Stellar spectra reconstruction from speckle spectroscopic data

Abstract

We describe a method to reconstruct stellar spectra from dispersed speckle data with diffraction-limited angular resolution. A shift-and-add (SAA) method is applied on many short exposure frames, each of which contains a dispersed speckle image and a corresponding nondispersed speckle image as a reference. The spectra of the binary star ADS 16836 were reconstructed in wideband and low dispersion mode from the data taken with the Hokudai speckle spectroscopic camera system using the Okayama 188 cm telescope. The result shows the well-separated spectra of the primary and the secondary stars, which are otherwise too close to be distinguishable due to atmospheric turbulence. These results also demonstrate high spatial resolution spectroscopy for a binary star and for a resolvable hypergiant using our SAA speckle method.