New Windows into the Substellar Mass Function

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This project is studying the formation of brown dwarfs by characterizing the initial mass distribution function of substellar objects. In order to understand the properties of the substellar population and to test theories of brown dwarf and star formation, two fundamental questions are being addressed: (1) what is the lowest mass object which can form in isolation, and (2) how does the substellar initial mass distribution vary with environment? Two spectrophotometric surveys are tailored to these questions on the basis of the unique spectral characteristics of substellar objects. The surveys look for the presence of methane absorption, typical of young brown dwarfs of 0.2 Jupiter masses, and for water absorption, present in the infrared spectra of all young brown dwarfs, and they take advantage of a new generation of wide-field infrared cameras with an unprecedented combination of sensitivity and field of view. Thus the substellar initial mass function is determined to much lower masses and over a much wider range of environments compared to previous work. The program will also produce a very populous sample of young brown dwarfs amenable for follow-up studies.