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

http://arxiv.org/abs/2112.13924


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.

Read this paper on arXiv…

G. Preston, C. Sneden and M. Chadid
Thu, 30 Dec 21
62/71

Comments: accepted for the Astronomical Journal