Huge magnetic spots may explain weird light patterns of super-hot stars


Oct 22, 2019
The paper cited in abstract said, "For more than six decades, the quest to understand the formation of hot (about 20,000−30,000 K) extreme horizontal branch (EHB) stars in Galactic globular clusters has remained one of the most elusive in stellar evolutionary theory. Here we report on two discoveries that challenge the idea of the stable luminosity of EHB stars. The first mode of EHB variability is periodic and cannot be ascribed to either binary evolution or pulsation. Instead, we attribute it here to the presence of magnetic spots: superficial chemical inhomogeneities whose projected rotation induces the variability. The second mode of EHB variability is aperiodic and manifests itself on timescales of years. In two cases, six-year-long light curves display superflare events that are several million times more energetic than solar analogues..."

Globular clusters (GCs) would be a tough place to live on an exoplanet located in the GC. The report stated "Scientists were studying a class of fairly small, unusually hot stars that have very little hydrogen."

The EHB must start in the GC as ZAMS plots on the H-R diagram, and then slowly evolve into EHB stars in the GC.