Infrared imaging of M Cas B using rapid image motion compensation

The orbital parameters and component masses of the μ Cas binary system can provide a measure of the helium abundance in the early Galaxy. In a continuing effort to measure these characteristics, we have obtained the first direct images of the low mass companion to μ Cas A using techniques for high speed correction of image motion at 1.25 and 1.65 μm. These techniques include real-time tracking of the brightest infrared speckle at 75 Hz and of the visible centroid at 500 Hz. Mu Cas B is easily detected with a magnitude difference relative to the primary of >4 at a separation of ∼1.4 arcsec.