# Techniques for High-Contrast Imaging in Multi-Star Systems II: Multi-Star Wavefront Control

## TL;DR

This paper presents advanced wavefront control techniques enabling direct imaging of exoplanets in multi-star systems, overcoming previous limitations caused by diffraction and aberrations, demonstrated through simulations of the Alpha Centauri system.

## Contribution

It introduces combined multi-star wavefront control and super-Nyquist techniques to achieve high-contrast imaging at any angular separation in multi-star systems.

## Key findings

- Achieved at least 8×10⁻⁹ mean contrast in simulations
- Demonstrated imaging capability in the Alpha Centauri system
- Extended high-contrast imaging to broader angular separations

## Abstract

Direct imaging of exoplanets represents a challenge for astronomical instrumentation due to the high-contrast ratio and small angular separation between the host star and the faint planet. Multi-star systems pose additional challenges for coronagraphic instruments due to the diffraction and aberration leakage caused by companion stars. Consequently, many scientifically valuable multi-star systems are excluded from direct imaging target lists for exoplanet surveys and characterization missions. Multi-star wavefront control (MSWC) is a technique that uses a coronagraphic instrument's deformable mirror (DM) to create high-contrast regions in the focal plane in the presence of multiple stars. Our previous paper introduced the Super-Nyquist Wavefront Control (SNWC) technique that uses a diffraction grating to enable the DM to generate high-contrast regions beyond the nominal region correctable by the DM. These two techniques can be combined to generate high-contrast regions for multi-star systems at any angular separation. As a case study, a high-contrast wavefront control (WC) simulation that applies these techniques shows that the habitable region of the Alpha Centauri system can be imaged reaching at least $8 \times 10^{-9}$ mean contrast in 10\% broadband light in one-sided dark holes from 1.6-5.5$\lambda/D$.