COMMISSION 27 OF THE I. A. U.
        INFORMATION BULLETIN ON VARIABLE STARS
                    Number 1996

                                  Konkoly Observatory
                                  Budapest
                                  1981 July 23

                                  HU ISSN 0374-0676


     HD 224113 - A NEW ECLIPSING, DOUBLE-LINED BINARY *


The optical variability of the B5 IV-star HD 224113 was 
discovered accidentally by the author in July 1978 at the ESO-
site in La Silla/Chile. Up to that time this system was known
as a single-lined spectroscopic binary (Archer and Feast, 1958).
Subsequent uvby-photometry (ESO 50cm telescope) and spectroscopy 
in the blue, red and infrared region (1.5m telescope,
mostly 12 A/mm) during August 1979 and 1980 revealed an Algol
type light curve and led to the detection of the secondary
spectrum on IIIa-J(B) plates. This offers now the opportunity                 

                         [FIGURE 1]

               Fig. 1   The V-light curve

* based on observations collected at the European Southern
 Observatory.

to derive the dimensions of this system in absolute units
which is especially important in the case of early type non-
main sequence stars.
Fig. 1 shows the hitherto incomplete light curve (1970 measurements) 
transformed into the Johnson V-system. Both, the complete 
secondary minimum and the ascending part of the primary
minimum, are measured in two observation runs with a time 
difference of about one year. Therefore a precise period could be
derived which is slightly shorter than that previously known.
The epoch of the primary minimum is given by the formula:
          HJD 244 3698.5118 + 2.445088d E
The light curve clearly demonstrates some complications of
the system: Reflection and ellipticity effects, and the 
influence of gas streams or circumstellar material are small but
definitly present. Moreover the displacement of the secondary
minimum to phase 0.476 indicates a non-zero eccentricity of
the orbit in contradiction to Lucy and Sweeney (1971), who
obtained a circular orbit recalculating the available spectroscopic 
data.

No rectification has been attempted because of the lack of
sufficient data outside the minima. However, a fairly good 
representation of both minima could be obtained with the tentative 
parameters (Merrill-Russell method): k = 0.44, r_2 = 0.103,
i = 82d, x = 0.6. The well observed secondary minimum probably
is an occultation very near to totality. (The minimum light of
the primary minimum (transit) has been estimated to be around
6.325m according to some V-measurements kindly provided by
H.J. Schober).
Fig. 2 shows the radial velocity curves derived from the CaII-
K-line only. This line is the only line of the secondary suitable 
for radial velocity measurements. Sometimes MgII 4481 seems
also to be present. Besides that the secondary spectrum causes
an asymmetry of the H-lines. From the spectral behaviour and
the derived photometric elements one can estimate the spectral
type of the secondary to be around A0. Some difficulties arise
measuring the K-lines: The primary line is blended by an interstellar 
component (radial velocity 0.7 km/s) and the secondary
line will be distorted for positive velocities by HeI 3936 of

                       [FIGURE 2]

 Fig. 2   The radial velocity curves, (dot) primary, (circle) secondary

the primary (see Fig. 3). The elements found from these radial
velocity curves are: K_1 = 86 km/s, K_2 = 190 km/s, gamma = 2 km/s.
There is a small difference (+- 3 km/s) for the gamma-values of the
individual curves which can be related to gas streams in the
system. Whereas K_1 is in quite good agreement with the result
by Archer and Feast, gamma differs appreciable from their value
(13 km/s). This may mainly be due to differences in the velocity 
systems but may also be a hint for a third body in the
system. However, the value obtained for omega (mean from the two
radial velocity curves and the light curve) amounts to 169d
(referring to the primary) and agrees well with 167d found by
Archer and Feast. Therefore the latter possibility must be
ruled out. The orbital eccentricity has been determined to be
e = 0.044. V-magnitude, semi-major axis, radius and mass for
both components are given in Table I.


                         [FIGURE 3]

 Fig. 3  Intensity tracings of the K-line region at two phases:
         phi=0.30 (top) and phi=0.68 (bottom).
         1: K-line primary, 2: K-line interstellar, 3: K-line
         secondary, 4: HeI 3936.


		          Table I.

		       Primary      Secondary

		V      6.20m        8.96m
		a      4.19 R_Sun   9.26 R_Sun
		R      3.15 R_Sun   1.39 R_Sun
		M      3.76 M_Sun   1.70 M_Sun



The preliminary results reported here will be used as initial
parameters for the final evaluation by means of computer simulation 
after completing especially the photometric data.


                          R. HAEFNER
                          Universitats-Sternwarte
                          Scheinerstr. 1
                          D-8000 Munchen 80
                          Germany

References:


Archer, S., Feast, M.W. 1958, M.N.A.S.S.A. 17, 9 [BIBCODE 1958MNSSA..17....9A ]
Lucy, L.B., Sweeney, M.A. 1971, Astron. Journ. 76, 544 [BIBCODE 1971AJ.....76..544L ]
Schober, H.J. 1980, private communication