Trends in team evolution in astronomy from 1961 to 2010. (Left) Fifty-year trend of parameters characterizing the three components of the distribution, derived from a functional fit (Eq. 1). The characteristic size (i.e., Poisson rate) of standard core teams has been rising throughout this period, whereas that of “core +1” teams has remained constant in the last two decades. The power-law slope has been getting shallower, i.e., the significance of the power-law component has been increasing. (Center) Fraction of articles produced by different modes of authorship (team types): standard core , “core +1” , and extended . (Right) Trends in the mean team size, overall and by team type (both types of core teams, , and extended teams, ). The increase in the overall mean team size in astronomy is primarily the result of the rapid growth of power-law (extended) teams.