We present initial results measuring the companion fraction of metal-poor stars ( [ Fe/H ] < - 2.0 ) .
We are employing the Lick Observatory planet-finding system to make high-precision Doppler observations of these objects .
The binary fraction of metal-poor stars provides important constraints on star formation in the early Galaxy \citep carney03 .
Although it has been shown that a majority of solar metallicity stars are in binaries , it is not clear if this is the case for metal-poor stars .
Is there a metallicity floor below which binary systems do not form or become rare ?
To test this we are determining binary fractions at metallicities below [ Fe/H ] = -2.0 .
Our measurments are not as precise as the planet finders ’ , but we are still finding errors of only 50 to 300 m/s , depending on the signal-to-noise of a spectrum and stellar atmosphere of the star .
At this precision we can be much more complete than previous studies in our search for stellar companions .