Physical characterization of asteroid (16583) Oersted combining stellar occultation and photometric data

¹ Charles University, Faculty of Mathematics and Physics, Institute of Astronomy, V Holešovickách 2, 18000, Prague 8, Czech Republic
² Université Côte d’Azur, CNRS-Lagrange, Observatoire de la Côte d’Azur, CS 34229, 06304 Nice Cedex 4, France
³ School of Physics and Astronomy, University of Leicester, Leicester LE1 7RH, UK
⁴ Department of Physics, The Catholic University of America, Washington, DC 20064, USA
⁵ Astrophysics Science Division, NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA
⁶ Center for Research and Exploration in Space Science and Technology, NASA/GSFC, Greenbelt, MD 20771, USA
⁷ SETI Institute, Carl Sagan Center, 189 Bernado Avenue, Mountain View, CA 94043, USA
⁸ Unistellar, 5 allé Marcel Leclerc, bâtiment B, 13008 Marseille, France

^★ Corresponding author: josef.hanus@mff.cuni.cz

Received: 8 July 2025
Accepted: 5 October 2025

Abstract

Context. We report a successful observation of a stellar occultation by asteroid (16583) Oersted, which provides a detailed physical characterization of its shape, spin state, and surface properties.

Aims. Our goal is to determine the physical parameters of Oersted by combining multi-chord occultation timing, sparse optical photometry, and thermal infrared observations. Asteroids of this size (~20 km) are rarely modeled in such detail due to observational limitations, making Oersted a valuable case study.

Methods. We applied convex light curve inversion to sparse photometric data to derive an initial shape and spin state. We then refined and scaled this model using non-convex shape modeling with the All-Data Asteroid Modelling (ADAM) algorithm, incorporating constraints from the occultation chord profile. Thermophysical modeling based on WISE thermal infrared fluxes was used to determine the asteroid’s effective diameter, geometric albedo, and thermal inertia.

Results. The non-convex shape model reveals localized surface concavities and provides a size estimate consistent with radiometric measurements. The derived thermal inertia is typical for asteroids of comparable size.

Conclusions. This work demonstrates the effectiveness of combining stellar occultations, photometry, and thermal infrared data for asteroid modeling and highlights the valuable contributions of citizen scientists, who played a key role in capturing the occultation and constraining the profile of the asteroid.