# The SPHERE view of three interacting twin disc systems in polarised light

**Authors:** Philipp Weber, Sebastián Pérez, Greta Guidi, Nicolás T. Kurtovic, Alice Zurlo, Antonio Garufi, Paola Pinilla, Satoshi Mayama, Rob G. van Holstein, Cornelis P. Dullemond, Nicolás Cuello, David Principe, Lucas Cieza, Camilo González-Ruilova, Julien Girard  
**arXiv:** [2211.14322](https://arxiv.org/abs/2211.14322)  
**Date:** 2022-11-25  
**Summary page:** https://www.summarizepaper.com/en/paper/2211.14322v1/

## Key points

- The paper explores the effects of gravitational interactions among stellar systems during early stages of evolution in dense stellar environments.
- Three known interacting twin-disc systems were studied: AS 205, EM* SR 24, and FU Orionis.
- Near-infrared polarised light observations were taken using the SPHERE/IRDIS instrument.
- Spirals likely caused by gravitational interaction and connecting filaments between stars were revealed.
- The local angle of linear polarisation indicated the source whose light dominates the scattering process from the bridging region between two stars.
- Polarised intensity resulting from scattering with multiple relevant light sources results from an incoherent summation of individual contributions that can produce nulls of polarised intensity in an image.
- Comparing polarised light observations with other data at similar resolution (namely ALMA continuum and gas emission) allowed researchers to discuss the geometry and content of these systems further.
- This study provides valuable insights into how gravitational interactions among stellar systems shape disc structures around individual stars in dense stellar environments, which has important implications for understanding star formation processes and dynamics within such environments.

## Summary

This paper explores the effects of gravitational interactions among stellar systems during the early stages of evolution in dense stellar environments. The study focuses on three known interacting twin-disc systems, namely AS 205, EM* SR 24, and FU Orionis. Near-infrared polarised light observations were taken using the SPHERE/IRDIS instrument, which revealed spirals likely caused by gravitational interaction and connecting filaments between the stars. The complex polarised intensity was analysed with particular attention to multiple light sources in these systems. The local angle of linear polarisation indicated the source whose light dominates the scattering process from the bridging region between two stars. Additionally, it was shown that polarised intensity resulting from scattering with multiple relevant light sources results from an incoherent summation of individual contributions that can produce nulls of polarised intensity in an image. By comparing polarised light observations with other data at similar resolution (namely ALMA continuum and gas emission), researchers were able to discuss the geometry and content of these systems further. Overall, this study provides valuable insights into how gravitational interactions among stellar systems shape disc structures around individual stars in dense stellar environments. These findings have important implications for understanding star formation processes and dynamics within such environments.