Stellar Multiplicity via Speckle Interferometry with the 3.6 m Devasthal Optical Telescope

TL;DR

This paper demonstrates the use of speckle interferometry with the 3.6 m Devasthal Optical Telescope to resolve binary stars, measure their orbital parameters, and employ Bayesian inference for faint companions, showcasing a cost-effective high-resolution technique.

Contribution

It introduces a methodology for using a medium-sized telescope as a high-resolution interferometer and applies Bayesian modeling to analyze speckle patterns for binary star systems.

Findings

Successfully resolved binary systems with speckle interferometry.

Measured orbital separations and position angles of binaries.

Estimated orbital parameters for faint companions using Bayesian inference.

Abstract

Conventional ground-based optical telescopes, even those with large apertures, primarily observe stars, close binaries, and multiple systems as unresolved point sources through photometric measurements. Spectroscopy can identify multiple stellar components within a system, but both techniques are fundamentally limited in resolving stellar surfaces and providing direct angular separations. Although photometric and spectroscopic observations yield critical information on magnitudes/flux, metallicities, and orbital properties, complementary high-angular-resolution methods are required to constrain additional system characteristics, including angular orbital parameters, model-independent distances, radii, and stellar masses. The limitations of these two methods arise due to the Diffraction Limit of the telescopes and atmospheric turbulence. Speckle Interferometry (SI) is a clever and affordable method for ground-based telescopes to work around atmospheric turbulence. In this work, we utilize the speckle images obtained by the 3.6 m DOT and demonstrate the capability of SI to resolve binary systems, measure their orbital separations, and determine their position angles. For systems with faint companions where conventional analysis fails, we employ Bayesian inference to model speckle patterns and estimate orbital parameters with high precision. These results establish the effective methodology for using a medium-sized, 4-m class telescope like the DOT as a high-resolution stellar interferometer and demonstrate the potential of speckle interferometry as a powerful technique to advance optical interferometric studies within Indian astronomy.