Spectroscopic characterization of a sample of southern visual binaries
1
INAF – Osservatorio Astronomico di Padova, Vicolo dell' Osservatorio 5, 35122 Padova, Italy e-mail: desidera@pd.astro.it
2
European Southern Observatory, Casilla 19001, Santiago, Chile
Received:
23
January
2006
Accepted:
22
February
2006
Aims.We present the spectroscopic characterization of 56 pairs of visual binaries with similar components, based on high resolution spectra acquired with FEROS at ESO La Silla.
Methods.For all stars, we measured radial and rotational velocities and CaII H&K emission.
Results.Five previously unknown double lined spectroscopic binaries
were found. Six other pairs show velocity differences
that are not compatible with the orbital motion of the wide pair,
indicating the presence of further companion(s) in the system.
The fraction of visual binaries that contain
additional spectroscopic components is 
%,
compatible with other literature estimates.
The ages of the components of the pairs derived from
chromospheric activity typically show apparent differences of
about 0.2 dex.
A few pairs show a rather large difference in activity
level, but in most cases this is consistent with
the variability of chromospheric emission observed
for the Sun along its magnetic cycle.
Key words: stars: binaries: visual / stars: binaries: spectroscopic / stars: activity / stars: rotation / techniques: radial velocities / techniques: spectroscopic
© ESO, 2006