An Etymological Dictionary of Astronomy and Astrophysics
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Star formation rate per unit → mass. More specifically, the → star formation rate in a galaxy divided by the → stellar mass of the galaxy. Observations of galaxies over a wide range of → redshifts suggest that the slope of the SFR-M_* relation is about unity, which implies that their sSFR does not depend strongly on stellar mass. Specific star formation rates increase out to z ~ 2 and are constant, or perhaps slowly increasing, from z = 2 out to z = 6, though with a large scatter, sSFR ~ 2-10 Gyr^-1 (Lehnert et al., 2015, A&A 577, A112, and references therein).

→ specific; → star; → formation; → rate.

The rate at which a molecular cloud or a galaxy is currently converting gas into stars. It is given by the ratio of the number of stars to the star formation time-scale.

→ star formation; → rate.