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Figure 1: Wavelength displacements of stellar spectra in the Hyades. Differences between spectroscopically measured radial velocities, and astrometrically determined radial motion are plotted as function of both B-V, and projected rotational velocity (proportional to symbol area). Spectra of rapidly rotating early-type stars appear systematically more blueshifted than those of slower-rotating later-type ones. Only points with nominal differential velocity errors <3 km s-1 are plotted. In the absence of effects in stellar atmospheres or due to spectroscopic techniques, the naively expected spectral displacements should equal the marked line which estimates the gravitational redshift for main-sequence stars. Corresponding spectral types for main-sequence stars are marked at the top.

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In the text

Figure 2: Differences between spectroscopic and astrometric radial velocities versus stellar rotational velocity (top), and relative spectroscopic velocities for clusters without such astrometric data (bottom). For each cluster, the values are normalized to have correspond to the median radial velocity of stars with  60 km s-1. The Hyades: black points are from Madsen et al. (2002); open circles are M dwarfs (known binaries excluded) from Reid & Mahoney (2000); asterisks are other assumed cluster members. The Pleiades: open circles are M dwarfs from Terndrup et al. (2000). For the Hyades, stars with errors >3 km s-1 are omitted; for other clusters those with >10 km s-1. Those with no errors in the literature were assigned the value 2 km s-1.

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In the text

	Figure 3: Convective velocities from a grid of 55 main-sequence hydrodynamical model atmospheres (Ludwig et al. 1999). Shown is the root-mean-square horizontal (open) and vertical (solid circles) convective velocity at Rosseland optical depth unity, as function of B-V. The corresponding effective-temperature scale is at the top.
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In the text