COMMISSION 27 OF THE I. A. U.
       INFORMATION BULLETIN ON VARIABLE STARS
                 Number 1175

                              Konkoly Observatory
                              Budapest
                              1976 September 9



        CA II EMISSION IN THE RS CVn STAR HR 1099


   Recently HR 1099 (ADS 2644A) a G-type star with strong Ca II H and
K reversals, has been shown to be an RS CVn binary, in fact the brightest
known member of the class (Bopp and Fekel 1976; Landis and Hall 1976).
In a survey of seven RS CVn stars (not including HR 1099), Weiler (1976)
reported variations in the H and K and Halpha emission lines. In several cases,
the phase of emission maximum coincided with the minimum of the wavelike
distortion that is often present in these systems.
   Spectrograms suitable for an investigation of possible variability
in the H and K lines of HR 1099 were obtained at Kitt Peak National
Observatory during December 1974. The spectra were obtained with the No. 2
0.9m reflector and Cassegrain spectrograph; the dispersion was 63 Angstrom mm^-1 .
The spectra were widened to 0.6 mm and are well exposed in the lambdalambda3900-4000
region. The dispersion used was insufficient to resolve the components of
the double-line spectroscopic binary. From high dispersion spectra (Bopp
and Fekel 1976) it is known that the primary (more massive) component has
emission several times stronger than the secondary. Thus the lower 
dispersion data essentially test only the primary for Ca II variability.
   Microdensitometer tracings of eleven spectra were made at Ritter
Observatory. We measured equivalent widths of H and K relative to the
interpolated local continuum. Though this required some subjective 
estimates of line profile and continuum placement, random errors should be 
comparable to those of ordinary photographic equivalent width measures (~15%).


                    CA II EMISSION IN HR 1099
           HJD                         EW(Angstrom)
Plate #  2442000+  phi(ORB) phi(PHOT)   K        H

5494a    405.646    0.754    0.379    0.71      1.18
5494b    405.669    0.762    0.386    0.95      1.21
5494d    405.766    0.796    0.421    1.00      1.48
5498a    406.734    0.138    0.763    1.16      1.61
5500a    408.648    0.812    0.437    1.05      1.52
5500c    408.692    0.828    0.453    0.85      1.78
5504c    409.659    0.168    0.793    1.28      1.25
5507c    410.610    0.503    0.128    1.31      1.65
5508a    410.640    0.514    0.139    1.42      1.44
5508b    410.648    0.517    0.142    1.29      1.78
5509b    411.660    0.873    0.498    1.16      1.30


The results are given in the table, where orbital phases,
phi(ORB) are computed from

  T_0(JD) = 2442763.909 + 2.83782 E

and the phase of the distortion wave, phi(PHOT) is computed with the same
period, but epoch T_0(JD) = 2442770.65.
    The data show no convincing evidence of variation in the Ca II H-line.
There may be some variability evident in the K-line, with minimum equivalent
width being seen near phi(PHOT) - 0.4-0.5. This corresponds to the phase of
broad-band photometric maximum and resembles the behavior seen in
Weiler's observations of other RS CVn variables. Further spectroscopy of
HR 1099 is clearly needed.
    I am grateful to Dr. W. Sandmann for assistance during the observations.

                     BERNARD W. BOPP
                     Ritter Observatory
                     The University of Toledo
                     Toledo, OH 43606
References:
Bopp, B. W., and Fekel, F. 1976, Astron. Jour., in press.
Landis, H. J., and Hall, D. S. 1976, I.B.V.S. 1113.
Weiler, E. J. 1976, Ph.D. dissertation, Northwestern University. [BIBCODE 1976PhDT.........9W ]