To explain its great rotational speed, it has been argued that FK Comae Berenices is either a recently coalesced binary or has been spun up by angular momentum transfer via mass transfer from an unseen companion. Upper limits on radial velocity variation put severe constraints on any binary model. A series of 51 spectroscopic observations of FK Com during an eight night observing run in 1989 revealed regular variation of projected rotational speed with rotational phase. These variations are suggestive of strong nonradial pulsations at about half the rotational period. We postulate that the pulsations were excited by a recent binary merger. Less extensive data obtained in 1987 and 1992 show different patterns of line-width variation. Thus it appears that the pulsation spectrum is changing on timescales significantly less than two years.
All Science Journal Classification (ASJC) codes
- Astronomy and Astrophysics
- Space and Planetary Science