COMMISSION 27 OF THE I. A. U.
        INFORMATION BULLETIN ON VARIABLE STARS
                    Number 2044

                                 Konkoly Observatory
                                 Budapest
                                 1981 November 19

                                 HU ISSN 0374-0676




           THE ECLIPSING BINARY HD 124195




  The runaway star HD 124195 was observed in 1975 with the
Dutch satellite ANS in the ultraviolet. The star has V = 6.11,
B - V = +0.05, MK type: B5V. It has a variable radial velocity.
The pointing direction of ANS was: Ra(1950) = 14h 10m 15s,
D(1950) = -54d 23.5m. ANS has a field of view of 2.5 x 2.5 arc
minutes.
  In two consecutive half years 13 observations were obtained
(see Table I). Observations 6 and 7 are about 0.5 magnitudes
fainter than the remaining 11 observations. On the basis of the
groundbased colours and spectral type, and unreddened colours
in the visual of Fitzgerald (1970), and in the ultraviolet of
Wesselius et al. (1980) I have predicted the ultraviolet magnitudes 
of HD 124195. The result is shown in the last line of
Table I. It is apparent that the 11 bright observations agree
quite well with this expectation.

  While encountering this object in an earlier stage of the
ANS data reduction I thought it was due to an - as yet unknown -
observational problem. After many studies based on ANS material,
and an extensive comparison with other ultraviolet data
(Gilra et al., 1982) I had become reasonably convinced that the
observed depression was real, i.e. we are observing an eclipse
of HD 124195.
  Indeed I found that the star is listed as a variable in
Kukarkin's catalogue under the name: V716 Cen. Schoeffel and
Koehler (1965) published a lightcurve showing a primary minimum
of about 0.6 magnitudes and a secondary one of 0.3 magnitudes.
The next year Popper described 6 spectrograms of this star: he
found only single lines. Hube (1970) published three radial
velocities of HD 124195: +92, +95, +10 km/s, on average
"+65.9 var".


                    Table I

           ANS Observations on HD 124195


No.  Date         m1550N  m1550W  m1800    m2200   m2500   m3300
----------------------------------------------------------------
 1   1975.10873   4.743   4.729   4.921    5.665   5.530   5.624
 2   1975.11043   4.754   4.729   4.896    5.660   5.532   5.631
 3   1975.11044   4.746   4.728   4.898    5.655   5.530   5.632
 4   1975.11268           4.722   4.894    5.643   5.529   5.606
 5   1975.11269           4.728   4.895    5.640   5.526   5.604
 6   1975.11378   5.296           5.439    6.179   6.048   6.129
 7   1975.11378   5.295           5.430    6.178   6.056   6.123
 8   1975.61623           4.715   4.889    5.640   5.524   5.625
 9   1975.61623   4.735           4.887    5.638   5.528   5.625
10   1975.61881           4.718   4.895    5.640   5.520   5.624
11   1975.61882   4.733           4.893    5.646   5.531   5.624
12   1975.61900           4.752   4.930    5.671   5.560   5.654
13   1975.61900   4.756           4.923    5.679   5.555   5.660
14   prediction           4.76    4.92     5.61    5.46    5.61
15   average      4.745           4.902    5.652   5.533   5.628
16   rms error     .009            .015     .014    .013    .017
17   eclipse      0.551           0.533    0.527   0.519   0.498
----------------------------------------------------------------


  On the basis of Hube's result, and apparently unaware of the
previous studies establishing the star as an eclipsing binary,
Bekenstein and Bowers (1974) included it in a list of potential
runaway stars on the basis of the high peculiar velocity derived
from Hube's +65.9. This large peculiar velocity is due to the
binary nature, and consequently the star is not a runaway star.
  Each of the observations consists   typically of 10 samples
on the star, preceded and/or followed by 6 samples dark current
of the photomultipliers;each sample lasts 8 seconds. The data
reduction on an observation results in five net fluxes, one for
each photometric channel (they are registered simultaneously).
The internal error in each of these net fluxes is smaller than
0.5%. During the observations in the eclipse phase (lasting 208
seconds) the flux did not vary too.
   HD 124195 has a period of Min = JD 2438524.410 + 1.49008
days. The ANS observation has been done 2638.044 periods later,
i.e. 1.6 hours after minimum. Judging from Schoeffel and
Koehler's lightcurve I predict a depression in the visible of
0.47 mag and an increase in intensity in 208 seconds of
0.004 mag. Row 15 and 16 of Table I present the average of the
11 ANS observations apparently done outside of both eclipse
phases, and row 17 presents the difference between this average
and the eclipse observations. We see that there is a small color 
effect: the depression is 0.55 mag at 1550 A to 0.50 mag at
3300 A. The predicted depression at V of 0.47 mag seems perfectly
in agreement with the UV depressions, and the ANS observations
are apparently on the rising part of the primary minimum.
  It might be possible to derive some properties of the secondary, 
but I will leave that to more experienced binary star specialists. 
It might be worthwhile to obtain more observations on
this star in order to establish its properties.





                  P.R. WESSELIUS

                  Dept. of Space Research,
                  P.O. Box 800,
                  Groningen,
                  The Netherlands


References:

Bekenstein, J.D., Bowers, R.L.: 1974, Astrophys. J. 190, 653. [BIBCODE 1974ApJ...190..653B ]
Fitzgerald, M.P.: 1970, Astron.Astrophys. 4, 234. [BIBCODE 1970A&A.....4..234F ]
Gilra, D.P., Jamar, C., Koornneef, J., Meade, M.R., Wesselius,
      P.R.: 1982, in preparation.
Hube, D.P.: 1970, Mem. R.A.S. 72, 233. [BIBCODE 1970MmRAS..72..233H ]
Popper, D.M.: 1966, Astron. J. 71, 175. [BIBCODE 1966AJ.....71S.175P ]
Schoeffel, E., Koehler, U.: 1965, IAU 
      Inf.Bull. on Variable Stars No. 77.
Wesselius, P.R., v.Duinen, R.J., Aalders, J.W.G., Kester, D.:
      1980, Astron. Astrophys. 85, 221. [BIBCODE 1980A&A....85..221W ]