Physical properties of trans-Neptunian object (143707) 2003 UY₁₁₇ derived from stellar occultation and photometric observations

¹ Instituto de Astrofísica de Andalucía, IAA-CSIC, Glorieta de la Astronomía s/n, 18008 Granada, Spain
² Institut Polytechnique des Sciences Avancées IPSA, 94200 Ivrysur-Seine, France
³ IMCCE, Observatoire de Paris, PSL Research University, CNRS, Sorbonne Université, Univ. Lille, 75014 Paris, France
⁴ Federal University of Technology-Paraná (UTFPR/PPGFA), Curitiba, PR, Brazil
⁵ Laboratório Interinstitucional de e-Astronomia - LIneA - and INCT do e-Universo, Av. Pastor Martin Luther King Jr, 126 - Del Castilho, Nova América Offices, Torre 3000 / sala 817, Rio de Janeiro, RJ 20765-000, Brazil
⁶ LESIA, Observatoire de Paris, Université PSL, CNRS, Sorbonne Université, 5 place Jules Janssen, 92190 Meudon, France
⁷ Florida Space Institute, University of Central Florida, Orlando, FL 32826-0650, USA
⁸ Federal University of Uberlândia (UFU), Physics Institute, Av. João Naves de Ávila 2121, Uberlândia, MG 38408-100, Brazil
⁹ Universidade do Rio de Janeiro - Observatório do Valongo, Ladeira do Pedro Antonio 43, Rio de Janeiro, RJ 20.080-090, Brazil
¹⁰ Federal University of Technology - Paraná (PPGFA/UTFPR-Curitiba), Av. Sete de Setembro, 3165 Curitiba, PR, Brazil
¹¹ Departments of Astronomy and of Earth and Planetary Science, 501 Campbell Hall, University of California, Berkeley, CA 94720, USA
¹² naXys, Department of Mathematics, University of Namur, Rue de Bruxelles 61, 5000 Namur, Belgium
¹³ Observatório Nacional/MCTI, Rua Gal. José Cristino 77, Rio de Janeiro RJ 20921-400, Brazil
¹⁴ UNESP-São Paulo State University, Grupo de Dinâmica Orbital e Planetologia, CEP 12516-410 Guaratinguetá, SP, Brazil
¹⁵ Sociedad Astronómica Granadina, Apartado de Correos 195, 18080 Granada, Spain
¹⁶ Agrupación Astronómica de Eivissa, C. Lucio Oculacio s/n, 07800 Ibiza, Spain
¹⁷ Observatorio Astronómico de Albox, Apt. 63, 04800 Albox, Almeria, Spain
¹⁸ Astronomical Institute of the Romanian Academy, 5 Cut¸itul de Argint, 040557 Bucharest, Romania
¹⁹ Centro Astronómico Hispano en Andalucía, Observatorio de Calar Alto, Sierra de los Filabres, 04550 Gérgal, Almeria, Spain
²⁰ University of Liège, 4000 Liège, Belgium
²¹ Instituto de Astrofísica de Canarias (IAC), C/Vía Láctea s/n, 38205 La Laguna, Tenerife, Spain
²² Instituto de Física Aplicada a las Ciencias y las Tecnologías, Universidad de Alicante, Alicante, San Vicente del Rapeig, Spain
²³ Agrupación Astronómica de Sabadell, Prat de la Riba sn, 08206 Sabadell, Spain
²⁴ International Occultation Timing Association/European Section, Am Brombeerhag 13, 30459 Hannover, Germany
²⁵ Rue de Mariembourg 45, 5670 Dourbes, Belgium
²⁶ TÜBITAK National Observatory, Akdeniz University Campus, 07058 Antalya, Turkey
²⁷ Department of Astronomy and Space Sciences, Faculty of Science, Istanbul University, 34116 Istanbul, Turkey
²⁸ Istanbul University Observatory Research and Application Centre, 34116 Istanbul, Turkey
²⁹ School of Mathematical and Physical Sciences, Macquarie University, Sydney NSW 2109, Australia
³⁰ Astrophysics and Space Technologies Research Centre, Macquarie University, Sydney NSW 2109, Australia

^★ Corresponding author; mike@kretlow.de

Received: 1 July 2024
Accepted: 13 September 2024

Abstract

Context. Trans-Neptunian objects (TNOs) are considered to be among the most primitive objects in our Solar System. Knowledge of their primary physical properties is essential for understanding their origin and the evolution of the outer Solar System. In this context, stellar occultations are a powerful and sensitive technique for studying these distant and faint objects.

Aims. We aim to obtain the size, shape, absolute magnitude, and geometric albedo for TNO (143707) 2003 UY₁₁₇.

Methods. We predicted a stellar occultation by this TNO for 2020 October 23 UT and ran a specific campaign to investigate this event. We derived the projected profile shape and size from the occultation observations by means of an elliptical fit to the occultation chords. We also performed photometric observations of (143707) 2003 UY₁₁₇ to obtain the absolute magnitude and the rotational period from the observed rotational light curve. Finally, we combined these results to derive the three-dimensional shape, volume-equivalent diameter, and geometric albedo for this TNO.

Results. From the stellar occultation, we obtained a projected ellipse with axes of (282 ± 18) × (184 ± 32) km. The area-equivalent diameter for this ellipse is D_eq,A = 228 ± 21 km. From our photometric R band observations, we derived an absolute magnitude of H_V = 5.97 ± 0.07 mag using V − R = 0.46 ± 0.07 mag, which was derived from a V band subset of these data. The rotational light curve has a peak-to-valley amplitude of ∆m = 0.36 ± 0.13 mag. We find the most likely rotation period to be P = 12.376 ± 0.0033 hours. By combining the occultation with the rotational light curve results and assuming a triaxial ellipsoid, we derived axes of a × b × c = (332 ± 24) km × (216 ± 24) km × (180₋₂₄⁺²⁸) km for this ellipsoid, and therefore a volume-equivalent diameter of D_eq,V = 235 ± 25 km. Finally, the values for the absolute magnitude and for the area-equivalent diameter yield a geometric albedo of p_V = 0.139 ± 0.027.