Extended Data Fig. 4: Binary evolution models for extremely-short-orbital-period sdB binaries.
From: A seven-Earth-radius helium-burning star inside a 20.5-min detached binary
Two models are differentiated owing to the different core masses of sdB stars. Mass transfers are expected to begin at around 14 and 17 min for Msd = 0.33 M⊙ and Msd = 0.36 M⊙, respectively. The red arrows denote the direction of evolution.
