Distribution of spin-axes longitudes and shape elongations of main-belt asteroids

Abstract

Context: Large all-sky surveys provide us with a lot of photometric data that are sparse in time (typically few measurements per night) and can be potentially used for the determination of shapes and rotational states of asteroids. The method which is generally used to derive these parameters is the lightcurve inversion. However, for most asteroids their sparse data are not accurate enough to derive a unique model and the lightcurve inversion method is thus not very efficient. Aims: To fully utilize photometry sparse in time, we developed a new simplified model and applied it on the data from the Lowell photometric database. Our aim was to derive spin axis orientations and shape elongations of asteroids and to reconstruct distributions of these parameters for selected subpopulations to find if there are some differences. Methods: We model asteroids as geometrically scattering triaxial ellipsoids. Observed values of mean brightness and the dispersion of brightness are compared with computed values obtained from the parameters of the model -- ecliptical longitude $\lambda$ and latitude $\beta$ of the pole and the ratios $a/b$, $b/c$ of axes of the ellipsoid. These parameters are optimized to get the best agreement with the observation. Results: We found that the distribution of $\lambda$ for main-belt asteroids is not uniform (in agreement with findings of Bowell et al., 2014, M&PS, 49, 95) and is dependent on the inclination of orbit. Surprisingly, the non-uniformity of $\lambda$ distribution is larger for asteroids residing on low-inclination orbits. We also studied distributions of $a/b$ for several groups of asteroids and found that small asteroids ($D<25$km) are on average more elongated than large ones.

10 pages; Accepted for publication in A&A

References in corpus (5)

• Constraining the cometary flux through the asteroid belt during the late heavy bombardment
• Asteroids' physical models from combined dense and sparse photometry and scaling of the YORP effect by the observed obliquity distribution
• The shape distribution of asteroid families -- evidence for evolution driven by small impacts
• Against the biases in spins and shapes of asteroids
• Testing the inversion of asteroids' Gaia photometry combined with ground-based observations

Cited by in corpus (13)

• APO Time Resolved Color Photometry of Highly-Elongated Interstellar Object 1I/'Oumuamua
• Source regions of carbonaceous meteorites and NEOs
• Reconstruction of asteroid spin states from Gaia DR3 photometry
• Spin states of asteroids in the Eos collisional family
• A binary main belt comet
• Photometric survey, modelling, and scaling of long-period and low-amplitude asteroids
• Thermal properties of slowly rotating asteroids: Results from a targeted survey
• Combined spin orientation and phase function of asteroids
• Asteroid migration due to the Yarkovsky effect and the distribution of the Eos family
• Asteroid spin-states of a 4 Gyr collisional family
• Main-belt and Trojan Asteroid Phase Curves from the ATLAS Survey
• High-Resolution Simulations of Catastrophic Disruptions: Resultant Shape Distributions
• Considering contact forces during the formation of planetesimals by gravitational collapse: mutual orbits, spin states, and shapes