COMMISSION 27 OF THE I. A. U.
      INFORMATION BULLETIN ON VARIABLE STARS
                  Number 1584

                              Konkoly Observatory
                              Budapest
                              1979 April 13




       HR 5343 A NEW DELTA SCUTI TYPE VARIABLE


The star HR 5343 (mv = 5.28) has been found variable when it was
used as a comparison star in the photometric observations of the
Am star 22 Boo (mv = 5.27). The study of 22 Boo is part of a largest
program whose aim is to check the constancy of evolved Am star and
whose results will be published elsewhere (Garrido et al. 1979).
The star HR 5343 that we reported here as variable was found constant 
by Breger (1969) inside a limit of 0.002 mag when he observed
it during 2.7 and 2.4 hours in two differents nights.



Observations

Observations have been performed during summer 1978 in a photometric
station at 2609 m of altitude in Sierra Nevada (Spain). The observing
equipment consisting in a 30 cm Cassegrain telescope, a photoelectric
photometer equipped with an unrefrigerated EMI 6256 A photomultiplier
and an analogical recorder. Only one filter, close to the B of the
Johnson's system has been used.
The star has been observed during three nights. The magnitude differences 
HR 5343-22 Boo are shown in Figure 1. The figure also includes
a plot of the magnitude differences between 22 Boo and the second
comparison star HR 5346 (mv = 6.30, dF4) as a monitoring of the 
measurement accuracy. The amplitude of the light variations is about
0.03 mag. and does not change Significantly from one night to another.
A period estimation has been obtained from a night by night Fourier
analysis of the data. We found periods slightly different for each
night with a mean value of 0.04 d.

                        [FIGURE 1]

Fig. 1 - Light curves showing the magnitude difference
HR 5343 - 22 Boo (crosses) and 22 Boo - HR 5346 (points) versus
the heliocentric julian date. The number which appears in the
corner of each light curve is the julian day of the observation.



Spectral Classification

A photometric calibration of HR 5343 (Philip et al. 1976) gives
Mv = 2.54 and log Te = 3.88 which places this star in the extension
of the cepheid instability strip close to the main sequence. The
period and luminosity found are in agreement with the period-
luminosity-color relation for delta Scuti stars, Mv = -3.052 log P +
8.456 (b - y)0 - 3.121 (+- 0.31 mag) (Breger, 1979) which gives
Mv = 2.58.
Its classification as Am in the Bright Star Catalogue (Hoffleit, 1964)
would indicate that this star contradict the well established fact
that main sequence Am stars do not pulsate. However, another spectral
classification by Bertaud and Floquet (1967) shows that HR 5343 is
a normal F0 IV star having Mv I(lambda 4031 - 34) and Ca I ( lambda 4227) 
lines weaker than usual. So the classification as Am is probably wrong.



Conclusion

The position of this star in the HR diagram, the value of the period
and the shape of the light curves suggest its classification as
delta Scuti variable. The value of the pulsational constant, Q = 0.025,
obtained from log Q = -6.454 +log P + 0.5 log g + 0.1 M_bol + log Te
(Petersen and Jorgensen, 1972), corresponds to a pulsation in the
first overtone.





                       V. COSTA
                       R. GARRIDO
                       M. SAEZ

                       Instituto de Astrofisica
                       de Andalucia
                       Apdo. 2144
                       Granada
                       Spain




References:

Bertaud, C. and Floquet, M. 1967, J. Obs. 50, 425. [BIBCODE 1967JO.....50..425B ]
Breger, M. 1969, Astrophys. J., Suppl. Ser. 19, 79. [BIBCODE 1969ApJS...19...79B ]
Breger, M. 1979, preprint.
Garrido, R., Costa, V., Lopez de Coca, P. 1979, preprint.
Hoffleit, 1964, Catalogue of Bright Stars, 3 ed. (New Haven Yale
   University press).
Petersen, J.O. and Jorgensen, H.E. 1972, Astron. Astrophys. 17, 367. [BIBCODE 1972A&A....17..367P ]
Philip, A.G.D., Miller, T.M. and Relyea, L.J. 1976, Dudley Obs. Rep.
    no 12.