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arXiv · 2009.06642

OGLE-GAL-ACEP-091 -- The First Known Multi-Mode Anomalous Cepheid

I. Soszyński·R. Smolec·A. Udalski·M. K. Szymański·P. Pietrukowicz·D. M. Skowron·J. Skowron·P. Mróz·R. Poleski·S. Kozłowski·P. Iwanek·M. Wrona·M. Gromadzki·K. Ulaczyk·K. Rybicki
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Abstract

Anomalous Cepheids (ACs) are metal-deficient, core-helium-burning pulsating stars with masses in the range 1.2-2.2 M_S. Until recently, all known ACs were pure single-mode pulsators. The first candidate for an AC pulsating in more than one radial mode - OGLE-GAL-ACEP-091 - was recently identified in the Milky Way based on the photometric database of the Optical Gravitational Lensing Experiment (OGLE) survey. We analyze this object showing that it is actually a triple-mode pulsator. Its position in the Petersen diagram, the light-curve morphology quantified by Fourier coefficients, and absolute magnitudes derived from the Gaia parallax are consistent with the assumption that OGLE-GAL-ACEP-091 is an AC. Our grid of linear pulsation models indicates that OGLE-GAL-ACEP-091 is a 1.8 M_S star with a metallicity of about [Fe/H] = -0.5 dex.

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I. Soszyński, R. Smolec, A. Udalski, M. K. Szymański, P. Pietrukowicz, D. M. Skowron, J. Skowron, P. Mróz, R. Poleski, S. Kozłowski, P. Iwanek, M. Wrona, M. Gromadzki, K. Ulaczyk, K. Rybicki. 2020-09-14. OGLE-GAL-ACEP-091 -- The First Known Multi-Mode Anomalous Cepheid. https://doi.org/10.3847/2041-8213%2Fabb817

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