High Contrast, High Angular Resolution Optical Speckle Imaging: Uncovering Hidden Stellar Companions

TL;DR

This paper demonstrates that modern image reconstruction techniques like MFBD significantly improve the detection of faint, close-in stellar companions using high angular resolution speckle imaging on large telescopes.

Contribution

It introduces the application of Multi-Frame Blind Deconvolution to speckle imaging, achieving higher contrast and more precise measurements of stellar companions than previous Fourier-based methods.

Findings

MFBD achieves contrast levels of ~5×10^{-3} to ~10^{-4}.

Reconstructed images provide higher precision astrometry.

Most stellar companions to solar-like stars can be imaged in optical to near-IR bands.

Abstract

We explore the possibility of detecting very faint, very close-in stellar companions using large aperture ground-based telescopes and the technique of optical speckle imaging. We examine the state of high angular resolution speckle imaging and contrast levels being achieved using current speckle cameras on the Gemini 8-m telescope. We then explore the use of the modern image reconstruction technique - Multi-Frame Blind Deconvolution (MFBD) - applied to speckle imaging from the Gemini 8-m telescope. We show that MFBD allows us to measure the flux ratio of the imaged stars to high accuracy and the reconstructed images yield higher precision astrometry. Both of these advances provide a large refinement in the derived astrophysical parameters compared with current Fourier techniques. MFBD image reconstructions reach contrast levels of $\sim$5$\times$10$^{-3}$, near the diffraction limit, to $\sim$10$^{-4}$ about 1.0 arcsec away. At these deep contrast levels with angular limits starting near the 8-m diffraction limit ($\sim$20 mas), most stellar companions to a solar-like stars can be imaged in the optical to near-IR bandpass (320-1000 nm).