Techniques for High Contrast Imaging in Multi-Star Systems I: Super-Nyquist Wavefront Control

Abstract

Extra-solar planets direct imaging is now a reality with the deployment and commissioning of the first generation of specialized ground-based instruments (GPI, SPHERE, P1640 and SCExAO). These systems allow of planets $10^7$ times fainter than their host star. For space-based missions (EXCEDE, EXO-C, EXO-S, WFIRST), various teams have demonstrated laboratory contrasts reaching $10^{-10}$ within a few diffraction limits from the star. However, all of these current and future systems are designed to detect faint planets around a single host star or unresolved multiples, while most non M-dwarf stars such as Alpha Centauri belong to multi-star systems. Direct imaging around binaries/multiple systems at a level of contrast allowing Earth-like planet detection is challenging because the region of interest is contaminated by the hosts star companion as well as the host Generally, the light leakage is caused by both diffraction and aberrations in the system. Moreover, the region of interest usually falls outside the correcting zone of the deformable mirror (DM) for the companion. Until now, it has been thought that removing the light of a companion star is too challenging, leading to the exclusion of binary systems from target lists of direct imaging coronographic missions. In this paper, we will show different new techniques for high-contrast imaging of planets around multi-star systems and detail the Super-Nyquist Wavefront Control (SNWC) method, which allows to control wavefront errors beyond nominal control region of the DM. Using the SNWC we reached contrasts around $5\times 10^{-9}$ in a 10% bandwidth.

26 pages, 18 figures, submitted to ApJ

References in corpus (4)

• The Gemini Planet Imager: First Light
• Exploring Exoplanet Populations with NASA's Kepler Mission
• Planetary Candidates Observed by Kepler IV: Planet Sample From Q1-Q8 (22 Months)
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• Characterization of exoplanets from their formation III: The statistics of planetary luminosities
• Observing Exoplanets with High-Dispersion Coronagraphy. II. Demonstration of an Active Single-Mode Fiber Injection Unit
• The Habitable Exoplanet Observatory (HabEx) Mission Concept Study Interim Report
• Techniques for High-Contrast Imaging in Multi-Star Systems II: Multi-Star Wavefront Control
• Flight mask designs of the Roman Space Telescope Coronagraph Instrument
• How to Directly Image a Habitable Planet Around Alpha Centauri with a ~30-45cm Space Telescope
• A review of simulation and performance modeling for the Roman coronagraph instrument
• A method to directly image exoplanets in multi-star systems such as Alpha-Centauri
• High contrast imaging of exoplanets on ELTs using a super-Nyquist wavefront control scheme
• CoronaGraph Instrument Reference stars for Exoplanets (CorGI-REx) I. Preliminary Vetting and Implications for the Roman Coronagraph and Habitable Worlds Observatory
• Searching for Faint Comoving Companions to the $\alpha$ Centauri system in the VVV Survey Infrared Images
• TDEM final report: Enhanced direct imaging exoplanet detection with astrometry mass determination