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that have evolved off the main sequence. More recently, Hipparcos parallax measurements have yielded
reliable differentiation between true main sequence stars and slightly evolved stars. In addition,
measurements of stellar lithium abundance, and spectroscopically derived metallicity, can provide
additional constraints on age and help refine detections of grand minimum analogs in solar-type stars. At
the same time, some evidence suggests that instantaneous Ca, H, and K flux measurements alone may be
unsuitable for detecting grand minimum analog candidates: at least one plausible candidate has been
identified in time series data including a flat activity cycle but with chromospheric activity greater than
present-day solar activity. Based on the most recent studies, an estimate emerges in the range of 5 to 6
percent for the fraction of the Sun's lifetime spent in a low-activity and reduced-luminosity state
analogous to the Maunder Minimum.
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