The Initial Mass Function of Low‐Mass Stars and Brown Dwarfs in Taurus

By combining deep optical imaging and infrared spectroscopy with data from the Two-Micron All-Sky Survey (2MASS) and from previous studies (e.g., Briceño et al.), I have measured the initial mass function (IMF) for a reddening-limited sample in four fields in the Taurus star-forming region. This IMF is representative of the young populations within these fields for masses above 0.02 M ☉ . Relative to the similarly derived IMF for the Trapezium Cluster (Luhman et al.), the IMF for Taurus exhibits a modest deficit of stars above 1 solar mass (i.e., steeper slope), the same turnover mass (~0.8 M ☉ ), and a significant deficit of brown dwarfs. If the IMF in Taurus were the same as that in the Trapezium, 12.8 ± 1.8 brown dwarfs (>0.02 M ☉ ) are expected in these Taurus fields where only one brown dwarf candidate is found. These results are used to test theories of the IMF.