Rotational velocities of the giants in symbiotic stars - II. Are S-type symbiotics synchronized?

We have measured the projected rotational velocities (vsini) of the mass donors for 29 S-type symbiotic stars (SSs) using high-resolution spectroscopic observations and the cross-correlation function (CCF) method. The results of the CCF have been controlled with synthetic spectra. The typical rotational velocity of the K and M giants in S-type symbiotics appeared to be 4.5 < vsini < 11.7 kms^-1. In a subsample of 16 S-type SSs (with known orbital periods and well-measured vsini), 15 have deviations from synchronization less than the 3σ level. This means that we did not find evidence for a statistically significant deviation from the synchronization for any of these 15 objects. The deviation from synchronization is statistically significant (at confidence level >99 per cent) only for the recurrent nova RS Oph.

For 22 S-type symbiotics we give clues as to what their orbital periods could be.

Based on observations obtained in ESO programmes 073.D-0724A and 074.D-0114.

E-mail: rkz@astro.bas.bg (RKZ); mfb@astro.livjm.ac.uk (MFB); andreja.gomboc@fmf.uni-lj.si (AG)