COMMISSION 27 OF THE I. A. U.
           INFORMATION BULLETIN ON VARIABLE STARS
                        Number 2580

                                        Konkoly Observatory
                                        Budapest
                                        7 September 1984

                                        HU ISSN 0374-0676

                  HD 91948 IS NOT A Be STAR

 Goraya and Padalia (1984) have recently suggested that HD 91948 is a Be
star. This suggestion is based on a single spectral scan that shows that the
hydrogen lines of HD 91948 are missing or filled in by emission, a poorly
documented measurement of B-V (Padalia 1980), and the similarity of the
colour variations of HD 91948 observed on one night by Padalia (1980) to
those of the Be stars 88 Her and Pleione. We wish to point out that their
conclusions conflict with the published data on this star and offer an
alternate interpretation.
 Gorza (1971) obtained 37 12 A/mm spectrograms of HD 91948 during the
period 1969-1971. He tentatively classified the star F6V. This is consistent
with Perry's (1969) uvby photometry and the S2/68 ultraviolet fluxes
(Thompson et al. 1978). These data show no evidence of either reddened or
unreddened continuum radiation from a source hotter than 6500 K. We also
note that the energy distribution of HD 91948 shown in Figure 2 of Goraya
and Padalia (1984) appears to be somewhat redder than that of their F0V
comparison star.
  Padalia (1980) measured B-V=+0.016, and suggested that HD 91948 is an
A0V star. His wording suggests that he does not attach a great deal of
weight to this suggestion because he lacks U observations. However, Goraya
and Padalia (1984) claim that. 'From his photoelectric observations he
determined its spectral type to be A0V.' It is not clear from the text of
Padalia's (1980) note how the B-V measure was calibrated. The wording
implies that it is based on adopted colours for the comparison star, but
these are not documented. Since there are better photometric data which
conflict with this measure, we believe that it should be ignored.
  The similarities of the colour variations of HD 91948 to those of some Be
stars is a very weak argument for the Be classification. There are many
types of small-amplitude photometric variables that have larger variations
in the ultraviolet. Thus the case for the Be nature of HD 91948 rests
solely on the apparent hydrogen emission observed by Goraya and Padalia in
their spectrum scan of 29 April 1984. In view of the data cited above, it
is clear that a Be model is untenable and some other explanation must be
sought.
 We considered the possibility that Goraya and Padalia observed the wrong
star, but we can find no obvious candidate for a misidentification. One of
us (CTB) examined all of Gorza's spectra and found no evidence for any
emission. This suggests that the emission appears infrequently. Since no
information is given on the instrumental configuration used to obtain the
observations, it is also possible that the emission observed by Goraya and
Padalia is due to the visual companion. Since it is at least 3' away from
the primary along a line perpendicular to the slit, it would not have
contaminated any of Gorza's spectrograms, but a wider slit may have been
used for the scanner observations.
 The visual companion is estimated to be slightly more than 4 mag
fainter than HD 91948, which would give it a spectral type near M0 if
it forms a physical system with HD 91948. The unseen spectroscopic
companion could also be a dM star. Goraya and Padalia's observations
suggest that one of these stars is a flare star. The observed emission
(or absence of absorption) in the spectrum scan and the colour and time
dependences of the photometric variations can all be accounted for if one
of the companions occasionally flares by 3-4 mag for a few hours. These
would be large flares, but they fall within the range of behaviour observed
in the dMe stars.


                     C.T. BOLTON and RON W. LYONS
                     David Dunlap Observatory
                     P.O.Box 360
                     Richmond Hill, Ontario L4C 4Y6
                     Canada

References:
Goraya, P.S., Padalia, T.D.: 1984, Inf. Bull. Variable Stars, No. 2542
Gorza, W.: 1971, J. Roy. Astron. Soc. Canada, 65, 277 [BIBCODE 1971JRASC..65..277G ]
Padalia, T. D.: 1980, Inf. Bull. Variable Stars, No. 1733
Perry, C.L.: 1969, Astron.J., 74, 705 [BIBCODE 1969AJ.....74..705P ]
Thompson, G.I., Nandy, K., Jamar, C., Monfils, A., Houziaux, L., Carnochan,
   D.J., Wilson, R.: 1978, Catalogue of Stellar Ultraviolet Fluxes, (London:
   Science Research Council) [BIBCODE 1978csuf.book.....T ]