The different error origins are the zero-point
for each observing run, the choice of synthetic spectra and a
possible peculiarity of the star (shell, binary or multiple),
the noise of CCD being negligible. The zero-point
error was determined as described in Sect. 2.4.
The error on the radial velocity arising from the choice of
the synthetic spectrum depends
on vsini and : it is lower than 0.1kms-1 for
vsini25kms-1, about 1.0kms-1 for
vsini =125kms-1, and gets 9kms-1 for
vsini=250kms-1 and 12500K.
is the rms of the zero-point of each run, , depending on synthetic spectrum, is given in Table2 and gives an estimation of the asymmetry of the peak. To check the reality of this estimation, the unit-weight error was computed: for each star having several measurements vi, the mean radial velocity was computed and the distribution of the values has shown that the estimation of was slightly pessimistic. Subsequently, the given internal error has been adopted as 0.85.
The radial velocities obtained by correlation were compared with those obtained by the classical method of individual measurements of spectral lines upon a part of the same spectrum. In the classical method in which the internal error estimation is strongly function of the vsini of stars, the number of measured lines decreases quickly with the projected rotational velocity. Comparable internal rms are found for stars with small vsini, the correlation method becoming quickly more accurate for vsini>30kms-1.
Our radial velocities were compared to those already published.
We have used the homogeneous radial velocities published by
Andersen & Nordström (1983) and
Nordström & Andersen (1985),
quoted AN in Table3, and those published in the WEB
et al. 1995) and Barbier-Brossat & Figon (1998) catalogues quoted B in
In all cases, variable radial velocities are excluded as well as those whose
discrepancy (dv) with our results exceeds 8kms-1.
Moreover, in the WEB and Barbier-Brossat & Figon catalogues, we have eliminated those
with less than 3 measurements and an error greater than 2.2kms-1.
138 common stars remained with AN and 164 with B.
Our results are more reliable, probably due to a better
resolution, but unfortunately have often only one measurement making
an eventual undetectable binary (stars having a published radial velocity
have been observed only to obtain vsini).
As can be seen in Table3, the
average of dv is close to zero showing that our radial velocities are statistically
in the same system as the literature.
The independence of from the spectral type has been verified
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