COMMISSION 27 OF THE I. A. U.
                INFORMATION BULLETIN ON VARIABLE STARS
                          Number 2214



                                                     Konkoly Observatory
                                                     Budapest
                                                     1982 October 21

                                                     HU ISSN 0374-0676


                     HD 37847: A NEW VARIABLE STAR


  Because Bidelman and MacConnell (1973) reported Ca II H and K emission,
we suspected HD 37847 might be an RS CVn binary and therefore might show the
photometric wave characteristic of most stars of that type. According to
their table VII, mv = 7.0m and the spectral type is G8 III + F.
  Henry, observing with the 24-inch Cassegrain at Dyer, obtained data on
8 nights between JD 2444605.7 and 2444688.5. Henry and Sherlin, observing
with the 48-inch Newtonian at Cloudcroft, obtained data on 7 nights between
JD 2444959.9 and 2445022.6. All observations were made in V with BD -20deg1150
as the comparison star. The individual differential magnitudes, corrected
for differential extinction and transformed differentially to V of the UBV
system, have been sent to the I.A.U. Commission 27 Archive for Unpublished
Observations of Variable Stars (Breger 1979), where they are available as
file no. 106.

Examination of our data showed immediately that HD 37847 is variable,
with an amplitude of DeltaV = 0.32m. A period-finding program based on an 
approach similar to that of Lafler and Kinman (1965) yielded a period of 28.22d,
with an uncertainty of only about +/- 0.01. The figure below is a plot of the
nightly means, where DeltaV is in the sense variable minus comparison. The 
plusses are for Dyer, the circles for Cloudcroft. Phase is computed with the
ephemeris

                      JD = 2444652.0+ 28.22d n,

where the initial epoch is a time of minimum light. Because of the gap 
between 0.4P and 0.8P in phase, we cannot be certain if the point near 0.4P 
represents the full maximum brightness.
Additional photometry should be obtained to define the entire light
curve, although the period seems well determined. We have been in communication 
with Luis Balona and T. Lloyd Evans of the South African Astronomical 
Observatory, who tell us they have been obtaining spectroscopic
and photometric observations of this star (and all of the stars in table VII



                              [FIGURE 1]


of Bidelman and MacConnell). If radial velocity measures indicate that
HD 37847 is a binary system with an orbital Period around 28 days, then it
would be a long-period RS CVn binary by the definition of Hall (1976).


                        GREGORY W. HENRY
                        JERRY SHERLIN

                        Cloudcroft Observatory
                        Cloudcroft, New Mexico 88317

                        DOUGLAS S. HALL

                        Dyer Observatory
                        Vanderbilt University
                        Nashville, Tennessee 37235





References:
Bidelman, W. P and MacConnell, D. J. 1973, A.J. 78, 687. [BIBCODE 1973AJ.....78..687B ]
Breger, M. 1979, I.B.V.S. No. 1659.
Hall, D. S. 1976, I.A.U. Colloq. No. 29, 287. [BIBCODE 1976ASSL...60..287H ]
Lafler, J. and Kinman, T. D. 1965, Ap. J. Suppl. 11, 216. [BIBCODE 1965ApJS...11..216L ]


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