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Fourier Coefficients of OGLE Variables. III. δ Scuti Stars

Morgan S. M., Simet M., Bargenquast S.

Acta Astronomica

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1998

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Vol. 48, No. 3

509--518

EN

Fourier coefficients for δ Scuti from the OGLE dark matter survey of the Galactic bulge are compared to the coefficients of similar stars, mainly High Amplitude δ Scuti and SX Phe stars. While in previous studies there appears to be a division amongst the δ Scuti stars based upon the R21 parameter, such a division is not apparent in the OGLE stars. There does though appear to be a separation of the δ Scuti stars based upon the φ31 variable. This separation is not likely due to a metal variation and its cause is not known. Values for the extinction towards the Galactic bulge can be used to estimate a distance of approximately 7.6 kpc for the δ Scuti stars. One variable does appear to be located beyond the Galactic bulge at a distance of approximately 21 kpc.

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Fourier Coefficients of OGLE Variables. II. RR Lyraes

Morgan S. M., Simet M., Bargenquast S.

Acta Astronomica

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1998

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Vol. 48, No. 2

341--353

EN

Fourier coefficients for RR Lyraes in the OGLE survey are compared to the coefficients of field and cluster RR Lyraes. Based upon the location of the Bailey type ab and c stars for a range of metallicity, it appears that the vast majority of the OGLE variables have a [Fe/H] near -1.1. Using both empirical and theoretical relations for the Fourier coefficients, stellar characteristics are found to be similar to those derived in other RR Lyrae studies. There are also some stars in the OGLE sample which appear to be of a slightly different metal abundance, as well as some which are members of the Sagittarius dwarf galaxy. These latter stars do show a slight metal deficiency relative to most of the OGLE stars. The OGLE variables give a distance to the Galactic bulge of approximately 8 kpc, and a distance to the Sagittarius dwarf galaxy of about 25 kpc.

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Fourier Coefficients of OGLE Variables. I. Parameters for the Baade's Window, MM5-A, MM5-B, MM7-A, and MM7-B Field Variables

Morgan S. M., Simet M., Bargenquast S.

Acta Astronomica

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1998

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Vol. 48, No. 2

331--339

EN

Fourier coefficients for the variable stars in the OGLE survey of the Galactic center were derived. In most cases the classification of the variable type is confirmed but there are some cases where the classification is brought into question. The Fourier coefficients for all of the variables including RR Lyraes, δ Scuti and SX Phe stars, as well as an Anomalous Cepheid are presented. In general the distribution of the Fourier coefficients for the different types of variable stars in this study lie within the observed ranges of other studies.