Delta Scuti stars


The main purpose of the COROT space mission is the investigation of the low amplitude Delta Scuti stars. Most targets in the seismo field will be Delta Scuti stars covered both the main sequence and the post main sequence evolution phase. However, it is sure that low amplitude Delta Scuti stars will be found on the exofields, too. However, it is questionable that in the spectrum of the low amplitude, short period Delta Scuti stars the closely spaced excited modes can be identified or not with 8 minutes sampling. Since it is possible to observe some stars on the exofields with an oversampling chanel (32 seconds as on the seismo fields), it is interesting to investigate whether oversampling channel is needed or not.


As we mentioned the capacity of MUFRAN restrict our calculation into 6.2 c/d domain. In such a frequency range the published frequencies of FG Virginis was used in the synthetic data set. The accepted sinus and cosinus amplitudes and amplitudes that are close to the amplitudes obtained in the real data set of the star. For the modes with the highest amplitudes it is 0.003 mag, while 0.01 mag for the modes with middle amplitudes and 0.0006 mag for the modes with the lowest amplitudes.

Sinus amplitude
Cosinus amplitude

The speciality of the data set are the high frequency closely spaced modes and the low amplitudes.

The frequencies were not search by one after others. A search for modes with the same amplitude was carried out in a single step for the presentation.

The steps of the frequency search:

1. stepf1 = 19.8679930.0018056.58
 f2 = 21.0519580.0018057.36
 f3 = 23.4030020.0018056.31
 f4 = 24.2281280.0018052.22
2. stepf5 = 19.227999 54.51
 f6 = 20.287999 54.53
 f7 = 21.231987 54.83
 f8 = 24.199985 54.91
 f9 = 25.4320030.0008654.37
 f10 = 21.551 63.43
 f11 = 24.354 63.44
 f12 = 22.3720.0002263.43

All the frequecy values used in the generation was found in the frequency search procedure. It seems that the low amplitude Delta Scuti stars does not need oversampling on the exofields for asteroseismological investigation.

Spectra and light curves of FG Vir: