A study of asteroid pole-latitude distribution based on an extended set of shape models derived by the lightcurve inversion method

TL;DR

This study expands the set of asteroid shape models derived from lightcurve inversion, analyzes their physical properties, and investigates the distribution of asteroid pole latitudes to understand underlying physical and evolutionary processes.

Contribution

The paper introduces 80 new asteroid models from combined sparse and dense photometry, increasing the total models to about 200, and provides a statistical analysis of their physical properties and pole latitude distribution.

Findings

Small asteroids (D < 30 km) tend to have pole latitudes clustered near the ecliptic poles, likely due to YORP effect.

Large asteroids (D > 60 km) show an excess of prograde rotators, suggesting primordial origins.

The latitude distribution patterns support theories of asteroid spin evolution and primordial characteristics.

Abstract

Tens of thousands of sparse-in-time lightcurves from astrometric projects are publicly available. We investigate these data and use them in the lightcurve inversion method to derive new asteroid models. By having a greater number of models with known physical properties, we can gain a better insight into the nature of individual objects and into the whole asteroid population. We use sparse photometry from selected observatories from the AstDyS database, either alone or in combination with dense lightcurves, to determine new asteroid models by the lightcurve inversion method. We present 80 new asteroid models derived from combined data sets where sparse photometry is taken from the AstDyS database and dense lightcurves are from the Uppsala Asteroid Photometric Catalogue (UAPC) and from several individual observers. For 18 asteroids, we present updated shape solutions based on new photometric data. The addition of new models increases the total number of models derived by the lightcurve inversion method to ~200. We also present a simple statistical analysis of physical properties of asteroids where we look for possible correlations between various physical parameters with an emphasis on the spin vector. We present the observed and de-biased distributions of ecliptic latitudes with respect to different size ranges of asteroids as well as a simple theoretical model of the latitude distribution and then compare its predictions with the observed distributions. From this analysis we find that the latitude distribution of small asteroids (D < 30 km) is clustered towards ecliptic poles and can be explained by the YORP thermal effect while the latitude distribution of larger asteroids (D > 60 km) exhibits an evident excess of prograde rotators, probably of primordial origin.