Properties of slowly rotating asteroids from the Convex Inversion Thermophysical Model

Abstract

Results from the TESS mission showed that previous studies strngly underestimated the number of slow rotators, revealing the importance of studying those asteroids. For most slowly rotating asteroids (P > 12), no spin and shape model is available because of observation selection effects. This hampers determination of their thermal parameters and accurate sizes. We continue our campaign in minimising selection effects among main belt asteroids. Our targets are slow rotators with low light-curve amplitudes. The goal is to provide their scaled spin and shape models together with thermal inertia, albedo, and surface roughness to complete the statistics. Rich multi-apparition datasets of dense light curves are supplemented with data from Kepler and TESS. In addition to data in the visible range, we also use thermal data from infrared space observatories (IRAS, Akari and WISE) in a combined optimisation process using the Convex Inversion Thermophysical Model (CITPM). This novel method has so far been applied to only a few targets, and in this work we further validate the method. We present the models of 16 slow rotators. All provide good fits to both thermal and visible data. The obtained sizes are on average accurate at the 5% precision, with diameters in the range from 25 to 145 km. The rotation periods of our targets range from 11 to 59 hours, and the thermal inertia covers a wide range of values, from 2 to <400 SI units, not showing any correlation with the period. With this work we increase the sample of slow rotators with reliable spin and shape models and known thermal inertia by 40%. The thermal inertia values of our sample do not display a previously suggested increasing trend with rotation period, which might be due to their small skin depth.

Accepted to Astronomy & Astrophysics. 10 pages + appendices

References in corpus (18)

• The Transiting Exoplanet Survey Satellite
• The K2 Mission: Characterization and Early results
• Global regolith thermophysical properties of the Moon from the Diviner Lunar Radiometer Experiment
• Thermal inertia of near-Earth asteroids and implications for the magnitude of the Yarkovsky effect
• Combining asteroid models derived by lightcurve inversion with asteroidal occultation silhouettes
• Thermal inertia of main belt asteroids smaller than 100 km from IRAS data
• Hayabusa-2 Mission Target Asteroid 162173 Ryugu (1999 JU3): Searching for the Object's Spin-Axis Orientation
• Asteroids' physical models from combined dense and sparse photometry and scaling of the YORP effect by the observed obliquity distribution
• Thermophysical modeling of asteroids from WISE thermal infrared data - Significance of the shape model and the pole orientation uncertainties
• Asteroid models reconstructed from ATLAS photometry
• Precise astrometry and diameters of asteroids from occultations -- a data-set of observations and their interpretation
• Thermal Tomography of Asteroid Surface Structure
• Against the biases in spins and shapes of asteroids
• Photometric survey, modelling, and scaling of long-period and low-amplitude asteroids
• Thermal properties of slowly rotating asteroids: Results from a targeted survey
• Thermal properties of large main-belt asteroids observed by Herschel PACS
• Asteroid shapes and thermal properties from combined optical and mid-infrared photometry inversion
• Asteroid Thermal Inertia Estimates from Remote Infrared Observations: The Effects of Surface Roughness and Rotation Rate

Cited by in corpus (7)

• Reconstruction of asteroid spin states from Gaia DR3 photometry
• Combined spin orientation and phase function of asteroids
• Rotation periods of asteroids from light curves of TESS data
• Asteroid phase curves using sparse Gaia DR2 data and differential dense light curves
• Scaling slowly rotating asteroids by stellar occultations
• Asteroid sizes determined with thermophysical model and stellar occultations
• An astrometric mass estimate for asteroid (223) Rosa