The Chromospheric Emission--Age Relation for Stars of the Lower Main Sequence and Its Implications for the Star Formation Rate

Abstract

An attempt is made to formulate the relationship between age and chromospheric emission (CE) in late-type dwarf stars. Evidence is reviewed that a deterministic relationship of this type actually exists, and that for stars of known age, either a power-law relation or a curve corresponding to a constant star formation rate fits equally well. Further observations should be able to demonstrate either that there is a real excess of young stars near the sun or that the evolution of CE for a low-mass star goes through a slow initial decline, a rapid decline at intermediate ages, and finally a slow decline for old stars like the sun.