COMMISSION 27 OF THE I. A. U.
            INFORMATION BULLETIN ON VARIABLE STARS
                        Number 3171

                                       Konkoly Observatory
                                       Budapest
                                       30 March 1988

                                       HU ISSN 0374-0676


        RECENT BEHAVIOUR OF THE YELLOW SUPERGIANT RHO Cas

  Rho Cas has previously revealed complex photometric and spectroscopic changes.
Quasi-periodicities of various lengths have been suggested, with the most
convincing being that of Sheffer and Lambert (1986) who derived a dominant 
radial pulsation mode of about 520 days from a comprehensive examination of line
profile changes. The light variations have had excellent coverage by the visual
observers of the AAVSO and appear to show most recently a semi-regular to
irregular phasing of approximate amplitude less than 0.4 magnitudes. Photometrically,
Leiker, and Hoff (1987) have published the most current comprehensive
light curve for JD 2446604 - 6994.
  Rho Cas has been added to the long-term monitoring program of the Corralitos
Observatory. Observations in BV colors were carried out with the 0.6 m. telescope
and single channel photon-counting photometer equipped with an EMI 9924A 


                               [FIGURE 1]

           Figure 1. V and B-V observations for Rho Cas.


photomultiplier tube. The comparison stars used were HD 223173 (V=5.51; B-V=1.65)
and Tau Cas (V=4.867; B-V=+1.116). No variations greater than 0.01 in either
Y or B-V were noted for the comparison stars.

  The data are shown in Figure 1 graphically and given in Table I. Generally,
a gentle decline in V magnitude from Leiker and Hoff's last values and 
interesting mirrored behaviour in B-V (though of greater range) are noted.

                   Table I.

     JD-2440000  V      B-V         JD-2440000  V      B-V
      
      6994.9389 4.49   +1.37         7089.6299 4.40   +1.27
      7045.8541 4.45    1.37         7106.7076 4.39    1.28
      7046.8291 4.45    1.36         7125.6986 4.39    1.28
      7047.8236 4.44    1.38         7126.6313 4.42    1.26
      7049.7556 4.42    1.36         7127.6472 4.43    1.27
      7050.8486 4.44    1.35         7128.6264 4.42    1.27
      7051.7069 4.43    1.36         7169.6035 4.53    1.36
      7062.8014 4.43    1.32         7170.6160 4.48    1.30
      7066.7938 4.39    1.32         7173.6062 4.51    1.31
      7067.6924 4.40    1.33         7174.5840 4.58    1.29
      7087.8312 4.41    1.25         7175.5917 4.49    1.33
      7088.7785 4.37    1.27


                             [FIGURE 2]

           Figure 2. Mean H-alpha line profile for Rho Cas.



                      Table II


              H-alpha feature mean radial velocities:
                emission peak    -71.3 km s^-1
                line profile center -63.6
                deepest absorption -48.4
              mean stellar radial velocity:
                -44.5 +/- 5.1 km s^-1 (from 12 lines)

  Two spectra of Rho Cas were obtained by the author with the Kitt Peak
Observatory coude feed telescope and CCD camera. The spectra were centered at
H-alpha and showed the presence of a single emission peak distorting the profile of
the line to the blue. The spectra were taken on JD 2447119,7208 and 7122.6313.
  There was shown no sensible change in line profile or radial velocity between
the two nights, Table II lists the mean radial velocities, and Figure 2 the
line profile.





                        E.M. HALBEDEL

                        Corralitos Observatory
                        P.O. Box 16314
                        Las Cruces, NM 88004
                        U.S.A.





References:
Leiker, P.S. and Hoff, D.B., 1987, Inf. Bull. Var. Stars, No. 3020
Sheffer, Y. and Lambert, D., 1986, Publ.Astr.Soc. Pacific, 98, 914 [BIBCODE 1986PASP...98..914S ]