X-ray to bolometric luminosity ratio of β Hyi (circles). The light gray curve mimics the solar X-ray variation over Cycle 24, replicated in time and stretched to a period of 12 yr, then adjusted to the apparent X-ray modulation amplitude of β Hyi. Archival ROSAT fluxes from various catalogs are shown as the yellow, orange, and red circles, XMM-Newton as the blue circle, and Chandra as the green open circle. Horizontal dashed and dot-dashed lines mark the mean normalized X-ray luminosity of β Hyi and ±1σ uncertainties. White squares represent the Mg II time-series scaled to match the amplitude of the X-ray variation.