THE ASTRONOMICAL JOURNAL       VOLUME 105, NUMBER 6, PAGE 2265        JUNE 1993

  CHROMOSPHERICALLY ACTIVE STARS. X. SPECTROSCOPY AND PHOTOMETRY OF HD 212280

                               FRANCIS C. FEKEL

    Center of Excellence in Information Systems, Tennesee State University,
   330 Tenth Avenue North, Nashville, Tennessee 37203-3401 and Space Science
             Laboratory, ES-52, NASA Marshall Space Flight Center,
                           Huntsville Alabama 35812
                   Electronic mail: fekel@ssl.msfc.nasa.gov

                    JARED C. BROWNING AND GREGORY W. HENRY

    Center of Excellence in Information Systems, Tennesee State University,
            330 Tenth Avenue North, Nashville, Tennessee 37203-3401
                       Electronic mail: henry@tsu.bitnet

                      MARY D. MORTON AND DOUGLAS S. HALL

 Dyer Observatory, Department of Physics and Astronomy, Vanderbilt University,
                          Nashville, Tennessee 37235
                   Electronic Mail: hallxxds@vuctrvax.bitnet


                                   ABSTRACT

    The system HD 212280 is a chromospherically active double lined
    spectroscopic binary with an orbital period of 45.284 days and an
    eccentricity of 0.50.  The spectrum is composite with spectral types of
    G8 IV and F5-8 V for the components.  An estimated inclination of 78
    deg +/- 8 deg results in masses of 1.7 and 1.4 solar masses for the G
    subgiant and mid-F star, respectively.  The distance to the system is
    estimated to be 112 pc.  Photometric observations obtained between 1987
    November and 1992 June reveal that HD 212280 is a newly identified
    variable star with a V amplitude of about 0.15 mag and a mean period of
    29.46 days.  Our V data were divided into 11 sets and in all but one
    case two spots were required to fit the data.  Lifetimes of 650 days
    and a minimum of 1350 days have been determined for two of the four
    spots.  These lifetimes are consistent with the results of Hall & Busby
    [Active Close Binaries, Proceedings of the NATO Advanced Studies Inst.
    (Kluwer, Dordecht) (1990)].  The differential rotation coefficient of
    0.05 is relatively small.  Since the system has an eccentric orbit and
    one component is significantly evolved, its evolutionary status is of
    particular interest.  The age of the system is about 1.9 x 10^9 years.
    The G subgiant is rotating slower than pseudosynchronously while the
    F-type star is rotating faster.  The system and its components are
    compared to the circularization and synchronization time scales of
    Tassoul & Tassoul (ApJ, 395, 259, 1992).