Rotational velocities of the giants in symbiotic stars – III. Evidence of fast rotation in S-type symbiotics

We have measured the projected rotational velocities (v sin i) in a number of symbiotic stars and M giants using high-resolution spectroscopic observations. On the basis of our measurements and data from the literature, we compare the rotation of mass donors in symbiotics with v sin i of field giants and find that: (i) the K giants in S-type symbiotics rotate at v sin i > 4.5 km s−1, which is 2–4 times faster than the field K giants; (ii) the M giants in S-type symbiotics rotate on average 1.5 times faster than the field M giants. Statistical tests show that these differences are highly significant – p-value