RADIAL-VELOCITIES, ROTATIONS, AND DUPLICITY OF A SAMPLE OF EARLY F-TYPE DWARFS

We present new radial and rotational velocities for 595 nearby early F dwarfs, based on digital spectra cross-correlated with individually o ptimised synthetic template spectra. The selection of optimum template s, the determination of rotational velocities, and the extraction of v elocities from the blended spectra of double-lined spectroscopic binar ies are discussed in some detail. We find 170 spectroscopic binaries i n the sample and determine orbits for 18 double-lined and 2 single-lin ed binaries, including some spectroscopic triples. 73 stars are listed with too rapid rotation to yield useful radial velocities (i.e. v sin i > 120 km s(-1)). We discuss the binary frequency in the sample, and the influence of unrecognised binaries on the definition of clean met allicity groups of young F dwarfs and the determination of their kinem atical properties.