A Comparison of Photometric Metallicity Calculation Methods Based on OGLE-IV RRab Stars in the Magellanic Clouds

Dorota M. Skowron and the OGLE Team

We use almost 6 500 V- and I-band fine quality light curves of fundamental mode RR Lyrae (RRab) stars from the OGLE-IV survey to compare three different photometric metallicity calculation methods. We calculate [Fe/H] from relations developed for the Johnson V-band, I-band, and for the Kepler Kp-band, and find significant discrepancies between the [Fe/H] distributions. We also show that the relation between the V-and I-band phase parameter φ₃₁ used to estimate the iron abundance depends on metallicity, which limits its applicability. Finally, we construct a metallicity map of the Magellanic Clouds and find a metallicity gradient in the Large Magellanic Cloud, but not in the Small Magellanic Cloud.

Proceedings of the Polish Astronomical Society, vol. 6, 88-92 (2018)

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