rotators, there are currently 15 bodies with a period longer than 1000 hours.^[1] According to theMinor Planet Center, the sharp lower limit of approximately 2.2 hours is due to the fact that most smaller bodies are thought to berubble piles – conglomerations of smaller pieces, loosely coalesced under the influence of gravity – that fly apart if the period is shorter than this limit. The few minor planets rotating faster than 2.2 hours, therefore, can not be merely held together byself-gravity, but must be formed of a contiguous solid.^[3]

Potentially slow rotators have only an inaccurate period, estimated based on a fragmentary lightcurve and inconclusive measurement. They are listed separately from the more precise periods, which have aLCDB quality code,U, of 2 or 3 (unambiguous result). The periods forpotentially slow rotators may be completely wrong (U = 1), have no complete and conclusive result (U = n.a.), or large error margins of more than 30% (U = 2−). A trailing plus sign (+) or minus sign (–) indicate slightly better or worse quality, respectively, than the unsigned value.^[4]

As withorbital periods, a rotational period can besidereal orsynodic to describe a full rotation with respect to thefixed stars (sidereal) andSun (synodic), respectively. In most cases, the periods given in this list are synodic, not sidereal.^[5][6] However, in most cases the difference between these two different measures is not significant.^[6] This is the case for allmain-belt asteroids, which account for 97.5% of all minor planets.

This list contains the slowest-rotating minor planets withperiods of at least 1000 hours, or 412⁄3 days. See§ Potentially slow rotators for minor planets with an insufficiently accurate period—that is, aLCDB quality code of less than 2.

back to top

back to top

back to top

back to top

back to top