COMMISSION 27 OF THE I. A. U.
            INFORMATION BULLETIN ON VARIABLE STARS
                         Number 3679   

                                            Konkoly Observatory
                                            Budapest
                                            7 November 1991

                                            HU ISSN 0374 - 0676


          THE IUE SPECTRUM OF THE SHELL STAR HD 50845


HD 50845 = BD-1d 1447 = SAO 133883, visual magnitude 8.2, was found to be a
variable velocity shell object with an underlying F5V star (Sahade and
Ringuelet 1985; Sahade, Ringuelet and Rotstein 1987).

In order to learn more about this interesting object, two IUE images (SWP 30288
and LWP 10103) were secured at the Goddard IUE Observatory on day 41, year
1987, in the small dispersion, large aperture mode. The exposure times were of
3600s and 460s, respectively. There is a third LWP image (LWP 10102)
available, too weak for analysis.

The IUE spectrum of HD 50845 is shown in Fig. 1. The SWP image is too weak to
permit any conclusion, while the LWP image is undoubtedly an absorption
spectrum.


                               [FIGURE 1]

 Fig. 1. The IUE spectrum of HD 50845 (full line) and Kurucz's continuum
 for Teff=6700dK, log g=4.5 (broken line).


The comparison of our IUE spectrum of HD 50845 with Kurucz's (1979) LTE
model-atmosphere calculations shows that the best fitting for the continuous
spectrum corresponds to the effective temperature of that of an F5 star and a
gravity value around that of a main sequence object (as also shown in Fig. 1).
Moreover, our IUE spectrum of HD 50845 looks very similar to that of a normal
middle F dwarf (cf. Heck et a1. 19R4).

No other conclusions seem to be justified by the IUE material at our disposal.

We are indebted to the Goddard IUE Observatory staff for so efficiently
securing and processing the images of HD 50845 for us.


Jorge Sahade ^1,2
C.C. 677, Observatorio Astronomica
1900 La Plata, and
C.C. 5, Instituto Argentino de
Radioastronomia
1894 Villa Elisa (Bs. As.)
Argentina

Rodolfo Barba ^3
Facultad de Ciencias Astronomicas y
Geofisicas,
Universidad Nacional de La Plata
1900 La Plata
Argentina

Yoji Kondo ^1
Code 684
NASA-GSFC, U.S.A.

1 Guest observer, IUE observatory.
2 Member of the Carrera del Investigador Cientifico, CONICET, Argentina.
3 Fellow, CONICET, Argentina.

REFERENCES

Heck, A., Egret, D., Jaschek, M. and Jaschek, C. 1984, IUE Low-Dispersion
      Spectra Reference Atlas - Part 1. Normal Stars, (ESA SP-1052).
Kurucz, R.L. 1979, Ap. J. Suppl. 40, 1. [BIBCODE 1979ApJS...40....1K ]
Sahade, J. and Ringuelet, A.E. 1985, I.B.V.S., No 2710.
Sahade, J., Ringuelet, A.E. and Rotstein, N. 1987, P.A.S.P. 99, 971. [BIBCODE 1987PASP...99..971S ]