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arXiv · 2112.13924

Hydrogen and Helium Shock Phenomena during Rising Light in RR Lyrae Fundamental Mode Pulsators

George W. Preston·Christopher Sneden·Merieme Chadid
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Abstract

We present measurements of H and He emission and absorption lines produced in RRab fundamental mode pulsators during primary light rise. The lines define universal progressions of rise and decay in metal-poor RRab stars. Such a progression cannot be constructed for He in metal-rich RRab (those with [Fe/H]> -0.8) because weak He I emission is detected in only two of the six metal-rich RRab in our survey. Great variety exists in the phase variations of the blue- and red-shifted absorption components of the 5876 A line during pre- and post-emission phases. Detection of measurable He II 4686 A emission in eight RRab, three of them Blazhko variables, provides an additional constraint on ionization of Helium.

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George W. Preston, Christopher Sneden, Merieme Chadid. 2021-12-27. Hydrogen and Helium Shock Phenomena during Rising Light in RR Lyrae Fundamental Mode Pulsators. https://doi.org/10.3847/1538-3881%2Fac46ca

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