COMMISSION 27 OF THE I. A. U.
         INFORMATION BULLETIN ON VARIABLE STARS
                     Number 1970

                                   Konkoly Observatory
                                   Budapest
                                   1981 May 25

                                   HU ISSN 0374-0676


       HD 114842, A NEW SHORT PERIOD VARIABLE STAR


   During a search for the periodic content of the Delta
Scuti star HR 5005 we had to choose an extra comparison star
from those previously considered by Jerzykiewicz (1975). He
took HR 5014 and HR 5059 as standard stars but concluded that
HR 5014 was most likely a variable itself. With this 
conclusion in mind, a third standard star had to be considered. 
Following the criteria for choosing the comparison stars, as
stated in Baglin et al. (1973) or in Warman et al., (1974),
this would have to be close to our problem star, (<=2d), of
about the same magnitude as the variable (6.5 for HR 5005) and
approximately of the same spectral type. Since one third of
the stars that lie within the instability strip are variable
(Breger, 1979) we chose an F8 (HD 114842) that should be outside
these limits.
   On analyzing the light curves of all our observed stars,
one can conclude that the original consideration of Jerzykiewicz
can be attributed to a different air mass extinction since these
two standard stars are more than 9 minutes apart. Our analysis
showed that the light curve of these two stars behave similarly
on all nights although, on revising the literature it was found
that HR 5014 is reported as a double star in the Bright Star
Catalogue and by Jeffers et al. (1963) in the Index Catalogue
of Visual Double Stars, where it is reported that this star
was observed in 1959 by Finsen who established it as a double
system and determined a separation of 0".1, an angle of 
inclination of 27", and also that both components are of the same
brightness, 7.1 mag. No further information of this system
has been available to us, so we cannot conclude if the slight
difference observed is due to the binarity. But due to the
fact that it has been reported as double, it cannot be taken
as a standard in the present study and was just taken as a
check star for the atmospheric conditions.
    The equipment utilized was the 60-inch telescope at the
San Pedro Martir Observatory, Mexico. An 1P21 cooled detector
and Johnson's V filter were employed. For each reported point
of the differential photometry, six ten-second integrations               
were obtained; to the average of this flux a ten-second 
integration of the sky was subtracted and the magnitude was
obtained by means of the familiar relation m=-2.5 log F. Our
data point are accurate to 0.004 mag; the average time span
between successive reported points is of about eleven minutes
and the accuracy in time is of 2 minutes.
    The results are presented in Figure 1. The amplitude is
of about 0.035 mag, but the period, determined from peak to peak,
is rather irregular, suggesting the presence of several 
simultaneous modes of pulsation; the shortest is of about 0.056 d,
whereas the largest indicates a figure closer to 0.191 d. The
average period is of 0.095 d. Its spectral type is rather
late, an F8; nevertheless, due to the characteristics shown,
(short period of the order of hours, low amplitude variation
and an F spectral type) one might conclude that, more likely,
this is a Delta Scuti Pulsator.
    Breger, (1979) in his recent review article does not list
another star as late as this one. Of course, the possibility
that it lies outside the instability border exists, but another
more likely possibility is that its spectral type is inaccurately
determined. Pena et al. (1981) have shown that, in general, the
spectral types of the Delta Scuti stars are not very accurately
determined. We encourage the obtention of spectra of this
star to fix its position univocally in both the PLCR and the HR
diagrams and establish its pulsational nature.


                     [FIGURE 1]                                


                      R. PENICHE, J. H. PENA
                      Instituto de Astronomia
                Universidad Nacional Autonoma de Mexico


                    
References:


Baglin, A., Breger, M., Chevalier, C., Hauck, B., le Contel,
     J. M., Sareyan, J. P., and Valtier, J. C. 1973, Astron.
     and Astrophys. 23, 221. [BIBCODE 1973A&A....23..221B ]
Breger, M. 1979, Publ. Astron. Soc. of Pac., 91, 5. [BIBCODE 1979PASP...91....5B ]
Jeffers, H. M., Van den Bos, W. H., Grebby, F. M., 1963, Publ.
     of Lick Observ. Vol. XXI, parts I, II.  [BIBCODE 1963icvd.book.....J ]
Jerzykiewicz, M., 1975, Publ. Astron. Soc. of Pac., 87, 817. [BIBCODE 1975PASP...87..817J ]
Pena, J. H., Peniche, R. and Warman, J. 1981, to be published
     in the April issue of The Publ. Astron. Soc. of Pac.
Warman, J., Malacara, Z, and Breger, M. 1974, Rev. Mexicana                
     Astr. and Astrof., 1, 143. [BIBCODE 1974RMxAA...1..143W ]