The Nature of Overluminous F Stars Observed in a Radial‐Velocity Survey

We have conducted a radial-velocity survey of bright (V < 9), overluminous, F stars within 80 pc. The criterion of overluminosity is ΔM = M - MV ≥ 0.5, where MV is the absolute magnitude based on the Hipparcos parallax and M is the absolute magnitude from uvby photometry. For F stars, overluminosity at a level of ΔM > 0.15 has been argued to be indicative of the presence of a bright companion, so many of the overluminous "single" F stars are expected to be, in fact, binaries with comparably bright components. Therefore, the main goals of the survey have been to gain insight into the nature of overluminous F stars and to test specifically the hypothesis of the duplicity of overluminous F stars by searching for previously unrecognized binary stars among them. Other goals of this project included the determination, wherever possible, of the orbits of the binaries discovered as a result of the survey and comparing the properties of the binaries with those of the visually single stars with constant radial velocity. The program list comprised 111 stars that appear in the Hipparcos catalog as single, plus seven members of multiple systems whose components have individual entries in the catalog.