FULL ADAPTIVE OPTICS IMAGES OF ADS-9731 AND MU-CASSIOPEIAE - ORBITS AND MASSES

The double double ADS 9731 and the nearby Population II astrometric bi nary mu Cas have been imaged with full adaptive optics employed at the 1.5 m telescope belonging to the USAF Phillips Laboratory's Star-fire Optical Range near Albuquerque, New Mexico. On 1994 May 4 at a wavele ngth of 0.85 mu m, the Delta mag values and separations for ADS 9731 c omponents AB were observed to be 2.19 and 1.''127, 0.90 and 1.''55 for CD, and 0.40 and 14.''8 between A and C. Combining these observations with earlier ones, we have obtained circular, highly inclined, long-p eriod (834 and 1230 yr) preliminary orbits for both pairs and derived their masses along with other astrophysical quantities. However, consi deration of stellar evolutionary models leads to a disagreement in the derived distance to the system (108.1 pc) and/or masses, which will p erhaps be resolved by subsequent orbital refinement. The first ever re al-time images at short wavelengths (<1 mu m) of the faint companion t o the astrometric binary mu Cas A component were easily made at 0.85 m u m on 1994 August 28 and October 22, with movement noted between the two dates. The Delta mag value was determined to be 4.9 +/- 0.1, and t he separation on the two dates was 0.''73 and 0.''66. Combining our me asurements with astrometric data from both Sproul and Allegheny Observ atories, we make a simultaneous fit for a new master orbit and find ma sses of 0.742 +/- 0.059 and 0.173 +/- 0.011 M. for A and B, respective ly. From further analysis we derive a presumably primordial helium abu ndance for mu Cas of Y = 0.24 +/- 0.07 for an assumed age of 10(10) yr and the latest measured metallicity of Z = 0.0021.