Asteroids’ physical models from combined dense and sparse photometry and scaling of the YORP effect by the observed obliquity distribution

Abstract

Context. The larger number of models of asteroid shapes and their rotational states derived by the lightcurve inversion give us better insight into both the nature of individual objects and the whole asteroid population. With a larger statistical sample we can study the physical properties of asteroid populations, such as main-belt asteroids or individual asteroid families, in more detail. Shape models can also be used in combination with other types of observational data (IR, adaptive optics images, stellar occultations), e.g., to determine sizes and thermal properties. Aims. We use all available photometric data of asteroids to derive their physical models by the lightcurve inversion method and compare the observed pole latitude distributions of all asteroids with known convex shape models with the simulated pole latitude distributions. Methods. We used classical dense photometric lightcurves from several sources (Uppsala Asteroid Photometric Catalogue, Palomar Transient Factory survey, and from individual observers) and sparse-in-time photometry from the U.S. Naval Observatory in Flagstaff, Catalina Sky Survey, and La Palma surveys (IAU codes 689, 703, 950) in the lightcurve inversion method to determine asteroid convex models and their rotational states. We also extended a simple dynamical model for the spin evolution of asteroids used in our previous paper. Results. We present 119 new asteroid models derived from combined dense and sparse-in-time photometry. We discuss the reliability of asteroid shape models derived only from Catalina Sky Survey data (IAU code 703) and present 20 such models. By using different values for a scaling parameter c YORP (corresponds to the magnitude of the YORP momentum) in the dynamical model for the spin evolution and by comparing synthetic and observed pole-latitude distributions, we were able to constrain the typical values of the c YORP parameter as between 0.05 and 0.6.

In search of the source of asteroid (101955) Bennu: Applications of the stochastic YORP model

“…9 and 10) yields parameters near d YORP ¼ 0:4; c reorient ¼ 0:9, and c YORP ¼ 0:5-0.7, in agreement with the modeling work in Hanuš et al (2013). This suggests we need YORP to be a little weaker than the nominal values (value of unity), with more time between YORP cycles.…”

“…As one moves to larger diameters, the obliquities spread somewhat to lower latitudes. Hanuš et al (2011Hanuš et al ( , 2013 concluded that their findings were compatible with a sample of objects that evolved due to the YORP effect.…”

“…The solid line shows our fit for our synthetic km-size asteroids evolving under our static YORP model. Hanuš et al, 2013). It is exceedingly arduous to resolve the pole positions for small main belt asteroids, so the data presented by the authors only includes objects with D < 30 km.…”

Shape Models and Physical Properties of Asteroids

“…Combining these datasets with dense lightcurves allowed some authors to increase the modelled population of asteroids from 100 (classical photometry) to 400 (combination of classical and sparse photometric data), using a modified version of the convex lightcurve inversion method (e.g. [17], [18]). The resulting models resemble the ones obtained with dense lightcurves (are equivalent in terms of spin solution) but the shape model is usually a low-resolution, "angular" convex shape, due to the limited quality of the data.…”

Asteroids@home—A BOINC distributed computing project for asteroid shape reconstruction

“…Since the publication of the method, models of about 500 asteroids were derived by this technique (Ďurech et al, 2009;Ďurech et al, 2011;Hanuš et al, 2011Hanuš et al, , 2013bMarciniak et al, 2011, for example); most of them are publicly available in the Database of Asteroid Models from Inversion Techniques (DAMIT 1 , Durech et al, 2010). At this site, the source codes for the lightcurve inversion called convexinv can be downloaded.…”