Spectroscopy of subsystems in four multiple stars

The primary of the chromospherically active star HIP9642 is a 4.8day double-lined pair; the outer 420 year visual orbit is updated, but remains poorly constrained. HIP12780 is a quadruple system consisting of the resolved 6.7year pair FIN 379 Aa,Ab, for which the combined orbit, masses, and orbital parallax are determined here, and the single-lined binary Ba,Bb with a period of 27.8 days.

HIP28790 is a young quintuple system composed of two close binaries, Aa,Ab and Ba,Bb, with periods of 221 and 13 days, respectively, and a single distant component C. Its subsystem Ba,Bb is peculiar, having a spectroscopic mass ratio of 0.89 but a magnitude difference of ~2.2mag. HIP64478 also contains five stars: the A-component is a 29year visual pair with a previously known 4 day twin subsystem, while the B-component is a contact binary with a period of 5.8hr, seen nearly pole-on.