DETECTING FAINT SECONDARIES OF SPECTROSCOPIC BINARIES - HD 101177B AND 149414A

We have observed HD 101177B and 149414A, two known single-lined binari es, and directly measured the radial velocities of their secondaries, enabling us to derive the mass ratios of the two systems. Using high s ignal-to-noise ratio spectra obtained mostly with the William Herschel Telescope, and a new algorithm to analyse composite spectra, TODCOR, We show that the mass ratios of HD 101177B and 149414A are 0.48 +/- 0. 03 and 0.57 +/- 0.02, respectively. These are two of the lowest mass r atios ever measured around normal G or K dwarf stars. These two system s demonstrate the potential of the present approach, which can turn ma ny of the known single-lined binaries into double-lined systems. Such work has important implications for the study of the mass-ratio distri bution of many samples of binaries.