Letter to the Editor

Characterisation of the main belt asteroid (223) Rosa

A proposed flyby target of ESA’s JUICE mission

¹ Université Côte d’Azur, CNRS–Lagrange, Observatoire de la Côte d’Azur, CS 34229, 06304 NICE Cedex 4, France
e-mail: chrysa.avdellidou@oca.eu
² INAF – Astronomical Observatory of Padova, Vicolo Dell’Osservatorio 5, 35122 Padova, Italy
³ Center of Studies and Activities for Space, CISAS, G. Colombo, University of Padova, 35131 Padova, Italy
⁴ INAF – Osservatorio Astronomico di Roma, Via Frascati 33, 00040 Monte Porzio Catone, RM, Italy
⁵ LESIA, Université de Paris, Observatoire de Paris, Université PSL, Sorbonne Université, CNRS, 92190 MEUDON, France
⁶ Arecibo Observatory, University of Central Florida, HC-3 Box 53995, Arecibo, PR 00612, USA
⁷ Institut Universitaire de France (IUF), 1 rue Descartes, 75231 PARIS CEDEX 05, France
⁸ Lowell Observatory, 1400 W. Mars Hill Road, Flagstaff, AZ 86001, USA
⁹ Dipartimento di Scienze e Tecnologie, Università Parthenope, Centro Direzionale Isola C4, 80143 Napoli, Italy
¹⁰ INAF – Istituto di Astrofisica e Planetologia Spaziale, Via Fosso del Cavaliere 100, 00133 Roma, Italy

Received: 6 November 2021
Accepted: 25 November 2021

Abstract

Context. The ESA JUICE space mission, on its way to study Jupiter’s environment and icy moons, will pass twice through the main asteroid belt. For this reason, the possibility to perform an asteroid flyby has been investigated.

Aims. We aim to gain insight into the physical properties of the outer main belt asteroid (223) Rosa, which has been proposed as a potential JUICE flyby target.

Methods. We report new visible and near-infrared spectroscopic observations at different rotation phases. Additionally, we perform a literature review of all the available physical properties, such as diameter, albedo, mass, and rotational period.

Results. We find that asteroid Rosa is an X-type asteroid that shows no significant spectral variability combining the new and literature spectroscopic data. Its large size and orbital semimajor axis in the outer main belt indicate that Rosa does not belong to the Themis family, while its albedo is only marginally compatible with the family. Rosa’s estimated density is in agreement with those of other low-albedo X-type asteroids. Hence, we propose that Rosa is a planetesimal that accreted in the protoplanetary disk beyond the snow line.