Oppenheimer also works on ultracool white dwarfs, the end states of 99% of stars, including the Sun, their role in comprising the baryonic dark matter, as well as coronagraphy, the art of seeing faint celestial objects next to bright ones. Oppenheimer has served on numerous NASA advisory committees including the TPF Science and Technology Definition Team, The NASA Astrophysics Senior review for 2014, 2016 (Chair), and 2019, as well as various NSF and NRC committees. Oppenheimer has been a member of NASA's Exoplanet Technology Assessment Committee since 2015.