Multi-band infrared imaging reveals dusty spiral arcs around the binary B[e] star 3 Puppis

Context. The star 3 Puppis is the brightest known to exhibit the B[e] phenomenon. Although recent studies have classified this A-type star within the supergiant group, the influence of its binary nature on the circumstellar environment (CE) remains difficult to model. Aims. To resolve its dusty regions at angular scales of 5-10 milliarcseconds (mas), we conducted high angular resolution interferometric observations with the mid-infrared beam combiner VLTI/MATISSE across the 3-12 μm wavelength range. Methods. Since the ( u , v ) coverage enables image reconstruction, we present an innovative statistical interferometric imaging technique based on the MiRA software to produce averaged images. Applied to MATISSE data, this systematic approach facilitates the selection of an optimal set of reconstructions, improving the robustness and fidelity of the recovered features. We also applied SPARCO, an independent imaging tool well suited to systems with a bright central source surrounded by a fainter and extended CE. Results. The images obtained with both tools in the L, M, and N spectral bands show good agreement and clearly reveal an asymmetric elongated structure located at ∼17 mas (∼10 au at 631 pc) to the south-east of the image centre, with a density contrast of ∼20%. A second asymmetry to the north-west and a skewed inner rim are also detected. Simple geometric modelling, inspired by the reconstructed images, provides quantitative constraints on the morphology, position, and flux contribution of the CE and its asymmetries. Conclusions. Our final MATISSE images are consistent with previous VLTI observations but also reveal a more complex CE with large-scale clumps in the south-east and north-west disc regions of 3 Puppis. Finally, based on a hydrodynamic simulation, we conclude that the tidal spiral wake perturbations driven by the central binary, which are dynamically excited at Lindblad resonances within the circumbinary disc, provide the best interpretation for the radial extent and curvature of the elongated structures observed across all bands.

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