CDROM/AJ/V105/P2265     HD 212280 (Fekel+ 1993)
================================================================================
Chromospherically Active Stars. X. Spectroscopy and Photometry of HD 212280
      Francis C. Fekel, Jared C. Browning, Gregory W. Henry, Mary D. Morton &
      Douglas S. Hall
      <1993, AJ, 105, 2265>
      =1993AJ....105.2265F
================================================================================

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).


File Summary:
--------------------------------------------------------------------------------
File Name    Lrecl    Records    Explanations
--------------------------------------------------------------------------------
table1.dat      67         32    Velocity observations of HD 212280
--------------------------------------------------------------------------------

Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
   Bytes Format  Units    Label    Explanations
--------------------------------------------------------------------------------
   1-10   F10.3  ---      HJD      Heliocen. Julian Date of mid obs. - 2,400,000
  11      A1     ---      Note    *[abc ] Footnote
  12-14   3X     ---      ---      Blank
  15-19   F5.3   ---      Phase   *Phase of the observation
  20-23   4X     ---      ---      Blank
  24-28   F5.1   km/s     Vel_a    Observed velocity of component A
  29-32   4X     ---      ---      Blank
  33-37   F5.1   km/s     O-C_a   *Residual for component A
  38-40   3X     ---      ---      Blank
  41-45   F5.1   km/s     Vel_b    []? Observed velocity of component B
  46-50   5X     ---      ---      Blank
  51-54   F4.1   km/s     O-C_b   *[]? Residual for compnent
  55-58   4X     ---      ---      Blank
  59-67   A9     ---      Std      Velocity standard star
--------------------------------------------------------------------------------

Notes for file: table1.dat
--------------------------------------------------------------------------------
Footnote:
  'a' -- DDO observation; 'b' -- Blended velocity, weight = 0.5;
  'c' -- central wavelength = 6700A

Phase:
  Phase of the observation with zero phase being periastron passage

O-C_a, O-C_b:
  Residual to the fit or observed minus calculated velocity of the
  component
--------------------------------------------------------------------------------

================================================================================
(End)                                             Lee Brotzman [ADS] 06-Mar-1995