Unmasking (44) Nysa: Evidence for a trilobate structure
Abstract
Context. (44) Nysa is one of the largest known E-type asteroids. Light curve inversion models have indicated that it may have an elongated shape commonly found in large binary systems. Aims. We aimed to identify the morphology and presence of possible satellites orbiting Nysa. Methods. We observed Nysa with the visible-wavelengths adaptive-optics instruments SHARK-VIS and SPHERE/ZIMPOL in order to image the object with the highest possible spatial resolution, and visually identified surface features on the object. A shape model was constructed from these images and photometric light curves using the ADAM code. Results. Imaging revealed a highly unusual morphology with multiple distinct surface features, including two distinct valleys most easily interpreted as colli. A faint satellite was identified in the deconvolution residuals in multiple datasets. Conclusions. We determine that (44) Nysa is a binary system most likely consisting of a contact-trinary or highly-irregular, coherent primary object and a small satellite.
Cite
@article{arxiv.2607.25786,
title = {Unmasking (44) Nysa: Evidence for a trilobate structure},
author = {Kate Minker and Anthony Berdeu and Gianluca Li Causi and Josef Hanuš and Michaël Marsset and Al Conrad and Fernando Pedichini and Simone Antoniucci and Piero Vaccari and Nick Moskovitz and Benoit Carry and Tom Polakis and Marin Ferrais and Emmanuël Jehin and Roberto Bonamico and Rhiannon Hicks and Daejhanae Smith and M. Amine Miftah and Ester Marini},
journal= {arXiv preprint arXiv:2607.25786},
year = {2026}
}
Comments
12 pages, 8 figures, 5 tables. Accepted as a letter by A&A. Associated videos are available in the journal article, press release, or by contacting K. Minker and provide the best view of the processed data