Poster Abstracts

Name/Affiliation:  Adam Schneider (University of Toledo)

Title:  Investigating the T/Y Boundary with HST/WFC3

The coolest brown dwarfs are indispensable touchstones for ultracool model atmospheres and are a vital component of the volume-limited sample of stars and brown dwarfs in the solar neighborhood. In the last few years, the Wide-field Infrared Survey Explorer (WISE) has uncovered hundreds of nearby cool brown dwarfs, including members of the new Y spectral class. Using the Wide Field Camera 3 (WFC3) aboard the Hubble Space Telescope (HST), we have extended the spectral coverage for a significant sample of the known late-type T and Y dwarfs to include the Y, J, and H bands. Here I present our complete sample of late type dwarfs for which we have obtained HST grism observations (23 total). The increased wavelength coverage allows us to 1) search for spectroscopic features predicted to emerge at low effective temperatures (e.g. ammonia bands), 2) construct a smooth spectral sequence across the T/Y boundary, 3) derive improved estimates of the the atmospheric properties of the brown dwarfs, and 4) begin to place tighter constraints on the field mass function.